Vehicle communication system using existing roadway loops

Claim 2

A communication system for enabling transfer of information between a vehicle and a stationary information location having a vehicle detector loop antenna, said loop antenna comprising part of a circuit containing conventional vehicle detector signals normally lying within a given frequency range, said system comprising: vehicle mounted transmitter means for enabling transmission of a preselected information signal over a relatively small distance range to said stationary information location for sensing by said vehicle detector loop antenna; vehicle mounted receiver means for receiving another information signal transmitted from said stationary information location via said vehicle detector loop antenna, said receiver means including means for distinguishing said another information signal from the conventional vehicle detector signals present in said vehicle detector loop antenna which lie within said given frequency range, said another information signal being transmitted in a transmitting frequency range different from said given frequency range of said conventional vehicle detector signals; and vehicle mounted antenna means selectively coupled to said transmitter means and said receiver means for inductive interaction with said vehicle detector loop antenna.

Claim 3

The communication system of claim 1 wherein said distinguishing means includes filter means having a signal pass band within the transmitting frequency range of said another information signal so that said conventional vehicle detector signals are rejected by said filter means.

Claim 4

The communication system of claim 2 wherein said another information signal is transmitted at a predetermined frequency outside the frequency range of said conventional vehicle detector signals, and wherein said distinguishing means further includes amplifier means coupled to the output of said filter means, a narrow band filter means for passing signals having said predetermined frequency, and detector means for converting those signals passing through said narrow band filter means to a signal form conformable with an associated control logic circuit.

Claim 5

The communication system of claim 1 wherein said vehicle mounted transmitter means includes means for generating a carrier frequency signal lying within said transmitting frequency range and containing said preselected information signal, and means coupled to said generating means and said vehicle mounted antenna means for amplifying said carrier frequency signal.

Claim 6

The communication system of claim 4 wherein said generating means includes an oscillator means for generating a carrier source signal, divider means for converting said carrier source signal to a carrier signal lying within said transmitting frequency range, and means for imparting said preselected information signal to said carrier frequency signal.

Claim 7

The communication system of claim 5 wherein said divider means includes means for generating a clock signal for said imparting means from said carrier source signal.

Claim 8

The communication system of claim 5 wherein said oscillator means comprises a crystal controlled oscillator.

Claim 9

A communication system for enabling transfer of information between a vehicle having an antenna and a stationary information location having a vehicle detector system, said vehicle detector system including a vehicle detector system loop antenna, said loop antenna comprising part of a circuit containing conventional vehicle detector signals normally lying within a given frequency range, said communication system comprising: stationary transmitter means for enabling transmission of a preselected information signal over a relatively small distance range to said vehicle for sensing by the vehicle antenna, said stationary transmitter means providing transmission of said preselected information signal in a transmitting frequency range different from the frequency range of the conventional vehicle detector system signals; and stationary receiver means for receiving another information signal transmitted from the vehicle via said vehicle antenna; said vehicle detector system loop antenna being selectively coupled to said stationary transmitter means and said receiver means for inductive interaction with the vehicle antenna, said stationary receiver means including means for distinguishing said another information signal from the conventional vehicle detector signals present in said vehicle detector system loop antenna.

Claim 10

A communication system for enabling transfer of information between a vehicle having an antenna and a stationary information location having a vehicle detector system, said vehicle detector system including a vehicle detector system loop antenna, said loop antenna comprising part of a circuit containing conventional vehicle detector signals normally lying within a given frequency range, said communication system comprising: stationary transmitter means for enabling transmission of a preselected information signal over a relatively small distance range to said vehicle for sensing by the vehicle antenna, said stationary transmitter means providing transmission of said preselected information signal in a transmitting frequency range different from the frequency range of the conventional vehicle detector system signals; and stationary receiver means for receiving another information signal transmitted from the vehicle via said vehicle antenna; said vehicle detector system loop antenna being selectively coupled to said stationary transmitter means and said receiver means for inductive interaction with the vehicle antenna, said stationary receiver means including means for distinguishing said another information signal from the conventional vehicle detector signals present in said vehicle detector system loop antenna.

Claim 11

The communication system of claim 8 wherein said preselected information signal and said another information signal are both transmitted in the same transmitting frequency range, and wherein said distinguishing means includes filter means having a signal pass band within said transmitting frequency range so that said conventional vehicle detector signals are rejected by said filter means.

Claim 12

The communication system of claim 9 wherein said preselected information signal and said another information signal are both transmitted at a predetermined transmitter frequency outside the frequency range of said conventional vehicle detector signals, and wherein said distinguishing means further includes amplifier means coupled to the output of said filter means, a narrow band filter means for passing signals having said predetermined transmitting frequency, and detector means for converting those signals passing through said narrow band filter means to a signal form conformable with an associated control logic circuit.

Claim 13

The communication system of claim 8 wherein said stationary transmitter means includes means for generating a carrier frequency signal lying within said transmitting frequency range and containing said preselected information signal, and means coupled to said generating means and said vehicle detector system loop antenna for amplifying said carrier frequency signal.

Claim 14

The communication system of claim 11 wherein said generating means includes an oscillator means for generating a carrier source signal, divider means for converting said carrier source signal to a carrier signal lying within said transmitting frequency range, and means for imparting said preselected information signal to said carrier signal.

Claim 15

The communication system of claim 12 wherein said divider means includes means for generating a clock signal for said imparting means from said carrier source signal.

Claim 16

The communication system of claim 12 wherein said oscillator means comprises a crystal controlled oscillator.