Automatic vehicle identification system capable of vehicle lane discrimination
First Claim
1. An automatic vehicle identification system capable of vehicle lane discrimination, the system comprising:
- a) a first directional antenna focused on a first vehicle lane;
b) a first interrogator unit in electrical communication with said first directional antenna, said interrogator unit being operable to transmit a first downlink message to, and to receive a first uplink message from, said first directional antenna;
c) a second directional antenna focused on a second vehicle lane;
d) a second interrogator unit in electrical communication with said second directional antenna, said interrogator unit being operable to transmit a second downlink message to, and to receive a second uplink message from, said second directional antenna;
e) a remote transponder carried on a vehicle in one of said vehicle lanes, said transponder having a transponder antenna operable to receive RF transmissions and having a field strength comparator operable to receive signals from said transponder antenna and to compare a first field strength pulse received from said first directional antenna to a second field strength pulse received from said second directional antenna.
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Accused Products
Abstract
A method of identifying an object and determining in which of at least two areas the object is located is disclosed. The method includes the steps of: focusing a first directional antenna (18) on a first area (28a), focusing a second directional antenna on a second area (28b), transmitting a first field strength pulse (44) from said first directional antenna (18), transmitting a second field strength pulse (46) from said second directional antenna (18), and comparing in a transponder (14) the first field strength pulse (44) to the second field strength pulse (46) to determine in which of the two areas (28a,28b) the transponder (14) is located. Other devices, systems and methods are also disclosed.
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Citations
37 Claims
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1. An automatic vehicle identification system capable of vehicle lane discrimination, the system comprising:
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a) a first directional antenna focused on a first vehicle lane; b) a first interrogator unit in electrical communication with said first directional antenna, said interrogator unit being operable to transmit a first downlink message to, and to receive a first uplink message from, said first directional antenna; c) a second directional antenna focused on a second vehicle lane; d) a second interrogator unit in electrical communication with said second directional antenna, said interrogator unit being operable to transmit a second downlink message to, and to receive a second uplink message from, said second directional antenna; e) a remote transponder carried on a vehicle in one of said vehicle lanes, said transponder having a transponder antenna operable to receive RF transmissions and having a field strength comparator operable to receive signals from said transponder antenna and to compare a first field strength pulse received from said first directional antenna to a second field strength pulse received from said second directional antenna. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An automatic vehicle identification system capable of vehicle lane discrimination, the system comprising:
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a) a first directional antenna focused on a first vehicle lane; b) a second directional antenna focused on a second vehicle lane; c) a first remote transponder carried on a first vehicle in said first vehicle lane, said transponder comprising a first transponder antenna operable to receive RF transmissions, a first field strength detector which converts a signal supplied by said first transponder antenna to a voltage which upon exceeding a threshold activates said first transponder, a first field strength comparator which compares a first field strength pulse received from said first directional antenna by said first transponder antenna to a second field strength pulse received from said second directional antenna by said first transponder antenna, a first field demodulator which is operable to demodulate an amplitude modulated first downlink message from the signal supplied by said first transponder antenna, a first transponder control circuit which receives said first demodulated downlink message from said first field demodulator and a signal from said first field strength comparator indicating whether the first vehicle is travelling in said first lane or said second lane, and a first backscatter modulator which, upon reception by said first transponder control circuit said first downlink message, is operable to backscatter modulate a first continuous wave signal applied to said first transponder antenna to generate a first uplink message, said first backscatter modulator operating under control of said first transponder control circuit; d) a second remote transponder carried on a second vehicle in said second vehicle lane, said transponder comprising a second transponder antenna operable to receive RF transmissions, a second field strength detector which converts a signal supplied by said second transponder antenna to a voltage which upon exceeding a threshold activates said second transponder, a second field strength comparator which compares a first field strength pulse received from said first directional antenna by said second transponder antenna to a second field strength pulse received from said second directional antenna by said second transponder antenna, a second field demodulator which is operable to demodulate an amplitude modulated second downlink message from the signal supplied by said second transponder antenna, a second transponder control circuit which receives said second demodulated downlink message from said second field demodulator and a signal from said second field strength comparator indicating whether the second vehicle is travelling in said first second lane or said second lane, and a second backscatter modulator which, upon reception by said second transponder control circuit said second downlink message, is operable to backscatter modulate a second continuous wave signal applied to said second transponder antenna to generate a second uplink message, said second backscatter modulator operating under control of said second transponder control circuit; and e) a toll plaza comprising i) a reference oscillator generating a reference carrier wave, ii) a first interrogator unit in electrical communication with said first directional antenna and with said reference oscillator, said interrogator unit having (1) a first transmitter which transmits a first wake-up burst which is of sufficient field strength at a first pre-selected distance to trigger said first field strength detector to activate said first transponder, transmits a downlink message to said first remote transponder, said downlink message being transmitted using On-Off Keying, and said transmitter further transmitting a first continuous wave illumination signal onto said first transponder so said first transponder may backscatter modulate said first continuous wave illumination signal to generate said first uplink message, (2) a first receiver for reception of said first uplink message and for separation of said first uplink message from spurious non-modulated reflections, and (3) a first control circuit for control of said first transmitter and said first receiver, said first control circuit operable to direct said first transmitter to send said first wake-up burst, followed by said first downlink message, said downlink message having periods of RF energy transmission including a first field strength pulse and periods during which no RF energy is transmitted including a first field strength pause, and said first control circuit still further operable to direct said first transmitter to send said first continuous wave illumination signal following said first downlink message and coincident with said first continuous wave illumination signal to direct said first receiver to receive said first uplink message; and iii) a second interrogator unit in electrical communication with said second directional antenna and with said reference oscillator, said second interrogator unit coordinated by said reference oscillator to said first interrogator unit and having (1) a second transmitter which transmits a second wake-up burst which is of sufficient field strength at a second pre-selected distance to trigger said second field strength detector to activate said second transponder, transmits a downlink message to said second remote transponder, said downlink message being transmitted using On-Off Keying, and said transmitter further transmitting a second continuous wave illumination signal onto said second transponder so said second transponder may backscatter modulate said second continuous wave illumination signal to generate said second uplink message, (2) a second receiver for reception of said second uplink message and for separation of said second uplink message from spurious non-modulated reflections, and (3) a second control circuit for control of said second transmitter and said second receiver, said second control circuit operable to direct said second transmitter to send said second wake-up burst, followed by said second downlink message, said downlink message having periods of RF energy transmission including a second field strength pulse during said first field strength pause and periods during which no RF energy is transmitted including the time during which said first field strength pulse is transmitted, and said second control circuit still further operable to direct said second transmitter to send said second continuous wave illumination signal following said second downlink message and coincident with said sending of said second continuous wave illumination signal to direct said second receiver to receive said second uplink message.
