Star receiver burst processing

• US 7,653,150 B2
• Filed: 03/02/2007
• Issued: 01/26/2010
• Est. Priority Date: 08/21/2000
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Thesling, William H., Vanderaar, Mark
• Primary Examiner(s): Ghebretinsae; Temesghen
• Application Number:
  US11/681,359
• Publication Number:
  US 20070147567A1
• Time in Patent Office: 1,061 Days
• Field of Search: 375/343, 375/226, 375/222, 375/316, 375/371, 375/355
• US Class Current: 375/316
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 27/2338 using sampling H04L27/2331 - H04L27/2335 take precedence

Abstract

Architecture for processing a record of burst information in a transmission link. A waveform sampler samples a received waveform containing a record of symbols imposed on a carrier signal. Symbol phase of the record symbols is determined utilizing one or more metrics. Any residual carrier error is corrected, and the carrier signal is removed. The phase and time-of-arrival of the burst information associated with a maximum positive correlation value are then determined.

Claims

1. A method of record processing comprising:

receiving an oversampled record of symbols capturing a data burst;

obtaining, with one or more metrics, a reduced number of samples representative of the symbols from the oversampled record of symbols;

estimating a residual carrier phase and frequency utilizing at least a subset of the reduced number of samples;

removing at least part of the estimated residual carrier phase and frequency from the reduced number of samples to produce a first corrected set of symbols; and

resolving a calculated phase ambiguity for the first corrected set of samples to produce a second corrected set of symbols.

2. The method of claim 1, wherein the obtaining step comprises:

obtaining the reduced number of samples to yield one sample per symbol for the captured data burst.

3. The method of claim 1, wherein the obtaining step comprises:

determining sinusoidal correlations using the oversampled record of symbols;

identifying an index location using the sinusoidal correlations to yield one or more interpolation points; and

obtaining the reduced number of samples using the one or more interpolation points.

4. The method of claim 1, wherein the obtaining step comprises:

calculating burst information using the oversampled record of symbols;

normalizing the burst information; and

obtaining the reduced number of samples using the normalized burst information.

5. The method of claim 1, wherein the one or more metrics comprises using a maximized square symbol amplitude, maximized symbol amplitude, or a minimized symbol variance.

6. The method of claim 1, further comprising:

computing a fast Fourier transform on at least a subset of the reduced number of samples;

computing power spectral density using the computed fast Fourier transform; and

computing the residual carrier frequency using the computed power spectral density.

7. The method of claim 6, wherein the at least a subset of the reduced number of samples used to compute the fast Fourier transform are padded.

8. The method of claim 1, wherein the resolving step comprises:

performing a time offset and phase rotation for the first corrected set of samples to produce the second corrected set of samples.

9. The method of claim 1, further comprising:

correlating the first corrected set of samples with a predetermined sequence of symbols; and

selecting a time offset and phase rotation generating a maximum positive correlation between the first corrected set of samples and the predetermined sequence of symbols, the time offset and phase rotation comprising the calculated phase ambiguity.

10. The method of claim 1, further comprising:

decoding the second corrected set of symbols.

11. The method of claim 1, further comprising:

receiving a wireless signal carrying the data burst via a satellite return transmission link; and

processing the received wireless signal to produce the oversampled record of symbols.

12. A method of record processing comprising:

receiving consecutive data bursts in adjacent time division multiple access time slots in a frequency channel;

producing an oversampled record of each symbol for each of the consecutive data bursts;

obtaining, utilizing one or more metrics, a reduced number of samples representative of the record of symbols for each oversampled record of symbols;

estimating a residual carrier phase and frequency utilizing at least a subset of each reduced number of samples;

removing at least part of the estimated residual carrier phase and frequency from each reduced number of samples to produce a first corrected set of symbols for each consecutive data burst; and

resolving a calculated phase ambiguity for each of the first corrected set of samples to produce a second corrected set of symbols for each consecutive data burst.

13. The method of claim 12, wherein,

a first data burst of the consecutive data bursts is received from a first user;

and

a second data burst of the consecutive data bursts, adjacent in time to the first data burst, is received from a second user.

14. The method of claim 12, wherein the second corrected set of symbols includes record data of the second data burst, the record data received in a signal from the second user before the signal is acquired.

15. The method of claim 12, wherein the second corrected set of symbols includes record data of the second data burst received without acquiring a signal carrying the second data burst.

16. A device comprising:

a filter unit configured to produce an oversampled record of symbols capturing a data burst; and

a processor unit, coupled with the filter unit, and configured to;

obtain, with one or more metrics, a reduced number of samples representative of the symbols from the oversampled record of symbols;

estimate a residual carrier phase and frequency utilizing at least a subset of the reduced number of samples;

remove at least part of the estimated residual carrier phase and frequency from the reduced number of samples to produce a first corrected set of symbols; and

resolve a calculated phase ambiguity for the first corrected set of samples to produce a second corrected set of symbols.

17. The device of claim 16, wherein,

the processor unit obtains the reduced number of samples yielding one sample per symbol for the captured data burst.

18. The device of claim 16, wherein, the processor unit is further configured to:

compute a fast Fourier transform on at least a subset of the reduced number of samples; and

compute the residual carrier frequency using the computed fast Fourier transform.

19. The device of claim 18, wherein the at least a subset of the reduced number of samples used to compute the fast Fourier transform are padded.

20. The device of claim 16, wherein the processor unit is configured to resolve the calculated phase ambiguity by performing a time offset and phase rotation for the first corrected set of samples to produce the second corrected set of samples.

21. The device of claim 16, wherein the processor unit is configured to:

correlate the first corrected set of samples with a predetermined sequence of symbols; and

select a time offset and phase rotation generating a maximum positive correlation, the time offset and phase rotation comprising the calculated phase ambiguity.

22. The device of claim 16, wherein the filter unit is configured to produce an oversampled record of symbols from a signal that has not first been acquired.

23. The device of claim 16, further comprising:

a decoder unit, coupled with the processor unit, and configured to decode the second corrected set of symbols.

24. The device of claim 16, wherein the processor unit comprises a plurality of processors.