Abstract: A double superheterodyne type microwave detector is constructed from a reception antenna; a first local oscillator; a second local oscillator; reception means for detecting microwaves having prescribed frequencies based on signals obtained by carrying out a first mixing in which the output of the first local oscillator is mixed with the microwaves picked up by the antenna, and a second mixing in which the signals obtained from the first mixing are mixed with the output of the second local oscillator; judgement means for judging whether or not an actual microwave signal which forms a detection target has been detected by the reception means; alarm means for outputting an alarm when the judgement means judges an actual microwave signal to have been received by the reception means; and first control means for suspending the first mixing when the reception means detects a microwave signal having a prescribed frequency; wherein the judgement of whether or not the prescribed frequency microwave signal detected by t

Abstract: Apparatus for monitoring opening of sealed enclosures, especially, but not exclusively, sealed containers containing goods-in-transit, such as goods vehicles, maritime containers or transport containers of the kind carried by tractor-trailers, ships, trains or aeroplanes comprises a radio receiver unit having at least one antenna for reception of radio signals. The receiver unit is housed within the enclosure and operates to scan a predetermined band of radio frequencies, periodically or continuously, and detect a sudden change in signal level. When it detects such a change in radio signal level, the receiver generates an alarm signal. Alternatively, the receiver may detect the difference between internal and external radio signal levels and determine the container to have been opened if the difference is less than a preset threshold.

Abstract: A frequency scheme for a police radar detector enables the K band and the K.sub.a band to be scanned during a single sweep of a local oscillator which drives a mixer at its fundamental operating mode to produce intermediate frequency signals around 5 Ghz. The frequency scheme simultaneously activates two or four frequency conversion paths in the police radar detector. Accordingly, a radar warning alarm can be given upon detection of radar signals in any one of the frequency conversion paths. The ambiguity as to which one of the two or four frequency conversion paths is receiving a detected radar signal is resolved by applying first and second modulation signals to first and second local oscillators, respectively, so that the radar band of the detected radar signal can also be included within the radar warning alarm. The first and second modulation signals are in quadrature to one another and quadrature correlation is used to determine which frequency conversion path is receiving a radar signal.

Abstract: An input stage for a police radar detector includes a single mixer together with at least one preamplifier to detect radar signals in the X, K and K.sub.a bands. A preamplifier may be used on the X band alone, the K band alone, the K.sub.a band alone, the X and K bands or the X, K and K.sub.a bands. The use of these preamplifiers provides better noise figure; however, multiple responses cannot be scanned at the same time in bands utilizing a preamplifier with sufficient selectivity to reduce noise in its respective image bands to tolerable levels so that some or all of the receiver responses are swept independently with the preamplifier or preamplifiers being enabled one at a time as appropriate for each band being scanned. Since more sweep time is required when multiple responses are no longer swept simultaneously, a currently preferred form of the input stage couples the K.sub.a band signals to a single mixer through a preamplifier which permits multiple responses to be swept in the K.sub.

Abstract: In methods and apparatus for generating an LPC-encoded noise signal from an LPC-encoded speech signal, excitation parameters of the LPC-encoded speech signal for a current frame are randomized upon detection of speech in the current frame. For frames in which no speech is detected, LPC coefficients and frame energy for the current frame may be replaced with respective averages calculated over the current frame and a plurality of preceding frames. For frames in which speech is detected, LPC coefficients for the current frame may be replaced with respective averages of LPC coefficients used to replace LPC coefficients of an immediately previous frame. The comfort noise generation technique is particularly suitable for use in echo suppressors for digital cellular radio systems.

Abstract: An apparatus for detecting abnormal radio-frequency signals has an antenna responsive to a radio-frequency signal. The radio frequency signal has a plurality of signal components, each of which has an associated amplitude. A circuit attenuates each of the plurality of signal components having an amplitude not greater than a threshold value and generates a suspect signal comprising each of the plurality of signal components having an amplitude greater than the threshold value. A circuit then compares the suspect signal to a plurality of preselected signal types. When the suspect signal does not correspond to any of the preselected signal types, a circuit generates an alarm. In a method of detecting usage of a radio-frequency weapon, a signal having an amplitude, is received. A background signal amplitude of a plurality of components of the signal is determined.

