Carrier-frequency synchronization system for improved amplitude modulation and television broadcast reception

• US 20020172313A1
• Filed: 05/17/2001
• Published: 11/21/2002
• Est. Priority Date: 05/17/2001
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Smith, Stephen F., Moore, James A.
• Granted Patent: US 6,563,893 B2
• Time in Patent Office: Days
• US Class Current: 375/376
• CPC Class Codes: H03D 3/248 with means for eliminating interfering signals, e.g. by multiple phase locked loops multiple loops in general H03L7/07, H03L7/22

Abstract

Systems and methods are described for carrier-frequency synchronization for improved AM and TV broadcast reception. A method includes synchronizing a carrier frequency of a broadcast signal with a remote reference frequency. An apparatus includes a reference signal receiver; a phase comparator coupled to the reference signal receiver; a voltage controlled oscillator coupled to the phase comparator; and a radio frequency output coupled to the voltage controlled oscillator.

Claims

1. A method, comprising synchronizing a carrier frequency of a broadcast signal with a remote reference frequency.

2. The method of claim 1, wherein synchronizing includes repetitively synchronizing.

3. The method of claim 2, wherein repetitively synchronizing includes continuously synchronizing.

4. The method of claim 1, wherein the remote reference frequency includes a demodulated reference frequency.

5. The method of claim 1, wherein the remote reference frequency is a common reference frequency.

6. The method of claim 1, wherein synchronizing includes dividing the reference frequency, comparing the divided reference frequency to a divided carrier-frequency signal and adjusting a phase of the divided carrier-frequency signal to approach a phase of the divided reference frequency.

7. The method of claim 1, wherein synchronizing includes comparing the reference frequency to a local reference frequency, adjusting a phase of the local reference frequency to approach a phase of the reference frequency, dividing the local reference frequency, comparing the divided local reference frequency to a divided carrier-frequency signal and adjusting a phase of the divided carrier-frequency signal to approach a phase of the divided local reference frequency.

8. The method of claim 1, wherein synchronizing includes comparing the reference frequency to a local reference frequency, adjusting a phase of the local reference frequency to approach a phase of the reference frequency, multiplying the local reference frequency and controlling a numerically controlled oscillator with the multiplied local reference frequency.

9. The method of claim 1, further comprising deriving the reference frequency from at least one source selected from the group consisting of GPS satellites, GOES satellites, LORAN-C, OMEGA, WWVB, WWV, WWVH, CHU, and CDMA cell-phone base stations.

10. The method of claim 1, further comprising deriving the remote reference frequency from a digital data network.

11. The method of claim 1, further comprising synchronizing another carrier frequency of another broadcast signal with the remote reference frequency, wherein both the carrier frequency and the another carrier frequency are of a same nominal frequency.

12. The method of claim 11, further comprising modulating both the carrier of the broadcast signal and the another carrier of the another broadcast signal with a common audio program feed.

13. The method of claim 12, further comprising equalizing the control of the carrier average phase of the broadcast signal and the control of the another carrier average phase of the another broadcast signal.

14. The method of claim 12 wherein the modulation of the carrier of the broadcast signal and the modulation of the another carrier of the another broadcast signal are substantially equally delayed from a central network source.

15. The method of claim 14, further comprising augmenting at least one member selected from the group consisting of the broadcast signal and the another broadcast signal with a repeater of the same nominal frequency.

16. The method of claim 15, further comprising augmenting at least one member selected from the group consisting of the broadcast signal and the another broadcast signal with a repeater whose carrier frequency is synchronized with the remote reference frequency.

17. The method of claim 15, further comprising augmenting at least one member selected from the group consisting of the broadcast signal and the another broadcast signal with a repeater whose carrier frequency is synchronized with one member selected from the group consisting of said carrier frequency and said another carrier frequency.

18. The method of claim 15, further comprising augmenting at least one member selected from the group consisting of the broadcast signal and the another broadcast signal with a repeater whose average carrier phase is controlled using one member selected from the group consisting of said carrier frequency and said another carrier frequency.

