PREDICTIVE SIGNAL CANCELLATION FOR EXTRACTING 1 MB/s MIL-STD-1553 COMPONENT FROM COMPOSITE HIGH PERFORMANCE 1553 SIGNAL

• US 20100232554A1
• Filed: 05/12/2010
• Published: 09/16/2010
• Est. Priority Date: 07/26/2005
• Status: Active Grant

• Current Assignee: Data Device Corporation (Transdigm Group Incorporated)
• Original Assignee: Data Device Corporation (Transdigm Group Incorporated)
• Inventors: Glass, Michael
• Granted Patent: US 8,223,905 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H04L 25/0264 Arrangements for coupling to transmission lines duplexing arrangements H04L5/14; line equalisers, line build-out devices H04L25/03878

Abstract

Method and apparatus for maximizing the usable bandwidth for High Performance 1553 terminals operating concurrently on the same physical bus with legacy 1 Mb/s MIL-STD-1553 terminals. More specifically, the method and apparatus provides implementation for predictive cancellation by synthesizing an estimate of the 1 Mb/s MIL-STD-1553 component of a composite 1 Mb/s plus High Performance 1553 input signal using either of two different techniques: (1) a combination of digital and analog techniques; and (2) an all digital technique. The synthesized signal is then subtracted from the composite signal. Both techniques employ an algorithm for minimizing the effects of clock skew between 1 Mb/s 1553 transmitting clocks and the local High Performance 1553 sampling clock. Both techniques also incorporate an adaptation algorithm for developing and maintaining digital models of 1 Mb/s 1553 signals received from multiple 1 Mb/s 1553 terminals on a bus.

Claims

1. A 1553 communication system, comprising:

a data bus carrying primary signals having a 1553 component and a non-1553 component;

a cancelation system comprising;

an input port for receiving a 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 signal and for outputting 1553 decoded data; and

a cancelation circuit, comprising;

an interference measurement unit for producing an interference signal; and

a cancelation unit for subtracting the interference signal from the sampled signal and for producing an output signal.

2. An interference cancelation method for canceling interference of 1553 signals within an non-1553 data communications system overlayed on a 1553 data communications system, the method comprising the steps of:

acquiring from a data bus a sampled signal, the sampled signal comprising non-1553 encoded data and 1553 encoded data;

decoding the 1553 encoded data within the primary signal to produce a decoded 1553 data;

producing a variant of a an interfering signal based on the sampled signal; and

subtracting the variant of the interfering signal from the sampled signal and producing an output signal with a substantially canceled 1553 component.

3. A 1553 communication system comprising a data bus carrying signals having a 1553 component and a non-1553 component, the interference cancelation system comprising:

a unit for separating from said signal on said bus a first component S1 and a second component S3, said S1 including mostly said 1553 component within a first frequency band, and said S3 including mostly said S3 component and a non-1553 component within a second frequency band;

a 1553 decoder for extracting from said first primary component S1 a 1553 decoded signal; and

an interference canceller for synthesizing a variant of said 1553 component within said second frequency band based on said 1553 decoded signal and said second primary component, and for subtracting said variant of said 1553 component within said second frequency band from said second component S3 in producing an output including mostly a non-1553 component.

4. A 1553 communication system comprising a data bus carrying a combined signal comprising a 1553 signal and a High Performance 1553 signal, comprising:

a system for canceling the 1553 signal, comprising;

an input for receiving the combined 1553 and High Performance 1553 signal from the data bus;

a unit connected to said input, for extracting the 1553 signal and outputting 1553 decoded data; and

a cancellation circuit comprising;

a unit for receiving said 1553 decoded data for producing a cancelling signal; and

a cancellation unit for subtracting the cancelling signal from the combined signal to produce an output signal.

5. The cancellation system of claim 4, wherein the unit for extracting the 1553 decoded data is a 1553 receiver.

6. The system of claim 4, wherein the 1553 decoded data comprises a 1553 decoded bit stream.

7. The system of claim 4, further comprising a 1553 word timing estimator.

8. The system of claim 4, further comprising a unit for estimating a clock error of the 1553 decoded data.

9. A method for canceling 1553 signals from a High Performance 1553 signal in a 1553 data communication system, the method comprising the steps of:

acquiring from a data bus a combined signal comprising High Performance 1553 encoded data and 1553 encoded data;

decoding the 1553 encoded data to produce decoded 1553 data;

producing a cancelling signal based on the decoded 1553; and

subtracting the canceling signal from the combined signal and producing an output signal with a substantially cancelled 1553 component.

