Radio receiver that digitizes a received signal at a plurality of digitization frequencies

• US 6,337,885 B1
• Filed: 02/13/1998
• Issued: 01/08/2002
• Est. Priority Date: 02/13/1998
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hellberg, Lars Richard Birger
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): JIANG, LENNY R
• Application Number:
  US09/023,873
• Time in Patent Office: 1,425 Days
• Field of Search: 375/267, 375/316-346, 375/347, 455/135, 455/132, 455/133, 455/137, 455/150.1, 455/303-315, 329/316, 329/302, 329/363
• US Class Current: 375/316
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H04B 7/12 Frequency diversity

Abstract

A radio receiver converts an original frequency of a modulated received signal into a plurality of digitization frequencies and digitizes the modulated received signal at each one of the plurality of digitization frequencies. The receiver determines a plurality of reception quality measures associated with each one of the digitized modulated received signals at each one of the plurality of digitization frequencies. The receiver demodulates the modulated received signal using a digitized modulated signal at a digitization frequency that provides a better reception quality than those of another digitization frequency.

Claims

1. A radio receiver, comprising:

an A/D conversion stage that converts a modulated received signal into a plurality of offset frequency signals and digitizes the plurality of offset frequency signals to provide a corresponding plurality of digitized outputs;

a digital signal processor that determines a plurality of reception quality measures associated with the plurality of the digitized outputs; and

a demodulator that demodulates the modulated received signal, wherein the demodulator demodulates the modulated received signal using the digitized outputs corresponding to an offset frequency signal that provides a better reception quality than that of another offset frequency signal.

2. The receiver of claim 1, wherein the A/D conversion stage digitizes the plurality of offset frequency signals substantially simultaneously.

3. The receiver of claim 2, wherein the A/D conversion stage includes a plurality of A/D branches comprising a plurality of frequency converters coupled to a corresponding plurality of A/D converters, wherein the frequency converters convert an original frequency of the modulated received signal into the plurality of offset frequencies during concurrent sampling intervals, and wherein the plurality of A/D converters simultaneously digitize the converted modulated received signal during the concurrent sampling interval.

4. The receiver of claim 2, wherein the plurality of A/D converters digitize the plurality of offset frequency signals at a rate defined by a sampling frequency f_s.

5. The receiver of claim 1, wherein the A/D conversion stage digitizes the plurality of offset frequency signals substantially non-simultaneously.

6. The receiver of claim 5, wherein the A/D conversion stage includes a frequency converter circuit that converts an original frequency of the modulated received signal into the plurality of offset frequency signals at a corresponding plurality of non-current sampling intervals, and a A/D converter that digitizes the offset frequency signals during the non-concurrent sampling intervals.

7. The receiver of claim 6, wherein the frequency converter circuit comprises a hopping synthesizer.

8. The receiver of claim 1, wherein the plurality of offset frequencies are offset from each other by a predefined frequency interval.

9. The receiver of claim 1, further including a dithering circuit for introducing a dithering signal at the A/D conversion stage.

10. A radio receiver, comprising:

a pre-A/D conversion stage that converts an original frequency of a modulated received signal into a plurality of digitization frequencies;

an A/D conversion stage that digitizes the received signal at each one of the plurality of digitization frequencies to provide a corresponding plurality of digitized outputs;

a post-A/D conversion stage that converts each one of the plurality of digitized outputs at the digitization frequencies to a common frequency; and

a demodulator that demodulates the received signal using a digitized output.

11. The radio receiver of claim 10, wherein the digitized output for demodulating the received signal is a selected one of the plurality of digitized outputs.

12. The radio receiver of claim 10, wherein the digitized output for demodulating the modulated received signal is produced by combining at least two digitized outputs among said plurality of digitized outputs.

13. The radio receiver of claim 10 further including a digital signal processor that demodulates the received signal by selecting a digitized output corresponding to a digitization frequency that provides a better reception quality than another digitization frequency.

14. The receiver of claim 10, wherein the A/D conversion stage digitizes the modulated received signal at the plurality of digitization frequencies substantially simultaneously.

15. The receiver of claim 14, wherein the pre-A/D conversion stage includes a plurality of frequency converters and the A/D conversion stage includes a plurality of A/D converters correspondingly coupled to the plurality of frequency converters, wherein the frequency converters convert an original frequency of the modulated received signal into the plurality of digitization frequencies during concurrent sampling intervals, and wherein the plurality of A/D converters simultaneously digitize the modulated received signal during the concurrent sampling intervals.

16. The receiver of claim 15, wherein the post-A/D conversation stage includes a plurality of quadrature frequency converters that are correspondingly coupled to the outputs of the plurality of A/D converters.

17. The receiver of claim 15, wherein the plurality of A/D converters digitize the modulated received signal at a rate defined by a sampling frequency f_s.

18. The receiver of claim 10, wherein the A/D conversion stage digitizes the modulated received signal at the plurality of digitization frequencies substantially non-simultaneously.

19. The receiver of claim 18, wherein the pre-A/D conversion stage includes a frequency converter that converts an original frequency of the modulated received signal into the plurality of digitization frequencies at a corresponding plurality of non-concurrent sampling intervals, and the A/D conversion stage includes a A/D converter that non-simultaneously digitizes the modulated received signal during the non-concurrent sampling time intervals.

20. The receiver of claim 19, wherein the post-A/D conversation stage includes a quadrature frequency converter coupled to the output of the A/D converter.

21. The receiver of claim 19, wherein the frequency converter comprises a hopping synthesizer.

22. The receiver of claim 10, wherein the plurality of digitization frequencies are offset from each other by a predefined frequency interval.

23. The receiver of claim 10 further including a dithering circuit for introducing a dithering signal at the A/D conversion stage.

24. A method for demodulating a modulated signal, comprising:

converting an original frequency of a modulated received signal into a plurality of offset frequency signals;

digitizing the plurality of offset frequency signals to provide a corresponding plurality of digitized outputs;

converting each one of the plurality of digitized outputs to a common frequency; and

demodulating the received signal using a digitized output.

25. The method of claim 24, wherein the digitized output for demodulating the received signal is a selected one of the plurality of digitized outputs.

26. The method of claim 24, wherein the digitized output for demodulating the received signal is produced by combining at least two digitized outputs among said plurality of digitized outputs.

27. The method of claim 24 further including the step of:

determining a plurality of reception quality measures associated with each one of the digitized modulated received signals corresponding to the plurality of offset frequency signals.

28. The method of claim 24, wherein the plurality of offset frequency signals are digitized substantially simultaneously.

29. The method of claim 24, wherein the plurality of offset frequency signals are digitized substantially non-simultaneously at a corresponding plurality of non-current sampling intervals.

30. The method of claim 29, wherein the plurality of offset frequencies are offset from each other by a predefined number of channel spacings.

31. The method of claim 29, further including the step of introducing a dithering signal while digitizing the modulated received signal.

32. The receiver of claim 24, wherein the plurality of A/D converters digitize the plurality of offset frequency signals at a rate defined by a sampling frequency f_s.