Abstract: A raw signal is delayed in a delay circuit (1) and then supplied to one of the input terminals of a selection circuit (8). The raw signal is also supplied to another delay circuit (2) to be delayed. Subsequently, data of this delayed signal is processed by spline interpolation in an interpolation circuit (4), and the interpolation values are supplied to the other of the input terminals of the selection circuit (8). Further, a timer (7) is operated according to an output signal from a noise detection circuit (6) which detects noise in the raw signal. When noise is detected, the selection circuit (8) switches to select the output from the interpolation circuit (4), thereby achieving interpolation of noisy sections.

Abstract: An AM radio receiver comprises an RF amplifier, a first mixer that converts the RF signal to a first intermediate-frequency signal, a first bandpass filter that band-limits the first intermediate-frequency signal, a second mixer that converts the output from the first bandpass filter to a second intermediate-frequency signal, a second bandpass filter that band-limits the second intermediate-frequency signal, an intermediate-frequency amplifier that amplifies the output from the second bandpass filter, an AM detector that demodulates the output from the intermediate-frequency amplifier and provides output of an audio signal, and a noise detector for detecting and eliminating ambient noise. The noise detector comprises a first noise detector that detects noise from the RF signal and eliminates the noise contained in the first intermediate-frequency signal, and a second noise detector that detects noise from the second intermediate-frequency signal and eliminates that noise.

Abstract: A technique for processing telephone calls from a plurality of telephone sources in a vehicle audio system suitably includes providing a first call using a first one of the telephone sources to a user via the vehicle audio system, notifying the user of a second call received via a second one of the telephone sources while the first call is active, and processing an instruction from the user to either suspend the first call and accept the second call or to continue providing the first call. The technique may be implemented in a vehicle audio system that includes an onboard telephone, and may be adapted to work with wireless or other portable telephones carried by drivers and passengers in the vehicle.

Abstract: A simple region-specific broadcasting system for broadcasting information pertinent to motor vehicles in sequential regions of a roadway or highway directly to such vehicles when the vehicles are passing through such sequential regions. Existing cellular facilities and resources may be advantageously used in the implementation of the system. A system for broadcasting short range RF real-time information to motor vehicles traveling along a roadway implemented through a sequence of transceiving short range broadcast stations along said highway, the stations spaced so that the broadcast ranges of said stations tangentially overlap each other. Each of the sequence of motor vehicles moving along this roadway should include a transceiver for the short range RF signals.

Abstract: Most of on-vehicle DSRC apparatus are mounted on a dashboard of a vehicle and downsized not to hinder vision. Therefore the number of switches disposed on a panel is limited, while increase in number of functions is expected. Moreover, since an on-vehicle DSRC apparatus is operated while driving, a function key method adapted to operate keys visually is not applicable. Accordingly, an apparatus capable of performing multiple functions, in which can be assigned to one switch and operation can be performed without viewing, is demanded. A press button is operated to punch Morse code. Different functions are preliminarily allotted to respective punching patterns. A switch determination section stores the allotted functions, analyzes a press pattern and determines a function to be allotted. One switch serves multiple functions including sound volume setting, history confirmation, and on-vehicle apparatus identification number, achieving a small size on-vehicle DSRC apparatus at reasonable price.

Abstract: An object is to provide a noise removing circuit that can be integrally formed on a semiconductor substrate and can improve the accuracy of noise component removal. The noise removing circuit comprises a highpass filter detecting a noise component included in an input signal, a pulse generating circuit generating a pulse signal corresponding to the detected noise component, an analog delaying circuit 252 delaying the input signal, and an outputting circuit removing the noise component included in the delayed signal according to the output timing of the pulse signal. The analog delaying circuit 252 delays the output timing of the input signal by making switches 51 to 56 electrically continuous in a sequential order, by holding the voltage of the input signal at each time point in a plurality of capacitors 81 to 86, and by extracting the held voltage before being updated by making switches 61 to 66 electrically continuous.

