Vehicle proximity sensing and control system
First Claim
1. A proximity sensing and control system for a vehicle having powered drive means, the system comprising, in combination:
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field within the desired operating range of the system;
a radio receiver and associated receiving antenna for sensing the level of the electromagnetic field thereat, one of said antennas being mounted on said vehicle and the other antenna being mounted remote therefrom, so the spacing therebetween varies as the vehicle is moved;
first control means for carrying out a first control operation when the transmitting and receiving antennas are relatively widely spaced apart;
second control means for carrying out a second control operation when the transmitters and receiving antennas are relatively closely spaced apart, the relative signal strengths at the receiving antenna being vastly different for these two relative spacings;
said radio receiver including a given received signal output point;
first and second range sensing circuits connected in parallel to said received signal output point and respectively including first and second signal level detecting means responsive to given signal levels indicative respectively of said relatively wide and close spacings of said transmitting and receiving antennas by initiation of operation respectively of said first and second control means, and first and second adjusting means associated with said first and second range sensing circuits for adjusting the level of the received signal at said received signal output point which effects operation of the associated control means.
2 Assignments
0 Petitions
Accused Products
Abstract
A position detecting and control system for a vehicle includes a low frequency transmitter and associated antenna and a receiver and associated antenna, one of the antennas being mounted on the vehicle so the distance between the antenna carried by the vehicle and the other antenna is determined by the amplitude of the signal induced in the receiving antenna. The frequency of the transmitter is such that the distances to be monitored are a small fraction of the wavelength of the frequency involved, and any significant signal variations due to signal reflections which can reinforce or cancel the received signal are avoided. The system monitors at least two different spacings between the transmitting and receiving antennas where the signals received at the receiving antenna are of widely different orders of magnitude. Separate range detecting circuits are coupled to a common point of the receiver, each of which includes an attenuator at the input thereof for adjusting the level of the signal to be fed to an associated signal level detector which operates a control device when the signal at the receiver output point involved reaches a level indicating the associated spacing to be monitored.
24 Citations
21 Claims
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1. A proximity sensing and control system for a vehicle having powered drive means, the system comprising, in combination:
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field within the desired operating range of the system;
a radio receiver and associated receiving antenna for sensing the level of the electromagnetic field thereat, one of said antennas being mounted on said vehicle and the other antenna being mounted remote therefrom, so the spacing therebetween varies as the vehicle is moved;
first control means for carrying out a first control operation when the transmitting and receiving antennas are relatively widely spaced apart;
second control means for carrying out a second control operation when the transmitters and receiving antennas are relatively closely spaced apart, the relative signal strengths at the receiving antenna being vastly different for these two relative spacings;
said radio receiver including a given received signal output point;
first and second range sensing circuits connected in parallel to said received signal output point and respectively including first and second signal level detecting means responsive to given signal levels indicative respectively of said relatively wide and close spacings of said transmitting and receiving antennas by initiation of operation respectively of said first and second control means, and first and second adjusting means associated with said first and second range sensing circuits for adjusting the level of the received signal at said received signal output point which effects operation of the associated control means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field within the desired operating range of the system;
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15. A proximity sensing and control system for a vehicle having powered drive means, the sytem comprising, in combination:
- a radio transmitter and associated transmitting antenna associated with the system to radiate an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field in the desired operating range of the system;
a radio receiver and associated receiving antenna for sensing the level of the electromagnetic field thereat, one of said antennas being mounted on said vehicle and the other antenna being mounted remote therefrom, so the spacing therebetween varies as the vehicle is moved;
the receiver including an amplifier capable of amplifying signals over at least about the order of magnitude of 60db input voltage range, such range corresponding to the electromagnetic field strength at the extremeties of the desired operating distances;
A plurality of range sensing circuits including respective signal attenuators coupled to the output of said amplifier and capable of attenuating the wide input signal levels to similar levels from signals corresponding to those received at the associated monitoring distances to be detected; and
a signal processing circuit following each of said attenuators, each of said processing circuits including, in the order named, a clipper, narrow band filter, signal level detector and control device coupled in tandem, said filter having a bandwidth which is a small fraction of the bandwidth of said receiver amplifier and at least as wide as required to accommodate the expected frequency variations of the desired signal, said clipper clipping the voltage at a level which is greater than the level which the desired signal is required to operate the signal level detector, the control means being operated by the associated signal level detector when the signal level is reached corresponding to the transmitting to receiving antenna spacing to be monitored there by.
- a radio transmitter and associated transmitting antenna associated with the system to radiate an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field in the desired operating range of the system;
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16. A proximity sesing and control system for a vehicle having powered drive means, the system comprising, in combination:
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally ocur, and the induction field component predominates in strength over the electric field within the desired operating range of the system;
a radio receiver and associated receiving antenna for sensing the level of the electromagnetic field thereat, and providing at a received amplified signal output point an amplifier proportional to the signal sensed by the receiving antenna, one of said antennas being mounted on said vehicle and the other antenna being mounted remote therefrom, so the spacing therebetween varies as the vehicle is moved;
control means for carrying out one or more control operations in response to the amplitude of the signal received by said receiving antennas indicating one or more spacings between said transmitting and receiving antennas;
range sensing circuit means including signal level detecting means responsive to a given signal level by operating said control means means adjusting the level of the received signal at said received signal output point which effects operation of the associated control means, clipper means associated with said range sensing circuit means coupled between said received amplifier signal output point and the input of said signal level detecting means, which clipper means clips the waveform of a signal fed thereto at a level above that which the receive signals thereat would attain when said transmitting and receiving antennas are at one or more given spacings to be monitored and narrow bandpass filter means coupled to the output of said clipper means which filter means passes only signals of at least or not much more than a range of frequencies compatible with the frequency stability of said transmitter.