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9. A method of identifying an object and determining in which of at least two areas the object is located, the method comprising:
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a) focusing a first directional antenna on a first area; b) focusing a second directional antenna on a second area; c) transmitting a first field strength pulse by a first interrogator unit in electrical communication with said first directional antenna; d) transmitting a second field strength pulse by a second interrogator unit in electrical communication with said second directional antenna; and e) comparing in a transponder the first field strength pulse received from said first directional antenna to the second field strength pulse received from said second directional antenna whereby the transponder can determine in which of the two areas it is located by the relative magnitude of the received first and second field strength pulses. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. An automatic vehicle identification system capable of vehicle lane discrimination, the system comprising:
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a. a first directional antenna focused on a first vehicle lane; b. a first interrogator unit in electrical communication with said first directional antenna, said interrogator unit being operable to transmit a first downlink message to, and to receive a first uplink message from, said first directional antenna; c. a second directional antenna focused on a second vehicle lane; d. a second interrogator unit in electrical communication with said second directional antenna, said interrogator unit being operable to transmit a second downlink message to, and to receive a second uplink message from, said second directional antenna; and e. a remote transponder carried on a vehicle in one of said vehicle lanes, said transponder having i. a transponder antenna operable to receive RF transmissions, ii. a field strength comparator operable to receive signals from said transponder antenna and to compare a first field strength pulse received from said first directional antenna to a second field strength pulse received from said second directional antenna, iii. a modulator operable to modulate a carrier with information contained within said remote transponder, and iv. a control circuit for receiving the results of said field strength comparison and for enabling said modulator. - View Dependent Claims (27, 28)
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29. A remote transponder for communicating with an interrogator for the purposes of automatic vehicle identification, said transponder carried on a vehicle travelling on a vehicle lane and comprising:
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a. a transponder antenna operable to receive RF transmissions; b. a field strength comparator operable to receive signals from said transponder antenna and to compare a first field strength pulse received from a first interrogator directional antenna to a second field strength pulse received from a second interrogator directional antenna; and c. a control circuit for receiving the results of said field strength comparison and for enabling said transponder to respond to interrogations from the interrogator associated with the vehicle lane in which the vehicle carrying said transponder is travelling. - View Dependent Claims (30, 31, 32)
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33. A toll plaza comprising:
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a. a first directional antenna focused on a first vehicle lane; b. a second directional antenna focused on a second vehicle lane; c. a first interrogator in electrical communication with said first directional antenna; d. a second interrogator in electrical communication with said second directional antenna; e. a control circuit for control of said first and second interrogator units, said control circuit operable to direct each of said first and second interrogator units to send selected periods of RF energy transmission wherein each interrogator unit sends an identifying field strength pulse via its respective directional antenna during a period in which no RF energy is transmitted from the other interrogator unit whereby said transponder may compare the first field strength pulse received from said first directional antenna to a second field strength pulse received from said second directional antenna. - View Dependent Claims (34)
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35. An interrogator for use in an automatic vehicle, said interrogator comprising:
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a. a transmitter, said transmitter operable to transmit a downlink message to said transponder; and b. a control circuit for control of said transmitter, said control circuit operable to direct said transmitter to send said downlink message, wherein said downlink message comprises periods of RF energy transmission including a field strength pulse and periods during which no RF energy is transmitted including a field strength pause, whereby a remote transponder may compare the amplitude, as received at said transponder, of said field strength pulse to the amplitude of another field strength pulse emitted by another interrogator during said field strength pause. - View Dependent Claims (36)
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37. An interrogator for use in an automatic vehicle, said interrogator comprising:
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a. a transmitter, said transmitter operable to; i. transmit a wake-up burst, which is of sufficient field strength at a pre-selected distance to activate a transponder, ii. transmit a downlink message to said transponder, and iii. transmit a continuous wave illumination signal onto said transponder such that said transponder may backscatter modulate said continuous wave illumination signal thereby generating an uplink message; b. a receiver for reception of said uplink message and for separation of said uplink message from spurious non-modulated reflections; and c. a control circuit for control of said transmitter and said receiver, said control circuit operable to direct said transmitter to send said wake-up burst, followed by said downlink message, said downlink message having periods of RF energy transmission including a field strength pulse and periods during which no RF energy is transmitted including a field strength pause, and said control circuit still further operable to direct said transmitter to send said continuous wave illumination signal following said downlink message and coincident with said continuous wave illumination signal to direct said receiver to receive said uplink message.
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Specification