Abstract: When power is supplied from a power transmitting side device 1, a FET 103 is turned ON and +12V direct current of a power source 101 is supplied to respective power receiving side devices. When transmission data is transmitted from the power transmitting side device 1, +5V direct current of a power source 201-1 is supplied to a terminal a, and a transistor 104 is turned ON/OFF due to a pulse-like voltage change of the transmission data, whereby the transmission data becomes a pulse-like 0V+5V output waveform, and is output to the respective power receiving side devices. When the power transmitting side device 1 receives reply data from the power receiving side device, the power receiving side device changes a voltage to a 3.5V+5V pulse as reply data. A photocoupler 105 detects the voltage change, whereby the power transmitting side device 1 receives the reply data from the power receiving side device.

Abstract: Co-channel interference in a wireless network is identified and quantified. Rather that using color code identification, a more reliable identification property of each co-channel component of the received composite signal is used, namely, the time of arrival of a known part of a signal. Detection and timing measurement is performed even in presence of stronger signals by focusing selectively on bursts having fixed contents (e.g., the FCCH burst used in GSM for frequency correction). The repetitive measurements of the time-of-arrival of each of the interfering components of the signal during a drive test enables determination of the geographical location of the interfering co-channel base stations.

Abstract: An antenna diversity system for receiving frequency-modulated (FM) radio signals with the phase-controlled summation of antenna signals for motor vehicles equipped with a multi-antenna system having at least two antenna output signals, and a receiver with an input for each of a first and a second received signal path, wherein the second of the two received signal paths contains a phase-shifter controlled by a phase-controller. The received signal has the same phase on the output of the phase-shifter as in the first signal path. The two received signals are added up in a phase-coincident manner in a summation circuit, and the added-up signal is supplied to the FM frequency modulator.

Abstract: Method for calibrating a motor vehicle hands-free access system comprising a control unit (UC) with an emitting antenna (AE) and an antenna controller (PA), consists in: 1. sending to the control unit (UC), from a measurement apparatus (AM) equipped with a receiving antenna (AR) connected to the control unit (UC) via a wire link (LF), a message to configure the control unit (UC) in calibration mode, 2. transmitting a signal via said emitting and receiving antennas (AE, AR) to said measurement apparatus (AM), 3. measuring characteristics of the received signal, comparing them with reference values and sending calibration data via the wire link (LF), 4. on receipt of the data, modifying the parameters of the antenna controller (PA). Using this method, it is possible to correct certain operating defects of the hands-free access systems through an operation at the end of the motor vehicle assembly line.

Abstract: A receiver receives an electromagnetic signal via an antenna mounted on an antenna mast. A signal evaluator determines or measures a signal quality level associated with the received electromagnetic signal. The signal quality compares the determined signal quality level to a threshold minimum signal quality level. A current elevational position of the antenna mast is detected or tracked. The antenna mast is raised to a greater height than the current elevational position if the compared signal quality level is less than the threshold minimum signal quality level and if the current elevational position is less than a maximum height of the antenna mast.

Abstract: A multipath noise reducer extracts a high-frequency signal from a demodulated signal obtained from a frequency-modulated signal, and generates a noise reduction coefficient from the extracted high-frequency signal. The demodulated signal is also separated into high-frequency and low-frequency components, the high-frequency component is multiplied by the noise reduction coefficient, and the resulting product is added to the low-frequency component. An output signal is thereby obtained in which the spike noise that characterizes multipath reception of a frequency-modulated signal is reduced with relatively little distortion of other parts of the signal, including the parts between noise spikes. The distortion can be further reduced by replacing the demodulated signal with an interpolated signal during noise spikes before the low-frequency component is separated.

Abstract: A dielectric multilayer substrate 220 is formed by laminating first through third dielectric layers 201 through 203. A plurality of conductor patches 204a through 204d are arranged on the upper surface of the first dielectric layer 201, and a microstrip line 205 for antenna feeding is arranged between the first and second dielectric layers. A ground layer 206 is arranged between the second and third dielectric layers 202 and 203, and microstrip lines 208a and 208b for a high-frequency circuit are arranged on the lower surface of the third dielectric layer 203. The microstrip line 205 for antenna feeding and the microstrip line 208a for the high-frequency circuit are electromagnetically coupled with each other via a slot hole 207 provided for the ground layer 206. With this arrangement, the efficiency and directivity of the antenna are improved.

