Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
DETAILED OFFICE ACTION
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 2024-09-10, 2024-11-14 and 2025-01-31 in compliance with the provisions of 37 CFR 1.97 has been considered by the examiner and made of record in the application file.
Claim Status
Claims 1- 20 are pending in this application and are under examination in this Office Action. No claims have been allowed.
Claim Rejections - 35 USC § 112(b)
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION. —The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claim 13 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor, or for pre-AIA the applicant regards as the invention.
Regarding claim 13,
the claim recites “... modulating the first signal light using the second subcarrier” and then ends, without completing the limitation (the claim text stops after “second subcarrier” and proceeds to claim 14). As written, claim 13 is incomplete and therefore indefinite. Additionally, “the second subcarrier” does not clearly identify the intended structure (e.g., “the second subcarrier signal” of claim 11).
Claim Rejections – 35 U.S.C. § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for the obviousness rejections set forth in this Office Action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
As reiterated by the Supreme Court in KSR, and as set forth in MPEP 2141 (R-01.2024), II, the factual inquiries of Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), applied for establishing a background for determining obviousness under 35 U.S.C. §103, are summarized as follows:
Determining the scope and content of the prior art;
Ascertaining the differences between the prior art and the claims at issue;
Resolving the level of ordinary skill in the pertinent art; and
Considering objective evidence indicative of obviousness or non-obviousness, if present.
This application currently names joint inventors. In considering patentability of the claims, the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 C.F.R. § 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. § 102(b)(2)(C) for any potential 35 U.S.C. § 102(a)(2) prior art against the later invention.
Claims 1, 3 ,5 ,11 ,13 and 15 are rejected under 35 U.S.C. §103 as being unpatentable over Way (US20050286908A1) in view of Tanaka et al. (US20020149826A1).
Claim 1
Way teaches using electronic signal mixers to mix an encoded/baseband signal with a local oscillator signal to produce a modulation control signal “First modulation processing / mixers generating a modulation-control (subcarrier) signal” “[0010] In yet another example, a device is described to include a plurality of electronic duobinary signal modulators to respectively receive and modulate input binary signals and to output duobinary encoded signals, and a plurality of local oscillators to produce a plurality of local oscillator Signals corresponding to the electronic duobinary Signal modulators, respectively. This device also includes a plurality of electronic Signal mixers each of which is coupled to mix a duobinary encoded Signal with a local oscillator Signal from a corresponding local oscillator to produce a modulation control Signal. An optical Single Sideband modulator is further included to receive an input CW beam at an optical carrier frequency and to modulate the beam in response to the modulation control Signals from the electronic Signal mixers to produce an optical output comprising the optical carrier, optical Single Sideband Subcarriers at frequencies different from the optical carrier. [0011] These and other examples, implementations, and their applications and operations are described in greater detail in the attached drawings, the detailed description and the claims……… [0025] The transmitter 110 includes two or more duobinary modulators 111A and 11B for modulating input binary data channels to produce duobinary encoded Signals. Each duobinary encodes signal is then Sent into a respective analog signal mixer (e.g., 113A or 113B) to mix with a local oscillator Signal to produce a modulation control Signal………” [Way, ¶ [0010], ¶ [0011], ¶ [0025]].
Way teaches an optical single sideband modulator that receives an input CW beam at an optical carrier frequency and produces an optical output comprising the optical carrier and optical single-sideband subcarriers at frequencies different from the optical carrier, “Optical single-sideband modulator receiving a CW optical carrier and producing an optical output with the carrier and single-sideband subcarriers at frequencies different from the carrier” “…………...a device is described to include a plurality of electronic duobinary signal modulators to respectively receive and modulate input binary signals and to output duobinary encoded signals, and a plurality of local oscillators to produce a plurality of local oscillator Signals corresponding to the electronic duobinary Signal modulators, respectively. This device also includes a plurality of electronic Signal mixers each of which is coupled to mix a duobinary encoded Signal with a local oscillator Signal from a corresponding local oscillator to produce a modulation control Signal. An optical Single Sideband modulator is further included to receive an input CW beam at an optical carrier frequency and to modulate the beam in response to the modulation control Signals from the electronic Signal mixers to produce an optical output comprising the optical carrier, optical Single Sideband Subcarriers at frequencies different from the optical carrier…………….” [Way, ¶ [0010]]
Way further teaches producing an optical output beam comprising optical subcarriers at optical subcarrier frequencies different from the optical carrier frequency, “……...14. A method, comprising: using a first analog Signal mixer to mix a first duobinary Signal which represents a first data channel Signal and a first local oscillator Signal at a first local oscillator frequency to produce a first modulation control Signal; using a Second analog signal mixer to mix a Second duobinary signal which represents a Second data channel Signal and a Second local oscillator Signal at a second local oscillator frequency different from the first local oscillator frequency to produce a Second modulation control Signal; and applying the first and Second modulation control signals to modulate a CW laser beam at an optical carrier frequency to produce an optical output beam which comprises optical Subcarriers at optical Subcarrier frequencies different from the optical carrier frequency to carry to carry the first and the second data channels……….” [Way, Claim 14].
Additionally, Way teaches that the mixer output signal can be used to modulate a CW optical carrier beam “Second modulation processing / using the mixer output to modulate a CW optical carrier beam”, “………… [0027] FIG. 2 illustrates the operation of each analog mixer 113A or 113B. FIG. 2A shows an example of the transfer function of an analog microwave mixer (the mixer 113A or 113B). Note that the transfer function has two phase regions with a phase shift of 180 degrees (t). The three-level duobinary signal received by the mixer is shown in FIG.2B. The operation of the transfer function in FIG. 2A on the duobinary signal in FIG. 2B produces the mixer output signal shown in FIG. 2C where signal with two intensity levels: “mark” and "space' States. Due to the phase change in the transfer function of the analog mixer, the “mark” States can have one of two phase values, 0 and TL, corresponding to the logic states “1” and “-1” of the duobinary encoded Signal. This mixer output Signal can be used to modulate a CW optical carrier beam. [0028] The subcarrier multiplexed (SCM) duobinary modulation technique shown in FIG. 1 uses the 3-level duobinary Signal to directly drive a microwave mixer whose output voltage-versus-bias Voltage transfer function is similar to the Sinusoidal power-bias Voltage transfer function of an optical Mach-Zehnder modulator. The amplitude and phase of marks and Spaces at the output of the microwave mixer are shown in FIG. 2C where each pulse waveform is Superimposed on a BPSK microwave subcarrier. A typical microwave spectrum at the output of a duobinary Subcarrier is shown in FIG. 2D, in which the microwave Subcarrier frequency is at 14.7GHZ. This microwave subcarrier is then applied to amplitude-modulate an optical Mach-Zehnder modulator. Therefore, to a certain extent, the present modulation method effectuates a microwave-PSK/AM modulation. The demodulation is carried out by using an optical filter to extract the microwave-PSK/AM signal and sent directly to a baseband optical receiver as illustrated by the receiver 133 in FIG. 1………” [Way, ¶ [0027], ¶ [0028]].
However, within analogous art, Tanaka teaches an optical carrier that is branched into separate paths, amplitude-modulated with a phase-shifted version of the modulation signal, and then combined to form an optical single-sideband modulated signal, “[0001] ……….an optical single Sideband modulated Signal generator using a phase shifting method and, more particularly, to an optical Single-sideband modulated Signal generator which effectively Suppresses the upper or lower Sideband of an optical double-Sideband Signal, generated by amplitude-modulation of an optical Signal, to derive therefrom an optical Single-sideband modulated Signal. [0002] In this kind of technical field, it is conventional to use such a system as shown in FIG. 21, wherein an electric modulation signal 100 for the amplitude-modulation of an optical signal is phase-shifted by a 90° phase shifter 101 in an electric Signal Stage, then the original modulation signal 100 and the phase-shifted modulation signal 102 are used to amplitude-modulated optical Signals in Separate optical amplitude modulators 103 and 104, and the thus amplitude modulated optical signals are combined by a combined 105 into an optical Single-sideband modulated Signal 106. Inci dentally, an optical carrier 107 is branched by a two-output waveguide branching unit 108 into a first waveguide path 109 and a second waveguide path 110. The optical carrier 107 branched to the first waveguide path 109 is applied via an optical 90 phase shifter 111 to the optical amplitude modulator 104. The optical carrier 107 branched to the second waveguide path 110 is fed directly to the optical amplitude modulator 103………...” [Tanaka, ¶ [0001], ¶ [0002]].