19. The method of claim 15, further comprising augmenting at least one member selected from the group consisting of the broadcast signal and the another broadcast signal with a repeater whose average transmitting power is controlled using one member selected from the group consisting of a received power from the broadcast station and another received power of the another broadcast station.

20. The method of claim 15, further comprising augmenting at least one member selected from the group consisting of the broadcast signal and the another broadcast signal with a repeater having an audio modulation delay that is controlled using one member selected from the group consisting of the broadcast signal and the another broadcast signal.

21. The method of claim 15, further comprising monitoring a master skywave signal.

22. The method of claim 21, wherein monitoring the master skywave signal includes monitoring an average phase of the master skywave signal.

23. The method of claim 21, wherein monitoring the master skywave signal includes monitoring an average amplitude of the master skywave signal.

24. The method of claim 21, wherein monitoring the master skywave signal includes monitoring an average delay of the master skywave signal.

25. A computer program, comprising computer or machine readable program elements translatable for implementing the method of claim 1.

26. An apparatus for performing the method of claim 1.

27. An electromagnetic waveform produced by the method of claim 1.

28. A communication, comprising the electromagnetic waveform of claim 27.

29. An electronic medium, comprising a program for performing the method of claim 1.

30. An apparatus, comprising the electronic medium of claim 29.

31. A process, comprising utilizing the apparatus of claim 30.

32. An apparatus, comprising:

a reference signal receiver;

a phase comparator coupled to the reference signal receiver;

a voltage-controlled oscillator coupled to the phase comparator; and

a radio-frequency output coupled to the voltage-controlled oscillator.

33. The apparatus of claim 32, further comprising a first divider circuit coupled between the reference signal receiver and the phase comparator;

and a second divider circuit coupled between the phase comparator and the voltage-controlled oscillator.

34. The apparatus of claim 32, further comprising a first divider circuit coupled between the voltage-controlled oscillator and the radio-frequency output;

another phase comparator coupled between the first divider circuit and the radio-frequency output; and

a second divider circuit coupled between the another phase comparator and the radio-frequency output.

35. The apparatus of claim 32, further comprising a multiplier coupled between the voltage-controlled oscillator and the radio-frequency output;

a numerically controlled oscillator coupled between the multiplier and the radio-frequency output;

a phase-to-amplitude converter coupled between the numerically controlled oscillator and the radio-frequency output; and

a digital-to-analog converter coupled between the phase-to-amplitude converter and the radio-frequency output.

36. The apparatus of claim 32, wherein the reference signal receiver includes a multichannel global positioning system satellite receiver.

37. The apparatus of claim 32, wherein the reference signal receiver derives the reference frequency from at least one source selected from the group consisting of GPS satellites, GOES satellites, LORAN-C, OMEGA, WWVB, WWV, WWVH, CHU, and CDMA cell-phone base stations.

38. The apparatus of claim 32, wherein the reference signal receiver derives the reference frequency from a digital data network.

39. The apparatus of claim 32, further comprising an antenna coupled to the reference signal receiver.

40. The apparatus of claim 32, further comprising a transmitter coupled to the radio frequency output.

41. The apparatus of claim 40, further comprising an antenna coupled to the transmitter.

42. The apparatus of claim 32, further comprising a low-pass filter coupled between the reference signal receiver and the phase comparator and an amplifier coupled between the low-pass filter and the phase comparator.

43. The apparatus of claim 32, further comprising a buffer/comparator coupled between the phase comparator and the voltage-controlled oscillator.

44. The apparatus of claim 32, further comprising an output buffer coupled between the voltage-controlled oscillator and the radio-frequency output.

45. A method for broadcasting which comprises utilizing the apparatus of claim 32.

46. A broadcast station, comprising the apparatus of claim 32.

47. A network, comprising the broadcast station of claim 46.

48. The network of claim 47, further comprising a repeater to augment coverage in a local area.

49. The network of claim 48, further comprising a monitor to receive a master skywave signal.

50. A kit, comprising:

the apparatus of claim 32.

51. The kit of claim 50, further comprising a connector that can be coupled to the radio frequency output and instructions.