Abstract: A noise blanker (40, 106) monitors and removes noise from a sampled signal by adaptive filtering (98, 150) the sampled signal to generate trained adaptive filter prediction coefficients. The sampled signal is provided as an output signal when the noise blanker is in a training mode. A noise monitor (34, 154) detects whether noise contained within the sampled signal exceeds a predetermined threshold and provides a control signal in response to the detecting. The noise blanker is placed in a prediction mode for a predetermined amount of time in response to asserting the control signal. A prediction output signal is generated using a plurality of prediction coefficients as an all-pole filter. The prediction output signal has minimal noise content.

Abstract: A method of suppressing ambient noise in telephone calls between at least two telephone partners measures the ambient noise and determines the parameters for suppressing this ambient noise on the basis of an algorithm. When using a cell phone in a motor vehicle, the vehicle parameters are detected when it is detected that a connection is being established. On the basis of the vehicle parameters currently being detected, the starting parameters for the interference noise suppression are derived from a characteristics map which was determined in the application.

Abstract: A multipath noise reducer detects and removes the individual noise spikes occurring in an interval of multipath noise, thereby reducing the multipath noise with minimal distortion of the audio output signal. The multipath noise spikes are detected by comparing a rectified signal with a threshold signal derived from the rectified signal. When the multipath noise reducer is used in an FM stereo radio receiver, stereo separation may also be controlled according to the detection of multipath noise.

Abstract: The present invention is a method and system for extracting information from a received signal with minimal loss due to noise. The system comprises of a transformer, for correlating the received signal to a wavelet function and producing wavelet decomposition coefficients, and a threshold circuit, which is responsive to the received signal, for applying predetermined threshold values based on the type of signal. Also included in the system is a filter, coupled to the transformer and threshold circuit, for altering the wavelet decomposition coefficients produced by the transformer using threshold values applied by the threshold circuit to produce altered wavelet coefficients from which the received signal is reconstructed with reduced noise.

Abstract: A noise removal unit mounted on a car radio according to the invention removes multipath noise and pulse noise from FM demodulated signals. At this time, the noise removal unit removes all of the multipath noise. Also, in case where the generation density of noise is high, the noise removal unit reduces the detection sensitivity so as not to detect pulse noise, particularly of small level, as noise. Comparing to multipath noise, pulse noise is noise rendering a large correction error than multipath noise. Therefore, in case where the generation density of pulse noise is high, by adapting the unit not to remove pulse noise of small level, it is made possible to reduce distortion of the FM demodulated signals to a minimum. Accordingly, it is made to reduce deterioration of the quality of FM voices to a minimum.

Abstract: First, a digital section constituting a linearizer is activated. Then, a feedback loop for updating a distortion compensation coefficient is opened. Then, the analog section on the antenna side is activated from an ADC, including a PA, etc., or a DAC. Then, both the ATT value of an ATT installed in a feedback route for updating the distortion compensation coefficient and the signal delay amount of a signal delay unit are adjusted to make a state such that the distortion compensation coefficient can be accurately updated. Then, the feedback loop is closed, a distortion compensation table having the distortion compensation coefficient as an entry is generated and after the generation is completed, the operation shifts to the normal operation.

Abstract: Apparatus for extracting a primary signal from a GSM signal containing co-channel interference partitions a signal burst into successive segments. Known characteristics of the GSM signal channel are used to estimate propagation path characteristics in respect of the first segment, and these are used to demodulate the segment. The demodulated signal is then used in a recursive process to estimate revised propagation path characteristics which are used for demodulating the subsequent segment. The demodulated segments and the estimated path characteristics are also used to derive segment signals representing the primary signal component alone, and these segment signals are used to reconstitute the primary signal. The derived primary signal can be subtracted from the received signal to extract the co-channel interfering signal. The apparatus functions with an omni-directional antenna, mounted for example on a moving vehicle.

