Target position radar
First Claim
1. In a Doppler traffic radar, a method of producing signal information in the radar receiver indicative of the relative position of one of a plurality of spaced-apart targets moving at different speeds, said method comprising the steps of:
- (a) providing an antenna having first and second relative power density radiation patterns which diverge from each other at an angle selected to cause the patterns to overlap in a predetermined interrelationship;
(b) transmitting radio frequency energy in a manner to cause simultaneous presence in said patterns of transmitted energy of the same frequency;
(c) receiving a return signal from said one target in response to said first pattern and providing therefrom a first Doppler signal having an amplitude proportional to the relative power density characteristic of said first pattern;
(d) receiving said return signal from said one target in response to said second pattern and providing therefrom a second Doppler signal having the same frequency as said first Doppler signal and having an amplitude proportional to the relative power density characteristic of said second pattern; and
(e) detecting the amplitudes of said first and second Doppler signals, whereby their amplitude relationship indicates the position of said one target in the overlapped radiation patterns.
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Accused Products
Abstract
A traffic radar unit capable of looking past the lead vehicle of oncoming traffic and discovering and identifying a violator employs master and slave antennas having diverging boresights that provide overlapping relative power density radiation patterns. The radar return signal from a target of interest is received by each antenna to produce two independent Doppler signals of the same frequency which are processed by respective master and slave signal processing channels. In the illustrated embodiment, a reference boresight is established in the overlapped patterns such that a target position along the reference boresight occurs at the time that the amplitudes of the two Doppler signals are equal. Controllable high pass filters whose passbands are shifted upwardly in response to return signals of increasing amplitude attenuate stronger, lower frequency interfering signals. The presence of a second Doppler signal in either channel having a frequency near the signal of interest causes the receiver to abort the tracking mode.
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Citations
15 Claims
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1. In a Doppler traffic radar, a method of producing signal information in the radar receiver indicative of the relative position of one of a plurality of spaced-apart targets moving at different speeds, said method comprising the steps of:
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(a) providing an antenna having first and second relative power density radiation patterns which diverge from each other at an angle selected to cause the patterns to overlap in a predetermined interrelationship; (b) transmitting radio frequency energy in a manner to cause simultaneous presence in said patterns of transmitted energy of the same frequency; (c) receiving a return signal from said one target in response to said first pattern and providing therefrom a first Doppler signal having an amplitude proportional to the relative power density characteristic of said first pattern; (d) receiving said return signal from said one target in response to said second pattern and providing therefrom a second Doppler signal having the same frequency as said first Doppler signal and having an amplitude proportional to the relative power density characteristic of said second pattern; and (e) detecting the amplitudes of said first and second Doppler signals, whereby their amplitude relationship indicates the position of said one target in the overlapped radiation patterns. - View Dependent Claims (2, 3, 4)
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5. In a Doppler traffic radar, a method of identifying a moving target at the time it intersects a reference boresight, said method comprising the steps of:
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(a) providing first and second closely spaced antenna elements with their respective boresights diverging from each other and each defining a predetermined angle with respect to said reference boresight; (b) simultaenously exciting said antenna elements with radio frequency energy of the same frequency; (c) detecting a return signal from said target received by each antenna element to provide first and second Doppler signals of the same frequency derived from said first and second antenna elements respectively, each of said Doppler signals having an amplitude proportional to the relative power density radiation pattern of the corresponding antenna element; and (d) detecting the time at which the amplitudes of said first and second Doppler signals bear a predetermined relationship to each other corresponding to a target position along said reference boresight. - View Dependent Claims (6, 7, 8)
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9. In a traffic radar:
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master antenna means having a first predetermined relative power density radiation pattern; slave antenna means having a second predetermined relative power density radiation pattern overlapping said first pattern and establishing a reference boresight in the overlapped patterns; means for causing simultaneous presence in said patterns of transmitted radio frequency energy of the same frequency; a master signal processing channel connected to said master antenna means and including means for deriving a first Doppler signal from an incoming return signal, means for tracking said first Doppler signal, and output means for providing a first output signal representative of its amplitude; a slave signal processing channel connected to said slave antenna means and including means fo deriving a second Doppler signal from said incoming return signal having the same frequency as said first Doppler signal, means for tracking said second Doppler signal, and output means for providing a second output signal representative of the amplitude of said second Doppler signal; and means responsive to said first and second output signals for determining when the amplitudes of said first and second Doppler signals bear a predetermined relationship to each other corresponding to a target position along said reference boresight. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification