Combined radar assembly with linear and nonlinear radar

• US 9,476,973 B2
• Filed: 09/20/2013
• Issued: 10/25/2016
• Est. Priority Date: 09/20/2013
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Mazzaro, Gregory J, Sherbondy, Kelly D., Liao, DaHan
• Primary Examiner(s): Barker, Matthew M
• Application Number:
  US14/032,387
• Publication Number:
  US 20150084811A1
• Time in Patent Office: 1,131 Days
• US Class Current: 1/1
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/106 using transmission of pulses having some particular characteristics G01S13/12, G01S13/22, G01S13/24, G01S13/26, G01S13/28 and G01S13/30 take precedence
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

A radar assembly for linear and nonlinear radar transmission and reception comprising a signal generator; at least one filter operatively connected to the signal generator; a transmitter operatively connected to the at least one filter for transmitting radar signals; a receiver operative to receiving received signals comprising linear and nonlinear responses from the reflected transmitted signals; the receiver comprising a first channel for processing the linear response of the received signal; a second channel for the processing the nonlinear response of the received signal; at least one switch operative to select one of the first or second channels; at least one high pass filter operatively connected to the second channel to attenuate the linear response; at least one amplifier to amplify the nonlinear response; and at least one display operatively connected to both the first and second channels for displaying both linear and nonlinear responses.

Claims

1. A radar assembly for linear and nonlinear radar transmission and reception comprising:

a transmitter for transmitting radar signals;

the transmitter comprising;

at least one signal generator;

at least one filter operatively connected to the signal generator;

a receiver operative to receive signals comprising linear and nonlinear responses from reflected transmitted signals;

the receiver comprising;

a first channel configured to process the linear response from the received signal;

a second channel configured to process the nonlinear response from the received signal, wherein the second channel comprises at least one high pass filter configured to attenuate the linear response and at least one amplifier operatively connected to the at least one high pass filter and configured to amplify the nonlinear response;

at least one switch operative to select one of the first or second channels through the at least one switch;

at least one analog-to-digital converter for converting the analog received signal to a digitized data stream, and

at least one display operatively connected to both the first and second channels for displaying both the linear and nonlinear responses.

2. The assembly of claim 1 wherein the at least one signal generator comprises first and second signal generators, and wherein the first and second signal generators are operatively connected to third and fourth channels, the third channel comprising a signal combiner.

3. The assembly of claim 1 wherein the transmitter is configured to transmit at radio frequencies common to the excitation of both linear and nonlinear responses from targets.

4. The assembly of claim 1 wherein the at least one signal generator is configured to generate signal wave forms for both linear and nonlinear radar waveforms.

5. The assembly of claim 1 wherein the assembly is configured to operate in linear and nonlinear modes, whereby the at least one switch operates to switch between the linear and nonlinear modes.

6. The assembly of claim 1 wherein the signal generated by the at least one signal generator is one of a single-tone pulse and a modulated chirp pulse having a carrier frequency that begins at a first frequency and increases linearly over a predetermined time interval.

7. The assembly of claim 1 wherein the signal generated by the at least one signal generator is a stepped-frequency chirp pulse.

8. The assembly of claim 1 wherein the transmitter is operatively connected to a transmitter antenna and wherein the receiver is operatively connected to a receiver antenna.

9. The assembly of claim 1 wherein the at least one filter comprises a low-pass filter to remove self-generated nonlinear distortion and wherein at least one second amplifier is connected to the at least one filter to boost the power of the signal generated by the signal generator to excite nonlinear responses from a target.

10. A radar assembly for linear and nonlinear radar transmission and reception comprising:

a transmitter for transmitting radar signals, the transmitter comprising;

a signal generator;

at least one first filter operatively connected to at least one signal generator;

at least one first amplifier operatively connected to the at least one filter;

a receiver operative to receive the received signals comprising linear and nonlinear responses from reflected transmitted signals;

the receiver comprising;

a first channel configured to process the linear response from the received signal;

a second channel configured to process the + nonlinear response from the received signal, wherein the second channel comprises at least one high pass filter configured to attenuate the linear response and at least one second amplifier operatively connected to the at least one high pass filter and configured to amplify the nonlinear response;

at least one switch operative to select one of the first or second channels through the at least one switch;

and

at least one display operatively connected to both the first and second channels for displaying both the linear and nonlinear responses.

11. The assembly of claim 10 wherein the at least one first filter, the at least one first amplifier and the at least one transmitter operate to process both linear and nonlinear radar signals.

12. The assembly of claim 10 wherein the transmitter is operatively connected to a transmitter antenna and wherein the receiver is operatively connected to a receiver antenna.

13. The assembly of claim 10 wherein the signal generator is configured to generate both linear and nonlinear radar waveforms.

14. The assembly of claim 13 wherein the signal generator is configured to generate a single-tone pulse that can be represented by

V_AWG=A_env cos(2π

·

f_pulse·

t)s(t)

with a carrier frequency f_pulse, an amplitude A_env and the pulse modulation is given by the switching waveform s(t);

s(t)=u(t)−

u(t−

D_cT)=s(t+T)D_cT=T_env

where T is the period and D_c is duty cycle, and the pulse is active during the time interval T_env.

15. The assembly of claim 13 wherein the signal generator is configured to generate a linear frequency-modulated chirp pulse having a carrier frequency that begins at a first frequency and increases linearly over a predetermined time interval.

16. The assembly of claim 13 wherein the signal generator is configured to generate a stepped-frequency chirp pulse having a carrier frequency that steps between discrete values that can be represented by

V_AWG=A_env cos [2π

·

f(t)·

t]s(t)

17. The assembly of claim 10 wherein the at least one first filter comprises a low-pass filter configured to remove self-generated nonlinear distortion and wherein the at least one first amplifier is operatively connected to the at least one first filter to boost the power of the signal generated by the signal generator to excite nonlinear responses from a target.

18. A radar assembly for linear and nonlinear radar transmission and reception comprising:

a base;

a transmitter operatively connected to the base configured to transmit linear and nonlinear radar signals;

a receiver configured to receive signals comprising linear and nonlinear responses from reflected transmitted signals, the receiver being operatively connected to one of the base or transmitter;

the transmitter configured to transmit linear radar signals in a first mode and nonlinear radar signals in a second mode, and the receiver configured to receive linear responses from the reflected transmitted signals in the first mode and nonlinear responses from the reflected transmitted signals in the second mode;

at least one antenna operatively connected to the receiver and the transmitter; and

at least one switch operatively connected to the receiver and configured to select between a first channel configured to process the linear response and a second channel configured to process the nonlinear response.

19. The radar assembly of claim 18 wherein the receiver and transmitter are mounted on the base, and wherein the transmitted radar signals are reflected by targets that reflect linear radar signals and targets that reflect nonlinear radar signals.

20. The radar assembly of claim 18 wherein the transmitter comprises a linear radar transmitter portion and a nonlinear radar transmitter portion and the at least one antenna is alternately connected to the linear and nonlinear radar transmitter portions by the at least one switch;

and wherein the receiver comprises a linear radar receiver portion and a nonlinear radar receiver portion and the at least one antenna is alternately connected to the linear and nonlinear radar receiver portions by the at least one switch.