Abstract: A remotely installed transmitter capable of clearly picking up only the voice of a person who is talking despite being installed away from the speaker's mouth and without causing feedback despite increased sensitivity, and a hands-free two-way voice terminal device using such a transmitter.

Abstract: In known telecommunication systems comprising two separate radio systems each one using its own clock signal for defining its channels multiplexed in time, said radio systems cause too much interference with each other. By introducing a coupling between both radio systems for creating a predefined phase difference between their channels by adjusting at least one of said clock signals, the interference can be reduced, in particular in case said phase difference is continuously altered in time, by increasing or decreasing said phase difference all the time.

Abstract: A method and system for rejecting interfering signals in a wireless communication system employing antenna diversity. According to the method, the angle between an interfering signal and a desired carrier signal is determined and used to estimate an offset angle. The offset angle is incrementally adjusted such that, when added to the received signal, the carrier-to-interference (C/I) ratio of the received signal is substantially maximized.

Abstract: An electromagnetic and/or electric interference suppression device that reduces the severity of electromagnetic and/or electric interference of an asymmetric system. The suppression device utilizes an antenna to develop a voltage that is ideally equal to the interference voltage developed from interference signals. A tuned circuit having two opposing diodes, a capacitor, and an inductor mounted in series with each other, to create a voltage that approximates as closely as possible the interference voltage, neutralizing its effect on an asymmetric system.

Abstract: For eliminating the emphasis given an audio signal in the transmitter, an audio signal processor of an audio device (e.g., a car radio) contains a low-pass filter. In order to attenuate the spurious higher-frequency signal fractions in case of poor reception and accordingly low received field strength, the cutoff frequency of the low-pass filter is shifted in the direction of lower frequencies in accordance with a received field strength signal when the field strength becomes lower. In order to avoid external adjusting components and save pins on the IC chip, the field strength signal is supplied to an analog-to-digital converter and the latter supplies a digital signal to a low-pass filter whose cutoff frequency is variable. For this purpose the low-pass filter contains a number of integrated components one of which is connected or disconnected by a digit place of the digital signal in each case.

Abstract: A digitally-controlled frequency synthesizer circuit is provided. The synthesizer circuit has a synthesizer that provides as an output a signal that is based on a reference frequency supplied from a resonator circuit. The reference frequency of the resonator circuit can be tuned by varying the control voltage applied to a voltage variable capacitor that is coupled to the resonator circuit. The voltage variable capacitor is located on the synthesizer. A digital-to-analog converter is also located on the synthesizer. The digital-to-analog converter provides the analog control voltage for the voltage variable capacitor based on digital voltage control data.

Abstract: A noise suppressor, and associated method, suppresses periodic noise components of a communication signal. The period of the periodic noise components of the communication signal is determined by correlating the communication signal with the communication signal, delayed by various delay amounts. Once the period of the noise component portion is determined, a periodic signal exhibiting a corresponding periodicity is generated and subtracted from the communication signal. The resultant, difference signal forms a noise-suppressed communication signal. When embodied in a radiotelephonic device, background noise formed of an engine sound caused by the running engine of a motor vehicle at which the radiotelephonic device is operated can be suppressed during operation of the noise suppressor.

Abstract: A method and apparatus for suppressing noise in a radio receiver or the like due to electromagnetic interference generated by the firing of a spark plug which coordinates the operation of a noise blanker with the EST signal generated by an electronic engine control module or similar spark timing signal. The apparatus of the present invention comprises a noise blanker disposed within a radio receiver for blanking the output of the radio receiver for a predetermined duration after a predetermined time delay has elapsed after each EST signal pulse. The noise blanker is activated for a time duration slightly longer than the duration of the impulse noise. The noise blanker may also be designed to be deactivated when the desired signal level reaches a predetermined level. The apparatus of the present invention may be used in conjunction with other noise suppression systems to eliminate noise due to sources other than the electronic ignition system.