Way expressly discloses a practical subcarrier-multiplexed optical transmitter in which a mixer output drives an optical modulator to create an optical carrier and a separated sideband component. Tanaka et al. provides an established optical single-sideband (OSSB) modulator architecture (branching an optical carrier into separate paths, applying a 90° phase shift, amplitude modulation, and combining) that a POSITA would have recognized as an obvious implementation choice for Way’s OSSB modulator to ensure robust, predictable sideband suppression across wideband modulation signals. Using Tanaka’s OSSB modulator structure with Way’s SCM transmitter predictably provides spectral partitioning between the carrier component and the subcarrier sideband component, enabling downstream separation, reduced interference, and improved dispersion tolerance, while using standard RF mixers and electro-optic modulators. Accordingly, the claimed arrangement would have been an obvious implementation of known, well-understood optical modulation and transmission techniques as taught by Way and Tanaka.
Claim 3
With respect to claim 3, all limitations of claim 1 are taught by Way and Tanaka except wherein claim 3 additionally requires that the second modulation comprises modulating the first signal light using the second subcarrier signal. However, within analogous art, Way teaches that the second modulation processing comprises modulating the first signal light (CW optical carrier) using the mixed subcarrier control signal.
Way also teaches that the mixer output can be used to modulate a CW optical carrier beam (second modulation processing), “……… [0027] ………...where signal with two intensity levels: “mark” and "space' States. Due to the phase change in the transfer function of the analog mixer, the “mark” States can have one of two phase values, 0 and TL, corresponding to the logic states “1” and “-1” of the duobinary encoded Signal. This mixer output Signal can be used to modulate a CW optical carrier beam. [0028] The subcarrier multiplexed (SCM) duobinary modulation technique shown in FIG. 1 uses the 3-level duobinary Signal to directly drive a microwave mixer whose output voltage-versus-bias Voltage transfer function is similar to the Sinusoidal power-bias Voltage transfer function of an optical Mach-Zehnder modulator. The amplitude and phase of marks and Spaces at the output of the microwave………” [Way, ¶ [0027], [0028]].
Way further teaches producing an optical output beam including an optical carrier and optical subcarriers/sideband components at optical frequencies different from the optical carrier, “a plurality of electronic signal mixers each of which is coupled to mix a duobinary encoded signal with a local oscillator signal … to produce a modulation control signal. An optical single sideband modulator … receive an input CW beam at an optical carrier frequency and … produce an optical output comprising the optical carrier, optical single sideband subcarriers at frequencies different from the optical carrier.” [Way, ¶ [0010]].
“Produce an optical output beam which comprises optical subcarriers at optical subcarrier frequencies different from the optical carrier frequency …” [Way, claim 14].
A person of ordinary skill in the art (POSITA) would implement the second modulation by directly modulating the CW optical carrier using the mixer-generated subcarrier waveform because this is a conventional and reliable way to transfer an RF/subcarrier signal onto an optical carrier. This approach leverages commercially available electro-optic modulators and established RF drive practices, reducing implementation risk while providing a predictable optical spectrum containing the desired carrier and sideband components. It also preserves the subcarrier information in a form suitable for coherent or heterodyne reception and for subsequent filtering/demodulation. Accordingly, the claim 3 limitation reflects a straightforward application of known electro-optic modulation techniques taught by Way.
Claim 5
With respect to claim 5, all limitations of claim 1 are taught by Way and Tanaka except wherein claim 5 additionally requires that the modulator comprises a frequency mixer configured to perform the first modulation processing. However, within analogous art, Way teaches that the modulator comprises a frequency mixer configured to perform the first modulation processing.
Further, Way teaches implementing the first modulation processing using electronic signal mixers to mix a baseband/encoded signal with a local oscillator to generate a modulation-control (subcarrier) signal, and further teaches an optical single-sideband modulator that produces an optical output comprising an optical carrier and single-sideband subcarriers at frequencies different from the carrier, “a plurality of electronic signal mixers each of which is coupled to mix a duobinary encoded signal with a local oscillator signal … to produce a modulation control signal. An optical single sideband modulator … receive an input CW beam at an optical carrier frequency and … produce an optical output comprising the optical carrier, optical single sideband subcarriers at frequencies different from the optical carrier.” [Way, ¶ [0011]].
Way also teaches that the mixer output can be used to modulate a CW optical carrier beam (second modulation processing), “the operation of the transfer function … produces the mixer output signal … where signal with two intensity levels … This mixer output signal can be used to modulate a CW optical carrier beam.” [Way, ¶ [0028]]
A person of ordinary skill in the art (POSITA) would include a frequency mixer in the modulator because mixers are standard RF components for translating and combining signals to form a desired subcarrier waveform, including imposing code/data onto an RF tone. Mixer-based subcarrier generation reduces implementation complexity by allowing baseband or low-rate coding to be shifted to an RF center frequency without requiring wideband arbitrary waveform generation. Way demonstrates that such mixer outputs are directly usable to drive optical modulation, confirming feasibility and expected performance. Thus, the claim 5 limitation is an obvious implementation detail using well-known RF circuitry.
Claim 11
Way teaches using electronic signal mixers to mix an encoded/baseband signal with a local oscillator signal to produce a modulation control signal “First modulation processing / mixers generating a modulation-control (subcarrier) signal”, “a plurality of electronic signal mixers each of which is coupled to mix a duobinary encoded signal with a local oscillator signal … to produce a modulation control signal.” [Way, ¶ [0011]].
Way further teaches an optical single sideband modulator that receives an input CW beam at an optical carrier frequency and produces an optical output comprising the optical carrier and optical single-sideband subcarriers at frequencies different from the optical carrier “Optical single-sideband modulator receiving a CW optical carrier and producing an optical output with the carrier and single-sideband subcarriers at frequencies different from the carrier”, “An optical single sideband modulator … receive an input CW beam at an optical carrier frequency and … produce an optical output comprising the optical carrier, optical single sideband subcarriers at frequencies different from the optical carrier.” [Way, ¶ [0011]].
Way also teaches producing an optical output beam comprising optical subcarriers at optical subcarrier frequencies different from the optical carrier frequency “……...14. A method, comprising: using a first analog Signal mixer to mix a first duobinary Signal which represents a first data channel Signal and a first local oscillator Signal at a first local oscillator frequency to produce a first modulation control Signal; using a Second analog signal mixer to mix a Second duobinary signal which represents a Second data channel Signal and a Second local oscillator Signal at a second local oscillator frequency different from the first local oscillator frequency to produce a Second modulation control Signal; and applying the first and Second modulation control signals to modulate a CW laser beam at an optical carrier frequency to produce an optical output beam which comprises optical Subcarriers at optical Subcarrier frequencies different from the optical carrier frequency to carry to carry the first and the second data channels……….” [Way, Claim 14].
Further, Way teaches that the mixer output signal can be used to modulate a CW optical carrier beam “Second modulation processing / using the mixer output to modulate a CW optical carrier beam”, “This mixer output signal can be used to modulate a CW optical carrier beam.” [Way, ¶ [0028]].
However within analogous art, Tanaka teaches an optical carrier that is branched into separate paths, amplitude-modulated with a phase-shifted version of the modulation signal, and then combined to form an optical single-sideband modulated signal, as follows: “an electric modulation signal … is phase-shifted by a 90° phase shifter … the original modulation signal and the phase-shifted modulation signal … amplitude-modulated … and … combined … into an optical single-sideband modulated signal … [and] an optical carrier … is branched … into a first waveguide path and a second waveguide path … [and] combined … into an optical single-sideband modulated signal.” [Tanaka, ¶ [0002]].
Way expressly discloses a practical subcarrier-multiplexed optical transmitter in which a mixer output drives an optical modulator to create an optical carrier and a separated sideband component. Tanaka provides an established optical single-sideband (OSSB) modulator architecture (branching an optical carrier into separate paths, applying a 90° phase shift, amplitude modulation, and combining) that a POSITA would have recognized as an obvious implementation choice for Way’s OSSB modulator to ensure robust, predictable sideband suppression across wideband modulation signals. Using Tanaka’s OSSB modulator structure with Way’s SCM transmitter predictably provides spectral partitioning between the carrier component and the subcarrier sideband component, enabling downstream separation, reduced interference, and improved dispersion tolerance, while using standard RF mixers and electro-optic modulators. Accordingly, the claimed arrangement would have been an obvious implementation of known, well-understood optical modulation and transmission techniques as taught by Way and Tanaka.
Claim 13
With respect to claim 13, all limitations of claim 11 are taught by Way and Tanaka except wherein claim 13 additionally requires that the second modulation comprises modulating the first signal light using the second subcarrier. However, within analogous art Way teaches modulating a CW optical carrier beam using the mixer-generated subcarrier control signal.
Way also teaches that the mixer output can be used to modulate a CW optical carrier beam (second modulation processing), “the operation of the transfer function … produces the mixer output signal … where signal with two intensity levels … This mixer output signal can be used to modulate a CW optical carrier beam.” [Way, ¶ [0028]].
