04104630 is referenced by 69 patents and cites 6 patents.

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.

Title
Vehicle identification system, using microwaves
Application Number
5/698468
Publication Number
4104630
Application Date
June 21, 1976
Publication Date
August 1, 1978
Inventor
Norman E Chasek
24 Briar Brae Rd., Stamford, 06903
CT, US
Agent
Parmelee Johnson Bollinger & Bramblett
IPC
G01S 9/56
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