Phase tracking network

• US 3,971,996 A
• Filed: 02/10/1975
• Issued: 07/27/1976
• Est. Priority Date: 01/18/1973
• Status: Expired due to Term

• Current Assignee: Hycom, Inc.
• Original Assignee: Hycom, Inc.
• Inventors: Motley, David M., Cheng, King Y.
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US05/548,567
• Time in Patent Office: 533 Days
• Field of Search: 329/50, 329/104, 329/109, 329/122, 328/155, 179/1 P, 179/2 DP, 325/41, 325/49, 325/321, 325/323, 325/329, 325/476, 331/10, 331/17
• US Class Current: 327/233
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception
• CPC Class Codes: H04L 27/066 Carrier recovery circuits H04L27/2271 takes precedence
• CPC Class Codes: H04L 27/3818 using coherent demodulation, i.e. using one or more nominally phase synchronous carriers H04L27/227 and H04L27/389 take precedence
• CPC Class Codes: H04L 7/0062 detection of error based on data decision error, e.g. Mueller type detection
• CPC Class Codes: H04L 7/0331 with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock H04L7/0337 takes precedence

Abstract

A phase tracking network for correcting an undesirable first phase angle of a first signal, includes an error calculating circuit responsive to partial response data signals to provide a phase error signal. Filter means adapted to be coupled to the error calculating circuit is responsive to the linear and nonlinear characteristics of the phase error signal to provide a second phase angle in a second signal. A phase correction network coupled between the filter means and the error calculating circuit is responsive to the second phase angle in the second signal to correct the first phase angle in the first signal.

Claims

1. A phase tracking network for correcting the phase of a noncoherently demodulated signal comprising:

a phase correction network having an inphase channel and a quadrature channel and adapted to receive at least a first portion of the noncoherently demodulated signal in the inphase channel and a second portion of the noncoherently demodulated signal in the quadrature channel, the phase correction network including means for substantially correcting the phase of the noncoherently demodulated signal to provide at least one phase corrected signal in both of said channels;

first means responsive to the phase corrected signal to provide at least one detected data signal;

second means responsive to at least one of the detected data signal and the phase corrected signal to provide a phase correction signal; and

said correcting means being responsive to the phase correction signal to make a correction to the phase of the noncoherently demodulated signal.

2. The phase tracking network set forth in claim 1 wherein the first means includes:

a partial response detector responsive to the phase corrected signal to provide the detected data signal with partial response characteristics, and the second means is responsive to at least the detected data signal with partial response characteristics.

3. The phase tracking network set forth in claim 1 wherein the first means includes a (1,1) partial response detector.

4. A phase tracking network adapted to receive a noncoherently demodulated signal subject to phase jitter and frequency offset comprising:

phase correction means adapted to receive the noncoherently demodulated signal for substantially eliminating the phase jitter and the frequency offset from the noncoherently demodulated signal to provide at least one phase corrected signal;

first means responsive to the phase corrected signal to provide at least one detected data signal;

second means responsive to at least one of the detected data signal and the phase corrected signal to provide a phase correction signal, said phase correction signal being representative of a desired correction in both phase jitter and frequency offset; and

said phase correction means being responsive to the phase correction signal to substantially eliminate the phase jitter and frequency offset from the noncoherently demodulated signal.

5. A phase tracking network as defined in claim 4 wherein said first means includes a partial response detector for providing said detected data signal with partial response characteristics.

6. A phase tracking network as defined in claim 4 wherein said second means includes third means responsive to at least one of the detected data signal and the phase corrected signal to provide a phase error signal, fourth means responsive to the phase error signal to provide a first phase correction signal for correcting the frequency offset in the noncoherently demodulated signal, fifth means responsive to the phase error signal to provide a second phase correction signal for correcting the phase jitter in the noncoherently demodulated signal, and means for combining the first and second phase error signal to provide said phase correction signal.