A person of ordinary skill in the art (POSITA) would implement the second modulation by directly modulating the CW optical carrier using the mixer-generated subcarrier waveform because this is a conventional and reliable way to transfer an RF/subcarrier signal onto an optical carrier. This approach leverages commercially available electro-optic modulators and established RF drive practices, reducing implementation risk while providing a predictable optical spectrum containing the desired carrier and sideband components. It also preserves the subcarrier information in a form suitable for coherent or heterodyne reception and for subsequent filtering/demodulation. Accordingly, the claim 13 limitation reflects a straightforward application of known electro-optic modulation techniques taught by Way.
Claim 15
With respect to claim 15, all limitations of claim 11 are taught by Way and Tanaka except wherein claim 15 additionally requires the first modulation processing comprises frequency mixing. However, within analogous art Way teaches using a frequency mixer to generate the subcarrier modulation control signal, as set forth above.
Way further teaches implementing the first modulation processing using electronic signal mixers to mix a baseband/encoded signal with a local oscillator to generate a modulation-control (subcarrier) signal, and further teaches an optical single-sideband modulator that produces an optical output comprising an optical carrier and single-sideband subcarriers at frequencies different from the carrier, “a plurality of electronic signal mixers each of which is coupled to mix a duobinary encoded signal with a local oscillator signal … to produce a modulation control signal. An optical single sideband modulator … receive an input CW beam at an optical carrier frequency and … produce an optical output comprising the optical carrier, optical single sideband subcarriers at frequencies different from the optical carrier.” [Way, ¶ [0011]].
A person of ordinary skill in the art (POSITA) would include a frequency mixer in the modulator because mixers are standard RF components for translating and combining signals to form a desired subcarrier waveform, including imposing code/data onto an RF tone. Mixer-based subcarrier generation reduces implementation complexity by allowing baseband or low-rate coding to be shifted to an RF center frequency without requiring wideband arbitrary waveform generation. Way demonstrates that such mixer outputs are directly usable to drive optical modulation, confirming feasibility and expected performance. Thus, the claim 15 limitation is an obvious implementation detail using well-known RF circuitry.
Claims 2, 6, 7, 8, 12, 16, 17 and 18 are rejected under 35 U.S.C. §103 as being unpatentable over Way in view of Tanaka et al. and Xu et al. (Photonics 2021).
Claim 2
With respect to claim 2, all limitations of claim 1 are taught by Way and Tanaka, except wherein claim 2 additionally requires that the first modulation processing comprises phase modulation processing using a phase-coded signal.
Way does not expressly teach phase-coding/phase modulation of the subcarrier using a PRBS (or M-sequence). However, within analogous coherent ranging art, Xu teach phase-coded subcarrier modulation using a PRBS, “………...Principle of Coherent RMCW LiDARs, 2.1. Basic Concepts of RMCW LiDARs An RMCW LiDAR estimates the time delay of backscattered light by calculating the correlation between the reconstructed PRBS and the original PRBS. Typically, the PRBS is used to phase-code the Lightwave in a coherent RMCW LiDAR [23]. The light backscattered from the target is given as Ep(t) = E0 exp {i (wc + wd) (t − t) + b cos[qn(t − t)]} (1) in which b is the modulation factor, t is the time delay of backscattered light, wc and wd are the angular frequency of the optical carrier and the optical DFS. qn(t) is the PRBS which is shown in the top of Figure 1. To achieve maximum modulation depth, the value of qn(t)is set to 0 or _. Using coherent detection, the backscattered light beats with an LO in a BPD. From the beat signal, the PRBS can be reconstructed as Sp(t) = sin {b cos [qn (t − t)] + wd (t − t) + j]} (2) ……………” [Xu, p.3] “……… the performance of the proposed coherent RMCW LiDAR is analyzed by numeric simulations. The schematic diagram of the coherent RMCW LiDAR is shown in Figure 4. A 1550-nm continuous Lightwave is split into two parts. One part of the light is used as the LO and the other part is modulated by a phase-coded subcarrier in a Mach- Zehnder modulator. In the receiver, a BPD is used to detect the beat signal between the backscattered light and the LO. The power of the transmitted Lightwave and the LO is 100 mW and 2 mW. The modulation signal is a 1.25-GHz RF signal phase-coded with a 500-Mbits/s 12-bit M-sequence. The bandwidth, responsivity, transimpedance gain, and minimum noise equivalent power of the BPD is 1.6 GHz, 0.85 A/W, 16×103 V/A, and 9.3 pW/Hz1/2, respectively. The sampling rate of the analog-to-digital converter (ADC) is 5 GSa/s. Although the simulation is not as comprehensive as that given in Ref. [23], it clearly estimates the impacts of internal reflection and optical DFS……….” [Xu, p.6].
A person of ordinary skill in the art (POSITA) would have been motivated to phase-code (phase-modulate) the subcarrier in Way’s mixer-generated subcarrier drive because phase coding is a well-known technique for adding processing gain and improving detectability/robustness when a receiver performs correlation or matched filtering. Using a PRBS/M-sequence phase code allows the system to retain a constant-envelope RF tone while embedding a known code sequence, which improves resilience to amplitude noise and nonlinearities in RF and electro-optic components. In addition, phase-coded subcarriers support straightforward frequency-offset/Doppler compensation prior to correlation (as Xu explains), which is desirable whenever optical frequency shifts can degrade code alignment. Integrating a PRBS-based phase-coding stage ahead of or within Way’s mixer chain is a predictable substitution of one known modulation format for another, using standard RF/DSP building blocks, with a reasonable expectation of success.
Claim 6
With respect to claim 6, all limitations of claim 1 are taught by Way and Tanaka, except wherein claim 6 additionally requires beat-frequency processing between a second signal-light channel and a reflected signal light to obtain a Doppler frequency shift (DFS) signal and a third subcarrier signal, wherein the first and second signal-light channels are obtained by beam splitting a common laser output, and wherein the DFS band and third-subcarrier band do not overlap.
Way does not expressly teach coherent beat-frequency processing of reflected light for DFS extraction. However, within analogous coherent RMCW LiDAR art, Xu teach splitting a continuous laser into two channels (LO and modulated path) and using a balanced photodetector to obtain a beat signal having separable low-frequency (DFS) and high-frequency (coded-subcarrier) components, “……...the performance of the proposed coherent RMCW LiDAR is analyzed by numeric simulations. The schematic diagram of the coherent RMCW LiDAR is shown in Figure 4. A 1550-nm continuous light wave is split into two parts. One part of the light is used as the LO and the other part is modulated by a phase-coded subcarrier in a Mach- Zehnder modulator. In the receiver, a BPD is used to detect the beat signal between the backscattered light and the LO. The power of the transmitted Lightwave and the LO is 100 mW and 2 mW. The modulation signal is a 1.25-GHz RF signal phase-coded with a 500-Mbits/s 12-bit M-sequence. The bandwidth, responsivity, transimpedance gain, and minimum noise equivalent power of the BPD are 1.6 GHz, 0.85 A/W, 16×103 V/A, and 9.3 pW/Hz1/2, respectively. The sampling rate of the analog-to-digital converter (ADC) is 5 GSa/s. Although the simulation is not as comprehensive as that given in Ref. [23], it clearly estimates the impacts of internal reflection and optical DFS………” [Xu, p.6, Fig. 4]
PNG
media_image1.png
200
400
media_image1.png
Greyscale
Xu teach that coherent detection yields a beat signal having separable low-frequency (DFS) and high-frequency (coded-subcarrier) components, and that DFS from the low-frequency component is used to compensate the high-frequency component, “……...Since subcarrier modulation is used, the backscattered light consists of an optical carrier and optical sidebands. The phase-coded subcarrier is conveyed by the optical sidebands. A beat signal that consisted of a low-frequency signal and a high-frequency signal is generated, which can be respectively written as which are shown in the middle and bottom of Figure 2. The low-frequency signal is the beat signal between the backscattered optical carrier and the LO. On the other hand, the high-frequency signal is a delayed PRBS with a frequency offset, which is the beat signal of the backscattered optical sideband and the LO. The optical DFS is measured from the low-frequency signal and used to compensate for the frequency offset in the high-frequency signal……….” [Xu, p.5, Eqns. (11)-(12)]
PNG
media_image2.png
78
685
media_image2.png
Greyscale
Xu further teaches selecting the subcarrier much higher than DFS so filtering cleanly separates the two bands and enables compensation, “……A coherent RMCW LiDAR is built. To demonstrate the 3D imaging capability, a galvanometer scanning system is added behind the telescope to steer the laser beam. The other parts of the LiDAR are the same as Figure 4. The phase-coded subcarrier is generated by an arbitrary waveform generator (AWG, Tektronix AWG70001A). A 1550-nm Lightwave from a narrow line-width laser ((TeraXion PS-NLL)) is modulated by the phase-coded subcarrier in an MZM (Fujitsu FTM7938EZ). The modulated Lightwave is amplified to 100 mW and transmitted by a telescope with a 10-mm spot diameter. The backscattered light beats with a 2-mW local oscillator in a BPD (Thorlabs PDB480C-AC). The outputs of the BPD are recorded by an oscilloscope (Agilent, DSO9404) with a sampling rate of 5 GSa/s. The recorded signals are processed offline to extract the distance of targets. In addition, an optical spectrum analyzer (OSA, Yokogawa AQ6370D) is used to monitor the optical spectrum. Figure 7a shows the optical spectrum of the transmitted Lightwave, in which the subcarrier is a 1.25-GHz RF signal phase-coded by a 500-Mbit/s M-sequence. Since the optical carrier is suppressed in the MZM, most of the optical power is used for the optical sidebands which convey the phase-coded subcarrier. It is helpful to enhance the detection range. Figure 7b shows the beat signal between the backscattered light and the LO. An 85-MHz optical DFS is simulated by an acoustic-optic modulator (AOM), which is shown in the low-frequency region. The frequency of the subcarrier is much higher than the optical DFS so that the subcarrier can be readily separated by a filter. Finally, the optical DFS is individually measured from the low-frequency signal, which can be used to compensate for the phase-coded subcarrier in the high-frequency signal. An experiment is implemented to demonstrate the DFS mitigation in RMCW lidar, in which a 77-MHz optical DFS is simulated by the AOM and the length of a fiber spool is measured. Figure 8 shows the measurement results. The normalized correlation before Doppler compensation (blue line) only shows a peak at 0 m, which is caused by the internal reflection. It is impossible to extract the distance information due to the optical DFS. However, after Doppler compensation, the normalized correlation (red line) shows a peak at around 120 m. Meanwhile, the signal caused by internal reflection disappears. Therefore, the feasibility of the DFS mitigation is demonstrated………” [Xu, p.8].
