SYSTEMS AND METHODS FOR PROVIDING TRIGGER TIMING

• US 20080291080A1
• Filed: 05/25/2007
• Published: 11/27/2008
• Est. Priority Date: 05/25/2007
• Status: Active Grant

• Current Assignee: Chemring Sensors and Electronic Systems Incorporated
• Original Assignee: NIITEK, Inc.
• Inventors: Cummings, William, Hibbard, Mark, Wilens, David
• Granted Patent: US 9,316,729 B2
• Time in Patent Office: Days
• US Class Current: 342/176
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/222 using random or pseudorandom pulse repetition frequency
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: G01S 7/0235 Avoidance by time multiplex
• CPC Class Codes: G01S 7/28 Details of pulse systems
• CPC Class Codes: G01S 7/36 Means for anti-jamming , e.g. ECCM, i.e. electronic counter-counter measures

Abstract

A system for providing signal trigger pulses comprises an equivalent time sampling unit providing transmit and receive trigger pairs, and a control unit controlling the equivalent time sampling unit to provide pseudorandom delay length variations between the trigger pairs.

Claims

1. A system for providing signal trigger pulses, the system comprising:

an equivalent time sampling unit providing transmit and receive trigger pairs; and

a control unit controlling said equivalent time sampling unit to provide pseudorandom delay length variations between said trigger pairs.

2. The system of claim 1 wherein said system is included in a radar system such that the trigger pairs cause transmit and receive pulses

3. The system of claim 1 wherein said equivalent time sampling unit includes a delay unit comprising:

a variable delay component;

a fixed delay component; and

a switching component receiving inputs from said fixed and variable delay components, said switching component outputting one of said received inputs in response to signals from said control unit.

4. The system of claim 3 wherein said fixed delay unit comprises a length of coaxial cable with a known delay at a particular frequency.

5. The system of claim 3 wherein input from said fixed delay component comprises delay from both said variable delay component and said fixed delay component.

6. The system of claim 1 wherein successive transmit and receive pulse pairs have increasing offsets between corresponding transmit and receive pulses;

and

7. The system of claim 1 wherein said control unit comprises:

a pseudorandom number generator that exhausts a sequence of numbers before repeating.

8. The system of claim 1 wherein said equivalent time sampling unit reconstructs a wave from samples taken of a received wave, said reconstructed wave stretched out over a time greater than one cycle of said received wave.

9. The system of claim 1 further comprising:

a Radio Frequency (RF) unit in communication with said equivalent time sampling unit to receive said trigger pairs, said RF unit transmitting radar pulses and sampling returned signals in response to said trigger pairs; and

a radar logic unit receiving said sampled returned signals and analyzing said sampled returned signals according to a radar algorithm, said radar logic unit further providing humanly-perceptible output based upon said analyzing.

10. A method for producing and receiving signals, said method comprising:

performing equivalent time sampling by triggering transmit pulses followed by triggering corresponding receive pulses; and

separating subsequent transmit pulses by delays, variation in the lengths of said delays being pseudorandom.

11. The method of claim 10 further wherein said method is performed by a radar system transmitting and receiving electromagnetic waves over the air.

12. The method of claim 10 wherein said performing equivalent time sampling comprises:

as time increases, increasing a time offset between corresponding transmit and receive pulses so that a plurality of receive pulses sample a plurality of windows in a cycle of a received waveform; and

reconstructing said received waveform stretched over a length of equivalent time.

13. The method of claim 10 wherein any given two consecutive transmit pulses are separated by a delay generated by a process comprising:

generating a pseudorandom binary number;

inputting said pseudorandom binary number to a digital delay line, wherein said delay line produces a delay based upon said pseudorandom binary number;

generating another binary number, said another binary number generated by a pseudorandom algorithm;

inputting said another binary number to a multiplexing unit, wherein said multiplexing unit receives a first signal from said digital delay line and a second signal from a fixed delay source;

outputting one of said first and second signals as a transmit trigger from said multiplexing unit, said outputting based on said another binary number; and

generating a transmit pulse in response to said transmit trigger.

14. The method of claim 13 wherein said fixed delay source is a coaxial cable portion cut to a length corresponding to a known delay.

15. The method of claim 10 wherein any given two consecutive transmit pulses are separated by a delay generated by a process comprising:

generating a pseudorandom binary number;

inputting said pseudorandom binary number to a digital delay line, wherein said delay line produces a delay based upon said pseudorandom binary number;

outputting a delayed signal from said digital delay line as a transmit trigger; and

generating a transmit pulse in response to said transmit trigger.

16. The method of claim 10 further comprising:

analyzing output of said equivalent time sampling according to a radar algorithm; and

displaying the results of said analyzing.

17. The method of claim 16 wherein said analyzing comprises:

determining one or more of the items in the list consisting of;

a position of an object;

a speed of an object;

a shape of an object; and

a type of an object.

18. A method for sampling a signal, said method comprising:

providing a series of transmit and receive pulse pairs, wherein a time offset between a transmit operation and a receive operation in a given pulse pair is varied from a previous pulse pair so that said series of pulse pairs samples a returned wave; and

inserting delays between each pulse pair, wherein variations in the delays between successive pulse pairs are pseudorandom.

19. The method of claim 18 wherein a given pulse pair comprises:

a transmit pulse; and

a first receive pulse following said transmit pulse.

20. The method of claim 18 wherein said providing a series of transmit and receive pulse pairs comprises:

triggering receive pulses by delaying a transmit trigger signal.

21. The method of claim 18 wherein said providing a series of transmit and receive pulse pairs comprises:

triggering transmit pulses by delaying a receive trigger signal.

22. The method of claim 18 wherein said inserting delays between each pulse pair comprises:

inserting said delays between transmit pulses.

23. The method of claim 18 wherein said inserting delays between each pulse pair comprises:

generating a pseudorandom number;

controlling a variable delay component to provide a first delay to a clock based on said generated pseudorandom number, thereby producing a first delayed signal;

providing a second delay to a clock by a fixed delay component, thereby providing a second delayed signal; and

selectively outputting one of said first and second delayed signals to control a pulse.

24. The method of claim 23 wherein said controlled pulse is selected from the list consisting of:

a transmit pulse; and

a receive pulse.

25. The method of claim 23 wherein said fixed delay component is a portion of coaxial cable.

26. The method of claim 18 further comprising:

analyzing said sampled returned wave according to a radar algorithm; and

displaying results of said analyzing.

27. A radar system transmitting a signal and receiving a returned signal, said radar system comprising:

means for performing equivalent time sampling on said returned signal; and

means for varying a delay in a pulse repetition scheme of said equivalent time sampling means, said variation being pseudorandom.

28. The radar system of claim 27 further comprising:

means for analyzing results of said equivalent time sampling according to a radar algorithm; and

means for displaying results of said analyzing.

29. The radar system of claim 27 wherein said delay varying means comprises:

a variable delay component;

a fixed delay component; and

a switching component receiving inputs from said fixed and variable delay components, said switching component outputting one of said received inputs at a time, said switching component output triggering said pulse repetition.

30. The radar system of claim 27 wherein said fixed delay component comprises a length of coaxial cable.