CONTEST
Competed
$4,000
This contest is closed.
Problem
We request previously undiscovered prior art including patents and non-patent literature (for example academic papers, technical descriptions, etc.) in English and foreign languages that can help invalidate claim 22 of US patent 7,599,627 (‘627) - “Method and system for a polarization mode dispersion tolerant optical homodyne detection system with optimized transmission modulation.” The patent describes improved methods of modulating data for optical transmission.
In particular, we are interested in the feature referred to as “quadrature-return-to-zero,” a method of quadrature modulation, or modulating two signals onto two signal carriers. This method transmits two data signals (consisting of two distinct streams of data symbols, e.g. a series of -1 and +1) on adjacent carrier frequencies. By carefully selecting these carrier frequencies, the total transmitted power returns to zero at the same frequency as the data rate. As a result, the invention reduces the transmission power to zero between data symbols.
For example, two signals I (for example: [-1,1,-1,-1]) and Q (for example [-1,1,-1,1]) are modulated onto two carrier frequencies A (freq.=20GHz, Fig. 2a) and B (freq.=30GHz, Fig. 2b) respectively. The two waveforms of these carrier signals look like the following (in the time domain):
Fig. 1: Example of quadrature-return-to-zero modulation principle in the time domain: a) 20GHz carrier wave b) 30GHz carrier wave, and c) total signal power.
Each of these two carrier signals (A,B) is modulated to transmit data (I,Q) at a rate of 10GHz, the beat frequency of the pair of carrier waves. In effect, the two data signals are spread out by approximately fifty percent in the frequency domain. As a result, the total signal power (Fig. 2c) returns to zero between each pair of data symbols, each is transmitted at a data rate of 10GHz. In this example,
between the first symbol (I,Q)=(-1,-1) and the second (I,Q)=(1,1), the total signal power returns to zero. Fig. 2 traces the path which the signal follows between pairs of data symbols--returning approximately to zero in the transitional states between each symbol.
Fig. 2: Constellation Diagram, tracing the path of the signal in time as it transitions between pairs of symbols (I,Q).
If you are new, see patent and prior art basics and tips for Patexia's prior art contests, and refer to the submission notes below. The best qualifying submission is guaranteed to receive the prize. The following questions will help you understand what we are looking for in this study.
- Was the reference published before May 31st, 2000 (clearly dated)?
- Does it describe two quadrature-modulated data signals?
- Are the two data signals spread by approximately fifty percent in the frequency domain?
- Does the transmitted signal cross zero at the midpoint of the transition between every data symbol?
Questions
| # | Question | Value |
|---|---|---|
| 1 | Was the reference published before May 31st, 2000 (clearly dated)? | 0 |
| 2 | Does it describe two quadrature-modulated data signals? | 0 |
| 3 | Are the two data signals spread by approximately fifty percent in the frequency domain? | 0 |
| 4 | Does the transmitted signal cross zero at the midpoint of the transition between every data symbol? | 0 |
Additional Notes
UPDATE (1.25.2013): This deadline for this contest has been extended until Monday February 22nd, 2013.
Submission Notes
Submission deadline is Monday February 22nd, 2013
All work must be prepared by a single researcher
- The first researcher to satisfactorily respond to all 4 questions will receive the prize.
- Maximum of one entry per person allowed
- If you were referred, the referral prize ($500) will be paid to the referring user from the total prize pool of $4000.
- Entries must be in English
- Please make sure to answer all the questions and explain how we can find that in the reference
- In case you are submitting foreign references, please provide a translation of key sections
- If your reference has already been submitted by another researcher before you or is among the known references, it will not be considered for the contest.
- Please use “Ask a Question” to post general questions or feedback about the contest to the community.
- For specific questions, you can contact us directly by email at contests@patexia.com
- All submissions are subject to Patexia's contest legal terms. Failure to follow these rules may lead to disqualification from the contest
Known references
The following references are known prior art related to 7,599,627. Please do not resubmit them.
- US 7224906 B2
- US 6865348 B2
- US 6608868 B1
- US 6459519 B1
- US 6459521 B1
- US 2002/0109883 A1
- US 6404535 B1
- US 6362903 B1
- US 2001/0050962 A1
- US 6259836 B1
- US 6130766 A
- US 6141141 A
- US 6118566 A
- US 5999300 A
- US 5880870 A
- US 5638404 A
- US 5412351 A
- US 5222103 A
- US 5101450 A
- International Search Report to International Application No. PCT/US02/15884.