Abstract: A radar detector suppresses nuisance alerts due to detection of a third harmonic of a common LO signal of other radar detectors by detecting a second harmonic of the offending LO signal. If a detected radar signal in the K.sub.a band is of a frequency within a suspect range corresponding to possible third harmonic spurious LO signals, a determination is made as to whether a potential alert blocking signal around the second harmonic of a nominal 11.55 Ghz signal is also present. In the illustrated embodiment, the second harmonic alert blocking signal which is checked has a frequency which is 2/3 the frequency of the detected K.sub.a signal .+-. a guard band of, for example .+-.40 Mhz, and is within a range of frequencies from about 22.813 Ghz to about 23.8 Ghz. If no blocking signal has been detected within about 10 seconds before or within three sweeps after detection of the K.sub.a band signal in the suspect range, the detected K.sub.a band signal is reported.

Abstract: A synthesizer varies the receive frequency band so that a receiver can receive signals in the receive frequency band of the uplink incoming call channel of a portable telephone. A receiver demodulates, from a receive signal entered via an antenna, the incoming call response signal of a portable telephone connected by radio to a base station. A comparator detects, from the incoming call response signal, the portable telephone's own ID number or telephone number stored in a memory. The memory consists of an EEPROM. An alerting section, in response to the detection of the portable telephone's own ID number or telephone number, performs call operation. The alerting section is provided with a loudspeaker for emitting an alerting sound, an LED for intermittently emitting light and a vibrator for generating vibration. A call operation select button selects the setting or resetting of the loudspeaker, the LED and the vibrator. The call operation stop button stops call operation.

Abstract: Disclosed is a radar detector for frequency sweeping a wide band range by using a VCO circuit to detect a radar signal, wherein the frequency precision of the received band can be improved by using comparatively simple and inexpensive circuits.

Abstract: This invention relates to an alert receiver interface, apparatus and method, for receiving and automatically detecting the issuance of emergency, weather or other alert messages broadcast on a radio channel, or on another communication system, and recording that alert message into the receiver with an audible day and time stamp for later playback. Interface apparatus and methods between the alert receiver interface and other communication systems, including paging systems, whereby an alert message, or an alarm tone, is automatically relayed and repeated on an other communication system are disclosed. A method and apparatus for selectively activating an other communication system for only those alert messages of specific concern to users of an other communication system is also taught herein.

Abstract: A radar/laser speed detection countermeasure device for use on a motorcycle is disclosed which detects and annunciates radar and/or laser based speed detection devices in use in the immediate physical area for the purposes of speed limit law enforcement. The device consists of a main detector body mounted in an interior cavity of a motorcycle, which is electrically connected to a remote mounted sensing head unit and a remote mounted indication and control panel. Hidden components and interconnecting wiring reduce the chance of theft and preserve the appearance of customized motorcycles.

Abstract: A battery-powered selective call transceiver, operating in two-way communication with an RF communication system, can be put in a power saving state. A user control on the transceiver allows a user to select the duration of a power saving interval. The transceiver sends to the communication system a signal requesting that the transceiver enter a power saving state for the selected interval. Upon receipt of an acknowledgment signal from the system, the transceiver enters the power saving state.

Abstract: A wideband microwave detector includes: a first local oscillator outputting a first local oscillation output containing a basic wave component, a secondary high harmonic component and a tertiary high harmonic component and being swept within a predetermined frequency range; a first mixer performing frequency mixing of the first local oscillation output and an antenna input input through an antenna and outputting a first mixing output; a second local oscillator outputting a second local oscillation output; a second mixer performing frequency mixing of the first mixing output and the second local oscillation output for generating a second mixing output, a single frequency discriminator for detecting a specific frequency in a discrimination input, and mode selector switch alternately switching a single super heterodyne reception mode, in which the first mixing output of the first mixer is introduced into the frequency discriminator as the discrimination input and a double super heterodyne reception mode, in whic

Abstract: A passive aircraft proximity detector for use in highway vehicles. This invention includes a unique internal antenna (1) feeding a superheterodyne receiver (2). A novel reference system (3) provides phase synchronous local oscillator injection. A signal analysis system (4) determines the presence of a valid signal and activates a tracking indicator (5). The analysis system also provides range data to an indicator which displays the approximate range of the aircraft (6). A mutable timed audio alarm is also incorporated (7).

Abstract: A diversity control circuit which selects an optimum receiving signal in a diversity receiver and which corrects receiving signal levels in such a manner that characteristics in measuring systems for a plurality of receiving signal levels can be regarded as homogeneous. The circuit includes memory means which stores correction data and which responds to receiving signal levels to provide corrected signals conforming to a preselected characteristic.

Abstract: A radar detector system and method. The system includes a front-facing antenna and receiver and a rear-facing antenna and receiver. The two receivers are electrically connected to a single control head that includes separate light and sound indicators for each of the front-facing and the rear-facing receivers. A tone generator is included in the module to identify audibly the front-facing receiver and the rear-facing receiver.