Abstract: The disclosed system for estimating the ambient noise level in a listening space includes a memory for storing a plurality of noise values at memory locations therein, each of the noise values being representative of the ambient noise in the listening space associated with a corresponding set of conditions of the listening space. The system further includes an address generator for generating an address signal in response to a current set of conditions of the listening space so that the address signal accesses a location of the memory storing the noise value associated with the current set of conditions. The system further includes a noise signal generator for generating a noise signal in response to the address signal, the noise signal corresponding to the noise value associated with the current set of conditions so that the noise signal is representative of the ambient noise level.

Abstract: A voice controlled vehicle accessory system is responsive to voice commands and/or manual commands wherein the manual commands are entered via a single pushbutton 16 having multiple functions depending upon the instantaneous state of a system controller 10. A single housing houses the microphone for the voice recognition unit and the single pushbutton adjacent to each other in a common location in the vehicle, thereby reducing manufacturing costs and increasing user convenience since the two separate input functions are intuitively placed in a common location.

Abstract: A method and apparatus is disclosed in which a transformer which has at least one DC output and one input, and a precision timer which generates a control signal having a frequency within a predetermined range of an integer multiple of the carrier frequency spacing. A switch which is connected to the transformer controls the input of the transformer. A controller which is electrically connected to said DC output, said precision timer and the switch pulse width modulates said switch means at an integer multiple of the carrier frequency spacing whereby the DC output of the transformer is regulated.

Abstract: In a direct sequence spread spectrum code division multiple access receiver using interference cancellation, the signal for cancellation is derived by demodulating the unwanted signals and re-modulating a carrier to create a near replica for subtraction from a delayed version of the total received signal. Errors in the demodulation process degrade the cancellation. The present invention provides an optimal way of using the reliability information in the demodulator decision variable either to turn the cancellor off for unreliable bit decisions or to partially disable the cancellor according to the bit reliabilities.

Abstract: An integrated multi-layered microwave circuit includes a substrate which is constituted by dielectric layers and conductive layers laminated alternately. The conductive layer disposed at one major surface of the substrate forms a micro strip line which constitutes an antenna portion. The conductive layer disposed at the other major surface of the substrate forms a circuit pattern including a grounding line and a power source line, and then the circuit pattern forms a communication portion together with discrete parts incorporated in the circuit pattern. One of the intermediate conductive layers of the substrate constitutes a grounding layer and the other thereof constitutes a power source layer. In the substrate, a feeding via hole, a via hole for a power source, and a grounding via hole are formed so as to penetrate the substrate.

Abstract: A system (200) for muting a portable radio (104) includes a mobile radio (106) having a mute switch (108). Upon activating the mute switch (108), a signalling message is generated (ISW) by radio (106) that is in turn transmitted to the system central controller (202). The system central controller (202) then sends a mute signalling message (OSW) directed to portable radio (104). Upon decoding the signalling message, portable radio (104) is placed in a muted condition, thereby preventing the device from unmuting. Portable radio (104) can become automatically unmuted by either the pressing of the PTT switch found on radio (104) or by the radio user opening the door (116) of his vehicle (102).

Abstract: An automotive radio system employs a plurality of corrective actions in response to the detection of multipath interference to reduce distortion audible to a listener. The speed of the vehicle is determined since the number of multipath events per unit time and the expected duration of each multipath event vary according to vehicle speed. The corrective action taken in response to detection of multipath interference depends upon the vehicle speed. In a diversity antenna system, antenna switching is suspended at high vehicle speed while filtering of the audio output to reduce noise is suspended at lower vehicle speeds.

Abstract: In a noise enhancement system for use in a vehicle having an engine, a memory contains stored data representing desired sound relating to vehicle speed or the engine speed. The system is provided with a source of first signals indicative of the vehicle speed or the engine speed and a generator to generate vehicle engine noise desired by an occupant of a cabin of the vehicle. The generator includes a synthesizer to synthesize desired vehicle engine noise signals used to generate the desired vehicle engine noise and a microprocessor responsive to the first signals to use appropriate data of the stored data in dependence upon the vehicle speed or the engine speed indicated by the first signal to control the synthesizer to synthesize the desired engine noise in time with the vehicle speed or the engine speed indicated by the first signals.

