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 December 13, 2024 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 1-10 are pending in this application and are under examination in this Office Action. No claims have been allowed.
Drawings
The drawings are objected to as failing to comply with 37 CFR 1.84(p)(2), in view of 37 CFR 1.52(d), because FIG. 10 contains text that is not in the English alphabet, namely “低频方波.” The detailed description at paragraphs [0078]-[0080] identifies the corresponding feature as a low-frequency square wave. The non-English legend must be replaced with an English legend consistent with the originally filed disclosure. No new matter should be entered.
The drawings are further objected to because FIG. 8 labels the serial modulation section containing the first and second electro-optical conversion units as “(Photoelectric multiplier),” whereas the Specification at paragraphs [0063]-[0065] and [0075] describes the first and second electro-optical conversion units connected in series as forming an “optical multiplier,” and separately identifies the following detection stage as the photoelectric conversion unit. The drawing legend and the corresponding description must be made consistent. Further, FIG. 1 recites a “present corresponding relation,” while paragraph [0031] refers to a “pre-set corresponding relation” and claims 1 and 10 recite a “set corresponding relation.” The drawing text should be corrected to correspond to the originally filed disclosure. No new matter should be entered.
Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Specification
The disclosure is objected to because of the following informalities and inconsistent terminology. Appropriate correction is required. The specification should be amended in accordance with 37 CFR 1.71(a), without introduction of new matter.
Paragraph [0044]
states that “k1 and k1 are integers and k1 ≠ k2,” even though the immediately surrounding disclosure identifies the two indices as k1 and k2. Paragraph [0085] similarly states that when the selected two different moments are different, “k1 and k1 are different,” while the surrounding equation and discussion concern k1 and k2. These apparent typographical errors should be corrected consistently with the originally filed disclosure.
Paragraph [0094] states that “the second input signal of the second electro-optic conversion unit is a differential signal of the first output signal of the first electro-optic conversion unit.” This is inconsistent with claims 1 and 10 and with paragraphs [0037]-[0046], which repeatedly define the second input signal B[n] as a differential signal of the first input signal A[n]. Applicant is required to reconcile this inconsistency without introducing new matter. The Specification also uses inconsistent terminology concerning which correlation is determined.
Paragraph [0056] states that correlation operation processing on the first and second output signals obtains correlation of the first and second input signals, whereas paragraphs [0057], [0067], [0077], [0078], [0080]-[0084], and [0087]-[0093] repeatedly describe or define the measured correlation as correlation of the first and second output signals. Applicant is required to clarify and consistently identify the correlation used to determine delay skew, without introducing new matter.
paragraph [00143]
Supplement 8 at paragraph [00143] begins as “The method according to Supplement 1” but later states that “the apparatus further includes a delay calibration unit.” The disclosure should be corrected so that the method/apparatus terminology is internally consistent. No new matter should be entered.
Claim Objections
Claims 1, 8 and 10 are objected to under 37 CFR 1.75(d)(1) because of the following informalities. Appropriate correction is required.
Regarding claim 1,
Claim 1 recites “a processor coupled to a memory and configured to,” and then presents the processor functions in a grammatically nonparallel series: “input ...; to input ...; perform ...; determine ....” The preamble also recites “An apparatus to real-time monitor,” which is grammatically awkward.
Applicant should correct the claim so that the processor-function series and the preamble are grammatically consistent.
These informalities, standing alone, are not relied upon as a basis for the rejection under 35 U.S.C. 112(b).
Regarding claim 8,
Claim 8 recites “the delay skew between each output signal of the output signals of each of the plurality of first electro-optical conversion units and the output signal of the second electro-optical conversion unit.”
The repeated “each output signal of the output signals of each” wording is unnecessarily redundant and should be corrected for clarity and grammatical form consistent with the originally filed disclosure.
Regarding claim 10,
Claim 10 recites “performing a correlation operation processing.” This phrase is grammatically improper and should be corrected to state the intended processing operation in clear and consistent terminology.
Appropriate correction is required.
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 4 is rejected under 35 U.S.C. 112(b) 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 4,
Claim 4 recites, in pertinent part, “a product of a symbol sequence of a difference of the first input signal at two different moments and a finite number of a random amplitude sequence” and, alternatively, “a product of a symbol sequence of a difference of the first input signal at two different moments and an infinite number of a random amplitude sequence.”
The phrases “a finite number of a random amplitude sequence” and “an infinite number of a random amplitude sequence” do not establish reasonably clear boundaries for the claimed differential signal. As written, it is unclear whether “finite number” and “infinite number” refer to (i) the number of possible amplitude values in the random amplitude sequence, (ii) the number of samples or symbols in the sequence, (iii) the number of random amplitude sequences, (iv) the length or cardinality of the sequence, or (v) another characteristic of the random amplitude sequence. These alternatives define materially different claim scope, and the claim does not identify which meaning is intended.
The ambiguity is not resolved by the Specification. Paragraph [0044] identifies Amp1[n] as “the finite number of the random amplitude sequence” and then describes Amp1[n] merely as “a random amplitude sequence with a series of positive values.” Paragraph [0046] uses materially the same description for Amp2[n], identifying Amp2[n] as “the infinite number of the random amplitude sequence” and again describing it as “a random amplitude sequence with a series of positive values.” Thus, paragraphs [0044] and [0046] do not provide an objective distinction between what makes one random amplitude sequence “finite” and the other “infinite.”
Further, paragraph [0088] characterizes the alternatives using different terminology, namely “a random amplitude function with finite values” and “a random amplitude function with infinite values,” while paragraph [0089] again states that Amp1[n] “is a finite number of a random amplitude sequence” and Amp2[n] “is an infinite number of a random amplitude sequence.” The intrinsic disclosure therefore does not establish whether the claim is directed to a finite or infinite set of amplitude values, a finite or infinite sequence length, a finite or infinite number of sequences, or some other property.
