University of California

Mcewan Technologies, LLC

Other

Mcewen Technologies, LLC

Thomas E McEwan

Gregory E Dallum

A UWB RF detector employs a pulsed self-oscillating mixer (SOM) and an output integrator to provide low-noise preamplification, mixing and sampling. The SOM produces short-burst, microwave self-oscillations that are phase-locked to a clock. The self-oscillations are used for mixing. The SOM can also radiate UWB RF pulses. A one-transistor SOM can simultaneously implement both a UWB emitter and a UWB detector in a radar transceiver. A control loop can stabilize the self-oscillations at nanowatt levels. Nanowatt UWB radars and radios can be realized, thereby opening new spectral bands beyond those formally designated for UWB operation.

Self-oscillating UWB emitter-detector

A gated peak detector produces phase-independent, magnitude-only samples of an RF signal. Gate duration can span as few as two RF cycles or thousands of RF cycles. Response is linearly proportional to RF amplitude while being independent of RF phase and frequency. A quadrature implementation is disclosed. The RF magnitude sampler can finely resolve interferometric patterns produced by narrowband holographic pulse radar.

RF magnitude sampler for holographic radar

Narrow virtual transmit pulses are synthesized by differencing long-duration, staggered pulse repetition interval (PRI) transmit pulses. PRI is staggered at an intermediate frequency IF. Echoes from virtual pulses form IF-modulated interference patterns with a reference wave. Samples of interference patterns are IF-filtered to produce high spatial resolution holographic data. PRI stagger can be very small, e.g., 1-ns, to produce a 1-ns virtual pulse from very long, staggered transmit pulses. Occupied Bandwidth (OBW) can be less than 10 MHz due to long RF pulses needed for holography, while spatial resolution can be very high, corresponding to ultra-wideband (UWB) operation, due to short virtual pulses. X-Y antenna scanning can produce range-gated surface holograms from quadrature data. Multiple range gates can produce stacked-in-range holograms. Motion and vibration can be detected by changes in interference patterns within a range-gated zone.

Range gated holographic radar

An automatic pulse detector compares a radar video pulse to a delayed and amplified version of itself. The radar video pulse serves as an amplitude reference for a comparator. A delayed and amplified version of the same pulse serves as the pulse to be detected. Time of detection is amplitude independent and is not degraded by flat-topped pulses. Pulse detection occurs at a fixed, fractional point on the leading edge of a pulse where noise has less temporal influence than at the top of a pulse. Unlike a time-of-peak detector, the self-referencing pulse detector is well-suited to detecting wide, flat-topped pulses produced by expanded-time, pulse-echo radars operating in relatively narrow ISM bands.

Self-referencing radar pulse detector

A rate locked loop (RLL) regulates phase slip between two clock signals to provide precision timing for radar, TDR and laser ranging systems. Two clocks having a small mutual frequency offset exhibit a slowing changing relative phase, or phase slip, that produces a stroboscopic time expansion effect in a ranging system. A phase detector converts clock phase to voltage and the voltage is differentiated to provide a rate-of-change signal to a loop controller that precisely regulates the rate-of-phase change. The RLL controls a VCO to produce a constant, linear phase slip having phase errors below the time equivalent of 1-picosecond.

Rate locked loop radar timing system

A feedback loop corrects timing errors by reducing deviations from a constant radar sweep rate. Errors are detected and fed back to a phase corrector in a high gain feedback system. A precision radar rangefinder can be implemented with a direct digital synthesizer (DDS) that includes feedback error correction for reducing range errors by, for example, 100 times, or to 0.1 mm. An error-corrected DDS swept timing system can enable a new generation of highly flexible, repeatable and accurate radar, laser and guided wave rangefinders.

Error corrector for radar timing systems

A precision pulse detection system for time-of-flight sensors detects a zero axis crossing of a pulse after it crosses above and then falls below a threshold. Transmit and receive pulses flow through a common expanded-time receiver path to precision transmit and receive pulse detectors in a differential configuration. The detectors trigger on zero axis crossings that occur immediately after pulse lobes exceed and then drop below a threshold. Range errors caused by receiver variations cancel since transmit and receive pulses are affected equally. The system exhibits range measurement accuracies on the order of 1-picosecond without calibration even when used with transmitted pulse widths on the order of 500 picoseconds. The system can provide sub-millimeter accurate TDR, laser and radar sensors for measuring tank fill levels or for precision radiolocation systems including digital handwriting capture.

