Delay adjustment using sample rate converters

• US 8,804,865 B2
• Filed: 06/29/2011
• Issued: 08/12/2014
• Est. Priority Date: 06/29/2011
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Elenes, Javier, Taipale, Dana, Anderton, Dave
• Primary Examiner(s): Lugo, David B.
• Application Number:
  US13/172,260
• Publication Number:
  US 20130003894A1
• Time in Patent Office: 1,140 Days
• Field of Search: 375/260, 375/267, 375/340, 375/346
• US Class Current: 375/267
• CPC Class Codes: H04H 60/12 wherein another information is substituted for the portion of broadcast information
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

A method and apparatus for adjusting the delay of a first data stream relative to a second data stream is disclosed. An apparatus receives first and second data streams having identical content. A timing difference between the first and second data streams is estimated. At least the leading one of the data streams is applied to a sample rate converter. The sample rate converter is configured to receive a data stream at an input sampling rate and to output the data stream at an output sampling rate. Based on the estimated timing difference, delay is applied to the leading one of the data streams by changing the sampling rate of the sampling rate converter. The output sampling rate of the sampling rate converter may be adjusted until both data streams are aligned in time.

Claims

1. An apparatus, comprising:

a first sample rate converter coupled to receive a first data stream corresponding to content extracted from a first radio signal, wherein the first sample rate converter is configured to output the first data stream at a first current sampling rate; and

a first selection circuit coupled to provide the first data stream to the first sample rate converter;

wherein the apparatus is configured to adjust timing of the first data stream relative to a second data stream having identical content to the first data stream by changing the first current sampling rate of the first sample rate converter;

wherein the first selection unit is coupled to receive first program data extracted from an analog radio signal and second program data extracted from a digital radio signal, wherein the first selection circuit is configured to select one of the first program data and the second program data to provide as the first data stream.

2. The apparatus as recited in claim 1, wherein the second data stream corresponds to content extracted from a second radio signal simulcast with the first radio signal.

3. The apparatus as recited in claim 1, further comprising a second selection unit coupled to receive the first program data and the second program data, wherein the second selection unit is configured to select and provide, as the second data stream, the one of the first and second program data not selected by the first selection unit.

4. The apparatus as recited in claim 3, further comprising a second sample rate converter coupled to receive the second data stream, wherein the second sample rate converter is configured to operate at a constant sampling rate.

5. The apparatus as recited in claim 1, further comprising a second sample rate converter coupled to receive the second data stream, wherein the second sample rate converter is configured to operate at a second current sampling rate, and wherein the apparatus is configured to adjust timing of the first data stream relative to the second data stream by changing the second current sampling rate of the second sample rate converter.

6. The apparatus as recited in claim 1, further comprising:

a first interface unit configured to receive the first radio signal from an analog transmitter; and

a second interface unit configured to receive the second radio signal from a digital transmitter.

7. A method, comprising:

a radio receiver receiving a first data stream corresponding to content extracted from a first radio signal, wherein the radio receiver includes a first sample rate converter that outputs the first data stream at a first sampling rate;

the radio receiver adjusting the timing of the first data stream relative to a second data stream having identical content to the first data stream, wherein the adjusting comprises changing the first sampling rate of the first sample rate converter;

receiving first program data extracted from an analog radio signal and second program data extracted from a digital radio signal simulcast with the analog radio signal; and

selecting one of the first program data and the second program data to provide as the first data stream.

8. The method as recited in claim 7, wherein the second data stream corresponds to content extracted from a second radio signal simulcast with the first radio signal.

9. The method as recited in claim 7, further comprising:

the radio receiver selecting the other one of the first program data and the second program data to provide as the second data stream; and

the radio receiver providing the second data stream using a second sample rate converter having a constant sampling rate.

10. The method as recited in claim 7, wherein the radio receiver includes a second sample rate converter that receives the second data stream, wherein the method further comprises:

the radio receiver changing a sampling rate of the second sample rate converter to adjust the timing of the first data stream relative to the second data stream.

11. A radio receiver, comprising:

a first sample rate converter coupled to receive a first data stream corresponding to program content extracted from a first radio signal, wherein the first sample rate converter is configured to output the first data stream at a first sampling rate; and

a delay estimation unit configured to determine a delay of the first data stream relative to a second data stream, wherein the delay estimation unit is configured to provide an indication of the delay to the first sample rate converter;

wherein the first sample rate converter is configured to adjust the delay based on the indication by changing the first sampling rate;

wherein the first sample rate converter is coupled to receive the first data stream from a first selection unit, and wherein the radio receiver further includes a second selection unit coupled to provide the second data stream; and

wherein the first selection unit and the second selection unit are each configured to receive a first digital representation of program content extracted from an analog radio signal, and a second digital representation of the program content extracted from a digital radio signal.

12. The radio receiver as recited in claim 11, further comprising a second sample rate converter coupled to receive the second data stream and configured to output the second data stream at a second sampling rate, wherein the second sample rate converter is coupled to receive the indication of the delay, and wherein the second data stream corresponds to program content extracted from a second radio signal.

13. The radio receiver as recited in claim 12, wherein the second sample rate converter is configured to change the second sampling rate based on the indication.

14. The radio receiver as recited in claim 11, wherein the first selection unit is configured to select one of the first digital representation and the second digital representation to provide as the first data stream, and wherein the second selection unit is configured to select the other one of the first digital representation and the second digital representation to provide as the second data stream.

15. The radio receiver as recited in claim 11, wherein the radio receiver further includes a second sample rate converter coupled to receive the second data stream, wherein operation of the second sample rate converter is not based on the indication provided by the delay estimation unit.

16. The radio receiver as recited in claim 11, further comprising:

a first interface unit configured to receive the first radio signal from an analog transmitter; and

a second interface unit configured to receive the second radio signal from a digital transmitter.