Transponder having microprocessor generated frequency shift signals
First Claim
1. In a transponder for transmitting an electromagnetic signal based on previously stored information in said transponder, to a remote interrogating station when triggered by a signal transmitted from said station to said transponder, the improvement comprising:
- a microprocessor in said transponder having a predetermined cycle time;
means programming said microprocessor for generating a first number of pulses, each said pulse having a period corresponding to a first multiple of said cycle time, said first multiple defining a first signal frequency;
means programming said microprocessor for generating a second number of pulses, said pulses occurring at a period corresponding to a second multiple of said cycle time, said second multiple defining a second signal frequency;
means generating groups of said first and second pulses, said groups defining a frequency shift keyed signal; and
means modulating said frequency shift keyed signals in accordance with said stored information, thereby generating a transponder response to said interrogating station signal and,means in said transponder transmitting said frequency shift signals to said interrogating station.
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Accused Products
Abstract
An improved transponder for use in identifying an controlling vehicles wherein transponders mounted on vehicles respond to signals from a fixed location interrogator providing information relative to the vehicle or other data as required. The transponder disclosed in particular utilizes an improved method of providing frequency shift keyed (FSK) signals in response to a trigger or command signal received from a ground mounted loop or antenna. As disclosed, the transponder of the invention generates FSK signals through programming multiple microprocessor loops of predetermined duration, each loop providing microprocessor highs and lows for transmission to the interrogating station. Utilization of the inherently accurate microprocessor cycle time to generate distinct FSK signals avoids problems with ordinarily used analog frequency generating devices.
11 Citations
6 Claims
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1. In a transponder for transmitting an electromagnetic signal based on previously stored information in said transponder, to a remote interrogating station when triggered by a signal transmitted from said station to said transponder, the improvement comprising:
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a microprocessor in said transponder having a predetermined cycle time; means programming said microprocessor for generating a first number of pulses, each said pulse having a period corresponding to a first multiple of said cycle time, said first multiple defining a first signal frequency; means programming said microprocessor for generating a second number of pulses, said pulses occurring at a period corresponding to a second multiple of said cycle time, said second multiple defining a second signal frequency; means generating groups of said first and second pulses, said groups defining a frequency shift keyed signal; and means modulating said frequency shift keyed signals in accordance with said stored information, thereby generating a transponder response to said interrogating station signal and, means in said transponder transmitting said frequency shift signals to said interrogating station. - View Dependent Claims (2, 3, 4)
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5. In combination, a transponder mounted on a vehicle traversing a roadway, said transponder electromagnetically transmitting information relating to said vehicle to an adjacent interrogating station, when said transponder is signalled by said interrogator, comprising:
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a microprocessor; means storing information relating to a vehicle in said microprocessor; means in said transponder receiving an interrogator signal, said means enabling said microprocessor; means programming said microprocessor, for generating first and second frequency shift signals, said signals having first and second periods and duration, respectively; means in said program modulating said signals, with said vehicular information; and
,means in said transponder transmitting said frequency shift signals to said interrogator. - View Dependent Claims (6)
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Specification