Generating filter coefficients for a multi-channel notch rejection filter

• US 9,002,917 B2
• Filed: 07/30/2010
• Issued: 04/07/2015
• Est. Priority Date: 07/30/2010
• Status: Active Grant

• Current Assignee: National Instruments Corporation (Emerson Electric Company)
• Original Assignee: National Instruments Corporation (Emerson Electric Company)
• Inventors: Rubio, Hector, Foote, Garritt W.
• Primary Examiner(s): Ngo, Chuong D
• Assistant Examiner(s): SANDIFER, MATTHEW D
• Application Number:
  US12/847,685
• Publication Number:
  US 20120030269A1
• Time in Patent Office: 1,712 Days
• Field of Search: 708/270, 708300-323
• US Class Current: 708/322
• CPC Class Codes: H03H 17/025 Notch filters
• CPC Class Codes: H03H 17/0294 Variable filters; Programmable filters
• CPC Class Codes: H03H 2017/0298 DSP implementation
• CPC Class Codes: H03H 2218/06 Multiple-input, multiple-output [MIMO]; Multiple-input, single-output [MISO]
• CPC Class Codes: H03H 2218/10 Multiplier and or accumulator units

Abstract

Provided is a system for generating coefficient values. The system may include a base function generator and a series of accumulators including a leading and a last accumulator. In the series of accumulators, the data output of each accumulator, except the last, may be coupled to the data input of a successive adjacent accumulator. The base function generator may be configured to output, to the leading accumulator, a series of data values that may correspond to a base function that is a specified order derivative of a filter function. Each accumulator may be configured to: add a data value currently at its data input to a currently stored data value to produce an updated data value that may correspond to a respective value of a specified order integral of the base function; store the updated data value in the accumulator; and output the updated data value at its data output.

Claims

1. A method for processing data samples, the method comprising:

storing, in a base function generator block, a plurality of different base functions, wherein each base function of the plurality of different base functions is a respective specified order derivative of a corresponding respective filter function;

selecting in the base function generator block a base function from the plurality of different base functions;

producing, by the base function generator block, an initial sequence of data values corresponding to the selected base function;

producing, by a series of accumulator circuits, and based on the initial sequence of data values, a plurality of sequences of data values, wherein each accumulator circuit of the series of accumulator circuits comprises a data input and a data output, wherein the data output of each accumulator circuit, except the last accumulator circuit, is coupled to the data input of a successive adjacent accumulator circuit in the series of accumulator circuits;

selecting a sequence of filter coefficient values from the plurality of sequences of data values, by selection circuitry coupled to the data output of each of the plurality of accumulator circuits, corresponding to a specified order integral of the selected based function, wherein the specified order of the integral of the selected base function matches the respective specified order of the derivative of the respective filter function corresponding to the selected base function; and

modifying, by a processing element, respective values of one or more data samples of a data stream according to one or more filter coefficient values of the sequence of filter coefficient values.

2. The method of claim 1, further comprising:

generating the data stream from one or more analog signals.

3. The method of claim 1,

wherein said producing the initial sequence of data values comprises individually producing each successive data value of the initial sequence of data values.

4. The method of claim 1,

wherein said producing the plurality of sequences of data values comprises individually generating each successive data value of the plurality of sequences of data values.

5. The method of claim 1, further comprising:

storing, in a computer storage medium, first data corresponding to the base function;

wherein said producing the initial sequence of data values comprises;

accessing at least a portion of the stored first data; and

producing the initial sequence of data values according to the accessed at least a portion of the first data.

6. The method of claim 1,

wherein each sequence of data values of the plurality of sequences of data values corresponds to a different order integral of the base function.

7. The method of claim 1, wherein said generating the plurality of sequences of data values comprises:

generating a first sequence of data values of the plurality of sequences of data values; and

generating a second sequence of data values of the plurality of sequences of data values from the first sequence of data values of the plurality of sequences of data values.

8. The method of claim 7,

wherein the first and second sequences of data values each correspond to a different order integral of the base function;

wherein the first sequence of data values corresponds to a higher order integral of the base function than the second sequence of data values.

9. The method of claim 7,

wherein said generating the second sequence of data values from the first sequence of data values comprises:

for each given data value of one or more data values of the second sequence of data values, accumulating a corresponding subset of data values of the first sequence of data values.

10. The method of claim 9,

wherein the subset of data values consists of successive data values within the first sequence of data values.

11. The method of claim 1, wherein the base function corresponds to a plurality of delta functions.

12. The method of claim 1,

wherein the filter function represents a convolution of a plurality of functions, wherein the number of functions in the plurality of functions corresponds to the order of the specified order derivative of the filter function.

13. A system for generating coefficient values, comprising:

a series of accumulator circuits comprising a leading accumulator circuit and a last accumulator circuit, wherein each accumulator circuit of the series of accumulator circuits comprises a data input and a data output, wherein the data output of each accumulator circuit, except the last accumulator circuit, is coupled to the data input of a successive adjacent accumulator circuit in the series of accumulator circuits;

a base function generator configured to;

store a plurality of different base functions, wherein each base function of the plurality of different base functions is a respective specified order derivative of a corresponding respective filter function;

select a base function from the plurality of different base functions according to a filter select input; and

sequentially output a series of data values to the data input of the leading accumulator circuit, wherein the series of data values corresponds to the selected base function wherein each accumulator circuit is configured to;

(a) add a data value currently at the data input of the accumulator circuit to a currently stored data value in the accumulator circuit to produce an updated data value, wherein the updated data value corresponds to a respective value of a specified order integral of the base function;

(b) store the updated data value in the accumulator circuit; and

(c) output the updated data value at the data output of the accumulator circuit; and

a coefficient output configured to output a sequence of filter coefficient values corresponding to a specified order integral of the selected base function; and

selection circuitry coupled to the data output of each of the plurality of accumulator circuits and configured to selectively couple the data output of one of the plurality of accumulator circuits to the coefficient output according to the respective specified order of the derivative of the respective filter function corresponding to the selected base function;

wherein each filter coefficient value of the sequence of filter coefficient values corresponds to a current data value at the data output of the one of the plurality of accumulator circuits selectively coupled to the coefficient output.

14. The system of claim 13, further comprising:

a first input coupled to the selection circuitry and configured to receive control information;

wherein the selection circuitry is configured to identify the one of the at least two accumulators based on the received control information to selectively couple the data output of the one of the at least two accumulators to the coefficient output.

15. The system of claim 13, further comprising:

control circuitry coupled to each accumulator;

wherein the control circuitry is configured to assert an update enable signal to each accumulator; and

wherein each accumulator is configured to store and output the updated data value in response to receiving the update enable signal.

16. The system of claim 15, wherein the control circuitry is configured to assert the update enable signal to each accumulator for each data value output by the base function generator.

17. The system of claim 13,

wherein the base function generator comprises a storage medium configured to store information corresponding to the base function;

wherein each successive data value in the series of data values corresponds to a respective successive value of the base function; and

wherein the base function generator is configured to access in the storage medium at least a portion of the information corresponding to the base function to sequentially output the series of data values to the data input of the leading accumulator.

18. The system of claim 13,

wherein the series of data values corresponds to a function comprising a plurality of delta functions.

19. The system of claim 13, wherein each accumulator of the series of accumulators corresponds to a different order integral of the base function.