Precision pulse detection system for radar sensors

A pulse detection system for expanded time radar, laser and TDR sensors detects specific cycles within bursts of cycles. A sensor transmits and receives short bursts of RF cycles. A transmit pulse detector triggers on a selected cycle of the detected transmit burst and starts a range counter. A receive detector triggers on a selected cycle within a received echo burst to stop the range counter, thereby indicating range. Cycle selection is enabled by an analysis window of time. The detection system can provide accuracies on the order of one picosecond and is well-suited to accurate ranging along an electromagnetic guide wire.

Carrier phase detection system for radar sensors

Guided wave radar (GWR) pulses are launched onto an electromagnetic guide wire using a compact launcher that includes an impedance matching element. The impedance matching element produces reflections that cancel launcher reflections. Short range echoes can be accurately detected after impedance matching. GWR operation in small tanks and in tanks containing low dielectric constant materials, such as propane, can be enhanced with the compact impedance-matched launcher.

Reflection free launcher for electromagnetic guide wire

Transistor package leads form quarter-wave antenna elements that directly radiate RF energy into free space without the need for a separate antenna. The transistor operates at a fundamental frequency and radiates a harmonic, thereby allowing radiation at frequencies normally considered 'beyond cutoff' for a packaged transistor. This technique enables an additional 20 GHz of spectrum for use by surface mount technology. The transistor may be mounted on 1.6 mm thick glass-epoxy circuit board that also forms a quarter-wave reflector at 26 GHz. An optional dielectric lens produces a narrow beam and an optional planar filter rejects spurious fundamental emissions. A 26 GHz ultra-wideband (UWB) pulse-echo radar rangefinder implementation provides a low-cost upgrade to ultrasound.

RF transceiver having a directly radiating transistor

A varying magnetic field excites slight vibrations in an object and a radar sensor detects the vibrations at a harmonic of the excitation frequency. The synergy of the magnetic excitation and radar detection provides increased detection range compared to conventional magnetic metal detectors. The radar rejects background clutter by responding only to reflecting objects that are vibrating at a harmonic excitation field, thereby significantly improving detection reliability. As an exemplary arrangement, an ultra-wideband micropower impulse radar (MIR) is capable of being employed to provide superior materials penetration while providing range information. The magneto-radar may be applied to pre-screening magnetic resonance imaging (MRI) patients, landmine detection and finding hidden treasures.

Magneto-radar detector and method

Two or more receivers of known location receive RF bursts from a wireless moving object containing a transmitter that transmits periodic RF bursts. The receivers are gated with precision swept timing that repeats at the exact transmit RF burst period to produce precision expanded time representations of the received RF bursts. The expanded time representations correspond to RF burst arrival times from the transmitter, which are used to calculate the location of the transmitter. A writing pen application includes an RF transmitter in a writing pen and four RF receivers beneath the surface of a writing tablet where RF propagation from the pen to the receivers cannot be blocked by a user's hand. Two RF transmitters, one located at each end of the pen, may be employed to measure pen tilt and for 3-D tracking. Spatial resolution is more than 600 dpi at 100 location fixes per second.

Radiolocation system having writing pen application

A time-domain reflectometer (TDR) forms a pulse width modulated (PWM) signal directly on a transmission line, where the PWM width is proportional to range to a discontinuity on the transmission line. Two PWM detection methods can be used: (1) realtime, wherein the PWM signal is detected in realtime; and (2) expanded-time, wherein the PWM signal is time-expanded before detection for higher accuracy. Both methods convert the analog transmission-line PWM signal to a digital output PWM signal of identical duty-cycle for averaging, counting, or other processing to indicate range. In a preferred mode, a transmission line is sampled at a floating offset frequency relative to the transmission-line PWM frequency to form a PWM output having a floating time-expansion factor but a precise duty-cycle related to the location of the discontinuity. The essence of this TDR is low cost, precision and absolute simplicity. Applications include precision tank level sensing.

Direct PWM reflectometer

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

The pulse center detector (PCD) produces an amplitude-independent center-triggered range output for precision radar rangefinders and TDR systems. Pulse center triggering is accomplished by triggering leading-edge and trailing-edge detectors and summing the outputs to produce a computed center-triggered result. Since the occurrence time of a pulse center does not vary with amplitude, the PCD is amplitude-independent. The PCD overcomes limitations of prior automatic pulse detectors, such as the inherent latency of a constant fraction discriminator (CFD) and the uncertainty of a time-of-peak (TOP) detector. The PCD can be implemented with a single analog component&mdash;a comparator&mdash;and thus requires appreciably fewer analog components than prior automatic detectors while providing lower jitter. Applications include radar and TDR tank gauges, and radar rangefinders for robotics and automotive applications.

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Livermore, CA, United States of America

Thomas E McEwan