Beltronics Inc.

Bel-tronics Company

Escort Inc.

Beltronics USA Inc.

Glen D Martinson

Marcus Beaumont

Marian Mark Burin

Marian M Burin

Feliks K Lisowski

Stephen T Makk

A radar detector includes features to reduce emissions such as those typically generated by the detector's local oscillator. Two low noise amplifiers (LNA's), operating in X band and a combined K/Ka band, respectively amplify X and K/Ka band signals from separate antennae, and deliver those signals over separate, elongated and narrow signal paths to X and K/Ka mixers, where those signals are mixed with local oscillator (LO) signals to produce IF for detection. The elongated, narrow signal paths from the antennae to the mixers reduce LO emissions, and those emissions are further reduced by incorporating radar absorbers between the circuit board and detector case along the antenna-mixer path, including radar absorptive paint on the circuit board itself along this path, and sealing the case with a conductive sealing gasket.

Radar detector with reduced emissions

A method to optimize a mixer ( ) includes setting a DC bias current ( ) at a predetermined level correlated to an RF frequency or band of interest, and varying the power output ( ) of a local oscillator ( ) until the DC voltage ( ) of the mixer ( ) is at a predetermined voltage. The setting for the local oscillator ( ) is then stored, such as in volatile RAM ( ), for use during normal operation of the receiver ( ) to produce IF signals ( ) correlated to the RF frequencies or band or interest. The process may be implemented on power-up of the receiver and/or periodically during use thereof in the field to reoptimize the mixer ( ), and may be undertaken with different predetermined currents and voltages for different RF frequencies and/or bands.

Mixer optimization for active radar warning receiver

There is provided an image rejection mixer for downconversion of an incoming signal to a lower intermediate frequency signal, using the absolute difference of frequencies between the incoming signal and the local oscillator signal. The image rejection mixer is set up to accept and downconvert incoming signals at two discrete frequencies f.sub.h and f.sub.l, where the local oscillator frequency is positioned mid-way between those frequencies f.sub.h and f.sub.l. There are two signal paths in the image rejection mixer, either one or the other of which is chosen by positioning a controllable single pole, double throw switch into one of its two switch positions. The output of the switch is led to a mixing element, from which an intermediate frequency signal is derived. The first of the two signal paths from the input to the image rejection mixer to the mixing element has a bandpass characteristic centered at one or the other of the two input frequencies of interest; the other signal path has a bandstop characteristic centered at the same frequency. By choosing one or the other of the signal paths, an incoming signal at a designated one or the other of the incoming signal frequencies may be downconverted, and the image signal and any noise at that image signal frequency will be rejected.

Image rejection mixer

The present invention provides a broad band, multi-band radar detector which may be configured so as to have two or three down conversion stages. There are three mixers in the circuit, the second of which has a frequency synthesized local oscillator which is governed by a phase lock loop feedback circuit under the control of a microprocessor, so that the output frequency of the second local oscillator may be varied by an amount equal to .+-.f.sub.adj. The first local oscillator is also under the control of the microprocessor, so that a specific intermediate frequency signal from the first mixer may be derived. By varying the frequency of the second frequency synthesized local oscillator, the tuning range of the radar detector may be increased in each frequency band of interest by an amount equal to .+-.f.sub.adj for all frequency values in each respective frequency band of interest. The radar detector is a self-calibrating detector, so that the output frequency from the first swept local oscillator may be accurately controlled by determining the specific tuning voltage for a specific first local oscillator frequency at which a particular incoming radar signal may be detected. This is accomplished by bypassing the second mixer, and controlling its output frequency so that an harmonic frequency will mix with the first local oscillator frequency to give a calibration response for any predetermined input radar frequency. Accordingly, the problem of drift of the tuning capability of the radar detector may be accurately controlled.

Multi-conversion radar detector having increased tuning range and

A bi-directional portable laser light detection device for receiving and detecting laser light from one or more of a plurality of sources includes a laser light pipe that comprises a solid body of material that has a high index of refraction and has an input end, an output end, and at least one wall member connecting the input end and the output end. A generally planar laser light admitting zone on the exterior of the solid body at the input end thereof is oriented so as to generally face the expected direction of the path of laser light from a source along a first opposed path so that, in use, the laser light enters the solid body by way of the admitting zone so as to become admitted laser light. A generally planar laser light emitting zone on the exterior of the solid body at the output end thereof is oriented so as to generally face outwardly toward a laser light sensor such that laser light emitted from the laser light emitting zone is received by a laser light sensor. The external periphery of the solid body is shaped and dimensioned so as to transmit and internally reflect the admitted laser light to the laser light emitting zone. The laser light sensor is oriented so as to receive laser light emitted from the laser light emitting zone of the laser light pipe, and also so as to receive laser light along a second opposed path.

Bi-directional laser light detection device having a laser light pipe

A low voltage sensing circuit for a battery powered, micro-processor based circuit is provided. A standard voltage regulator has input voltage from a battery, and output voltage which is fed to a system requiring the same, which includes a micro-processor. A voltage divider is connected through a capacitor to an output port of the micro-processor; and the common point of the voltage divider is connected to the base or emitter of a transistor. Periodically, there is an output pulse from the output port of the micro-processor, which pulse has a predetermined length. During the output pulse from the micro-processor, the transistor may become conductive while the capacitor is recharging. Depending of the configuration, the fact that the transistor is conductive is indicative that the input voltage is either below or above a predetermined value. The width of the pulse that is created across a resistor connected to the collector of the transistor and also to an input port of the micro-processor, is indicative of how much below or above the predetermined value the input voltage from the battery has deviated. The predetermined input voltage is established by setting the values of the resistors in the series connected voltage divider.