Xu also teaches that coherent detection generates a beat signal having separable low-frequency and high-frequency components (Eqns. (11)-(12); Fig. 2), where the low-frequency component is the beat between the backscattered optical carrier and the LO (used to measure optical DFS), and the high-frequency component is the beat between the backscattered optical sideband and the LO (conveying the delayed PRBS/subcarrier) with a frequency offset. “... A beat signal that consisted of a low-frequency signal and a high-frequency signal is generated ... The optical DFS is measured from the low-frequency signal and used to compensate for the frequency offset in the high-frequency signal ...” [Xu, p.5, Eqns. (11)-(12)].
A person of ordinary skill in the art (POSITA) would have been motivated to combine Way’s OSSB/SCM optical transmitter architecture with Xu’s coherent beat-frequency receiver processing because both address subcarrier-based optical signaling, and Xu demonstrates that separating low-frequency DFS content from high-frequency coded-subcarrier content enables accurate DFS compensation and reliable correlation-based detection. Way provides a proven approach for generating and transmitting an optical carrier plus a separated subcarrier sideband using standard mixers and modulators; adopting that transmitter structure in a coherent ranging system predictably improves spectral control and facilitates downstream separation. Xu shows that a coherent receiver naturally produces a beat spectrum with distinct low-frequency and high-frequency regions and that the subcarrier frequency can be selected much higher than DFS to enable straightforward filtering. Combining these teachings is a predictable use of prior-art elements according to their established functions (subcarrier generation/transmission + coherent beat processing + filtering) with a reasonable expectation of success, yielding improved robustness and implement ability for DFS-mitigated detection.
Claim 7
With respect to claim 7, all limitations of claim 6 are taught by Way, Tanaka and Xu except wherein claim 7 additionally requires the beat frequency system comprises: a detector configured to perform the beat frequency processing; and a filter configured to perform filtering processing to obtain the Doppler frequency shift signal and the third subcarrier signal. However, within analogous art, Xu teaches that the beat-frequency system comprises a balanced photodetector and filtering/separation to obtain the DFS signal and the third-subcarrier signal.
Xu teach that coherent detection yields a beat signal having separable low-frequency (DFS) and high-frequency (coded-subcarrier) components, and that DFS from the low-frequency component is used to compensate the high-frequency component, “Since subcarrier modulation is used, the backscattered light consists of an optical carrier and optical sidebands. … A beat signal that consisted of a low-frequency signal and a high-frequency signal is generated … The low-frequency signal is the beat signal between the backscattered optical carrier and the LO … the high-frequency signal … is the beat signal of the backscattered optical sideband and the LO. The optical DFS is measured from the low-frequency signal and used to compensate for the frequency offset in the high-frequency signal.” [Xu, p.5, Eqns. (11)-(12)].
Xu further teaches selecting the subcarrier much higher than DFS so filtering cleanly separates the two bands and enables compensation, “The frequency of the subcarrier is much higher than the optical DFS so that the subcarrier can be readily separated by a filter. Finally, the optical DFS is individually measured from the low-frequency signal, which can be used to compensate for the phase-coded subcarrier in the high-frequency signal.” [Xu, p.8].
A person of ordinary skill in the art (POSITA) would employ a balanced photodetector for beat-frequency detection because balanced detection is a standard coherent-optics technique that improves SNR and suppresses common-mode noise (e.g., intensity noise), yielding more accurate DFS estimation and subcarrier recovery. Further, providing filtering to separate the DFS band from the subcarrier band is a routine and expected design step when the beat spectrum contains components at widely separated frequencies, as Xu explains. This separation enables independent processing paths (DFS measurement/compensation and coded-subcarrier extraction/correlation) without mutual interference. Accordingly, claim 7’s additional detector/filter structure would have been an obvious implementation taught by Xu within coherent beat-processing systems.
Claim 8
With respect to claim 8, all limitations of claim 6 are taught by Way, Tanaka and Xu except wherein claim 8 additionally requires the Doppler frequency shift signal is based on the second signal light and the single-frequency optical carrier signal in the reflected signal light, and wherein the third subcarrier signal is based on the second signal light and the optical sideband signal in the reflected signal light. However, within analogous art, Xu teaches that the backscattered/reflected light includes an optical carrier and optical sidebands (with the coded subcarrier conveyed by the sidebands), which corresponds to forming the DFS component from carrier beating and the subcarrier component from sideband beating.
“Since subcarrier modulation is used, the backscattered light consists of an optical carrier and optical sidebands. … A beat signal that consisted of a low-frequency signal and a high-frequency signal is generated … The low-frequency signal is the beat signal between the backscattered optical carrier and the LO … the high-frequency signal … is the beat signal of the backscattered optical sideband and the LO. The optical DFS is measured from the low-frequency signal and used to compensate for the frequency offset in the high-frequency signal.” [Xu, p.5, Eqns. (11)-(12)]
A person of ordinary skill in the art (POSITA) would recognize that, in subcarrier-modulated coherent systems, distinct beat components naturally arise from different optical spectral components (carrier vs. sidebands). Designing the receiver processing so that the DFS measurement primarily reflects the carrier-related low-frequency content while the coded-subcarrier measurement reflects the sideband-related higher-frequency content is a predictable and conventional interpretation of the coherent beat model. Xu expressly describes that the backscattered signal contains a carrier and sidebands and that the phase-coded subcarrier resides on the sidebands, confirming that this separation is an expected characteristic of the modulation format. Therefore, claim 8’s additional functional partitioning would have been obvious to a POSITA implementing coherent DFS mitigation and coded-subcarrier recovery.
Claim 12
With respect to claim 12, all limitations of claim 11 are taught by Way and Tanaka, except wherein claim 12 additionally requires phase-coding/phase modulation of the subcarrier using a PRBS (or M-sequence). However, within analogous art, Xu teach the phase-coded subcarrier modulation as set forth above. “The modulation signal is a 1.25-GHz RF signal phase-coded with a 500-Mbits/s 12-bit M-sequence. The bandwidth, responsivity, transimpedance gain, and minimum noise equivalent power of” [Xu, p.6]
“the value of θ n (t) is set to 0 or π. Using coherent detection, the backscattered light beats with an LO in a BPD.” [Xu, p.3]
A person of ordinary skill in the art (POSITA) would have been motivated to phase-code (phase-modulate) the subcarrier in Way’s mixer-generated subcarrier drive because phase coding is a well-known technique for adding processing gain and improving detectability/robustness when a receiver performs correlation or matched filtering. Using a PRBS/M-sequence phase code allows the system to retain a constant-envelope RF tone while embedding a known code sequence, which improves resilience to amplitude noise and nonlinearities in RF and electro-optic components. In addition, phase-coded subcarriers support straightforward frequency-offset/Doppler compensation prior to correlation (as Xu explains), which is desirable whenever optical frequency shifts can degrade code alignment. Integrating a PRBS-based phase-coding stage ahead of or within Way’s mixer chain is a predictable substitution of one known modulation format for another, using standard RF/DSP building blocks, with a reasonable expectation of success.