Abstract: A paging receiver is disclosed which is compatible with transmissions from analog or digital paging transmitters. The paging receiver has a command structure which permits it to be dynamically programmable to change its functionality including programming of the channels which the paging receiver is to receive. The programmability of the channels permits the paging receiver to be used for making national, regional, remote area, local area, and sublocal area pages, and pages to a group in the local area and to switch from channels which are heavily used during peak paging times to lesser used channels. The paging receiver transmits the paging receiver identification code digits in an order of increasing significance which significantly lessens power consumption for all paging receivers tuned to a particular frequency for determining if a page is to be received which prolongs paging receiver battery life.

Abstract: A radio receiver for use in a vehicle combines a radar receiver, a receiver for the citizen band, and a scanning receiver for public service bands which are controlled in operation and function by a microprocessor. The public service scanning receiver covers a range of public service bands from 37 MHz to 470 MHz. The receiver for the citizen band covers frequencies from 26 to 28 MHz. The radar receiver covers frequencies of traffic radars located in the X and K bands, from 8 to 24 GHz. In the preferred embodiment, a radar detector responds to radar signals in either the X or K band under control of the microprocessor, and is in a standby mode whether or not the operator is listening to reception on the citizen band or a public service band. A synthesizer either selects a desired channel in the citizen band or else scans a preselected group of public service frequencies that correspond to those assigned to a particular state, country or city.

Abstract: A remote output indicator for use with a radar detector providing a perceivable output indication to detect signals from an operating radar within an automobile having a rear window and a rear deck disposed near the rear window. The remote indicator includes a rear brake light housing and a mounting means for connecting the rear brake light housing to the automobile generally near the rear window. The radar detector is mountable within a housing space within the rear brake light indicator housing. A remote unit is disposed near the rear brake light indicator housing for sensing the radar detector perceivable output indications and providing an output signal in response thereto. A console receives the output signal from the remote unit and provides output indications which are perceivable by the driver of the automobile.

Abstract: According with the present disclosure to provide a suitable protective headgear for the sports vehicle operator/motorcyclist that incorporates internal radar detection electronics capable of detecting X and K band radar signals as well as any future bands that may be used. To provide both audio and visual alarm signals that will allow the operator to adjust speed accordingly to avoid violations. To provide the light panel display in the vision proximity of wearer so that the operator never has to look away from their immediate trajectory. To provide ventilation for both the wearer and the electronics inclosed therewith that would compensate for any additional heat caused by the electronic circuitry. Helmets would be sized to fit different size heads with a comfortable snug fit.

Abstract: A radar warning receiver for detecting and analyzing radar signals comprises a plurality of RF heads each tuned to a predetermined frequency band and connected to an antenna covering a preselected sector of reception of radar signals. Each of the heads includes a frequency converter converting the received signals to a common frequency base-band and producing an output signal in the base-band corresponding to the signal received by its antenna.

Abstract: A radar warning receiver is provided having an alarm indicator responsive to an electronic switch, the switch being activated and energizing the alarm in response to an alarm signal indicating the presence of a police radar signal, the switch being deactivated and de-energizing the alarm in response to a mute signal occurring during the occurrence of the alarm signal, the switch remaining deactivated until the alarm condition signal terminates and subsequently reoccurs.

Abstract: 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.

Abstract: A carrier current transceiver includes a transmitter section and a receiver section coupled to an AC power line. In the transmit mode, input data in the form of a logical "0" enables a carrier frequency signal to excite a tuned cavity. The tuned circuit includes a first winding of transformer, a capacitor and a damping resistor. A second winding of the transformer is capacitively coupled to the AC power line to produce a stepped down carrier current signal to represent a transmitted logical "0". A logical "1" is represented by absence of the carrier current signal. In the receive mode, a small carrier current signal representing a logical "0" is received via the AC line and is stepped up by the transformer and capacitively coupled to an input of the receiver section.

Abstract: The signal absence detector controls an operator circuit which periodically provides an operator signal to render the processor circuit in a communication receiver operative. The absence detector responds to a processed signal which is not of a predetermined character to terminate the operator signal. In one form of the invention, the operator circuit is a battery saver which intermittently provides a supply voltage. When the incoming signal is of the predetermined character, the supply voltage continues. The absence detector terminates the supply voltage when it is determined that the incoming signal does not have that character. In another form of the invention, the absence detector is employed in a scanning receiver, in which case the operator circuit steps the receiver between the various channels. The receiver will remain tuned to a channel as long as the incoming signal may be of the predetermined character.

