Monitoring process and system
First Claim
1. A process for monitoring a moving object, including the steps of:
- generating an optical signal modulated at a modulation frequency;
transmitting said optical signal across a path of said moving object;
detecting changes in a received signal due to movement of said object by monitoring substantially at said modulation frequency; and
determining at least one parameter of said object on the basis of said changes.
1 Assignment
0 Petitions
Accused Products
Abstract
A monitoring system includes a transmitter (102) with two transmit modules (208, 210) and a receiver (104) with two receive modules (212, 214). Each of the transmit modules (208, 210) generates an optical signal modulated at a unique frequency. The optical signals are transmitted across a roadway (112) and are detected by the receive modules (212, 214). When a vehicle (110) moves between the transmitter (102) and receiver (104), the optical signals are blocked. The receiver (104) generates timestamped make and break events corresponding to the blocking and unblocking of the signals, and these are used to determine parameters for the vehicle (110) such as velocity and vehicle classification. Because each signal is modulated at a different frequency, each receive module (212, 214) can distinguish the signals received from each of the transmit modules (208, 210), allowing the lane position of the vehicle (110) in a multi-lane roadway (112) to be determined.
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Citations
64 Claims
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1. A process for monitoring a moving object, including the steps of:
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generating an optical signal modulated at a modulation frequency;
transmitting said optical signal across a path of said moving object;
detecting changes in a received signal due to movement of said object by monitoring substantially at said modulation frequency; and
determining at least one parameter of said object on the basis of said changes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 38, 39, 40, 41, 42, 43, 44, 61, 62, 63)
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- 14. A process for determining a position of a moving object, including associating a time value with at least one make or break event for each of at least three signals due to the passage of said object between a transmitter and a receiver of each of said signals, at least one of said signals being substantially inclined with respect to another of said signals, and determining the position of said object in a direction substantially transverse to said moving direction by comparing said time values.
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20. A process for determining at least one parameter of a moving object from timestamped make and break events representing the making and breaking of first and second signals due to the passage of at least two moving objects past two detection locations for said signals, said locations mutually spaced in a moving direction of said objects, and said at least two moving objects being mutually spaced substantially transverse to said moving direction, said process including:
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selecting at least two events for said first signal;
for each selected event;
forming pairs of said selected event with events of the same type for said second signal;
for each pair, determining a velocity value from the timestamp values of said pair;
forming at least one pair of correlated event pairs by correlating event pairs for a selected event with event pairs for another selected event having a substantially equal velocity;
for each pair of correlated event pairs, determining a length value from timestamp values of said pair of correlated event pairs;
associating with said object a pair of correlated event pairs whose length value is less than a pre-determined value; and
determining at least one parameter of said object from timestamp values of said associated event pairs.
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21. A process for discriminating between objects moving in a moving direction and spaced substantially transverse to said moving direction, including:
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sending signals across a path of said moving objects;
detecting changes in state of said signals and recording events for said changes with respective times; and
processing said events of said signals to group events corresponding to a respective moving object on the basis of said times for said events. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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- 28. A process for monitoring a moving object, including receiving an optical signal modulated at a modulation frequency, converting said optical signal to an electrical signal, digitising said electrical signal, and downconverting said digitised signal to provide data representative of at least one parameter of said object.
- 32. A system for monitoring a moving object, including a receiver for receiving an optical signal modulated at a modulation frequency, said receiver including an input module for converting said optical signal to an electrical signal, an analog-to-digital (ADC) converter for digitising said electrical signal, and a digital signal processor (DSP) for demodulating said digitised signal and providing output data representative of at least one parameter of said object.
- 45. A receive module for receiving a signal modulated at a modulation frequency, said receive module including a sensor coupled to an input circuit having at least one variable resonant circuit, and feedback circuitry for matching the resonant frequency of said resonant circuit to said modulation frequency to maximise the input impedance of the input circuit at said modulation frequency.
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59. A receiver including at least two receive modules, said receive modules being mutually spaced in a moving direction of an object, and each receive module being adapted to receive an optical signal modulated at a unique frequency.
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60. A system for monitoring a moving object, including at least two transmitter modules for transmitting respective optical signals, each of said optical signals being modulated at a unique frequency.
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64. A monitoring system for vehicles, including:
transmit modules for transmitting separated optical signals at respective modulation frequencies across a carriageway for said vehicles;
receive modules for detecting optical signals substantially at said modulation frequencies, respectively;
means for generating make and break event data corresponding to unblocking and blocking of said signals by at least one of said vehicles; and
means for determining at least one parameter for the vehicle on the basis of said event data, which includes time values corresponding to said unblocking and blocking.
Specification