- Govind P. Agrawal, “Fiber-Optic Communication Systems”, Second Edition, John Wiley & Sons, Inc. 1997, Section 6.1.3 Heterodyne Detection, p. 242.
- Govind P. Agrawal, “Fiber-Optic Communication Systems”, Second Edition, John Wiley & Sons, Inc. 1997, Section 6.5.1 Phase Noise, p. 261.
- Govind P. Agrawal, “Fiber-Optic Communication Systems” Second Edition, John Wiley & Sons, Inc. 1997, Section 7.3.2 Nonlinear Crosstalk, Cross-Phase Modulation, p. 326.
- Govind P. Agrawal, “Fiber-Optic Communication Systems”, Second Edition, John Wiley & Sons, Inc. 1997, Section 6.1.2 Homodyne Detection, p. 241.
- Govind P. Agrawal, “Nonlinear Fiber Optics”, Second Edition, Academic Press, 1989, Section 9.4.1 Frequency-Selective Brillouin Amplification, pp. 394-396.
- Steve Yao, “Combat Polarization Impairments with Dynamic Polarization Controllers”, General Photonics Corp. 2000, www.generalphotonics.com.
- Hybrid AM-VSB/M-QAM Multichannel Video Transmission over 120 km of Standard Single-Mode Fiber with Cascaded Erbium-Doped Fiber Amplifiers, Hongxing Dai, Shlomo Ovadia, Senior Member, IEEE, and Chinlon Lin, Fellow, ZEEE, IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 8, NO. 12, DECEMBER 1996 (hereinafter “Dai Reference”).
- A 10 Gb/s 8 channel transmission experiment over 480 km with 120 km repeater spacing using frequency modulated RZ pulse format, Shigeki AISAWA, Noboru TAKACHIO, and Katsushi IWASHITA, 22nd European Conference on Optical Communication - ECOC’96, Oslo 2 (hereinafter “Aisawa Reference”).
- US Patent 6,118,566
- Comparison of NRZ- and RZ-Modulation Format for 40-Gb/s TDM Standard-Fiber Systems, D. Breuer and K. Petermann, IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 9, NO. 3, MARCH 1997 (hereinafter “Breuer Reference”)
- Evaluation of return-to-zero modulation for wavelength division-multiplexed transmission over conventional single-mode fiber, R.M. Jopson, A.H. Gnauck,* L.E. Nelson, L.D. Garrett,* C. Wolf, Crawford Hill Laboratory, Box 400, Holmdel, New Jersey 07733, OFC ’98 Technical Digest (hereinafter “Jopson Reference”).
- Polarization Insensitive Homodyne Detection with All Optical Processing Based on the Photorefractive Effect, JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 11, NO. 4, APRIL 1993 (hereinafter “JLT, Vol. 11, No. 4 Reference”)
- Demonstration of Return-to-zero Signaling in Both OOK and DPSK Formats to Improve Receiver Sensitivity in an Optically Preamplified Receiver, Walid A. Atia and Roy S. Bondurant, 0-7803-5634-9/99 (hereinafter “Atia Reference”)
- Sensitivity Enhancement of Optical Receivers by Impulsive Coding Peter J. Winzer and Andreas Kalmar JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 17, NO. 2, FEBRUARY 1999 (hereinafter “Winzer Reference”)
- Receiver Sensitivity Improvement by Impulsive Coding, L. Boivin, M. C. Nuss, Member, IEEE, J. Shah, D. A. B. Miller, Member, IEEE, and H. A. Haus, Life Fellow, IEEE IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 9, NO. 5, MAY 1997 (hereinafter “Boivin Reference”)
- US Patent 5,222103 entitled “Differential Quadrature Phase Shift Keying Encoder for Subcarrier Systems”, Filed Jan. 2, 1991; Issued Jun. 22, 1993 to Gross (hereinafter “US 5,222103 (Gross)”)
- US Patent 5,101,450 entitled “Quadrature Optical Phase Modulators for Lightwave Systems”, Filed Jan. 23, 1991; Issued Mar. 31, 1992 to Olshansky (hereinafter “US Patent 5,101,450 (Olshansky)”)
- US Patent 5,880,870 entitled “Optical Modulation System”, Filed Oct. 28, 1996; Issued Mar. 9, 1999 to Sieben (hereinafter “US Patent 5,880,870 (Sieben)”)
