Frequency drift estimation for low cost outdoor unit frequency conversions and system diagnostics

• US 8,229,383 B2
• Filed: 01/06/2010
• Issued: 07/24/2012
• Est. Priority Date: 01/06/2009
• Status: Expired due to Fees

• Current Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Popoli, Robert F.
• Primary Examiner(s): PHU, SANH D
• Application Number:
  US12/683,270
• Publication Number:
  US 20100172446A1
• Time in Patent Office: 930 Days
• Field of Search: 455/255, 455/232.1, 455/75, 455/77, 455/234.1, 375/340, 375/327, 375/354
• US Class Current: 455/255
• CPC Class Codes: H03J 7/04 where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving

Abstract

Systems and devices for controlling frequency drift in satellite broadcast systems. A receiver antenna system for a direct broadcast satellite signal communications system in accordance with one or more embodiments of the present invention comprises an oscillator, a mixer, coupled to the oscillator, for converting satellite signals at a first frequency to signals at an intermediate frequency, an analog-to-digital (A/D) converter, coupled to the mixer, for receiving the signals at the intermediate frequency and for converting the signals at the intermediate frequency at near-real-time to a digital data stream, a Digital Signal Processor (DSP), coupled to the A/D converter, for processing the digital data stream, and a drift estimator, coupled to the DSP, the drift estimator determining a frequency drift of the oscillator, wherein the receiver antenna system corrects the frequency drift of the oscillator using the determined frequency drift.

Claims

1. A receiver antenna system for a direct broadcast satellite signal communications system, comprising:

an oscillator;

a mixer, coupled to the oscillator, for converting satellite signals at a first frequency to signals at an intermediate frequency;

an analog-to-digital (A/D) converter, coupled to the mixer, for receiving the signals at the intermediate frequency and for converting the signals at the intermediate frequency at near-real-time to a digital data stream;

a Digital Signal Processor (DSP), coupled to the A/D converter, for processing the digital data stream; and

a drift estimator, coupled to the DSP, the drift estimator determining a frequency drift of the oscillator and driving a digital mixer within the DSP to compensate for the determined frequency drift, wherein the receiver antenna system corrects the frequency drift of the oscillator using the determined frequency drift.

2. The receiver antenna system of claim 1, wherein an output of the drift estimator is fed back to the oscillator to control the frequency drift of the oscillator.

3. The receiver antenna system of claim 1, further comprising an automatic gain control coupled between the mixer and the A/D converter.

4. The receiver antenna system of claim 1, wherein the A/D converter samples the signals at the intermediate frequency at a speed greater than 1 gigasample per second.

5. The receiver antenna system of claim 1, wherein the satellite signals are transmitted in at least the Ku-band of frequencies.

6. The receiver antenna system of claim 5, wherein the satellite signals are further transmitted in at least the Ka-band of frequencies.

7. The receiver antenna system of claim 6, further comprising a Digital-to Analog Converter (DAC), coupled to the DSP.

8. The receiver antenna system of claim 7, wherein an output of the DAC is mixed with a second oscillator, such that an output of the receiver antenna system is set to a desired band on a single wire interface.

9. A system for distributing a plurality of satellite signals on a single interface, comprising:

an oscillator for down-converting the plurality of satellite signals to signals at an intermediate frequency;

an Automatic Gain Controller (AGC) for gain controlling the signals at the intermediate frequency;

an analog-to-digital (A/D) converter, coupled to the AGC, for receiving the signals at the intermediate frequency, wherein the A/D converter directly samples the signals at the intermediate frequency; and

a Digital Signal Processor (DSP), coupled to the A/D converter, wherein a first output of the DSP determines the intermediate frequency and drives a compensatory frequency shift by controlling a digital mixer internal to the DSP and a second output of the DSP is an input to the single interface.

10. The system of claim 9, further comprising a Digital-to-Analog Converter (DAC), coupled to the second output of the DSP.

11. The system of claim 9, wherein the first output of the DSP determines the intermediate frequency by controlling a frequency of the oscillator.

12. The system of claim 11, wherein the oscillator is a Dielectric Resonance Oscillator (DRO).

13. The system of claim 9, wherein the plurality of satellite signals are transmitted in a plurality of frequency bands.

14. The system of claim 13, wherein the plurality of frequency bands comprises a Ka-band and a Ku-band.

15. The system of claim 14, wherein the DRO down-converts the Ka-band to at least a first intermediate frequency band and the DRO down-converts the Ku-band to a second intermediate frequency band as convenient for A/D conversion.

16. The system of claim 9, wherein the A/D converter samples the signals at the intermediate frequency at a rate greater than the Nyquist rate for the signals at the intermediate frequency.

17. The system of claim 10, wherein state information from at least one of the AGC, the ADC, the DSP, and the DAC provide a diagnostic output for the system.

18. The system of claim 17, wherein the diagnostic output comprises at least one of fault recognition, fault reporting, performance monitoring, installation aiding, and installation verification for the system.