Abstract: A mobile radio receiver, for example, a car radio, needs a circuit to detect and suppress adjacent-channel interference. This can be done by using bandpass filters (14) of differing bandwidth. The present invention dynamically adjusts bandwidth to an optimum value by continuously comparing (13) a first signal level, upstream of the bandpass filter, to a second signal level, downstream of the bandpass filter, to derive a difference value representative of adjacent-channel interference, then uses an electronically controlled selector switch (6) to select a particular filter (14.sub.N) whose bandwidth is sufficiently narrow to cut out the interfering broadcast signal. A table associating each magnitude range of interference with a particular filter bandwidth assures that bandwidth is broadened as interference diminishes, thereby assuring sufficient reception signal strength.

Abstract: A vehicular radio receiver includes a receiver main body provided adjacent to an antenna mounted on a vehicle body, a receiver operation unit provided in a compartment of the vehicle spaced from the receiver main body for sending a pulse signal for operating the receiver main body thereto, and a control circuit for forcibly and continuously lowering an output derived from the receiver main body during a time in which the pulse signal is transmitted from the receiver operation unit. Noises caused by the pulse signal transmitted to the receiver main body from the receiver operation unit are prevented from being audibly output from a speaker.

Abstract: An apparatus for reducing audio interference produced by a transducer (18) in response to an audio signal has a first input for receiving the audio signal and a second input (22) for receiving sound signals. The audio interference affects a speech recognition system (34). The second input provides a possibly contaminated signal representing the sound signals. The sound signals comprise a desired audio signal, and possibly comprise the audio interference. An interference reduction device (30) is coupled to the first and second inputs, for transforming the possibly contaminated signal into features that are substantially free from the effects of the audio interference.

Abstract: An improved FM car radio includes a recognition circuit for detecting intermittent multipath reception from the audio frequency signal, rather than from the intermediate frequency signal, as in prior art detectors. The output signal of the stereo decoder 6 is fed to a recognition circuit containing a 90.degree. phase shifter 14, a multiplier circuit 15, a low-pass filter 16, a rectifier 17, and another low-pass filter 18. The resulting output signal U.sub.q is a measure of the quality of the signal, and can be used to initiate re-tuning to an alternate transmitter. For faster response, the recognition circuit can include a second signal path and a quotient former stage 23, resulting in an output signal U.sub.q *. Either U.sub.q or U.sub.q * is fed back to a threshold value stage 19 for evaluation.

Abstract: A FM receiver quickly suppressing defective effect of multipath reflection interference is disclosed. A field strength detecting circuit (8) is responsive to output signals from preceding stage amplifiers (51) in an IF amplifying circuit (5) for detecting the field strength of the received signal. In response to the field strength detecting circuit (8), a soft muting control circuit (10) is operated, whereby a muting circuit (7) gradually mutes the output signal of a detector circuit (6). Furthermore, an alternate current signal detecting circuit (12) detects the alternate current signal component included in the output signal from the field strength detecting circuit (8), whereby the occurrence of multipath reflection interference is detected.

Abstract: A system for increasing the quality of the sound available from a broadcast, frequency modulated, radio frequency, stereophonic signal. Sound quality is promoted by: (1) so switching between available antennas that the signal available from the antenna receiving the incoming signal which is stronger and contains the least multipath distortion is processed into audio output signals, and (2) at least partially blending stereophonically related audio input signals into a monophonic signal if the modulation of the incoming first and second audio signals decreases below a selected threshold value and if: (a) the multipath distortion in the incoming signal reaches or exceeds a preselected threshold value, or (b) the strength of the incoming signal decreases to, or falls below, an also preselected threshold value.

Abstract: The reception of FM broadcast signals having a selected high sound quality is determined according to criteria including a low noise level and the absence of interference. The high quality information is employed to terminate a scan tuning operation or to activate an ultrasonic noise filter to improve listening quality of the FM audio output. The absence of noise and interference is determined by examining a particular frequency range from the FM field intensity line generated by an intermediate frequency circuit.