Claim 16
With respect to claim 16, all limitations of claim 11 are taught by Way and Tanaka, except wherein claim 16 additionally requires coherent beat-frequency processing between a split reference channel and reflected signal to obtain DFS and a third subcarrier, and to process them to obtain detection information. However, within analogous art, Xu teach splitting the laser into LO and modulated paths and obtaining a beat signal with separable DFS and coded-subcarrier content.
“A 1550-nm continuous Lightwave is split into two parts. One part of the light is used as the LO and the other part is modulated by a phase-coded subcarrier in a Mach-Zehnder modulator. In the receiver, a BPD is used to detect the beat signal between the backscattered light and the LO.” [Xu, Fig. 4, p.6].
Xu further teach that coherent detection yields a beat signal having separable low-frequency (DFS) and high-frequency (coded-subcarrier) components, and that DFS from the low-frequency component is used to compensate the high-frequency component “Since subcarrier modulation is used, the backscattered light consists of an optical carrier and optical sidebands. … A beat signal that consisted of a low-frequency signal and a high-frequency signal is generated … The low-frequency signal is the beat signal between the backscattered optical carrier and the LO … the high-frequency signal … is the beat signal of the backscattered optical sideband and the LO. The optical DFS is measured from the low-frequency signal and used to compensate for the frequency offset in the high-frequency signal.” [Xu, p.5, Eqns. (11)-(12)]
Xu also teaches selecting the subcarrier much higher than DFS so filtering cleanly separates the two bands and enables compensation, “The frequency of the subcarrier is much higher than the optical DFS so that the subcarrier can be readily separated by a filter. Finally, the optical DFS is individually measured from the low-frequency signal, which can be used to compensate for the phase-coded subcarrier in the high-frequency signal.” [Xu, p.8]
A person of ordinary skill in the art (POSITA) would have been motivated to combine Way’s OSSB/SCM optical transmitter architecture with Xu’s coherent beat-frequency receiver processing because both address subcarrier-based optical signaling, and Xu demonstrates that separating low-frequency DFS content from high-frequency coded-subcarrier content enables accurate DFS compensation and reliable correlation-based detection. Way provides a proven approach for generating and transmitting an optical carrier plus a separated subcarrier sideband using standard mixers and modulators; adopting that transmitter structure in a coherent ranging system predictably improves spectral control and facilitates downstream separation. Xu shows that a coherent receiver naturally produces a beat spectrum with distinct low-frequency and high-frequency regions and that the subcarrier frequency can be selected much higher than DFS to enable straightforward filtering. Combining these teachings is a predictable use of prior-art elements according to their established functions (subcarrier generation/transmission + coherent beat processing + filtering) with a reasonable expectation of success, yielding improved robustness and implement ability for DFS-mitigated detection.
Claim 17
With respect to claim 17, all limitations of claim 16 are taught by Way, Tanaka and Xu, except wherein claim 17 additionally requires the beat frequency processing comprises: performing, using the detector, the beat frequency processing; and performing filtering processing to obtain the Doppler frequency shift signal and the third subcarrier signal including using a balanced photodetector and filtering/separation to obtain DFS and the third subcarrier. However, within analogous art, Xu teach that coherent detection yields a beat signal having separable low-frequency (DFS) and high-frequency (coded-subcarrier) components, and that DFS from the low-frequency component is used to compensate the high-frequency component, “Since subcarrier modulation is used, the backscattered light consists of an optical carrier and optical sidebands. … A beat signal that consisted of a low-frequency signal and a high-frequency signal is generated … The low-frequency signal is the beat signal between the backscattered optical carrier and the LO … the high-frequency signal … is the beat signal of the backscattered optical sideband and the LO. The optical DFS is measured from the low-frequency signal and used to compensate for the frequency offset in the high-frequency signal.” [Xu, p.5, Eqns. (11)-(12)]
A person of ordinary skill in the art (POSITA) would employ a balanced photodetector for beat-frequency detection because balanced detection is a standard coherent-optics technique that improves SNR and suppresses common-mode noise (e.g., intensity noise), yielding more accurate DFS estimation and subcarrier recovery. Further, providing filtering to separate the DFS band from the subcarrier band is a routine and expected design step when the beat spectrum contains components at widely separated frequencies, as Xu explains. This separation enables independent processing paths (DFS measurement/compensation and coded-subcarrier extraction/correlation) without mutual interference. Accordingly, claim 17’s additional detector/filter structure would have been an obvious implementation taught by Xu within coherent beat-processing systems.
Claim 18
With respect to claim 18, all limitations of claim 16 are taught by Way, Tanaka and Xu, except wherein claim 18 additionally the Doppler frequency shift signal is obtained based on the second signal light and the single-frequency optical carrier signal in the reflected signal light, and wherein the third subcarrier signal is obtained based on the second signal light and the optical sideband signal in the reflected signal light. However, within analogous art,
Xu teaches that the backscattered light includes a carrier and sidebands and that the coded subcarrier is conveyed by the sidebands, as set forth above “Since subcarrier modulation is used, the backscattered light consists of an optical carrier and optical sidebands. The phase-coded subcarrier is conveyed by the optical sidebands.” [Xu, p.5]
A person of ordinary skill in the art (POSITA) would recognize that, in subcarrier-modulated coherent systems, distinct beat components naturally arise from different optical spectral components (carrier vs. sidebands). Designing the receiver processing so that the DFS measurement primarily reflects the carrier-related low-frequency content while the coded-subcarrier measurement reflects the sideband-related higher-frequency content is a predictable and conventional interpretation of the coherent beat model. Xu expressly describes that the backscattered signal contains a carrier and sidebands and that the phase-coded subcarrier resides on the sidebands, confirming that this separation is an expected characteristic of the modulation format. Therefore, claim 18’s additional functional partitioning would have been obvious to a POSITA implementing coherent DFS mitigation and coded-subcarrier recovery.
Claims 4 and 14 are rejected under 35 U.S.C. §103 as being unpatentable over Way in view of Tanaka et al. and further in view of Monteiro et al. (US20070086788A1) and Kaneda (US20170350964A1).
Claim 4
With respect to claim 4, all limitations of claim 1 are taught by Way and Tanaka, except wherein claim 4 additionally requires that the frequency band of the optical carrier and the frequency band of the optical sideband do not overlap at all.
Way teaches producing an optical output comprising an optical carrier and single-sideband subcarriers at frequencies different from the optical carrier, which corresponds to complete non-overlap between the carrier band and the sideband band, “a plurality of electronic signal mixers each of which is coupled to mix a duobinary encoded signal with a local oscillator signal … to produce a modulation control signal. An optical single sideband modulator … receive an input CW beam at an optical carrier frequency and … produce an optical output comprising the optical carrier, optical single sideband subcarriers at frequencies different from the optical carrier.” [Way, ¶ [0011]].
“Produce an optical output beam which comprises optical subcarriers at optical subcarrier frequencies different from the optical carrier frequency …” [Way, claim 14].
However, within analogous art, Monteiro teach generating an optical single-sideband signal while keeping the carrier present (not suppressed), thereby supporting a spectrum including both a distinct carrier component and a distinct single-sideband component without relying on a sideband-suppression filter, “……... [0009] It is an object of the invention to provide a low-cost optical single sideband modulator without wavelength stability problems. [0010] According to the present invention the optical single sideband modulator includes an amplitude modulator and a semiconductor optical amplifier SOA), using a chirp effect to convert an amplitude modulated optical signal into a single sideband signal without the help of a filter for eliminating one of the sidebands. [0011] The optical single sideband generator can be easily adapted to different bit rates by controlling the power of a modulated optical signal, which is fed to the SOA, or the operating Voltage. [0012] The main advantage of the invention is that the carrier is not suppressed and no information loss according to detuning of a sideband suppression filter result in a loss of information……...” [Monteiro, ¶ ¶ [0009]- [0012]].