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally ocur, and the induction field component predominates in strength over the electric field within the desired operating range of the system;
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17. A proximity sensing and control system for a vehicle having powered drive means, the system comprising, in combination:
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field within the desired operating range of the system, said transmitter including an output power amplifier stage to which said transmitting antenna is coupled, antenna circuit tuning means connected to said transmitting antenna for establishing a tuned circuit at at the desired transmitting frequency of the transmitter, said power amplifier stage being such that current flow through a given portion thereof decreases to a given desired low level when the power amplifier stage is not driven to a sufficient degree or the antenna circuit is de-tuned to an undesirable degree, and the current in said given portion of said power amplifier circuit rises to an undesiredly high level if the antenna circuit is short circuited;
a receiver and associated receiving antenna for sensing the level of the electromagnetic field thereat as a result of the signal generated by said transmitting antenna;
signal level detecting means associated with said receiver for effecting a given control operation when a signal in said receiver reaches a given level; and
a monitoring system for detecting the proper operation of said transmitter, said monitoring system including signal detector and level responsive means responsive to the reduction of current in said given portion of said power amplifier to said low level and also responsive to the raising of said power amplifier current to said undesirably high level for alerting in either case an operator as to a fault in the transmitter. - View Dependent Claims (18)
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field within the desired operating range of the system, said transmitter including an output power amplifier stage to which said transmitting antenna is coupled, antenna circuit tuning means connected to said transmitting antenna for establishing a tuned circuit at at the desired transmitting frequency of the transmitter, said power amplifier stage being such that current flow through a given portion thereof decreases to a given desired low level when the power amplifier stage is not driven to a sufficient degree or the antenna circuit is de-tuned to an undesirable degree, and the current in said given portion of said power amplifier circuit rises to an undesiredly high level if the antenna circuit is short circuited;
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19. A proximity sensing and control system for a vehicle having powered drive means, the system comprising, in combination:
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field within the desired operating range of the system;
a radio receiver and associated receiving antenna for sensing the level of the electromagnetic field thereat, one of said antennas being mounted on said vehicle and the other antenna being mounted remote therefrom, so the spacing therebetween varies as the vehicle is moved;
first control means for carrying out a first control operation when the transmitting and receiving antennas are relatively widely spaced apart;
second control means for carrying out a second control operation when the transmittersand receiving antennas are relatively closely spaced apart, the relative signal strengths at the receiving antenna being vastly different for these two relative spacings;
said radio receiver including a given received amplified signal output point;
first and second range sensing circuits respectively including first and second signal level detecting means responsive to given signal levels indicative respectively of said relatively wide and close spacings of said transmitting and receiving antennas by initiation of operation respectively of said first and second control means, and operation of said first control means automatically reducing and limiting the speed of said powered drive means and operation of said second control means stopping said vehicle independently of said manually operable control means. - View Dependent Claims (20)
- a radio transmitter and associated transmitting antenna associated with the system for radiating an alternating electromagnetic field at a low enough frequency such that signal reinforcement or attenuation at a receiving location due to signal reflections from nearby objects does not generally occur, and the induction field component predominates in strength over the electric field within the desired operating range of the system;
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21. In a control system comprising, a superheterodyne receiver and associated receiving antenna for sensing the level of a transmitted electromagnetic field thereat;
- said receiver comprising a first local oscillator, a mixer coupled to said receiving antenna and local oscillator to provide a beat intermediate frequency signal from the received signal received by said receiver antenna and the output of said local oscillator, and an intermediate frequency amplifier coupled to output of said first mixer; and
a signal level detecting means for effecting a control operation when the output signal of said amplifier reaches a given level;
the improvement comprising a monitoring system for monitoring the operation of the receiver said monitoring system comprising a signal generating means including a source of a signal having a frequency which when added or subtracted from the signal of said local oscillator produces a pilot signal substantailly different from said intermediate frequency but which passes through said intermediate frequency amplifier at an amplitude which can be detected when the receiver is operating properly;
a secon mixer for receiving the output of said local oscillator and said pilot signal generating means and producing said pilot signal at said second beat frequency;
means for adjusting the amplitude of the pilot signal produced by said second mixer;
a pilot signal detecting circuit coupled to the output of said intermediate frequency amplifier and including pilot signal level responsive means responsive to the dropping of the pilot signal fed thereto to a given monitoring level for indicating the presence of an inadequately operating receiver; and
said pilot signal detecting circuit including means for filtering out said intermediate frequency signal resulting from the signal received by said receiving antenna wherein the pilot signal level responsive means responds only to the pilot signal.
- said receiver comprising a first local oscillator, a mixer coupled to said receiving antenna and local oscillator to provide a beat intermediate frequency signal from the received signal received by said receiver antenna and the output of said local oscillator, and an intermediate frequency amplifier coupled to output of said first mixer; and
Specification