Low voltage sensing circuits for battery powered devices having a

A mixer is provided having a mixing element, an input signal port for incoming signals at a frequency f.sub.IN, a local oscillator signal port for signals from a local oscillator having a fundamental frequency f.sub.LO, and an output port from which the resultant frequency may be taken. Means are provided to impose a DC component of bias voltage across the mixing element at one of three levels. The mixer is such that it has a pair of conduction threshold voltages which are substantially symmetrical above and below zero volts, beyond which the mixing element will be conductive at least when a signal from the local oscillator is imposed on it. The signal from the local oscillator has substantially sinusoidal voltage waveform, with a peak-to-peak voltage which is greater than the voltage difference between the pair of conduction threshold voltages. When the first zero DC component bias voltage is imposed across the mixer element, the mixing element is conductive in respective symmetrical positive-going and negative-going senses, and the maximized resultant frequency is .vertline.f.sub.IN .+-.2f.sub.LO .vertline.. When the second DC component of bias voltage is imposed across the mixing element, it conducts only once per cycle of local oscillator voltage, so that the maximized resultant frequency is .vertline.f.sub.IN .+-.f.sub.LO .vertline.. When the third DC component of bias voltage is imposed across the mixing element, the value of voltage across the mixing element exceeds the threshold voltage in the same sense as the voltage shift for about 35% to about 55% of the period of the local oscillator voltage cycle making the mixer conductive, but it is also conductive in the opposite sense for at least a portion of the remaining period of the cycle, so that third harmonic mixing occurs, and the maximized resultant frequency is .vertline.f.sub.IN .+-.3f.sub.LO .vertline..

Mixer using fundamental frequency or second or third harmonic

The invention concerns radar detectors which are capable of monitoring at least two frequency bands. A broad band antenna is provided, together with a mixer comprising an anti-parallel pair of diodes, and at least one local oscillator. The local oscillator frequency is mixed with radar frequency from the antenna to produce an intermediate signal which is amplified further down converted detected and fed to signal processing circuitry to actuate an alarm when radar frequency of interest is detected. The most effective mixing with the RF input takes place at twice the local oscillator frequency. By application of direct current bias to the mixer, the most effective mixing with the RF input is changed to occur at the local oscillator frequency. The local oscillator is used to monitor two different radar frequencies by application and non-application of DC bias to the mixer. For multiband detectors, more than one local oscillator may be used.

Multiband radar detector

The invention concerns radar detection devices sensitive to signals from various different frequency bands. A broad band antenna is provided, together with a mixer and a plurality of local oscillators. Signals from the local oscillators are mixed one at a time with signals from the antenna, there being one local oscillator signal for each radar frequency or pair of frequencies of interest which may be received by the antenna. Each local oscillator signal is chosen so that when it is mixed with the respective radar frequency signal, an intermediate signal is produced which is the same for all mixtures. This intermediate signal is further down converted and fed to signal processing circuitry to produce an alarm when radar frequencies of interest are detected.

Multibrand radar detector having plural local oscillators

Radar detection and signal processing circuits are provided where, following a front end having an RF and local oscillator mixer to an I.F., which is then further mixed against a signal from a swept frequency oscillator, in the presence of a microwave frequency signal, the output of a band pass filter goes to a detector for frequency modulated intermediate frequency signals, and that detector has at least a first output signal that is fed to two pairs of complementary paired comparators, the outputs of which are set to low and high threshold levels. The first pair of complementary comparators has a low threshold level output which is examined by a microprocessor for the incidence of detected low threshold signal in a number of spaced cells--as determined by a clock which divides the detector output into time cells of the sweep period of the swept oscillator. Signal processing is provided so that the incidence of signals in a pair of spaced cells over a given number of consecutive sweeps causes an alarm. Likewise, a high threshold output is examined so that the incidence of a detected high threshold signal in a pair of spaced cells over a different, lower number of consecutive sweeps, causes an alarm. The sensitivity of the circuit may adjust up or down according to the number of low threshold signals that are detected; or dynamically if too many low threshold signals are detected in a small group of time cells.

Radar detection and signal processing circuit

A horn antenna construction, particularly for use in microwave radar detector circuits, comprises a molded horn element that is open at its bottom side, with a ridge molded into its flared top surface, and being electrically conductive at least at microwave frequencies such as in the X-band and K-band. The open bottom of the horn element mates to a conductive upper surface on a mounting board, and the horn is drawn down onto the mounting board so that its upper surface forms the bottom of the horn. Thus, the ridge is brought into physical and electrical contact with a feed strip formed in a microstrip board on the mounting board, that has a mixing diode or diodes associated therewith. By this construction, there is a positive and dimensionally stable association of the throat of the horn and the ridge to the feed strip and the mixing diode(s), without the necessity of any solder, inserted connectors or mounting pins, or the provision of any tuning posts or screws. Moreover, very efficient energy conversion, and thereby increased sensitivity, is assured because the horn, the feed strip and certain matching and terminating stubs on the microstrip board assure good isolation between the mixing ports and low energy loss at the mixer.

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Oakville, Canada

Glen D Martinson