Additionally in an analogous art, Kaneda further corroborates using carrier-suppressed single-sideband modulation to achieve strict carrier/sideband spectral separation in coherent ranging/LiDAR systems, “…………...that includes a modulator – based probe - light generator and a coherent optical receiver. The probe - light generator uses tunable carrier - suppressed single sideband modulation to generate frequency - chirped optical pulses for the optical - probe beam directed at the target. The coherent optical receiver uses a homodyne detection scheme in which a split portion of the optical - probe beam is used as an optical local oscillator signal for detecting a corresponding optical beam reflected by the target. The resulting electrical RF signals generated by the receiver can be processed, e.g., using a disclosed signal - processing method, to determine one or both of the distance to the target and the velocity of the target ……….” [Kaneda, Abstract]
A person of ordinary skill in the art (POSITA) would be motivated to ensure complete (non-overlapping) spectral separation between the carrier component and the sideband component because such separation simplifies the design of optical/electrical filters, reduces leakage and crosstalk between processing branches, and improves robustness to component tolerances and drift. In practical SCM/OSSB systems, complete separation relaxes filter roll-off requirements and reduces intermodulation artifacts, thereby improving demodulation accuracy and system stability. Way’s explicit OSSB structure predictably achieves this objective by placing the subcarrier sideband at optical frequencies distinct from the carrier. Therefore, configuring the system such that the carrier and sideband bands do not overlap at all would have been an obvious optimization of the known OSSB modulation format for its known benefits.
Claim 14
With respect to claim 14, all limitations of claim 11 are taught by Way and Tanaka except wherein claim 14 additionally requires that the frequency band of the single-frequency optical carrier signal and the frequency band of the optical sideband signal do not overlap.
Way’s OSSB structure places the subcarrier sideband at optical frequencies different from the carrier, corresponding to non-overlapping carrier/sideband bands “ A device, comprising: a plurality of analog signal mixers to respectively produce a plurality of analog modulation control signals that respectively carry a plurality of data channels, each analog Signal mixer configured to receive and mix a data channel encoded as a duobinary encoded Signal and a local oscillator Signal at a local oscillator frequency different from local oscillator frequencies received by other analog signal mixers to produce a corresponding analog modulation control Signal; and an optical modulator to receive an input CW laser beam at an optical carrier frequency and to modulate the input CW laser beam in response to the analog modulation control Signals to produce an optical output beam which comprises a plurality of different optical Subcarriers at optical Subcarrier frequencies different from the optical carrier frequency and respectively related to the local oscillator frequencies of the local oscillator Signals, wherein each optical Subcarrier carries a baseband Signal comprising information of a corresponding data channel of the data channels So that the different optical Subcarriers carry baseband Signals corresponding to the plurality of data channels, respectively…….” [Way, claim 1].
However, within analogous art, Monteiro teach generating an optical single-sideband signal while keeping the carrier present (not suppressed), thereby supporting a spectrum including both a distinct carrier component and a distinct single-sideband component without relying on a sideband-suppression filter, “……... [0009] It is an object of the invention to provide a low-cost optical single sideband modulator without wavelength stability problems. [0010] According to the present invention the optical single sideband modulator includes an amplitude modulator and a semiconductor optical amplifier (SOA), using a chirp effect to convert an amplitude modulated optical signal into a single sideband signal without the help of a filter for eliminating one of the sidebands. [0011] The optical single sideband generator can be easily adapted to different bit rates by controlling the power of a modulated optical signal, which is fed to the SOA, or the operating Voltage. [0012] The main advantage of the invention is that the carrier is not suppressed and no information loss according to detuning of a sideband suppression filter result in a loss of information……...” [Monteiro, ¶ ¶ [0009]- [0012]].
Additionally in an analogous art, Kaneda further corroborates using carrier-suppressed single-sideband modulation to achieve strict carrier/sideband spectral separation in coherent ranging/LiDAR systems, “…………...that includes a modulator – based probe - light generator and a coherent optical receiver. The probe - light generator uses tunable carrier - suppressed single sideband modulation to generate frequency - chirped optical pulses for the optical - probe beam directed at the target. The coherent optical receiver uses a homodyne detection scheme in which a split portion of the optical - probe beam is used as an optical local oscillator signal for detecting a corresponding optical beam reflected by the target. The resulting electrical RF signals generated by the receiver can be processed, e.g., using a disclosed signal - processing method, to determine one or both of the distance to the target and the velocity of the target ……….” [Kaneda, Abstract]
A person of ordinary skill in the art (POSITA) would be motivated to ensure non-overlapping spectral separation between the carrier component and the sideband component because such separation simplifies optical/electrical filtering, improves robustness to dispersion and receiver leakage, and provides a predictable spectrum for coherent detection. Way already teaches an OSSB/SCM arrangement in which the sideband is placed at optical frequencies different from the carrier; Monteiro and Kaneda further confirm that OSSB modulation schemes intentionally maintain a distinct carrier component and a distinct single-sideband component. Accordingly, it would have been an obvious design choice to select the subcarrier offset and modulation bandwidth such that the carrier band and sideband band do not overlap, a predictable optimization yielding the claimed non-overlap.
Claims 9 and 19 are rejected under 35 U.S.C. §103 as being unpatentable over Way in view of Tanaka et al. and Xu et al. and further in view of Chao et al. (CN 105136175 A).
Claim 9
With respect to claim 9, all limitations of claim 7 are taught by Way, Tanaka and Xu except wherein claim 9 additionally requires that the filter comprises a first filter to obtain the DFS signal and a second filter to obtain the third subcarrier signal. within analogous art, Xu teaches that the DFS component (low-frequency beat) and the third-subcarrier component (high-frequency beat) are separable by filtering, but Xu does not expressly specify the exact filter blocks. However, within analogous coherent beat-processing circuitry, Shao teaches using dedicated band-pass and low-pass filtering blocks in the beat-signal demodulation chain.
Shao teaches a beat-signal demodulation chain including an electric bandpass filter, a low-noise amplifier, a power divider, a mixer, and a low-pass filter “The invention claims a self-mixing technique based on phase sensitive optical time domain reflectometry system. by the path detection and demodulation circuit is composed of two parts, an optical route in narrow line-width laser (1), optical coupler (2), an acousto-optic modulator (3), a pulse generator (4), circulator (5), optical fiber (6); the polarization controller (7); the circuit is composed of a power bandpass filter (10), low-noise amplifier (11), a power divider (12), a mixer (13), a low-pass filter(14), using self-mixing such simple structure not only can realize demodulation of the modulation signal, it also can avoid the frequency drift of the local optical signal caused by demodulation. Using the coherent phase sensitive optical time domain reflecting technology system of detecting way, frequency drift of the local light is a problem that must be considered. The invention well eliminates the local optical influence caused by frequency drift. The device works stably, it can more accurately measure the position and frequency of vibration in the plurality of measurements. [Shao, Abstract]
Shao further teaches that the balanced photodetector output is divided into two paths by a 50:50 power divider to produce two identical signals prior to mixing and low-pass filtering “……… A self-based phase sensitive optical time domain reflecting system of mixing technology, wherein the light path using the signal light and the local light for coherent demodulation, circuit by means of self-mixing demodulation signals; the two paths of signal using mixer mixing the external loading on the optical fiber signal demodulated, the specific structure is a narrow line-width laser (1) outputs the continuous light by an optical coupler (2) is divided into two paths, one path by the a custom-optic modulator (3) connected with the pulse generator (4) of modulation into the sensing optical fiber (6) by the circulator (5) is pulse light; the other path is connected with the coupler (8) through the polarization controller (7), back scattered light pulse light in optical fiber transmission process generated in the output from the other port via the circulator (5); the output of the scattered light and local light at the coupler (8) into a beam of light, then the balance detector (9) to beat, beat-frequency signal frequency determined by the frequency shift introduced by acousto-optic modulator (3), beat frequency signal after electric bandpass filter (10), a low-noise amplifier (11) amplifying filter, the electric signal output by the balance photodetector is divided into two paths, which is divided into two same signal divider(12) of the power dividing ratio is 50: 50, then demodulated by mixer (13), and finally after passing through the low-pass filter (14) by the data collecting card (15) collects and data processor (16) for processing………..” [Shao, claim 1].
A person of ordinary skill in the art (POSITA) would implement separate filters (e.g., band-pass/high-pass for the higher-frequency subcarrier branch and low-pass for the DFS branch) to enable simultaneous, optimized processing of each component with appropriate bandwidth and noise rejection. Using dedicated filters in separate branches is a standard signal-processing approach when two components occupy different spectral regions, because it improves isolation, allows independent gain/ADC scaling, and reduces mutual interference. Xu motivates this separation by emphasizing that the subcarrier frequency is much higher than DFS and can be separated by filtering; Shao provides a concrete circuit example employing band-pass filtering and low-pass filtering in a beat-signal processing chain. Accordingly, specifying a first filter for DFS and a second filter for the third-subcarrier is an obvious design choice that predictably improves performance and implement ability.
Claim 19
With respect to claim 19, all limitations of claim 17 are taught by Way, Tanaka and Xu, except wherein claim 19 additionally requires separate first and second filters for DFS and the third subcarrier. However, within analogous art, Shao teaches band-pass and low-pass filtering in a beat-signal processing chain.