Abstract: A mobile electric accessory apparatus for mounting on a vehicle equipped with a wireless transceiver unit such as a mobile radiotelephone and a separate wireless receiver unit such as a television receiver is adapted to limit operation of the wireless receiver unit, as by cutting off power thereto or inhibiting reception of a signal from the corresponding receiving antenna, when the wireless transceiver unit is being used, thereby preventing interference in the reception of the wireless receiver unit. If a receiving antenna nearest the transceiver antenna of the transceiver unit, when the latter is in use, is excluded from the antennas in a diversity reception system, good reception can be obtained. By disposing antenna for the transceiver unit and the antenna for the receiver unit on a single windshield glass adjacent mutually opposing edges thereof, the receiver unit will not have its reception disturbed by electric waves from the transceiver unit.

Abstract: A communication device (10) comprises an input for receiving a first audio signal (12) and an input (36) for receiving a second audio signal. The communication device (10) also includes a circular buffer (34) for storing the output digital audio signal (12) and for producing an output audio signal (20). The communication device (10) determines whether at least a portion of the output audio signal (20) is present in the second audio signal. If such a portion is present, the communication device (10) subtracts the portion of the output audio signal (20) from the second audio signal, to produce a third audio signal (26). A threshold detector, responsive to the third audio signal, produces a first control signal, when the level of the third audio signal increases to at least a first predetermined level, and a second control signal, when the level of the third audio signal decreases to a value lower than a second predetermined level, where the second predetermined level is lower than the first predetermined level.

Abstract: A phase shifted (28) version of an alternator noise signal (26) is coupled into a recovered signal (22) that has been corrupted by the alternator noise. The alternator noise signal (26), and phase shifted version thereof, add to zero (or near zero) so as to reduce alternator noise corruption of the recovered signal.

Abstract: A diversity receiver includes first and second antennae for receiving an RF signal, and an antenna switching circuit for selecting one of the first and second antennae. A first detection circuit having a high sensitivity, and a second detection circuit having a low sensitivity are provided, each detecting a noise signal contained within the received RF signal in different sensitivity. A field strength detection circuit is provided for detecting a field strength of the received RF signal, and a selection circuit is provided for selecting either one of the first and second detection circuits according to the output signal of the field strength detection circuit, and for providing a switching signal to the antenna switching circuit. Thus, when the field strength is relatively strong, the first detection circuit with high sensitivity is used for the noise detection, and when the field strength is relatively weak, the second detection circuit with low sensitivity is used for the noise detection.

Abstract: A radio (10) measures and stores (16, 18) the ambient sound (or noise) level of its environment. When a message is received, the current noise (or sound) level is compared to a threshold (56). If the ambient noise level is such that an audible tone may not be heard by the radio user, a silent alert is automatically activated (62) regardless of whether the silent enunciator has been previously selected (enabled) by the radio user. In another aspect of the present invention, if the ambient noise level is such that an audible tone may be inappropriate (i.e., library, courtroom, or certain hospital areas), the silent alert is also automatically activated regardless of whether the silent enunciator is enabled so as not to disturb others.

Abstract: A pulsating noise removal device includes first and second variable attenuators for varying signal levels of an audio signal component and a noise signal component both involved in an entered signal to use an output of the first variable attenuator to control the first and second variable attenuators and to use an output of the second attenuator to control a gate circuit for switching the entered signal, so that an inversion phenomenon is reliably prevented against a change either in the audio signal level or in the audio signal frequency.

Abstract: The present invention provides a diversity type automobile antenna system comprising a pair of high-frequency pickups for mounted on the vehicle body at one or more locations whereat surface high-frequency currents will be induced by radio or other waves with higher densities, said high-freqnency pickups being arranged such that one of said high-frequency pickups can complement the other with respect to sensitivity. The above locations on the vehicle body include the marginal edge of a closure such as trunk lid, roof or engine hook, and various connections between each adjacent vehicle portion of flat configuration such as pillars supporting the roof panel or trunk hinges. One of the high-frequency pickups are adapted to be automatically selected such that it can receive radio or other waves more sensitively.