Predictive signal cancellation for extracting 1 Mb/s MIL-STD-1553 component from composite high performance 1553 signal
View Patent ↗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.
1. A 1553 communication system comprising:
a data bus configured to carry primary signals having a 1 Mb/s 1553 component and a non-1Mb/s 1553 component;
an input port configured to receive a signal from the data bus, via an analog front end block and a sampling unit configured to sample the received signal;
a 1553 data extraction block connected to the input port, configured to extract 1553 data from the sampled signal and to output synthesized 1 Mb/s 1553 data; and
a cancellation circuit comprising:
an interference generation unit configured to produce an interference signal based on the synthesized 1 Mb/s 1553 data; and
a cancellation unit configured to subtract the interference signal from the sampled signal and to produce an output signal.
2. The 1553 communication system of claim 1 wherein the interference signal comprises a synthesis of one or more harmonics of the 1 Mb/s 1553 component.
3. An interference cancellation method for canceling interference of 1553 signals comprising the steps of:
acquiring from a data bus a sampled signal, the sampled signal comprising non- 1 Mb/s 1553 encoded data and 1 Mb/s 1553 encoded data;
synthesizing the 1 Mb/s 1553 encoded data within the sampled signal to produce synthesized 1 Mb/s 1553 data;
producing a variant of 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 cancelled 1 Mb/s 1553 component.
4. The method of claim 3 wherein the variant of the interfering signal comprises a synthesis of one or more harmonics of the 1 Mb/s 1553 component.
5. A 1553 communication system comprising:
a data bus configured to carry a signal having a 1 Mb/s 1553 component and a non-1 Mb/s 1553 component;
a unit configured to separate a first component and a second component from the signal on the data bus, the first component including mostly the 1 Mb/s 1553 component within a first frequency band, and the second component including most of the non-1 Mb/s 1553 component within a second frequency band;
a synthesizing circuit configured to extract from the first component a synthesized 1 Mb/s 1553 signal; and
an interference canceller configured to generate a variant of the 1 Mb/s 1553 component within the second frequency band based on the synthesized 1 Mb/s 1553 signal and the second component, to subtract the variant of the 1553 component within the second frequency band from the second component and to produce an output including mostly a non-1 Mb/s 1553 component.
6. The 1553 communication system of claim 5 wherein the variant of the 1 Mb/s 1553 component comprises a synthesis of one or more harmonics of the 1 Mb/s 1553 component.
7. A 1553 signal cancellation system for a 1553 communication system having a data bus carrying a combined signal that includes a 1553 signal and a High Performance 1553 signal, the cancellation system comprising:
an input configured to receive the combined signal from the data bus;
a unit, connected to the input, configured to extract the 1553 signal and to output synthesized 1553 data; and
a cancellation circuit comprising:
a unit configured to receive the synthesized 1553 data and to produce a cancelling signal; and
a cancellation unit configured to subtract the cancelling signal from the combined signal to produce an output signal.
8. The cancellation system of claim 7 , wherein the unit configured to extract the synthesized 1553 data is a 1553 receiver.
9. The cancellation system of claim 7 , wherein the synthesized 1553 data comprises a synthesized 1553 bit stream.
10. The cancellation system of claim 7 , further comprising a unit configured to estimate a clock error of the synthesized 1553 data.
11. The 1553 signal cancellation system of claim 7 wherein the 1553 signal is a 1 Mb/s 1553 signal and the cancelling signal comprises a synthesis of one or more harmonics of the 1 Mb/s 1553 signal.
12. A method for cancelling non-High Performance 1553 signals from a 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 non-High Performance 1553 encoded data;
synthesizing the non-High Performance 1553 encoded data to produce synthesized non-High Performance 1553 data;
producing a cancelling signal based on the synthesized non-High Performance 1553 data; and
subtracting the cancelling signal from the combined signal and producing an output signal that has the non-High Performance 1553 signals substantially cancelled therefrom.
13. The method of claim 12 wherein the non-High Performance 1553 signals includes a 1 Mb/s 1553 signal and one or more harmonics of the 1 Mb/s 1553 signal, the non-High Performance 1553 data comprises a synthesis of symbols carries in the 1 Mb/s 1553 signal, and the cancelling signal represents a synthesis of one or more harmonics of the 1 Mb/s 1553 signal.
14. In a 1553 communication system having a data bus carrying combined signals that include a non-High Performance 1553 component and a High Performance 1553 component, a system for cancelling the 1553 component from the combined signals comprising:
a unit configured to separate from the combined signals into a first component and a second component, the first component including mostly the non-High Performance 1553 component within a first frequency band, and the second component including mostly the non-High Performance 1553 component and the High Performance 1553 component within a second frequency band;
a unit configured to extract from the first component a non-High Performance 1553 synthesized signal; and
a unit configured to generate a non-High Performance 1553 component within the second frequency band based on the 1553 synthesized signal, to subtract the generated non-High Performance 1553 component within the second frequency band from the second component and to produce an output signal including mostly a High Performance 1553 component.
15. The cancelling system of claim 14 wherein the non-High Performance 1553 component includes a 1 Mb/s 1553 signal and one or more harmonics of the 1 Mb/s 1553 signal, the second component includes one or more harmonics of the 1 Mb/s 1553 signal within the second frequency band, the non-High Performance 1553 signal comprises a synthesis of symbols carries in the 1 Mb/s 1553 signal, and the generated non-High Performance 1553 component represents a synthesis of the one or more harmonics of the 1 Mb/s 1553 signal within the second frequency band.
16. A method employed by a terminal in a 1553 system for processing a 1553 signal from a received communication that may have a non-High Performance 1553 component and a High performance 1553 component, the method comprising:
synthesizing a non-High Performance 1553 signal for use in the 1553 system when no High performance 1553 component is present in the communication, comprising:
(a) receiving a non-High Performance 1553 message from a terminal in the system;
(b) determining an identity of a terminal that transmitted the non-High Performance 1553 message;
(c) detecting positive and negative zero-crossings of the non-High Performance 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 non-High Performance 1553 component from the High performance 1553 component when both of the components are received in the communication;
passing the received communication having both the non-High Performance 1553 component and the High Performance component through a filter to pass only the High Performance component and certain harmonics of the non-High Performance 1553 component; and
subtracting a synthesized version of the non-High Performance 1553 signal from the filtered received communication having both the 1553 component and the High Performance component.
17. The method of claim 16 wherein the non-High Performance 1553 signals includes a 1 Mb/s 1553 signal and one or more harmonics of the 1 Mb/s 1553 signal and the synthesized version of the non-High Performance 1553 signal represents a synthesis of one or more harmonics of the 1 Mb/s 1553 signal.
18. A method employed by a terminal in a 1553 system for processing a 1553 signal of a received communication that has a non-High Performance 1553 component and a High performance 1553 component, the method comprising:
separating a portion of the non-High Performance 1553 component from the received communication;
passing the received communication through a filter to pass only the High Performance component and certain harmonics of the non-High Performance 1553 component; and
subtracting a synthesized version of the non-High Performance 1553 signal from the filtered received communication.
19. The method of claim 18 wherein the non-High Performance 1553 component includes a 1 Mb/s 1553 signal and one or more harmonics of the 1 Mb/s 1553 signal and the synthesized version of the non-High Performance 1553 signal represents a synthesis of one or more harmonics of the 1 Mb/s 1553 signal.