Abstract: A device for producing a voice warning over a speaker which is also used with an entertainment sound production system such as a radio or cassette recorder. The voice warning device incorporates a switching device in the circuit between the speaker and a source of entertainment sound-bearing electric signals, and also incorporates a mechanism for selectively generating electric signals representing human voice sounds for conveying warnings. When a warning signal is being generated, the switching device is switched over from its state where it connects the speaker to the entertainment sound-bearing electric signals to its state where it connects the speaker to the warning signals. Optionally, several different speakers of an entertainment system may be selectively connected to said warning signals by several switching devices.

Abstract: A decoder circuit responds to a given code to provide an enabling signal for rendering an audio circuit operative. A push-button switch actuatable to monitor the channel is associated with timer and electronic switch.One connection places the receiver in either a monitor mode or a tone-squelch mode. A second connection places the receiver in condition to be unsquelched manually or by the carrier wave or by the proper code. The battery saver provides a continuous supply voltage during the first tone, the entirety of the code and for a time thereafter. The rate of the pulsed supply voltage produced after such time will be increased. Alternately, the receiver can be placed in the carrier-squelch mode. The receiver can be reset to the code-squelch mode and cause the pulsed supply voltage to revert to its usual rate. After the start of detection, pulses render ensuing circuitry nonresponsive to glitches.

Abstract: Method and apparatus for detecting a transmitter. The harmonics of an incrementally increasing fundamental frequency are mixed with input signals thus forming intermediate frequency signals. Frequencies occupied by background transmitters are identified by surveying the r-f spectrum at a remote point; these frequencies are then bypassed when scanning is performed in the area to be secured. Another method is also disclosed wherein an operator scans the r-f spectrum in an area, and records indications corresponding to the frequencies of signals not emanating from eavesdropping devices so that those frequencies will be bypassed on subsequent scans.

Abstract: To simulate presence of a traffic information signal in a traffic information receiver which is muted upon reproduction of tape cassette programs or operated at a predetermined level, a momentary-operating control button is connected to a timing circuit to establish a timing interval which, when exceeded, provides a signal to a traffic information transfer switch to transfer the signals received from the receiver through the traffic information channel to permit setting of the volume level under traffic information conditions as desired and to demonstrate the operability under such conditions; upon release of the button, the system reverts to reproduction of tape or traffic information signals received by the receiver. Traffic information can thus be simulated even though no traffic information is being radiated by the transmitter to which the receiver is tuned.

Abstract: A battery-powered receiver having a switch for disconnecting the battery from radio frequency detection circuits within the receiver upon receipt of a sequence of coded address and command signals. Each address and command signal is a radio frequency modulated with an audio or tone frequency. A tone decoder within the receiver is sensitive to audio signals whose frequencies lie within any one of sixteen predetermined frequency ranges. Stored at the output of the decoder is an address code of two or more numbers representing tone frequencies, these numbers being representative of the particular receiver or group of receivers. A sequence of audio signals detected by the tone detector is compared with the stored address code. If the address signals are followed by a coded command signal, made up of a tone signal or sequence of tone signals, the tone detector gives an output which causes the battery switch to be opened for a time determined by the coding of the command signal.

Abstract: A sensitive radar signal detector is provided which is operative to reliably detect low level radar radiation characteristic of scattered radiation of very short duration and unknown frequency. Received radar signals which are mixed with a swept frequency signal are passed through to a narrow band FM descriminator, the output of which is amplified by a unidirectional amplifier. The output of the amplifier, present when a signal is received, is utilized to momentarily slow the frequency swept local oscillator resulting in a time expansion of the characteristic S-shaped descriminator output signal. This results in the generation of a negative-going error signal between the two time expanded halves of the S-shaped descriminator response. The error signal when amplified produces a significant voltage spike which ensures reliable detection, to permit the detection of a single radar pulse with a reduced false alarm rate.

Abstract: An electronic transmitter-receiver system for warning a motor vehicle driver of the approach of an emergency motor vehicle such as an ambulance is disclosed. A transmitter equipped emergency motor vehicle transmits an omnidirectional, short range, radio frequency warning signal. A warning signal receiver associated with a motor vehicle proximate to the approaching emergency motor vehicle emits an audible warning within the passenger compartment of the motor vehicle in response to the radio frequency warning signal. The audible warning is heard by the driver of the motor vehicle thus alerting him to the impending traffic hazards associated with an approaching emergency motor vehicle. The intensity of the audible warning increases as the distance between the emergency motor vehicle and the motor vehicle to be warned decreases.

Abstract: Apparatus for sensing the presence of one or more of a multiplicity of radio waves of distinct frequencies, using a single horn and one or more radiation-receiving apertures with associated circuitry.