Accordingly, one of ordinary skill in the art cannot determine with reasonable certainty the metes and bounds of the alternatives reciting “a finite number of a random amplitude sequence” and “an infinite number of a random amplitude sequence.” Claim 4 is therefore indefinite under 35 U.S.C. 112(b).
Double Patenting
The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the "right to exclude" granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the conflicting claims are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); and In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969).
A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on nonstatutory double patenting provided the reference application or patent either is shown to be commonly owned with the examined application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. See MPEP § 717.02 for applications subject to examination under the first inventor to file provisions of the AIA as explained in MPEP § 2159. A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b).
The filing of a terminal disclaimer by itself is not a complete reply to a nonstatutory double patenting (NSDP) rejection. A complete reply requires that the terminal disclaimer be accompanied by a reply requesting reconsideration of the prior Office action. Even where the NSDP rejection is provisional, the reply must be complete. See MPEP § 804, subsection I.B.1. For a reply to a non-final Office action, see 37 CFR 1.111(a). For a reply to final Office action, see 37 CFR 1.113(c). A request for reconsideration, while not provided for in 37 CFR 1.113(c), may be filed after final for consideration. See MPEP §§ 706.07(e) and 714.13.
The USPTO Internet website contains terminal disclaimer forms which may be used. Please visit www.uspto.gov/patent/patents-forms. For more information about eTerminal Disclaimers, refer to www.uspto.gov/patents/apply/applying-online/eterminal-disclaimer.
The present rejection is provisional because the primary reference is a copending application. Any secondary reference relied upon below is prior art and is used only to support the obviousness analysis for the differences between the examined claim and the reference claim(s).
The present application and copending Application No. 19/025,307 identify Fujitsu Limited as applicant/assignee and share inventors Tong Ye, Zhenning Tao, and Xiaofei Su.
Claims 1, 2 and 4 are provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over claim 5 of copending Application No. 19/025,307 (US 2025/0274194 A1) in view of Matsubara et al. (US 2014/0146910 A1).
Although the claims at issue are not identical, they are not patentably distinct from each other because of the following:
This is a provisional nonstatutory double patenting rejection.
As per claim 1,
With respect to claim 1, the similarity limitations are shown below:
Instant application
Co-Pending Application No. 19/025,307
As per claim 1, An apparatus to real-time monitor a delay skew of a sub-signal of an optical transmitter, comprising: a processor coupled to a memory and configured to: input a first input signal to a first electro-optical conversion unit to obtain a first output signal; input a second input signal to a second electro-optical conversion unit to obtain a second output signal, wherein the second input signal is a differential signal of the first input signal; perform correlation operation processing on the first output signal and the second output signal to obtain a correlation of the first input signal and the second input signal; and determine a delay skew between outputs of the first and second electro-optical conversion units according to the correlation and a set corresponding relation between a correlation quantity and a time delay difference.
As per claim 5 (depending from claim 1), An apparatus for monitoring an analog characteristic of an optical transmitter, comprising a processor coupled to a memory configured to input a first signal to a first electro-optical converter to obtain an optical signal to-be-measured; input a second signal to a second electro-optical converter to obtain a modulated local signal; perform correlation processing on the optical signal to-be-measured and the modulated local signal to obtain at least one correlation quantity; and estimate an analog characteristic according to the correlation quantity; wherein the analog characteristic is IQ skew of the first electro-optical converter as a coherent transmitter; the first signal is A[n]; and the second signal is B[n]=A[n]-A[n-m] (for respective I/Q branches), i.e., a difference of the first signal at different moments.
The features of claim 1 of the current application that are not expressly recited in claim 5 of copending Application No. 19/025,307 are the more specific requirement that the delay skew be determined according to a "set corresponding relation between a correlation quantity and a time delay difference."
However, in analogous art, Matsubara teaches determining a delay quantity using correlation values obtained at different known delay values.
Matsubara calculates a first correlation value and a second correlation value at respective delays, forms a difference between the correlation values, and estimates the delay quantity from that correlation-versus-delay relationship.
Matsubara further teaches that the second delay is obtained by adding a certain known value to the first delay and that the optimum delay is obtained from the correlation relationship [Matsubara, Abstract; ¶¶ [0014]-[0018], ¶¶ [0062]-[0065], ¶¶ [0076]-[0086]; FIGS. 6-8; claims 1-2 and 5-6].
One of ordinary skill in the art would have been motivated to apply the known correlation-to-delay estimation technique of Matsubara to the correlation-based IQ-skew monitoring apparatus of claim 5 of Application No. 19/025,307 because both are directed to using correlation information to determine a relative timing/delay quantity. The modification would merely use a known correlation-versus-delay relationship to obtain the already-recited skew quantity, with each element continuing to perform its established function and with predictable results.
Therefore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to determine the IQ skew recited in claim 5 of Application No. 19/025,307 according to a predetermined/set relationship between correlation quantity and time delay difference, as taught by Matsubara, as no more than the predictable use of known correlation-based delay estimation according to its established function.
As per claim 2,
claim 1 is incorporated. Claim 2 further recites that the first electro-optical conversion unit is a transmitter, or a partial modulation unit of a transmitter. Claim 5 of copending Application No. 19/025,307 expressly recites that the first electro-optical converter is a coherent transmitter.
Accordingly, the additional limitation of claim 2 is expressly encompassed by the reference claim and does not patentably distinguish claim 2 from the subject matter of claim 5 as modified above.
As per claim 4,
With respect to claim 4, the similarity limitations are shown below:
Instant application
Co-Pending Application No. 19/025,307
As per claim 4, The apparatus of claim 1, wherein the differential signal comprises, inter alia, a difference of the first input signal at two different moments.
As per claim 5, the second signal is B_I[n]=A_I[n]-A_I[n-m] and B_Q[n]=A_Q[n]-A_Q[n-m], m=1,2,...,M, and is input to the second electro-optical converter to generate the modulated local signal.
