Vehicle identification system, using microwaves
First Claim
1. A vehicle identification system comprising:
- a panel adapted to be mounted on a vehicle including tuned reflective means for directionally reflecting microwave energy in a predetermined frequency range,said panel also including transponder means comprising an antenna tuned to said predetermined frequency range, a digital coder, and a transponder circuit interconnecting said antenna and said fixed or adjustable coder for transmitting a coded signal upon reception by said antenna of microwave energy in said predetermined frequency range,an interrogating station including directional antenna means adapted to be aimed at a passing vehicle,transmitter means for transmitting microwave energy in said frequency range from said directional antenna means,a circulator interconnecting said antenna means and said transmitter, anda mixer and audio amplifier means also connected to the mixer for producing and amplifying a doppler beat frequency signal resulting from microwave energy reflected by the tuned reflective means on a passing vehicle for verifying that a vehicle is passing, irrespective of the operation of said transponder means, andsaid interrogating station also including intermediate frequency amplifier means for amplifying a coded intermediate frequency signal resulting from transmission of a coded signal by said transponder means for vehicle identification.
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Accused Products
Abstract
A vehicle identification system, using microwave, in which every vehicle to be identified has an identification panel attached to its side, containing a very low level power drain tunnel diode transponder and a digital coder plus a small battery and a resonant frequency array. Interrogating transmitter-receivers are placed at designated ground stations. For verification purposes there is a resonant reflective array printed on the identification panel to reflect back a doppler offset signal emitted by the interrogating transmitter, thereby registering that a vehicle with an identification panel has passed, even if the transponder has failed. Unlike optical scanners used for freight car identifications, this system cannot be disrupted by dirt, ice and snow. Vehicles do not have to slow down to be interrogated, and the emitted field strength from this plate is so low that F.C.C. licensing is not required. The code stored in the panel is readily programmable, if desired.
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Citations
12 Claims
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1. A vehicle identification system comprising:
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a panel adapted to be mounted on a vehicle including tuned reflective means for directionally reflecting microwave energy in a predetermined frequency range, said panel also including transponder means comprising an antenna tuned to said predetermined frequency range, a digital coder, and a transponder circuit interconnecting said antenna and said fixed or adjustable coder for transmitting a coded signal upon reception by said antenna of microwave energy in said predetermined frequency range, an interrogating station including directional antenna means adapted to be aimed at a passing vehicle, transmitter means for transmitting microwave energy in said frequency range from said directional antenna means, a circulator interconnecting said antenna means and said transmitter, and a mixer and audio amplifier means also connected to the mixer for producing and amplifying a doppler beat frequency signal resulting from microwave energy reflected by the tuned reflective means on a passing vehicle for verifying that a vehicle is passing, irrespective of the operation of said transponder means, and said interrogating station also including intermediate frequency amplifier means for amplifying a coded intermediate frequency signal resulting from transmission of a coded signal by said transponder means for vehicle identification. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A vehicle identification system comprising:
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tuned reflective means adapted to be mounted on a vehicle for directionally reflecting microwave energy in a predetermined frequency range, transponder means adapted to be mounted on the vehicle comprising an antenna tuned to said predetermined frequency range, a digital coder, and a transponder circuit interconnecting said antenna and said coder for transmitting a coded signal upon reception by said antenna of microwave energy in said predetermined frequency range, an interrogating station including directional antenna means adapted to be aimed at a passing vehicle, transmitter means for transmitting microwave energy in said frequency range from said directional antenna means, a mixer, a circulator interconnecting said directional antenna means and said transmitter and said mixer for producing a doppler beat frequency signal resulting from such transmitted microwave energy having been reflected by the tuned reflective means on a passing vehicle, audio amplifier means connected to said mixer for amplifying said doppler beat frequency signal for verifying that a vehicle is passing, irrespective of the operation of said transponder means, and said interrogating station also including intermediate frequency amplifier means for amplifying a coded intermediate frequency signal resulting from transmission of a coded signal by said transponder means for vehicle identification. - View Dependent Claims (12)
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Specification