Communications: electrical – Digital comparator systems
Patent
1976-12-22
1978-01-17
Boudreau, Leo H.
Communications: electrical
Digital comparator systems
343 65SS, G01S 956
Patent
active
040694720
ABSTRACT:
A foreground subject-identifying apparatus comprises a sweep signal generator for issuing a sweep signal having frequencies f.sub.s falling within a prescribed range; a carrier wave generator for producing a carrier wave having a frequency f.sub.0 ; a first frequency mixer for mixing output signals from the sweep signal generator and carrier wave generator to generate an output signal having a frequency f.sub.0 .+-.f.sub.s ; a first antenna through which to transmit an output signal from the first frequency mixer; a second antenna mounted on the foreground subject to receive an output signal sent forth from the first antenna; a coding circuit carried on the foreground subject which is provided with a plurality of resonance circuits resonating at different frequencies f.sub.T and adapted to form a specified code from a combination of these different resonance frequencies; a signal mixer for detecting an output signal from the second antenna to supply a signal having frequencies f.sub.s to the coding circuit and modulating the signal having a frequency f.sub.0 by resonance signals from the coding circuit to deliver a signal having a frequency f.sub.0 .+-.f.sub.T to the second antenna; a second frequency mixer for mixing an output signal having a frequency f.sub.0 from the carrier wave generator, and a signal having a frequency f.sub.0 .+-. f.sub.T received from the signal mixer through the second and first antennas and thereby issuing a signal having a frequency f.sub.T ; and a coded signal interpreting circuit for detecting resonance frequencies out of a signal delivered from the second frequency mixer, thereby interpreting a coded signal supplied from the coding circuit.
REFERENCES:
patent: 3072899 (1963-01-01), Kleist et al.
patent: 3169242 (1965-02-01), Davis et al.
patent: 3172102 (1965-03-01), Chapman
patent: 3384892 (1968-05-01), Postman
patent: 3427613 (1969-02-01), Kawahara et al.
patent: 3737911 (1973-06-01), Sakuragi et al.
patent: 3798642 (1974-03-01), Augenblick et al.
Kamata Shohichi
Kimura Yoshinori
Sakuragi Johji
Boudreau Leo H.
Tokyo Shibaura Electric Co. Ltd.
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