7. A phase tracking network adapted to correct the phase of a first signal, said phase tracking network comprising:

phase correction means for substantially correcting the phase of the first signal to provide at least one phase corrected signal;

detection means responsive to the phase corrected signal to provide a detected data signal;

an error calculator;

means for transmitting the detected data signal and the phase corrected signal to the error calculator;

said error calculator including means for combining said detected data signal and said phase corrected signal to provide a phase error signal;

means responsive to the phase error signal to provide a phase correction signal;

said phase correction means being responsive to the phase correction signal to substantially correct the phase of the first signal; and

each of said phase correction means, said detection means, and said error calculator having an I channel and a Q channel, said error calculator including means for providing an error signal which equals ##EQU11## where SGN(YQ) is the sign of the phase corrected signal in the Q channel, SGN(YI) is the sign of the phase corrected signal in the I channel, |DI| is the absolute value of the detected data signal in the I channel, |DQ| is the absolute value of the detected data signal in the Q channel, EI is the difference between the value of the phase corrected signal in the I channel and the value of the detected data signal in the I channel, and EQ is the difference between the value of the phase corrected signal in the Q channel and the value of the detected data signal in the Q channel.

8. A phase tracking network adapted to correct the phase of a first signal, said phase tracking network comprising:

phase correction means for substantially correcting the phase of the first signal to provide at least one phase corrected signal;

detection means responsive to the phase corrected signal to provide a detected data signal;

an error calculator;

means for transmitting the detected data signal and the phase corrected signal to the error calculator;

said error calculator including means for combining said detected data signal and said phase corrected signal to provide a phase error signal;

means responsive to the phase error signal to provide a phase correction signal;

said phase correction means being responsive to the phase correction signal to substantially correct the phase of the first signal; and

said error calculator including means for providing an error signal which equals ##EQU12## where EQ is the difference between the value of the phase corrected signal and the value of the detected data signal, SGN(YI) is the sign of the phase corrected signal, and |DI| is the absolute value of the detected data signal.

9. A phase tracking network adapted to correct the phase of a first signal, said phase tracking network comprising:

phase correction means for substantially correcting the phase of the first signal to provide at least one phase corrected signal;

detection means responsive to the phase corrected signal to provide a detected data signal;

an error calculator;

means for transmitting the detected data signal and the phase corrected signal to the error calculator;

said error calculator including means for combining said detected data signal and said phase corrected signal to provide a phase error signal;

means responsive to the phase error signal to provide a phase correction signal;

said phase correction means being responsive to the phase correction signal to substantially correct the phase of the first signal; and

said detection means includes a partial response detector responsive to the phase corrected signal from the phase correction means for processing the phase corrected signal to provide said detected data signal with partial response characteristics.

10. A phase tracking network as defined in claim 9 wherein said combining means is responsive to the sign of the phase corrected signal.

11. A phase tracking network as defined in claim 9 wherein said first signal includes a plurality of data groups with each adjacent pair of data groups being spaced in time by a baud interval, said means for providing a phase error signal providing said phase error signal in a first of said baud intervals, said phase correction signal in said first baud interval being representative of phase error in an immediately preceding baud interval, said phase correction means being responsive to the phase correction signal in said first baud interval to make a correction in the phase of the first signal in said first baud interval.

12. A phase tracking network as defined in claim 9 wherein the phase tracking network includes an inphase channel and a quadrature channel, each of said channels being adapted to receive components of the first signal, said phase correction means includes means responsive to the phase correction signal for providing a first quantity having a magnitude equal to the sine of a selected phase angle and a second quantity having a magnitude equal to the cosine of the selected phase angle, means for multiplying the first signal in the inphase channel by the first quantity to provide a first product, means for multipyling the first signal in the inphase channel by the second quantity to provide a second product, means for multiplying the first signal in the quadrature channel by the first quantity to provide a third product, means for multiplying the first signal in the quadrature channel by the second quantity to provide a fourth product, means for combining the first product and the fourth product to provide the phase corrected signal in the inphase channel, and means for combining the second product and the third product to provide the phase correction signal in the quadrature channel.

