FM-CW RADAR RANGE SYSTEM

• US 3,789,398 A
• Filed: 03/12/1959
• Issued: 01/29/1974
• Est. Priority Date: 03/12/1959
• Status: Expired due to Term

• Current Assignee: ITT Corporation (ITT, Inc.)
• Original Assignee: Stephen J. Erst
• Inventors: Erst, Stephen J.
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US03/799,048
• Time in Patent Office: 5,437 Days
• Field of Search: 343/14
• US Class Current: 342/128
• CPC Class Codes: G01S 13/342 using sinusoidal modulation
• CPC Class Codes: G01S 13/347 using more than one modulation frequency

Abstract

5. A continuous wave radar system comprising: a source of sine wave signals; first means for frequency modulating a carrier frequency with said sine wave signals to provide a first frequency modulated signal; means for transmitting said first frequency modulated signal; second means for frequency modulating a carrier frequency with said sine wave signals to provide a second frequency modulated signal, the carrier frequency of said second frequency modulating means being the same as the carrier frequency of said first modulating means; phase shifting means coupled between said source of sine wave signals and one of said modulating means; means for receiving said first frequency modulated signal reflected from a distant object; means for mixing the received signal with said second frequency modulated signal; band pass filter means coupled to the output circuit of said mixing means and tuned to pass one side band component at least as high as the sixth contained in the output from said mixing means; and detector means coupled to said band pass filter means; and means for providing a fixed phase displacement between said transmitted signal and said other frequency modulated signal sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

Claims

1. A continuous wave radar system comprising:

means for providing a frequency modulated signal;

means for transmitting said signal;

means for receiving the transmitted signal reflected from a distant object;

means for mixing the received signal with another frequency modulated signal identical in frequency and waveform to said transmitted signal;

detector means coupled to the output circuit of said mixing means by band pass filter means, said band pass filter means being tuned to pass one side band component at least as high as the sixth contained in the output signal from said mixing means; and

means for providing a fixed phase displacement between said transmitted signal and said other frequency modulated signal sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

2. A continuous wave radar system comprising:

a source of sine wave signals;

means for frequency modulating a carrier frequency with said sine wave signals;

means for transmiTting the frequency modulated signal;

means for receiving the transmitted signal reflected from a distant object;

means for mixing the received signal with another frequency modulated signal identical in frequency and waveform to said transmitted signal;

detector means coupled to the output circuit of said mixing means by band pass filter means, said band pass filter means being tuned to pass one side band component at least as high as the sixth contained in the output signal from said mixing means; and

means for providing a fixed phase displacement between said transmitted signal and said other frequency modulated signal sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

3. A continuous wave radar system comprising:

a source of sine wave signals;

means for frequency modulating a carrier frequency with said sine wave signals, said modulating means having a relatively high modulation index and relatively mow deviation thereby generating high order side bands and preventing the generation of amplitude modulation signals;

means for transmitting the frequency modulated signal;

means for receiving the transmitted signal reflected from a distant object;

means for mixing the received signal with another frequency modulated signal identical in frequency and waveform to said transmitted signal;

band pass filter means coupled to the output circuit of said mixing means and tuned to pass one side band component at least as high as the sixth contained in the output signal from said mixing means;

detector means coupled to said band pass filter means; and

means for providing a fixed phase displacement between said transmitted signal and said other frequency modulated signal sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

4. A continuous wave radar system comprising:

a source of sine wave signal;

first means for frequency modulating a carrier frequency with said sine wave signals to provide a first frequency modulated signal;

means for transmitting said first frequency modulated signal;

second means for frequency modulating a carrier frequency with said sine wave signals to provide a second frequency modulated signal, the carrier frequency of said second modulating means being the same as the carrier frequency of said first modulating means;

means for shifting the phase of one of said frequency modulated signals with respect to the other;

means for receiving said first frequency modulated signal reflected from a distant object;

means for mixing the received signal with said second frequency modulated signal;

band pass filter means coupled to the output circuit of said mixing means and tuned to pass one side band component at least as high as the sixth contained in the output from said mixing means; and

detector means coupled to said band pass filter means;

said phase shifting means shifting the phase of said one frequency modulated signal by a fixed amount sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