Shao further teaches a beat-signal demodulation chain including an electric bandpass filter, a low-noise amplifier, a power divider, a mixer, and a low-pass filter “The invention claims a self-mixing technique based on phase sensitive optical time domain reflectometry system. by the path detection and demodulation circuit is composed of two parts, an optical route in narrow line-width laser (1), optical coupler (2), an acousto-optic modulator (3), a pulse generator (4), circulator (5), optical fiber (6); the polarization controller (7); the circuit is composed of a power bandpass filter (10), low-noise amplifier (11), a power divider (12), a mixer (13), a low-pass filter(14), using self-mixing such simple structure not only can realize demodulation of the modulation signal, it also can avoid the frequency drift of the local optical signal caused by demodulation. Using the coherent phase sensitive optical time domain reflecting technology system of detecting way, frequency drift of the local light is a problem that must be considered. The invention well eliminates the local optical influence caused by frequency drift. The device works stably, it can more accurately measure the position and frequency of vibration in the plurality of measurements. [Shao, Abstract]
Shao also teaches that the balanced photodetector output is divided into two paths by a 50:50 power divider to produce two identical signals prior to mixing and low-pass filtering “……… A self-based phase sensitive optical time domain reflecting system of mixing technology, wherein the light path using the signal light and the local light for coherent demodulation, circuit by means of self-mixing demodulation signals; the two paths of signal using mixer mixing the external loading on the optical fiber signal demodulated, the specific structure is a narrow line-width laser (1) outputs the continuous light by an optical coupler (2) is divided into two paths, one path by the a custom-optic modulator (3) connected with the pulse generator (4) of modulation into the sensing optical fiber (6) by the circulator (5) is pulse light; the other path is connected with the coupler (8) through the polarization controller (7), back scattered light pulse light in optical fiber transmission process generated in the output from the other port via the circulator (5); the output of the scattered light and local light at the coupler (8) into a beam of light, then the balance detector (9) to beat, beat-frequency signal frequency determined by the frequency shift introduced by acousto-optic modulator (3), beat frequency signal after electric bandpass filter (10), a low-noise amplifier (11) amplifying filter, the electric signal output by the balance photodetector is divided into two paths, which is divided into two same signal divider(12) of the power dividing ratio is 50: 50, then demodulated by mixer (13), and finally after passing through the low-pass filter (14) by the data collecting card (15) collects and data processor (16) for processing………..” [Shao, claim 1].
A person of ordinary skill in the art (POSITA) would implement separate filters (e.g., band-pass/high-pass for the higher-frequency subcarrier branch and low-pass for the DFS branch) to enable simultaneous, optimized processing of each component with appropriate bandwidth and noise rejection. Using dedicated filters in separate branches is a standard signal-processing approach when two components occupy different spectral regions, because it improves isolation, allows independent gain/ADC scaling, and reduces mutual interference. Xu motivates this separation by emphasizing that the subcarrier frequency is much higher than DFS and can be separated by filtering; Shao provides a concrete circuit example employing band-pass filtering and low-pass filtering in a beat-signal processing chain. Accordingly, specifying a first filter for DFS and a second filter for the third-subcarrier is an obvious design choice that predictably improves performance and implement ability.
Claims 10 and 20 are rejected under 35 U.S.C. §103 as being unpatentable over Way in view of Tanaka et al. and Xu et al. and further in view of Chao et al. and further in view of Fan et al. (CN101765128A) and Wachter et al. (US5889490).
Claim 10
With respect to claim 10, all limitations of claim 9 are taught by Way, Tanaka, Xu and Shao except wherein claim 10 additionally requires that the filter further comprises a power divider having first and second filter inputs (i.e., a split/branch point that provides respective beat-signal inputs to the first filter and the second filter). However, within analogous art, Shao teaches a beat-signal demodulation chain including an electric bandpass filter, a low-noise amplifier, a power divider, a mixer, and a low-pass filter “The invention claims a self-mixing technique based on phase sensitive optical time domain reflectometry system. by the path detection and demodulation circuit is composed of two parts, an optical route in narrow line-width laser (1), optical coupler (2), an acousto-optic modulator (3), a pulse generator (4), circulator (5), optical fiber (6); the polarization controller (7); the circuit is composed of a power bandpass filter (10), low-noise amplifier (11), a power divider (12), a mixer (13), a low-pass filter(14), using self-mixing such simple structure not only can realize demodulation of the modulation signal, it also can avoid the frequency drift of the local optical signal caused by demodulation. Using the coherent phase sensitive optical time domain reflecting technology system of detecting way, frequency drift of the local light is a problem that must be considered. The invention well eliminates the local optical influence caused by frequency drift. The device works stably, it can more accurately measure the position and frequency of vibration in the plurality of measurements. [Shao, Abstract]
Shao further teaches that the balanced photodetector output is divided into two paths by a 50:50 power divider to produce two identical signals prior to mixing and low-pass filtering “……… A self-based phase sensitive optical time domain reflecting system of mixing technology, wherein the light path using the signal light and the local light for coherent demodulation, circuit by means of self-mixing demodulation signals; the two paths of signal using mixer mixing the external loading on the optical fiber signal demodulated, the specific structure is a narrow line-width laser (1) outputs the continuous light by an optical coupler (2) is divided into two paths, one path by the a custom-optic modulator (3) connected with the pulse generator (4) of modulation into the sensing optical fiber (6) by the circulator (5) is pulse light; the other path is connected with the coupler (8) through the polarization controller (7), back scattered light pulse light in optical fiber transmission process generated in the output from the other port via the circulator (5); the output of the scattered light and local light at the coupler (8) into a beam of light, then the balance detector (9) to beat, beat-frequency signal frequency determined by the frequency shift introduced by acousto-optic modulator (3), beat frequency signal after electric bandpass filter (10), a low-noise amplifier (11) amplifying filter, the electric signal output by the balance photodetector is divided into two paths, which is divided into two same signal divider(12) of the power dividing ratio is 50: 50, then demodulated by mixer (13), and finally after passing through the low-pass filter (14) by the data collecting card (15) collects and data processor (16) for processing………..” [Shao, claim 1].
However, within analogous art, Fan teaches a power divider/splitter that divides an input signal into first and second path signals and provides those respective split outputs as inputs to a low-pass filter branch and a band-pass filter branch (splitter output #1 to LPF input; splitter output #2 to BPF input), thereby providing the claimed first and second filter-input signals to two filter branches “……. This invention claims a device for testing dual-mode terminal and a method thereof, realizing unmanned automatic testing which raises the efficiency and lowers the interference between cells, wherein the technical solution is as follows: said device includes a power divider for dividing a firstinput signal into a first path signal and a second path signal; a first filter for filtering the first path signal into a first mode signal; a second filter for filtering the second path signal into a second mode signal; a first program controlled attenuator for tuning the signal strength of the first mode signal; a second program controlled attenuator for tuning the signal strength of the second mode signal; a control device for automatically controlling the signal tuning strength; a combiner for combining the tuned first mode signal and the second mode signal and outputting for dual-mode switching test. This invention is applied to the mobile communication field……… [0008] The technical solution of the invention is as follows: the invention claims a double-mode terminal testing device, comprising: [0009] divider, receiving the first input signal and converts it into a first path signal and the second path signal, (0010) first filter, connected with the output end of the power divider, receiving the first path signal, output the first mode signal after filtering processing,(0011) a second filter, connected with the output end of the divider. receiving the second signal, outputs the second mode signal after filtering processing, [0012] first program-controlled attenuator connected with the output end of the first filter, adjusting the signal strength of the first mode signal; 4……... [0019] the double-mode terminal testing device, wherein said first mode signal is a GSM signal and said first filter is a low-pass filter. [0020] the double-die terminal testing device, wherein said second mode signal is a TD-SCDMA signal and said first filter is a TD-SCDMA bandpass filter……… [0048] of the first embodiment of the double-mode terminal testing device of the present invention. Referring to FIG. 3, the double-mode terminal testing device 1 of the present embodiment comprises a divider10, a low-pass filter 11, bandpass filter 12 (e.g., TD-SCDMA bandpass filter), a first programmable attenuator 13, a second programmable attenuator 14, a computer 15 and a mixer 16. [0049] This embodiment device principle is as follows: the power splitter 10 receives an input signal from the cell network environment, the input signal including but not limited to a mixed signal of the GSM signal and the TD-SCDMA signal. divider for processing the input signal is divided into two paths of signal output10, wherein the