Harmonic techniques are employed to leverage low-cost, ordinary surface mount technology (SMT) to high microwave frequencies where tight beamforming with a small antenna makes reliable, high-accuracy pulse-echo radar systems possible. The implementation comprises a 24 GHz short-pulse transceiver comprised of a pulsed harmonic oscillator employed as a transmitter and an integrating, pulsed harmonic sampler employed as a receiver. The transmit oscillator generates a very short (0.5 ns) phase-coherent harmonic-rich oscillation at a sub-multiple of the actual transmitter frequency. A receiver local oscillator operates at a sub-multiple of the transmit frequency and is triggered with controlled timing to provide a very short (0.5 ns), phase-coherent local oscillator burst. The local oscillator burst is coupled to an integrating harmonic sampler to produce an integrated, equivalent-time replica of the received RF. The harmonic techniques overcome four major problems with non-harmonic approaches: 1) expensive, precision assembly, 2) high local oscillator noise, 3) sluggish oscillator startup, and 4) spurious local oscillator injection locking on external RF. The transceiver can be used for automotive backup and collision warning, precision radar rangefinding for fluid level sensing and robotics, precision radiolocation, wideband communications, and time-resolved holographic imaging.

Short pulse microwave transceiver

The invention is based on a distance-measuring device, in particular a hand-held distance-measuring device, having at least one measuring unit (12), one measuring housing (14) and a measuring unit carrier (16) which is provided for attaching the measuring unit (12) in the measuring device housing (14) in such a way that it can pivot relative to the measuring device housing (14) about a pivot axis (18) It is proposed that the measuring device housing (14) has, for the purpose of mounting the measuring unit carrier (16), at least one guide face (20) whose main extent (22) runs at least substantially parallel to a measuring direction (24) of the measuring unit (12)

Distance-measuring device

A method of using a directional sensor for the purposes of detecting the presence of a vehicle or an object within a zone of interest on a roadway or in a parking space. The method comprises the following steps: transmitting a microwave transmit pulse of less than 5 feet; radiating the transmitted pulse by a directional antenna system; receiving received pulses by an adjustable receive window; integrating or combining signals from multiple received pulses; amplifying and filtering the integrated receive signal; digitizing the combined signal; comparing the digitized signal to at least one preset or dynamically computed threshold values to determine the presence or absence of an object in the field of view of the sensor; and providing at least one pulse generator with rise and fall times of less than 3 ns each and capable of generating pulses less than 10 ns in duration.

Directional speed and distance sensor

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.

Loop powered radar rangefinder

A sensor for detecting a specific object (such as a hand) excellent in operation reliability and response, further excellent in mountability (dominance such as in size and design) on a vehicle, and much less in power consumption than conventional impulse radars. The object sensor comprises detecting wave transmitting means and reflected wave receiving means of an impulse radar and a judging circuit part (40) for turning on the detection output when the amplitude level of a signal component, in a frequency range corresponding to the moving speed range of a specific object, of a signal received by the reflected wave receiving means lies in a predetermined range corresponding to the reflection characteristics of the specific object.

Object sensor and controller

Two crystal oscillators are configured as a "plug-and-play" precision transmit-receive clock that requires no calibration during manufacture. A first crystal oscillator generates a transmit clock and a second crystal oscillator operates at a small offset from a harmonic of the first oscillator. A turnstile circuit selects pulses from the second oscillator to trigger a receive clock. Both the transmit and receive clocks operate at the same frequency. One edge of the receive clock is smoothly slipped, or swept, in phase across a limited range such as 0 to 36 degrees relative to the transmit clock with the slip rate set by the harmonic frequency offset. In one embodiment, a quadrature frequency-locked-loop is used to accurately control the slip rate while preventing false frequency locks. This timebase can be used to clock equivalent time radar, laser, and TDR ranging systems with picosecond accuracy. Applications include automotive backup and collision warning radars, precision radar rangefinders for fluid level sensing and robotics, and universal object/obstacle detection and ranging.

Thomas E. McEwan

Papers

Precision radar timebase using harmonically related offset oscillators