Claim 4 is written in the alternative. Claim 5 of Application No. 19/025,307 expressly recites the claimed alternative of forming the second signal as the difference between a present sample and a temporally displaced sample of the first signal.
Thus, the added limitation of claim 4 is expressly present in the reference claim and does not patentably distinguish claim 4 from the subject matter of claim 5 as modified above.
Claim 3 is provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over claim 5 of copending Application No. 19/025,307 in view of Matsubara et al. as applied above, and further in view of Khatana et al. (US 2012/0250793 A1).
Although the claims at issue are not identical, they are not patentably distinct from each other because of the following:
This is a provisional nonstatutory double patenting rejection.
As per claim 3,
As per claim 3, claim 1 is incorporated and the second electro-optical conversion unit is further required to output a finite number of states. Khatana teaches a QPSK optical transmitter having I- and Q-channel Mach-Zehnder modulators driven by binary/pseudorandom data streams.
The modulator therefore operates with a finite set of data/phase states [Khatana, ¶¶ [0016]-[0024], FIGS. 1A-5B].
One of ordinary skill in the art would have been motivated to use the known finite-state/binary modulation drive of Khatana for the second electro-optical converter of the correlation-based coherent transmitter monitoring apparatus because finite-state optical modulation was a conventional implementation for optical transmitter tributaries and would reduce
implementation complexity while preserving the same correlation/skew-monitoring function. The result would have been predictable.
Claim 5 is provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over claim 5 of copending Application No. 19/025,307 in view of Matsubara et al. as applied above, and further in view of Fludger et al. (US 9,991,953 B1).
Although the claims at issue are not identical, they are not patentably distinct from each other because of the following:
This is a provisional nonstatutory double patenting rejection.
As per claim 5,
As per claim 5, claim 1 is incorporated and the processor is further configured to determine a product signal of the first output signal and the second output signal via a photoelectric method or an optical method, and perform an electrical average operation on the product signal to obtain the correlation.
Fludger teaches transmitter-side I/Q time-skew self-calibration in which the optical output containing the I and Q tributaries is detected by a square-law photodetector, thereby producing a cross-product/beat term between the optical fields.
Fludger expressly teaches the photoelectric multiplication operation: “At 230, the optical output of the optical modulator is detected with the photodetector 122, converting the optical output to an electrical signal, and achieving a square law operation of the optical field in so doing.” [Fludger, col. 6; FIGS. 1-2].
Fludger further explains that, after square-law detection, the I and Q tributaries beat coherently; the resulting signal is mixed with low-frequency reference signals and low-pass filtered, and “E[ . . . ] is the expectation operator giving the mean average value.” [Fludger, cols. 7-8].
One of ordinary skill in the art would have been motivated to implement the generic correlation processing recited in claim 5 of Application No. 19/025,307 using Fludger’s known square-law/photoelectric product-and-average technique because both concern transmitter-side I/Q skew measurement from optical signal paths.
The modification supplies a known physical implementation of correlation photoelectric multiplication followed by electrical averaging while retaining the same correlation/skew-monitoring function, and would have yielded predictable results.
Claim 10 is provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over claim 17 of copending Application No. 19/025,307 in view of Bai (US 2007/0042735 A1) and Matsubara et al.
Although the claims at issue are not identical, they are not patentably distinct from each other because of the following:
This is a provisional nonstatutory double patenting rejection.
As per claim 10,
With respect to claim 10, the similarity limitations are shown below:
Instant application
Co-Pending Application No. 19/025,307
As per claim 10, A method of real-time monitoring a delay skew of a sub-signal of an optical transmitter, comprising: inputting a first input signal to a first electro-optical conversion unit to obtain a first output signal; inputting a second input signal to a second electro-optical conversion unit to obtain a second output signal, wherein the second input signal is a differential signal of the first input signal; performing correlation operation processing on the first and second output signals to obtain a correlation; and determining delay skew according to the correlation and a set corresponding relation between correlation quantity and time delay difference.
As per claim 17, A method of monitoring an analog characteristic of an optical transmitter, comprising: inputting a first signal to a first electro-optical converter to obtain an optical signal to-be-measured; inputting a second signal to a second electro-optical converter to obtain a modulated local signal, wherein the second signal is determined according to the first signal and a to-be-monitored analog characteristic; performing correlation processing on the optical signal to-be-measured and the modulated local signal to obtain at least one correlation quantity; and estimating an analog characteristic according to the correlation quantity.
The more specific limitations of claim 10 are that the monitored analog characteristic is delay skew, that the second input signal is a differential signal of the first input signal, and that the delay skew is determined using a set correlation-versus-time-delay relationship.
Bai teaches forming a delayed version of an electrical coded/input signal and determining a difference between the signal and its delayed version, with the resulting processed signal used in driving an electro-optical modulator [Bai, ¶¶ [0088]-[0090], ¶ [0113]; claims 18 and 30].
Matsubara, as discussed above, teaches estimating a delay quantity from correlation values obtained at known relative delay values and therefore provides the claimed correlation-to-delay determination relationship.
It would have been obvious to one of ordinary skill to use Bai's known signal-minus-delayed-signal differential drive as the second signal in the correlation-based optical-transmitter monitoring method of claim 17, particularly when the monitored analog characteristic is relative timing/skew, and to determine that skew using the known correlation-versus-delay relationship of Matsubara.
The combination uses known signal processing and correlation-based delay-estimation techniques for their established timing-measurement functions and would have yielded predictable results.
Accordingly, claims 1-5 and 10 are provisionally rejected on the ground of nonstatutory double patenting for the reasons set forth above.
Claims 6-9 are not subject to the provisional nonstatutory double patenting rejections set forth above.
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.
