Loop powered radar rangefinder
First Claim
1. A pulse-echo radar rangefinder coupleable to a two-wire process control loop for measuring range to a target, comprising:
- an antenna, a transmission line, a pulsed RF transmitter-receiver coupled by the transmission line to the antenna for transmitting RF pulses to the antenna and receiving RF pulses from the antenna, the RF pulses from the antenna including echo pulses from a target and reflected reference pulses from the antenna itself, the echo pulses being produced by radiating RF pulses from the antenna to the target and receiving reflected pulses back from the target, measurement circuitry coupled to the transmitter-receiver for determining range solely from the reference pulses and echo pulses.
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Accused Products
Abstract
A pulse-echo radar measures non-contact range while powered from a two-wire process control loop. A key improvement over prior loop-powered pulse-echo radar is the use of carrier-based emissions rather than carrier-free ultrawideband impulses, which are prohibited by FCC regulations. The radar is based on a swept range-gate homodyne transceiver having a single RF transistor and a single antenna separated from the radar transceiver by a transmission line. The transmission line offers operational flexibility while imparting a reflection, or timing fiducial, at the antenna plane. Time-of-flight measurements are based on the time difference between a reflected fiducial pulse and an echo pulse, thereby eliminating accuracy-degrading propagation delays in the transmitters and receivers of prior radars. The loop-powered rangefinder further incorporates a current regulator for improved signaling accuracy, a simplified sensitivity-time-control (STC) based on a variable transconductance element, and a jam detector. Applications include industrial tank level measurement and control, vehicular control, and robotics.
123 Citations
15 Claims
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1. A pulse-echo radar rangefinder coupleable to a two-wire process control loop for measuring range to a target, comprising:
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an antenna, a transmission line, a pulsed RF transmitter-receiver coupled by the transmission line to the antenna for transmitting RF pulses to the antenna and receiving RF pulses from the antenna, the RF pulses from the antenna including echo pulses from a target and reflected reference pulses from the antenna itself, the echo pulses being produced by radiating RF pulses from the antenna to the target and receiving reflected pulses back from the target, measurement circuitry coupled to the transmitter-receiver for determining range solely from the reference pulses and echo pulses. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A pulse-echo radar apparatus, comprising:
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a pulsed RF transmitter-receiver, an antenna for radiating pulses to a target and receiving reflected echo pulses back from the target, a transmission line or waveguide coupled between the transmitter-receiver and the antenna, range measurement circuitry responsive to the time-of-flight difference in reflections from the antenna and reflections from the target. - View Dependent Claims (8, 9, 10, 11)
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12. A method for measuring range to a target, comprising:
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transmitting an RF pulse to an antenna via a transmission line or waveguide, creating a first reflection at the antenna, receiving the first reflection, radiating the RF pulse from the antenna to a target, receiving a second reflection from the target with the antenna, measuring target range from the first and second received reflections. - View Dependent Claims (13, 14, 15)
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Specification