6. A continuous wave radar system comprising:

a source of sine wave signals;

means for frequency modulating a carrier frequency with said sine wave signals;

means for transmitting the frequency modulated signal;

means for receiving said signal reflected from a distant object;

means for mixing the received signal and a portion of the transmitted signal;

means for shifting the phase of said portion of said transmitted signal with respect to said transmitted signal;

band pass filter means coupled to the output circuit of said mixing means and tuned to pass one side band component at least as high as the sixth contained in the output from said mixing means; and

detector means coupled to said band pass filter means;

said phase shifting means shifting the phase of said portion of said transmitted signal by a fixed amount sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

7. A continuous wave radar system comprising:

a source of sine wave signals;

means for frequency modulating a carrier frequency with said sine wave signals;

means for transmitting the frequency modulated signal;

means for receiving said signal reflected from a distant object;

mixing means having one input circuit coupled to said receiving means and its other input circuit coupled to said modulating means by time delay means for mixing the received signal with a portion of the transmitted signal phase shifted with respect to the transmitted signal;

band pass filter means coupled to the output circuit of said mixing means and tuned to pass one side band component at least as high as the sixth contained in the output from said mixing means; and

detector means coupled to said band pass filter means;

said time delay means shifting the phase of said portion of said transmitted signal by a fixed amount sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

8. The method of obtaining radar range discrimination in a continuous wave radar system comprising the steps of:

generating a first frequency modulated signal;

transmitting said first frequency modulated signal;

receiving said signal reflected from a distant object;

mixing the received signal with a second frequency modulated signal identical in frequency and waveform to said first frequency modulated signal;

filtering the signal resulting from said mixing to pass one side band;

at least as high as the sixth; and

shifting the phase of one of said first and second frequency modulated signals with respect to the other by a fixed amount sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

9. The method of claim 8 comprising the additional step of detecting the signal resulting from said filtering.

10. The method of obtaining radar range discrimination in a continuous wave radar system comprising the steps of:

generating sine wave signals;

frequency modulating a carrier frequency with said sine wave signals with a relatively high modulation index and relatively low deviation to provide a first frequency modulated signal having high order side bands without amplitUde modulation signals;

receiving the transmitted signal reflected from a distnant object;

providing a second frequency modulated signal identical to said first frequency modulated signal;

mixing the received signal with said second frequency modulated signal;

filtering the signal resulting from said mixing to pass one side band at least as high as the sixth;

detecting the signal resulting from said filtering; and

shifting the phase from one of said frequency modulated signals with respect to the other by a fixed amount sufficient to provide in said one side band a first response peak at close range and a second response peak at a substaitially greater range with no response peaks therebetween.

11. The method of obtaining radar range discrimination in a continuous wave radar system comprising the steps of:

generating sine wave signals;

frequency modulating a carrier frequency with said sine wave signals to provide a first frequency modulated signal;

transmitting said first frequency modulated signal;

frequency modulating said carrier frequency with said sine wave signals to provide a second frequency modulated signal;

receiving the transmitted signalreflected from a distant object;

mixing the received signal with said second frequency modulated signal;

filtering the signal resulting from said mixing to pass one side band at least as high as the sixth;

detecting the signal resulting from said filtering; and

shifting the phase from one of said frequency modulated signals with respect to the other by a fixed amount sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.

12. The method of obtaining radar range discrimination in a continuous wave radar system comprising the steps of:

generating sine wave signals;

frequency modulating a carrier frequency with said sine wave signals to provide a first frequency modulated signal;

transmitting said first frequency modulated signal;

receiving the transmitted signal;

mixing the received signal and a portion of the transmitted signal;

filtering the signal resulting from said mixing to pass one side band at least as high as the sixth;

detecting the signal resulting from said filtering; and

phase shifting said transmitted signal portion with respect to the transmitted signal by a fixed amount sufficient to provide in said one side band a first response peak at close range and a second response peak at a substantially greater range with no response peaks therebetween.