The key to supporting a rejection under 35 U.S.C. § 103 is a clear articulation of the reason or reasons why the claimed invention would have been obvious, with an articulated reasoning having a rational underpinning. The analysis below identifies the teachings relied upon for each limitation and states a claim-specific reason for the proposed combination.
Claims 1, 2, 4 and 10 are rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al. (US 9,184,834 B1) in view of Zelensky et al. (US 2012/0189320 A1), and further in view of Bai.
Claim 1
As per claim 1, Zhang expressly teaches the core optical-transmitter skew-monitoring architecture recited by the claim, including separate in-phase and quadrature electro-optical modulation paths, electrical drive/training signals applied to those paths, optical outputs from the respective modulators, a low-bandwidth detector receiving the combined optical output, processor/memory-based control, and calculation of I/Q skew from a stored relationship between the measured detector quantity and skew.
Zhang teaches the first and second electro-optical conversion paths and the optical transmitter context: “The optical component 130 and 130' can include a set of Mach-Zehnder interferometers (or modulators) for the in-phase portion (I-tributary) and the quadrature portion (Q-tributary), respectively, of the optical M-QAM transmitter system 100.” [Zhang, col. 3; FIG. 1]
Zhang further teaches that each tributary has the electrical/analog/optical chain corresponding to an input signal driving an electro-optical unit: “The in-phase portion (I-tributary) of the optical M-QAM transmitter system 100 can include, for example, a digital-to-analog convertor associated with the digital domain, an amplifier associated with the analog domain, and a Mach-Zehnder modulator (MZM) associated with the optical domain. The quadrature-phase portion (Q-tributary) of the optical M-QAM transmitter system can include, for example, a digital-to-analog convertor associated with the digital domain, an amplifier associated with the analog domain, and a MZM associated with the optical domain.” [Zhang, col. 3; FIGS. 1-2]
Zhang expressly identifies the two separate modulators and their respective outputs: “The interferometric structure 240 includes the I-channel modulator 242, the Q-channel modulator 245 and the phase shifter 250. The I-channel modulator 242 can be, for example, a MZM associated with the in-phase portion of the optical M-QAM transmitter system 200. Similarly, the Q-channel modulator 245 can also be, for example, a MZM associated with the quadrature-phase portion of the optical M-QAM transmitter system 200. The combined output signal of the interferometric structure 240 can be detected by the detector 260.” [Zhang, col. 4; FIG. 2]
Zhang expressly teaches the claimed processor/memory implementation: “The output of the detector 260 is sent to a control module 270. The control module 270 can be a hardware module and/or software module stored in the memory and/or executed in a processor.” [Zhang, col. 4]
Zhang also expressly teaches that calibration uses electrical training signals supplied to both tributaries: “When the optical M-QAM transmitter system 200 is used in the calibration configuration, the digital pattern generator 210 sends identical training signals (or patterns of bits) to both the I-tributary and the Q-tributary.” [Zhang, col. 4, col. 5]
Zhang teaches determining the physical timing impairment from the optical detector output and a stored corresponding relation: “The skew calculator module 380 receives a signal representing the magnitude of the power associated with the output of the detector from the power monitor 376 and can access the entries of the skew database 378 (or lookup table) based on the signal received. The entries in the skew database 378 can contain or represent instructions and/or information that can be used by the skew calculator module 380 to calculate the skew between the I-tributary and the Q-tributary of the optical M-QAM transmitter system based on the output value of the detector 260, the pattern length of the training signal, and the bit rate of the training signal.” [Zhang, col. 10; FIG. 3]
Zhang further states in the disclosed calibration process: “At 412, the measured output power is analyzed using a lookup table based on the pattern length of the training signal and the bit rate of the training signal. ... The entries in the lookup table can contain or represent instructions and/or information that can allow, for example, the skew calculator module to calculate the skew between the I-tributary and the Q-tributary of the optical M-QAM transmitter system based on the output value of the detector, the pattern length of the training signal, and the bit rate of the training signal.” [Zhang, col. 13; FIG. 7]
Thus, Zhang teaches: (1) an optical transmitter whose timing skew is monitored; (2) first and second optical modulation paths; (3) respective electrical input/training signals applied to the first and second electro-optical modulation units; (4) respective modulated optical outputs; (5) a detector receiving the optical information from both branches; (6) processor/memory-based control; and (7) determining I/Q delay skew from a stored measured-quantity-to-skew relationship. Zhang does not, however, expressly state that the second electrical input is itself a differential signal of the first electrical input, and does not expressly characterize its measured optical quantity as the particular correlation recited by claim 1.
However, within directly analogous skew-compensation art, Zelensky teaches using correlation as the timing-skew measurement quantity and, importantly, teaches an explicit mathematical corresponding relation between correlation and skew.
Zelensky states: “The filter module 515 of some embodiments provides an output that corresponds to the first derivative of the I and Q samples. The current disclosure recognizes that in the presence of a time skew and a frequency offset there is a non-zero correlation between first derivatives of I and Q samples. A correlation module 520 is connected to the output of filter module 515, and determines a correlation between I and Q samples, the presence of correlation indicating that timing between channels may be skewed.” [Zelensky, ¶[0035]]
Zelensky then gives the explicit correlation/skew relation: “C=k*F*S*P, where: k is an implementation-based constant; C is the average correlation of I and Q derivatives; F is the frequency offset (normalized to sample rate); S is I to Q time skew (normalized to sample rate); and P is input signal power.” [Zelensky, ¶¶[0036]-[0041]]
Zelensky further teaches product formation and averaging of the correlation quantity: “In other embodiments, the correlation module 515 may determine the product of the first derivative of the I and Q samples and output a correlation information based on the magnitude of the product, which may be averaged over a predetermined time period.” [Zelensky, ¶[0042]]
Zelensky connects the measured correlation directly to skew correction: “The correlation module 520 provides the correlation information to a skew update module 525, which provides a skew update to the skew compensation module 505. In some embodiments, the correlation module 520 includes a low pass filter that outputs a filtered version of the average correlation that is used as an input to update filter taps of one or more finite impulse response (FIR) filters of the skew compensation module 505.” [Zelensky, ¶[0043]]
Accordingly, Zelensky supplies the limitation that the measured quantity is a correlation and that delay skew is determined according to a known corresponding relation between correlation quantity and time skew. The formula C=k·F·S·P is particularly significant because, with frequency offset F and signal power P known or measured, it is an explicit proportional relationship between correlation C and skew S.