13. A phase tracking network adapted to correct the phase of a first signal, said phase tracking network comprising:

phase correction means for substantially correcting the phase of the first signal to provide at least one phase corrected signal;

first means responsive to the phase corrected signal to provide a phase error signal;

second means responsive to the phase error signal to provide a first phase correction signal for correcting a first kind of phase error in the first signal;

third means responsive to the phase error signal to provide a second phase correction signal for correcting a second kind of phase error in the first signal, said first kind of phase error being different from said second kind of phase error;

means for combining the first and second phase error signals to provide a combined phase correction signal;

said phase correction means being responsive to said combined phase correction signal to correct the first and second kinds of phase error in the first signal; and

said first signal being noncoherently demodulated and said phase correction means including means for substantially correcting the phase of the noncoherently demodulated signal to provide said one phase corrected signal.

14. A phase tracking network adapted to correct the phase of a first signal, said phase tracking network comprising:

phase correction means for substantially correcting the phase of the first signal to provide at least one phase corrected signal;

first means responsive to the phase corrected signal to provide a phase error signal;

second means responsive to the phase error signal to provide a first phase correction signal for correcting a first kind of phase error in the first signal;

third means responsive to the phase error signal to provide a second phase correction signal for correcting a second kind of phase error in the first signal, said first kind of phase error being different from said second kind of phase error;

means for combining the first and second phase error signals to provide a combined phase correction signal;

said phase correction means being responsive to said combined phase correction signal to correct the first and second kinds of phase error in the first signal; and

said first means includes detection means responsive to the phase corrected signal to provide at least one detected data signal, an error calculator, and means for separately transmitting the detected data signal and the phase corrected signal to the error calculator, and said error calculator including means for combining said detected data signal and said phase corrected signal to provide said phase error signal.

15. A phase tracking network as defined in claim 14 wherein said first signal is noncoherently demodulated and said phase correction means includes means for substantially correcting the phase of the noncoherently demodulated first signal to provide said phase corrected signal.

16. A phase tracking network as defined in claim 14 wherein said detection means includes a partial response detector whereby the detected data signal is provided with partial response characteristics.

17. A phase tracking network adapted to correct the phase of a first signal, said phase tracking network comprising:

phase correction means for substantially correcting the phase of the first signal to provide at least one phase corrected signal;

first means responsive to the phase corrected signal to provide a phase error signal;

second means responsive to the phase error signal to provide a first phase correction signal for correcting a first kind of phase error in the first signal;

third means responsive to the phase error signal to provide a second phase correction signal for correcting a second kind of phase error in the first signal, said first kind of phase error being different from said second kind of phase error;

means for combining the first and second phase error signals to provide a combined phase correction signal;

said phase correction means being responsive to said combined phase correction signal to correct the first and second kinds of phase error in the first signal; and

the first signal includes a plurality of data groups with each adjacent pair of data groups being spaced in time by a baud interval, said means for providing a combined phase correction signal providing said combined phase correction signal in a first of said baud intervals, said combined phase correction signal in said first baud interval being representative of phase error in an immediately preceding baud interval, said phase correction means being responsive to the combined phase correction signal in said first baud interval to make a correction in the phase of the first signal in said first baud interval.

18. A phase tracking network adapted to correct the phase of a first signal, said phase tracking network comprising:

phase correction means for substantially correcting the phase of the first signal to provide at least one phase corrected signal;

first means responsive to the phase corrected signal to provide a phase error signal;

second means responsive to the phase error signal to provide a first phase correction signal for correcting a first kind of phase error in the first signal;

third means responsive to the phase error signal to provide a second phase correction signal for correcting a second kind of phase error in the first signal, said first kind of phase error being different from said second kind of phase error;

means for combining the first and second phase error signals to provide a combined phase correction signal;

said phase correction means being responsive to said combined phase correction signal to correct the first and second kinds of phase error in the first signal; and

said second means including limiter means for limiting the effect which the phase error signal can have on the first phase correction signal.

19. A phase tracking network as defined in claim 18 wherein said third means includes limiter means for limiting the effect which the phase error signal can have on the second phase correction signal.

20. A phase tracking network as defined in claim 18 wherein said first kind of phase error includes phase jitter and said second kind of phase error includes frequency offset.

21. A phase tracking network as defined in claim 18 wherein at least one of said second and third means includes means for adjusting the gain of said one means relative to the other of said second and third means.

22. A phase tracking network as defined in claim 18 wherein said limiter means limits the rate of change of said first phase correction signal with respect to the phase error signal.