first path signal through low-pass filters 11, due to the lower frequency of the GSM signal (900 and 1800 MHz) can through the low-pass filter 11, and TD-SCDMA signal since the higher frequency (2000 MHz) are surrounded by the low-pass filter 11. Therefore, the low-pass filter 11outputs only the GSM signal. programmable attenuator 13 receives the GSM signal and adjust the GSM signal strength, programmable attenuator 13 by a computer 15. [0050] divider 10 of the second path signal through TD-SCDMA bandpass filter 12, GSM signal and TD-SCDMA signal through filtering back to control the TD-SCDMA signal strength for the second programmable attenuator 14. [0051] GSM signal and TD-SCDMA signal output to measuring terminal 16 through combiner 17 are combined……. [0054] FIG 4 shows a system frame of a second embodiment of the double-mode terminal testing device of the present invention. Referring to FIG. 4, the double-mode terminal testing device 2 of the present embodiment comprises a divider 20, a low-pass filter 21, bandpass filter 22 (e.g., TD-SCDMA bandpass filter), a first programmable attenuator 23, a second programmable attenuator 24, a third programmable attenuator 25, a computer 26 and a mixer 27. [0055] The device with two paths of input signal for the first input signal (mixed signal such as GSM signal and TD-SCDMA signal) from the cell network environment, after processing through the divider20 into two paths of signal output. the first path of signal passes the low-pass filter 21, due to the lower frequency of the GSM signal (900 and 1800 MHz) can through the low-pass filter 21, and TD-SCDMA signal (2000 MHz) is low-pass filter 21 filtering. Therefore, the output of the low-pass filter 21 only GSM signal. the first programmable attenuator 23 receives the GSM signal and adjust the GSM signal strength, the first programmable attenuator 23 by a computer 26. the second path of signal output by the divider 20 by TD-SCDMA bandpass filter 22, GSM signal and TD-SCDMA signal through filtering back to control the TD-SCDMA signal strength for the second programmable attenuator 24. [0056] for the other second input signal according to the need can be TD-SCDMA signal or GSM signal, but the frequency can be different with the first input signal. In this path, the third programmable attenuator 25 signal strength to receive the second input signal, the second input signal. computer 26 connect third programmable attenuator 25, intensity automatic control program-controlled attenuator 25 for signal conditioning. finally, each route signal through combiner 27combining output to the terminal 28….” [Fan, Abstract; ¶ ¶ [0008] - [0012]; ¶ ¶ [0019] - [0020]; ¶ ¶ [0048] - [0051]; Fig. 3; ¶¶ [0054]-[0056]; Fig. 4]
Additionally, in analogous art Wachter teaches splitting a bandpass-limited signal via a power splitter into first and second equal-component signals for parallel downstream processing (e.g., first and second demodulators) “……. FIG. 1 shows the general coherent burst method for Simultaneous measurement of coarse and fine distance…….FIG. 3 is a pictorial Schematic for describing an invention assembly and operation wherein phase of a transmitter Signal may be varied using a phase alternation Sequence……Referring now to FIG. 3, which shows a schematic of the principal componentry necessary for generation and hetero dyne demodulation of a transceiver Signal using the "four burst' phase alternation Sequence and having the following features: reference Signal (12), transmitter signal (14), receiver signal (20), reference oscillator (50), quadrature multiplexer (52), pulse generator (54), four orthogonal com ponents (56), demultiplexer (58), phase control signal (60), controller unit (62), transmitter phase signal (64), mixer (66), gating pulse (68), pulsing command (70), gated transmitter signal (72), transmitter (74), target (76), receiver (78), electronic representation (80), bandpass filter (82), band width limited signal (84), power splitter (86), first of two equal components signal (88), Second of two equal components signal (90), first of two demodulators (92), second of two demodulators (94), first secondary reference signal (96),Second Secondary reference signal (98), first signal thus issued (100), second signal thus issued (102), first phase component (104), Second phase component (106), processor unit (108) and phase control signal (110). Phase alternation in this configuration is achieved by varying the phase of TX relative to a constant RX phase. A reference oscillator (50), Such as a temperature-controlled crystal oscillator, provides a continuous reference Signal (12) to a quadrature multiplexer (52) and pulse generator (54). The multiplexer (52) serves to divide the continuous reference signal (12) into four orthogonal com ponents (56) having phases at 0°, 90°, 180°, and 270 relatives to a phase reference that is locked to the continuous reference signal (12). A demultiplexer (58) selects one of these four orthogonal components (56) in response to a phase control signal (60) issued by a controller unit (62), thereby producing a transmitter phase signal (64). The transmitter phase signal (64) is gated through a mixer (66) that Serves as a fast Switch under Stimulation of a gating pulse (68) derived from the pulse generator (54). The gating pulse (68) is issued in response to a pulsing command (70) issued by the controller unit (62). The gated transmitter signal (72) thereby produced drives a transmitter (74), causing it to emit a transmitter signal (14) ………...” [Wachter, Fig. 1, Fig. 3, Col. 9-10].
PNG
media_image3.png
783
631
media_image3.png
Greyscale
PNG
media_image4.png
747
708
media_image4.png
Greyscale
A person of ordinary skill in the art (POSITA) would implement the two-filter separation described by Xu using a power divider feeding two parallel filter branches (e.g., a low-pass DFS branch and a band-pass/high-pass subcarrier branch) because this enables simultaneous extraction of both components from the same beat signal without time-multiplexing, improves isolation/SNR by allowing each branch to be optimized for its band (bandwidth, gain, ADC scaling), and is a routine and predictable branch-and-filter architecture in IF/RF signal processing. Shao provides a concrete beat-signal demodulation chain that includes a power divider together with band-pass and low-pass filtering, and Wachter explicitly demonstrates splitting a bandpass-limited signal into first and second equal-component signals for parallel downstream processing branches. Fan provides an explicit implementation in which the power divider’s first output is routed to a low-pass filter input and the second output is routed to a band-pass filter input, confirming the predictability and routine nature of the split-and-filter design choice. Accordingly, configuring the filter stage with a power divider providing the first and second filter-input signals to the two filters would have been an obvious and predictable implementation.
Claim 20
With respect to claim 20, all limitations of claim 19 are taught by Way, Tanaka Xu and Shao, except wherein claim 20 additionally requires that the filter further comprises a power divider having first and second filter inputs (i.e., a split/branch point that provides respective beat-signal inputs to the first filter and the second filter). However, within analogous art, Shao teaches a beat-signal demodulation chain including an electric bandpass filter, a low-noise amplifier, a power divider, a mixer, and a low-pass filter. [Shao, Abstract]
Shao further teaches that the balanced photodetector output is divided into two paths by a 50:50 power divider to produce two identical signals prior to mixing and low-pass filtering. [Shao, claim 1]
However, within analogous art, Fan teaches a power divider/splitter that divides an input signal into first and second path signals and provides those respective split outputs as inputs to a low-pass filter branch and a band-pass filter branch (splitter output #1 to LPF input; splitter output #2 to BPF input), thereby providing the claimed first and second filter-input signals to two filter branches. [Fan, Abstract; ¶ ¶ [0008]-[0012]; ¶ ¶ [0019]-[0020]; ¶¶ [0048]-[0051]; Fig. 3; ¶¶ [0054]-[0056]; Fig. 4]
Additionally, Wachter teaches splitting a bandpass-limited signal via a power splitter into first and second equal-component signals for parallel downstream processing (e.g., first and second demodulators). [Wachter, Fig. 1/description]
A person of ordinary skill in the art (POSITA) would implement the two-filter separation described by Xu using a power divider feeding two parallel filter branches (e.g., a low-pass DFS branch and a band-pass/high-pass subcarrier branch) because this enables simultaneous extraction of both components from the same beat signal without time-multiplexing, improves isolation/SNR by allowing each branch to be optimized for its band (bandwidth, gain, ADC scaling), and is a routine and predictable branch-and-filter architecture in IF/RF signal processing. Shao provides a concrete beat-signal demodulation chain that includes a power divider together with band-pass and low-pass filtering, and Wachter explicitly demonstrates splitting a bandpass-limited signal into first and second equal-component signals for parallel downstream processing branches. Fan et al. provides an explicit implementation in which the power divider’s first output is routed to a low-pass filter input and the second output is routed to a band-pass filter input, confirming the predictability and routine nature of the split-and-filter design choice. Accordingly, configuring the filter stage with a power divider providing the first and second filter-input signals to the two filters would have been an obvious and predictable implementation.
It is noted that any citations to specific, pages, columns, lines, or figures in the prior art references and any interpretation of the reference should not be considered to be limiting in any way. A reference is relevant for all it contains and may be relied upon for all that it would have reasonably suggested to one having ordinary skill in the art. See MPEP 2123.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Mohammed Abdelraheem, whose telephone number is (571) 272-0656. The examiner can normally be reached Monday–Thursday.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO-supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, David Payne, can be reached at (571) 272-3024. The fax phone number for the organization where this application or proceeding is assigned is (571) 273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (in USA or Canada) or 571-272-1000.
/MOHAMMED ABDELRAHEEM/Examiner, Art Unit 2635
/DAVID C PAYNE/Supervisory Patent Examiner, Art Unit 2635