The remaining differential-signal limitation is taught by Bai.
Bai teaches forming a signal from the difference between a coded signal and a temporally delayed version of that same signal, and using the resulting processed signals to drive an electro-optical modulator.
Bai teaches the temporal delay itself: “In one embodiment, the coded signal 322 is represented by c(t), and the coded signal 328 is represented by c̄(t). Additionally, the delayed signal 614 is represented by c(t-Δt), and the delayed signal 624 is represented by c̄(t-Δt). Δt represents a period of time corresponding to p bits, and p is equal to q.” [Bai, US 2007/0042735 A1, PDF p. 22, ¶[0088]]
Bai expressly teaches the differential signal: “The coded signal 322 and the delayed signal 614 are received by the differential limiting amplifier 630. The difference between the coded signal 322 and the delayed signal 614 is represented by a differential signal c(t)-c(t-Δt). For example, the differential signal includes positive and negative pulses.” [Bai, ¶[0089]]
Bai similarly teaches the complementary branch: “The coded signal 328 and the delayed signal 624 are received by the differential limiting amplifier 640. The difference between the coded signal 328 and the delayed signal 624 is represented by a differential signal c̄(t)-c̄(t-Δt). For example, the differential signal includes positive and negative pulses.” [Bai, ¶[0090]]
Bai further claims the electro-optical use of that delayed-signal processing: “a first driver configured to receive the first processed signal and generate a first driving signal; a second driver configured to receive the second processed signal and generate a second driving signal; a light source configured to generate a light; an electro-optical modulator configured to receive the light, the first driving signal and the second driving signal, modulate the light with the first driving signal and the second driving signal, and generate an output optical signal.” [Bai, claim 10]
One of ordinary skill in the art would have been motivated to combine Zhang with Zelensky because Zhang already provides a transmitter-side I/Q-skew monitor, while Zelensky provides a known quantitative signal-processing technique for converting correlation of time-sensitive I/Q quantities into a relative I/Q timing-skew indication.
Zhang supplies the optical-transmitter hardware, detector, processor/memory, skew calculation, and delay-correction architecture. Zelensky is not relied upon for transmitter hardware. Although Zelensky performs its correlation calculation on received I/Q samples, its teaching is reasonably pertinent to Zhang’s transmitter-skew problem because both address the same relative I/Q timing error, and Zelensky expressly states that correlation of time-sensitive I/Q quantities indicates channel skew and provides the correlation-to-skew relation C=k·F·S·P. Applying that known correlation metric in Zhang’s existing transmitter calibration loop would have predictably provided a quantitative skew-sensitive measurement while retaining Zhang’s same optical paths, processor, lookup/calibration function, and delay adjustment.
One of ordinary skill in the art would have been further motivated to use the differential signal taught by Bai as the skew-sensitive second input in the combined Zhang/Zelensky system because Zelensky expressly derives its skew-sensitive correlation from first derivatives of the I and Q samples, while Bai teaches a standard finite-difference operation c(t)-c(t-Δt) that forms a timing-sensitive difference between two temporal samples of the same signal.
Zhang already sends the same training pattern through the two I/Q tributaries during calibration. Applying Bai’s known finite-difference operation to the copy used to drive the second electro-optical branch would therefore have yielded the claimed relationship in which the second input is a differential signal of the first input, without changing the ordinary modulation function of either branch.
The resulting correlation would remain directed to relative I/Q timing, and the correlation-to-skew relationship taught by Zelensky could then be used in Zhang’s existing processor-controlled skew calibration architecture.
The combination therefore applies known timing-difference and correlation-based skew-measurement techniques to Zhang’s known transmitter calibration system for their established functions, with a reasonable expectation of predictable results.
Accordingly, the combination of Zhang, Zelensky, and Bai teaches or renders obvious every limitation of claim 1: the optical-transmitter monitoring apparatus, processor and memory, first and second electro-optical conversion units and corresponding input/output signals, a second input formed as a differential of the first input, correlation processing of the two signal paths, and determination of delay skew according to the measured correlation and a predetermined correlation-to-time-delay relationship.
Claim 2
With respect to claim 2, all limitations of claim 1 are taught or rendered obvious by Zhang, Zelensky and Bai, except wherein claim 2 further requires that the first electro-optical conversion unit is a transmitter or a partial modulation unit of a transmitter.
However, within analogous art, Zhang expressly teaches precisely such partial transmitter modulation units.
Zhang states: “The I-channel modulator 242 can be, for example, a MZM associated with the in-phase portion of the optical M-QAM transmitter system 200. Similarly, the Q-channel modulator 245 can also be, for example, a MZM associated with the quadrature-phase portion of the optical M-QAM transmitter system 200.” [Zhang, col. 4; FIG. 2]
Thus, the first MZM is expressly a partial modulation unit of the overall optical M-QAM transmitter. No additional structural modification is necessary.
One of ordinary skill would have understood that selecting either the complete transmitter or one of its I/Q modulation branches as the “first electro-optical conversion unit” is simply selecting the monitored scope of the same known transmitter.
Claim 2 would therefore have been obvious.
Claim 4
With respect to claim 4, all limitations of claim 1 are taught or rendered obvious by Zhang, Zelensky and Bai, except wherein claim 4 further specifies alternative forms of the differential signal, including at least “a difference of the first input signal at two different moments.” Because claim 4 is drafted in the alternative, disclosure of that expressly recited alternative is sufficient to meet the additional limitation. Bai directly teaches that alternative.