10. In a 1553 communication system comprising a data bus carrying combined signals having a 1553 component and a High Performance 1553 component, a system for canceling the 1553 component from the combined signals, comprising:

a unit for separating from said combined signals on said bus a first component S1 and a second component S3, said S1 component including mostly said 1553 component within a first frequency band, and said S3 component including mostly said 1553 component and said High Performance 1553 component within a second frequency band;

a 1553 decoder for extracting from said S1 component a 1553 decoded signal; and

a unit for synthesizing a generated 1553 component within said second frequency band based on said 1553 decoded signals, and for subtracting said generated 1553 component within said second frequency band from said second component S3 and producing an output signal including mostly a non-1553 component.

11. A method for synthesizing a 1553 signal for use in a 1553 communications system, comprising:

receiving a communication comprising a combined analog signal having a 1 Mb/s component and a High performance 1553 component;

passing the combined signal through a filter to obtain the 1 Mb/s component;

detecting positive and negative zero-crossings of the 1 Mb/s component; and

generating digital symbols each being responsive to a detected zero-crossing to synthesize the received 1553 signal.

12. The method of claim 11, further comprising:

passing the combined signal through a second filter to pass the High performance 1553 component and at least one harmonic of the 1553 signal; and

subtracting the synthesized 1553 signal from the combined signal passed by the second filter.

13. A method for synthesizing a 1553 signal for use in a 1553 communications system, comprising:

(a) receiving a 1553 message from a terminal in the system;

(b) determining an identity of a terminal that transmitted the 1553 signal;

(c) detecting positive and negative zero-crossings of the 1553 signal;

selecting one of a group of stored digitized waveform signals responsive to each zero crossing, the selected digitized waveform signals being associated with the identified terminal and associated with the position of each bit of the message.

14. The method of claim 13 wherein the 1553 message is a wraparound message.

15. The method of claim 13 wherein the message comprises variable data word counts and include pseudo-random data patterns.

16. The method of claim 13 further comprising:

transmitting the data words in the wraparound message to the terminal.

17. The method of claim 13, wherein there are a plurality of terminals in the 1553 system, further comprising:

repeating steps (a) through (c) for each terminal in the system.

18. A method employed by a terminal in a 1553 system for canceling a 1553 signal from a received communication having a 1553 component and a High performance 1553 component, comprising:

synthesizing a 1553 signal for use in the 1553 system when no High performance 1553 component is present, comprising;

(a) receiving a 1553 message from a terminal in the system;

(b) determining an identity of a terminal that transmitted the 1553 message;

(c) detecting positive and negative zero-crossings of the 1553 message;

(d) selecting one of a group of stored digitized waveform signals responsive to each zero crossing, the selected digitized waveform signals being associated with the detected terminal and associated with the position of each bit of the message;

separating a 1553 component from the High performance 1553 component when both of said components are received;

passing the received communication having both the 1553 component and the High Performance component through a filter to pass only the High Performance

component and certain harmonics of the 1553 component; and

subtracting the synthesized 1553 signal from the received communication having both the 1553 component and the High Performance component.

19. A method for synthesizing a 1553 signal for use in a 1553 communication system having a plurality of terminals and configured to selectively transmit to said terminals a 1553 signal and a High performance 1553 signal either alone or as combined signals, comprising:

sequentially receiving, at one of said terminals, a wraparound message from all of the terminals in the 1553 system, which is only a 1553 message;

digitizing each wraparound message; and

modeling pulses resulting from each positive and negative transition of the wraparound message.

20. The method of claim 19 wherein the modeled pulses represent values of prior Manchester half-bits and 1553 signal transitions, including:

“

dead time”

-to-1,”

“

1”

-to-“

0,”

“

0”

-to-“

1,”

“

1”

-to-“

Dead time,” and

“

0”

-to-“

Dead time.”

21. The method of claim 19, further comprising:

during receipt of a 1553 data message signal and no High Performance 1553 signal, subtracting the synthesized signal from the received 1553 data signal and adjusting time delay parameters of the synthesized signal and the 1553 data signal to compensate for an effect of components in order to substantially null the result of the subtraction operation.

22. A method for synthesizing a 1553 signal for use in a 1553 communication system having a base terminal (BT) and a plurality of remote terminals (RTs) configured to transmit a 1553 signal and a High performance 1553 signal either alone or as combined signals, comprising:

the BT;

sending a wraparound message to all of the RTs in the 1553 system, which is only a 1553 message, and instructing the RTs to send the wraparound message to all of the other RTs in the 1553 system;

each of said RTs, for each received wraparound message;

identifying one of the BT or an RT sending the received wraparound message;

digitizing the received wraparound message; and

modeling a set of pulses resulting from each positive and negative transition of the received wraparound message;

associating set of pulses with the BT or RT that sent the wraparound message; and

storing the set of pulses and the associated BT or RT.

23. The method of claim 22, further comprising:

a RT, upon receipt of a combined 1553 signal and a High performance 1553 signal from the BT or another one of the RTs;

employing the stored set of pulses associated with the BT or said another one of the RTs for canceling the 1553 signal from the received combined 1553 signal and a High performance 1553 signal.