Communications: directive radio wave systems and devices (e.g. – Determining velocity
Patent
1995-06-07
1996-07-02
Sotomayor, John B.
Communications: directive radio wave systems and devices (e.g.,
Determining velocity
342108, 342114, 342115, G01S 1358
Patent
active
055326978
ABSTRACT:
A speed measuring apparatus includes: a modulation circuit for carrying out a direct spread modulation with respect to a transmission carrier signal using coded two-phase random signals; an antenna unit for transmitting the modulated transmission carrier signal as a radio-wave toward an object and for receiving a reflected wave from the object; a demodulation circuit for demodulating a signal corresponding to the received reflected wave using the transmission carrier signal, to thereby generate intermediate frequency signals; a correlation circuit for making correlation between the intermediate frequency signals and signals each having the same code as that of the coded two-phase random signal and having a phase delayed by a predetermined time; a Doppler detecting unit for extracting from an output signal of the correlation circuit a Doppler frequency component contained in a signal which has been propagated by way of a propagation path existing in a specified distance range, and for generating speed information based on the extracted Doppler frequency component; and a computing unit for computing a movement distance and a position of the railroad vehicle over the whole track, on a real-time basis, using the generated speed information and fixed-point position information input from an outside of the apparatus. By the constitution, it is possible to precisely measure a speed of the railroad vehicle without being subject to the influence by a slip or glide of the wheels under any circumstances. It is also possible to specify a movement distance and position of the vehicle on a real-time basis.
REFERENCES:
patent: 4107680 (1978-08-01), Kaplan
patent: 4115772 (1978-09-01), Valdes
patent: 4697186 (1987-09-01), Rock
patent: 5448243 (1995-09-01), Bethke et al.
patent: 5467091 (1995-11-01), Watkins et al.
"Spread Spectrum Systems With Commercial Applications", Robert C. Dixon, Direct Sequence Systems, 3rd Ed., pp. 18-33, 62-85, 114-133 and 158-193.
Hidaka Keiki
Uehara Shigekatsu
East Japan Railway Company
Mitsubishi Precision Co., Ltd.
Sotomayor John B.
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