Bai states: “The difference between the coded signal 322 and the delayed signal 614 is represented by a differential signal c(t)-c(t-Δt). For example, the differential signal includes positive and negative pulses.” [Bai, ¶[0089]]
In Bai, c(t) is the signal at a first moment and c(t-Δt) is the same signal at a second, earlier moment. This is the claimed difference of the first input signal at two different moments. Zelensky independently reinforces the same technical reason for using such a difference by teaching first derivatives of I/Q samples as the quantities whose correlation reveals timing skew.
Thus, adopting Bai’s signal-minus-delayed-signal as the differential probe in the Zhang/Zelensky skew monitor would have been a predictable finite-difference implementation of Zelensky’s derivative-based timing metric.
The other alternatives in claim 4 do not patentably distinguish the claim because the claim is satisfied when any one of the recited alternatives is met.
Accordingly, claim 4 would have been obvious over the cited combination.
Claim 10
Claim 10 recites the method counterpart of the apparatus of claim 1. The same combination of Zhang, Zelensky and Bai teaches the corresponding method steps for the same reasons set forth above.
Zhang expressly discloses operating the two optical branches with training signals and then measuring and calculating skew: “At 410, the output of the combined signal is measured using a low-speed detector. The combined signal includes the signals from the in-phase portion (I-tributary) and the quadrature portion (Q-tributary) of the optical M-QAM transmitter system. At 412, the measured output power is analyzed using a lookup table based on the pattern length of the training signal and the bit rate of the training signal. ... At 414, the skew is calculated at, for example, the skew calculator module.” [Zhang, col. 13; FIG. 7]
Zelensky provides the correlation-processing method step: “Initially, at block 1005, a plurality of in-phase and quadrature samples of an optical signal are received. At block 1010 a correlation between derivatives of the in-phase and quadrature samples is measured. A skew correction factor is generated, at block 1015, responsive to the correlation. The skew correction factor may be used to compensate for skew that is detected based on the measured correlation.” [Zelensky, ¶[0054]]
Bai supplies the method of forming the second signal as the difference between a signal and a delayed copy: “The coded signal 322 and the delayed signal 614 are received by the differential limiting amplifier 630. The difference between the coded signal 322 and the delayed signal 614 is represented by a differential signal c(t)-c(t-Δt).” [Bai, ¶[0089]]
A person of ordinary skill would have performed these known operations in Zhang’s transmitter for the same reasons articulated for claim 1: Zhang supplies the physical optical transmitter and skew-calibration sequence; Zelensky supplies a known correlation-to-skew signal-processing law (although its illustrated correlation is calculated from received I/Q samples); and Bai supplies the temporal-difference probe. Applying those known signal-processing operations to Zhang’s transmitter-side I/Q monitor would have been a predictable use of each teaching for its established timing-measurement function.
Performing the apparatus functions as method steps would have yielded the method of claim 10 with no unexpected result.
Accordingly, claim 10 would have been obvious.
Claims 3 and 9 are rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al. in view of Zelensky et al. and Bai, and further in view of Khatana et al.
Claim 3
With respect to claim 3, all limitations of claim 1 are taught or rendered obvious by Zhang, Zelensky and Bai, except wherein claim 3 further requires that the second electro-optical conversion unit output a finite number of states. Within analogous optical-QPSK transmitter art, Khatana expressly teaches Mach-Zehnder electro-optical modulators whose binary electrical data are converted into a finite set of optical phase states.
Khatana states: “FIG. 1A shows an example of a transmitter system 100 including an integrated circuit 105 feeding data to I and Q channels of an optical QPSK modulator. ... PSK modulators 120 and 140 may be realized as Mach-Zehnder modulators. Laser 145 is a light source for the system.” [Khatana, ¶[0016]; FIG. 1A]
Khatana further teaches the finite optical output states: “FIG. 3 shows the relationship between input data and output optical signals in a Mach-Zehnder optical modulator. An incoming data stream of logical ones and zeroes encoded as voltages is converted into equal amplitude light pulses with ones and zeroes represented by 0 or π phase shift.” [Khatana, ¶[0022]; FIG. 3]
The two optical phase values 0 and π are a finite number of output states of the electro-optical conversion unit. One of ordinary skill in the art would have been motivated to use such a finite-state MZM in the second branch of the Zhang/Zelensky/Bai correlation monitor because Zhang already employs MZMs in I/Q branches and binary/PRBS training signals, while finite-state modulation reduces implementation complexity and is the ordinary operating mode for binary/QPSK tributaries. Substituting the known finite-state MZM behavior of Khatana for Zhang’s already disclosed MZM would preserve the same optical modulation function and produce the predictable result of a second EO unit having finite optical states.
Claim 3 would therefore have been obvious.
Claim 9
With respect to claim 9, all limitations of claim 1 are taught or rendered obvious by Zhang, Zelensky and Bai, except wherein claim 9 further requires that the modulating light for the first and second EO conversion units come from identical or different laser light source(s). Because the claim is expressly disjunctive, a common/identical laser source for the two EO branches meets the additional limitation. Khatana expressly teaches a single laser feeding the I and Q PSK/Mach-Zehnder modulation paths.
Khatana states: “Data stream 110 passes through optional adjustable delay 115 before being input to phase-shift keying (PSK) modulator 120. Similarly, data stream 130 passes through optional adjustable delay 135 before being input to phase-shift keying (PSK) modulator 140. ... PSK modulators 120 and 140 may be realized as Mach-Zehnder modulators. Laser 145 is a light source for the system.” [Khatana, ¶[0016]; FIG. 1A]
One of ordinary skill would have been motivated to use the same laser for both branches of the combined monitor because coherent I/Q transmitters conventionally split a common optical carrier to the I and Q modulators, thereby providing a stable common carrier frequency and phase reference while reducing component count. Zhang itself likewise discloses a tunable laser providing the carrier wave for the optical M-QAM transmitter. Selecting the known common-laser arrangement of Khatana for the first and second EO branches is therefore a routine, predictable implementation.
