Interference cancellation system and method using impulse response

• US 7,907,690 B2
• Filed: 10/17/2006
• Issued: 03/15/2011
• Est. Priority Date: 10/17/2006
• Status: Active Grant

• Current Assignee: Edgewater Computer Systems Inc.
• Original Assignee: Edgewater Computer Systems Inc.
• Inventors: Price, George, Esmailian, Tooraj, Taylor, Doug, Fanson, John, Hazy, Laszlo
• Primary Examiner(s): Torres; Juan A
• Application Number:
  US11/550,283
• Publication Number:
  US 20080089451A1
• Time in Patent Office: 1,610 Days
• Field of Search: 375/350, 375/346, 375/285, 455/307, 708/300
• US Class Current: 375/350
• CPC Class Codes: H04L 12/40006 Architecture of a communication node current supply arrangements H04L12/10; intermediate storage or scheduling H04L49/90
• CPC Class Codes: H04L 2012/4028 the transportation system being an aircraft

Abstract

An interference cancellation (IC) system and method for use within a 1553 communication system comprising a data bus carrying primary signals having a 1553 component and a non-1553 component are provided. The IC system has an input port, a 1553 data extraction block and an interference cancellation circuit with an interference measurement and a cancellation block. The interference measurement block receives 1553 decoded data from the 1553 data extraction block and a sampled primary signal via the input port, and, within an impulse response block, produces an interference signal based on a 1553 impulse response system model. The cancellation block subtracts the interference signal from the sampled primary signal and produces an output signal with the 1553 component substantially cancelled. Furthermore, an IC system using adaptive filtering techniques within the impulse response block is provided. The Least Mean Squares (LMS) algorithm can be used as an adaptive filter technique.

Claims

1. Within a 1553 communication system comprising a data bus carrying primary signals having a 1553 component and a non-1553 component, an interference cancellation system comprising:

an input port for receiving a sampled primary signal from the data bus, via an analog-front end block comprising sampling means;

a 1553 data extraction block connected to said input port, for extracting 1553 data from said sampled primary signal and for outputting 1553 decoded data; and

an interference cancellation circuit comprising;

an interference measurement block for receiving said 1553 decoded data and said sampled primary signal, said interference measurement block comprising an impulse response block for producing an interference signal based on a 1553 impulse response system model and a generate reference block for producing a reference signal based on said 1553 decoded data and based on predetermined impulse sequences and wherein said impulse response block receives said reference signal; and

a cancellation block for subtracting the interference signal from the sampled primary signal and for producing an output signal with the 1553.

2. The interference cancellation system of claim 1, wherein said impulse response block comprises finite impulse response (FIR) filter for producing said interference signal based on determined impulse response coefficients.

3. The interference cancellation system of claim 1, wherein said impulse response block comprises infinite impulse response (IIR) filter for producing said interference signal.

4. The interference cancellation system of claim 1, wherein said impulse response block comprises an adaptive filter for determining impulse response coefficients and for producing said interference signal.

5. The interference cancellation system of claim 4, wherein said adaptive filter uses a Least Mean Square (LMS) algorithm.

6. The interference cancellation system of claim 5, wherein said Least Mean Square (LMS) algorithm uses a step size parameter that is a power of 2.

7. The interference cancellation system of claim 1, wherein said interference measurement block further comprises a resampler for producing a resampled reference signal.

8. The interference cancellation system of claim 1, wherein said analog-front-end comprises first sampling means for producing a first sampled primary signal sent to said 1553 data extraction block and second sampling means for producing a second sampled primary signal sent to said interference cancellation circuit.

9. The interference cancellation system of claim 8, wherein said interference cancellation circuit further comprises a first resampler for resampling said second sampled primary signal in producing a resampled second sampled primary signal and a second resampler for resampling said output signal in producing a resampled output signal.

10. The interference cancellation system of claim 8, wherein said interference cancellation circuit further comprises a first resampler for resampling said second sampled primary signal in producing a resampled second sampled primary signal and a second resampler for resampling said interference signal in producing a resampled interference signal.

11. The interference cancellation system of claim 1, wherein said interference measurement block further comprises an accumulate basis functions block for accumulating basis functions and wherein said impulse response block comprises an extract impulse response (IR) coefficients block for calculating impulse response coefficients w based on said accumulated basis functions.

12. The interference cancellation system of claim 11, wherein said extract IR coefficients block comprises means for calculating impulse response coefficients w based on a matrix equation ψ

w=φ

, wherein φ

is an invertible matrix constructed based on predefined 1553 symbol sequences that have associated basis functions, and φ

is a vector of said associated basis functions.

13. The interference cancellation system of claim 12, wherein said matrix equation represents and overdetermined system.

14. The interference cancellation system of claim 13, wherein said matrix ψ

is constructed such that it has a pseudoinverse that is a constant multiplied by the transpose of matrix ψ

.

15. The interference cancellation system of claim 11, wherein said extract IR coefficients block comprises means for calculating impulse response coefficients w based on a circular deconvolution.

16. The interference cancellation system of claim 11, wherein an impulse response block comprises an autocorrelation of said input sequence ψ

(n) as a unit impulse sequence.

17. The interference cancellation system of claim 1 used for substantially linear 1553 systems.