Claims
- 1. A method for measuring a distance to a target by transmitting a frequency-modulated electromagnetic wave to the target, receiving a reflected wave from the target, mixing the thus-received wave and the thus-transmitted wave into a beat transmitted wave into a beat wave and then detecting the beat wave, which comprises:
- mixing the beat wave with a sine wave having a frequency f.sub.1 and extracting an upper sideband wave of a plurality of sideband waves of the resultant mixed wave, and then mixing the thus extracted upper sideband wave with a sine wave having a frequency f.sub.2 and extracting a lower sideband wave of said plurality of sideband waves of said resulting mixed wave, so that phase modulation is applied to the beat wave according to the relationship: 1/.vertline.f.sub.1 -f.sub.2 .vertline.;
- counting the number of peaks of the thus-phase modulated beat wave for the period 1/.vertline.f.sub.1 -f.sub.2 .vertline. of the phase modulation; and thereafter,
- computing the distance to the target on the basis of the result of counting the number of peaks.
- 2. A method for measuring a distance to a target by transmitting a frequency-modulated electromagnetic wave to the target, receiving a reflected wave from the target, mixing the thus-received wave and the thus-transmitted wave into a beat wave and then detecting the beat wave, which comprises:
- moving a lance into the target area after calibrating said lance outside the target area;
- mixing the beat wave with a sine wave having a frequency f.sub.1 and extracting an upper sideband wave of a plurality of sideband waves of the resultant mixed wave, and then mixing the thus extracted upper sideband wave with a sine wave having a frequency f.sub.2 and extracting a lower sideband wave of said plurality of sideband waves of said resulting mixing wave, so that phase modulation is applied to the beat wave according to the relationship: 1/.vertline.f.sub.1 -f.sub.2 .vertline.;
- counting the number of peaks of the thus-phase modulated beat wave for the period 1/.vertline.f.sub.1 -f.sub.2 .vertline. of the phase modulation; and thereafter,
- computing the distance to the target on the basis of the result of counting the number of peaks.
- 3. A method for measuring a distance to a target by transmitting a frequency-modulated electromagnetic wave to the target, receiving a reflected wave from the target, mixing the thus-received wave and the thus-transmitted wave into a beat wave and then detecting the beat wave, which comprises:
- mixing the beat wave with a sine wave having a frequency f.sub.1 and extracting a lower sideband wave of a plurality of sideband waves of the resultant mixed wave, and then mixing the thus extracted lower sideband wave with a sine wave having a frequency f.sub.2 and extracting an upper sideband wave of said plurality of sideband waves of said resulting mixed wave, so that phase modulation is applied to the beat wave according to the relationship: 1/.vertline.f.sub.1 -f.sub.2 .vertline.;
- counting the number of peaks of the thus-phase modulated beat wave for the period 1/.vertline.f.sub.1 -f.sub.2 .vertline. of the phase modulation; and thereafter,
- computing the distance to the target on the basis of the result of counting the number of peaks.
- 4. A method for measuring a distance to a target by transmitting a frequency-modulated electromagnetic wave to the target, receiving a reflected wave from the target mixing the thus-received wave and the thus-transmitted wave into a beat wave and then detecting the beat wave, which comprises:
- moving a lance into the target area after calibrating said lance outside the target area;
- mixing the beat wave with a sine wave having a frequency f.sub.1 and extracting a lower sideband wave of a plurality of sideband waves of the resultant mixed wave, and then mixing the thus extracted lower sideband wave with a sine wave having a frequency f.sub.2 and extracting an upper sideband wave of said plurality of sideband waves of said resulting mixed wave, so that phase modulation is applied to the beat wave according to the relationship: 1/.vertline.f.sub.1 -f.sub.2 .vertline.;
- counting the number of peaks of the thus-phase modulated beat wave for the period 1/.vertline.f.sub.1 -f.sub.2 .vertline. of the phase modulation; and thereafter,
- computing the distance to the target on the basis of the result of counting the number of peaks.
Priority Claims (1)
Number |
Date |
Country |
Kind |
58-70808 |
Apr 1983 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 601,584, filed Apr. 18, 1984, now abandoned.
US Referenced Citations (16)
Non-Patent Literature Citations (3)
Entry |
Ismail, M. A. W., "A Precise New System of FM Radar", Proceedings of the IRE, Sep. 1956, pp. 1140-1145. |
Skolnik, Introduction to Radar Systems, pp. 96-101, 1962. |
Belsterling, C. A., "A Look at Level Measurement Methods", Instruments and Control Systems, Apr. 1981, pp. 37-45. |
Continuations (1)
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Number |
Date |
Country |
Parent |
601584 |
Apr 1984 |
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