Because claim 9 also expressly permits different laser sources, the demonstrated common-laser alternative is sufficient.
Claim 9 would therefore have been obvious.
Claim 5 is rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al. in view of Zelensky et al. and Bai, and further in view of Fludger et al. (US 9,991,953 B1).
Claim 5
With respect to claim 5, all limitations of claim 1 are taught or rendered obvious by Zhang, Zelensky and Bai, except wherein claim 5 further requires determining a product signal of the first and second optical outputs by a photoelectric or optical method and electrically averaging that product to obtain correlation.
However, within analogous art, Fludger expressly teaches square-law photodetection of the combined I/Q optical fields, which inherently produces the optical cross-product/beat term, and then low-frequency mixing/filtering; Zelensky expressly teaches forming the product of timing-sensitive I/Q quantities and averaging that product to obtain correlation.
Fludger teaches the photoelectric product operation: “At 230, the optical output of the optical modulator is detected with the photodetector 122, converting the optical output to an electrical signal, and achieving a square law operation of the optical field in so doing.” [Fludger, col. 6; FIGS. 1-2]
Fludger explains that the two tributaries form the desired product/beat term: “When the output optical signal of the modulator 112 falls on the “square law” photodetector (low bandwidth photodetector) 122, the output optical signal beats coherently with itself. ... When the mixers 124(1) and 124(2) mix the output of the photodetector 122 down to baseband, electrical homodyne detection occurs and the mixing term that is desired is obtained.” [Fludger, col. 5-6]
Fludger gives the cross-product explicitly after square-law detection and then filters/averages it: “After square-law detection, the I and Q tributaries beat coherently ... The first two terms generate high frequency components ... These are removed by the D.C. block and the low-bandwidth photo-detector ... The signal is then mixed with the low frequency cosine and sine reference signals ... and low-pass filtered. ... where E[ . . . ] is the expectation operator giving the mean average value.” [Fludger, col. 7-8]
Zelensky independently and more directly teaches the electrical product-and-average correlation operation: “the correlation module 515 may determine the product of the first derivative of the I and Q samples and output a correlation information based on the magnitude of the product, which may be averaged over a predetermined time period.” [Zelensky, ¶[0042]]
One of ordinary skill would have been motivated to combine the square-law/photoelectric product technique of Fludger with the correlation averaging taught by Zelensky in the two-branch optical transmitter of Zhang because Fludger and Zhang both address transmitter-side I/Q impairment/skew calibration, while Zelensky provides the known product-and-average form of a correlation metric. Square-law photodetection is a known physical multiplication mechanism: when the two optical fields are combined, the detector current contains the cross term between the fields, and low-pass filtering/expectation extracts a low-frequency average measurement. The combination uses each element for its established function and would have predictably provided the claimed photoelectric/optical product followed by electrical averaging.
Claim 6 is rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al. in view of Zelensky et al. and Bai, and further in view of Matsubara et al.
Claim 6
With respect to claim 6, all limitations of claim 1 are taught or rendered obvious by Zhang, Zelensky, and Bai. Bai further teaches forming a differential signal from two temporal positions of the same signal. Claim 6 additionally expresses those temporal positions as A[n+k1] and A[n+k2] and recites the affine corresponding relation S = k × (τ + (k1+k2)T/2).
Zelensky teaches the linear/proportional correlation-to-skew part of this relationship, and Matsubara teaches the midpoint/half-separation delay offset arising when two correlation measurements are taken at delay positions separated by a known amount.
Zelensky provides the proportional correlation-to-skew relationship: “C=k*F*S*P, where: k is an implementation-based constant; C is the average correlation of I and Q derivatives; F is the frequency offset (normalized to sample rate); S is I to Q time skew (normalized to sample rate); and P is input signal power.” [Zelensky, ¶¶[0036]-[0041]]
Matsubara teaches correlation values separated by a fixed temporal amount: “Difference Value(t)=Correlation Value between Ref(x) and FB(x+t)-Correlation Value between Ref(x) and FB(x+t+a) ... where X represents the timing when acquiring the data, t stands for a difference between the delay quantity given by the first delay adjusting unit and the delay quantity given by the second delay adjusting unit, and a denotes a fixed delay quantity.” [Matsubara, ¶¶[0076]-[0077], Mathematical Expression 1]
Matsubara expressly teaches the half-separation/midpoint correction: “the symbol a represents a difference between the delay value at the point P and the delay value at the point Q. Hence, what a/2 is added to the delay value at the point P is the optimum delay. What a/2 is added to the delay value at the point P corresponds to a delay value at a middle point of a line segment connecting the point P to the point Q.” [Matsubara, ¶[0082]; FIG. 6]
Matsubara repeats the result in its zero-crossing implementation: “Herein, the time t given when the sign of the difference value changes (e.g., when changing to positive from negative) shall be set to t0. At this time, the optimum delay is given by t0+a/2.” [Matsubara, ¶[0086]; FIG. 7]
The exact notation of claim 6 is not stated verbatim in Matsubara. Matsubara nevertheless teaches the underlying midpoint correction: when two correlation positions are separated by a known interval a, the optimum delay is referenced to the midpoint by adding a/2. For two finite-difference sample positions k1T and k2T, the corresponding temporal midpoint is (k1+k2)T/2.
Thus, Matsubara supplies the known half-separation/midpoint adjustment, while Zelensky supplies a calibrated proportional correlation-to-skew relation and Bai supplies the two-time finite-difference signal.
Re-indexing the two finite-difference samples from a particular pair of time positions to the general positions k1T and k2T changes only the time origin and sample indices. Incorporating the known midpoint offset into the calibrated linear correlation/skew relation likewise changes only the reference point of the delay measurement, not the physical measurement operation.
