Digital sampling rate conversion using a poly-phase filter and a polynomial interpolator

• US 7,245,237 B2
• Filed: 09/17/2002
• Issued: 07/17/2007
• Est. Priority Date: 09/17/2002
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Lopez-Estrada, Alex A.
• Primary Examiner(s): Nguyen; Khai M.
• Application Number:
  US10/245,547
• Publication Number:
  US 20040052300A1
• Time in Patent Office: 1,764 Days
• Field of Search: 341/61, 708/313
• US Class Current: 341/61
• CPC Class Codes: H03H 17/0273 Polyphase filters
• CPC Class Codes: H03H 17/0275 comprising non-recursive filters
• CPC Class Codes: H03H 17/0286 Combinations of filter structures
• CPC Class Codes: H03H 17/0621 with input-sampling frequency and output-delivery frequency which differ, e.g. extrapolation; Anti-aliasing
• CPC Class Codes: H03H 17/0642 the ratio being arbitrary or irrational
• CPC Class Codes: H03H 17/0657 where the output-delivery frequency is higher than the input sampling frequency, i.e. interpolation

Abstract

According to some embodiments, digital sampling rate conversion is performed using a poly-phase filter and a polynomial interpolator.

Claims

1. An apparatus, comprising:

a multi-stage poly-phase filter to receive information associated with an input sampling rate, wherein a stage in the multi-stage, poly-phase filter is associated with pre-computed filter coefficients;

a buffer between two of the filter stages, wherein the size of the buffer is adjusted based on at least one of the input sampling rate and an output sampling rate; and

a polynomial interpolator to receive over-sampled signals from the poly-phase filter and to provide information associated with the output sampling rate.

2. The apparatus of claim 1, wherein at least one of the input sampling rate and the output sampling rate comprise an arbitrary sampling rate.

3. The apparatus of claim 1, wherein the polynomial interpolator is associated with a zero or higher order approximation.

4. The apparatus of claim 1, wherein at least one of the received information and the provided information is associated with at least one of:

(i) a stream of information, or (ii) stored information.

5. The apparatus of claim 1, wherein at least one of the received information and the provided information is associated with at least one of:

(i) multimedia information, (ii) audio information, (iii) image information, (iv) video information, or (v) voice over Internet packet network information.

6. The apparatus of claim 1, wherein at least one of the poly-phase filter and the polynomial interpolator is associated with at least one of:

(i) a hardware device, and (ii) a software application.

7. A method, comprising:

generating via a multi-stage poly-phase filter a set of over-sampled signals based on information associated with an input sampling rate, wherein a stage in the filter is associated with pre-computed filter coefficients, and said generating is performed using at least one buffer between two of the filter stages, wherein the size of the buffer is adjusted based on at least one of the input sampling rate and an output sampling rate; and

performing a polynomial interpolation on a subset of the over-sampled signals to generate information associated with the output sampling rate.

8. The method of claim 7, further comprising:

determining the output sampling rate.

9. The method of claim 8, wherein the determination is based on at least one of:

(i) information associated with a destination device, (ii) a destination device identifier, (iii) a destination device type, (iv) a communication channel, or (v) bandwidth information.

10. The method of claim 7, further comprising:

receiving the information associated with the input sampling rate.

11. The method of claim 7, further comprising:

providing the information associated with the output sampling rate.

12. The method of claim 7, further comprising:

selecting the subset of over-sampled signals.

13. The method of claim 12, wherein the selection is based on a delay associated with:

${\mathrm{\delta <br><br>}}_m=\frac{L}{M}·<br><br>m-\lfloor <br><br>\frac{L}{M}·<br><br>m\rfloor <br><br><br><br><br><br>m=0,1,2,\mathrm{\dots <br><br>}<br><br>,M-1$

where L/M is an integer ratio associated with the input sampling frequency divided by the output sampling frequency and δ

_m is associated with an appropriate delay.

14. The method of claim 13, wherein at least one of the input sampling rate and the output sampling rate comprise an arbitrary sampling rate.

15. The method of claim 14, wherein the polynomial interpolation is associated with a zero or higher order approximation.

16. A computer-readable medium storing instructions adapted to be executed by a processor to perform a method, said method comprising:

generating, via a multi-stage poly-phase filter, a set of over-sampled signals based on information associated with an input sampling rate, wherein a stage in the filter is associated with pre-computed filter coefficients, and said generating is performed using at least one buffer between two of the filter stages, wherein the size of the buffer is adjusted based on at least one of the input sampling rate and an output sampling rate; and

performing a polynomial interpolation on a subset of the over-sampled signals to generate information associated with the output sampling rate.

17. The medium of claim 16, wherein at least one of the input sampling rate and the output sampling rate comprise an arbitrary sampling rate.

18. A network device, comprising:

an input port adapted to receive information associated with an arbitrary input sampling rate;

a multi-stage poly-phase filter coupled to the input port and adapted to generate a set of over-sampled signals, wherein a stage in the multi-stage, poly-phase filter is associated with pre-computed filter coefficients;

a buffer between two of the filter stages, wherein the size of the buffer is adjusted based on at least one of an input sampling rate and an output sampling rate;

a polynomial interpolator coupled to the poly-phase filter and adapted to perform a first order approximation to generate information associated with the output sampling rate; and

an output port coupled to the polynomial interpolator and adapted to provide information associated with an arbitrary output sampling rate.

19. The network device of claim 18, wherein the input port receives information from a source device and the output port provides information to a destination device.

20. The network device of claim 18, wherein the network device is associated with at least one of:

(i) a switch, or (ii) a router.