One of ordinary skill would have been motivated to use the midpoint-corrected affine calibration because a finite-difference probe is defined by two temporal sample positions, while Matsubara teaches referencing a delay estimate to the midpoint of two known correlation positions and Zelensky teaches a calibrated proportional correlation/skew law.
Applying those known calibrations to Bai’s two-time differential signal in Zhang’s transmitter would have predictably produced an affine correlation-versus-skew relation of the claimed form, with known scale factors incorporated into the calibration constant k.
Therefore, claim 6 would have been obvious.
Claims 7 and 8 are rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al. in view of Zelensky et al. and Bai, and further in view of Conroy et al. (US 2010/0080570 A1).
Claim 7
With respect to claim 7, all limitations of claim 1 are taught or rendered obvious by Zhang, Zelensky and Bai, except wherein claim 7 further requires applying the differential/correlation signal to the second electro-optical unit only at a set moment and, at other moments, applying a signal unrelated to the first input or a zero signal.
However, within analogous art, Conroy teaches a staggered, time-slotted skew-calibration pattern in a multichannel optical transmitter in which calibration light is generated one channel at a time, thereby isolating the timing measurement of a selected channel from the other channels.
Conroy states: “the basic concept of the skew control by staggered patterns is shown in this figure. Each polarization carries I and Q channels ... Before launching the signal to fiber, a portion of the signal ... is diverted to direct detection ... for electrical conversion to measure the skew among channels and polarizations. ... Therefore, a calibration pattern that generates light, one channel at a time, is one method of obtaining timing information for each channel using direct detection.” [Conroy, ¶[0039]; FIG. 6]
Conroy also teaches exclusive channel activation in successive time slots: “correlates to a reference frame calibration pattern, where a “1” logic value exclusively represents each of the IX, QX, Iy, and Qy signals in sequence; wherein generating the sequence of voltage pulses includes generating a timing voltage pulse sequentially, for each of the IX, QX, Iy, and Qy signals in the reference frame calibration pattern.” [Conroy, claim 3]
Because Conroy’s reference-frame pattern uses a logic value that exclusively represents each channel in sequence, a selected channel’s calibration drive is present in its assigned slot and not asserted as the selected calibration channel during the other channels’ slots. This provides the same timing logic as applying the probe at a set moment and suppressing that probe at other moments.
One of ordinary skill would have been motivated to apply Conroy’s known time-slot gating to the second differential probe of the Zhang/Zelensky/Bai monitor because the gating isolates the intended skew measurement from other channel activity and permits calibration to be scheduled in defined intervals.
Implementing the non-selected intervals with a zero drive, as expressly permitted by claim 7, is a predictable way to realize the inactive portion of that staggered calibration schedule.
The modification therefore amounts to a routine scheduling implementation of a known optical-skew calibration technique and would have yielded predictable results.
Claim 7 would therefore have been obvious.
Claim 8
With respect to claim 8, Zhang, Zelensky, and Bai teach or render obvious the claim 1 architecture. Claim 8 additionally requires a plurality of first electro-optical conversion units, determining each first unit’s delay skew relative to the output of the second electro-optical conversion unit using the correlation and set relation, and calibrating delay among the plurality based on the respective skews. Conroy teaches the missing multi-channel calibration concept: measuring the timing of multiple optical-transmitter signal paths and adjusting the respective delay paths according to the measured timing differences.
Conroy teaches multiple independently delayed optical-signal paths: “Shown are modulation drivers (MDs) 600, 602, 604, and 606. Calibration modules 608, 610, 612, and 614 represent additional time delay that may be added in the respective channels IX, QX, Iy, and Qy.” [Conroy, ¶[0038]; FIG. 6]
Conroy teaches measuring the timing of each channel and using the differences to adjust its delay: “Once each pulse is detected, the time of arrival for each non-zero pattern, T1, T2, T3, and T4, is recorded and compared to the expected, Tb, time duration of the calibration pattern. Alternately, the start and/or stop times of the timing voltage patterns can be compared to the start and/or stop times of the calibration pattern. The differences can be used to generate proportional signals to delay or advance the associated channel.” [Conroy, ¶[0039]]
Conroy expressly teaches comparing channel timing and minimizing misalignment by adjusting the four delay paths: “comparing timing voltages associated with the IX, QX, Iy, and Qy signal paths; and, minimizing misalignment between the timing voltages and the reference frame calibration pattern in response to adjusting time delay modules in the IX, QX, Iy, and Qy signal paths.” [Conroy, claim 1]
One of ordinary skill would have been motivated to extend the known Zhang/Zelensky/Bai two-branch measurement to multiple first electro-optical branches using Conroy’s multi-channel calibration approach because Conroy expressly demonstrates that timing of multiple transmitter paths can be measured separately and the corresponding delay paths can then be adjusted.
Using the same second electro-optical conversion path as the timing reference while repeating the already-known branch/reference measurement for each first branch is a finite repetition of the same measurement operation and provides a common delay reference; it does not require the second path to perform a new function.
Conroy expressly demonstrates that the respective timing differences of multiple optical signal paths can be measured and used to delay or advance each path.
Conroy need not disclose the identical two-unit correlation architecture to supply this additional teaching; the base combination supplies that architecture, while Conroy supplies the known reason to repeat a timing measurement across multiple transmitter paths and to use the resulting respective timing differences to calibrate those paths.
Accordingly, the combined system performs the same known operation for each first branch: obtain the branch/reference correlation, determine that branch’s skew from the known relation, and calibrate the corresponding delay based on the measured skew.
No element is required to operate in a new or unpredictable manner.
Accordingly, claim 8 would have been obvious.
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
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/MOHAMMED ABDELRAHEEM/
Examiner, Art Unit 2635
/DAVID C PAYNE/Supervisory Patent Examiner, Art Unit 2635
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