Abstract: A wireless communication device receives audio data from a base station via a radio frequency (RF) communication link (i.e., a forward link) and transmits audio data to the base station via the RF communication link (i.e., a reverse link). The wireless communication device uses the inherent functionality of the reverse link, including an audio input device (120) to determine whether the wireless communication device is operating in a high noise environment. A signal analyzer (124) analyzes the audio signal on the reverse link and determines whether the ambient noise level exceeds predetermined threshold. If so, the signal analyzer (124) activates a filter (126) to filter the audio signal being provided to an audio output transducer (122). Band limiting the audio signal provided to the audio output transducer (122) improves intelligibility of the audio signal in the presence of noise.

Abstract: In a cellular telephone, a method of reducing background noise of an audio signal resulting from a received signal. Each digital sample of the audio signal is used to calculate an average energy of the audio signal over a number of samples. When the average energy is less than a threshold, a gain factor is calculated using the average energy and the threshold. The amplitude of the audio sample is then adjusted according to the gain factor.

Abstract: An audio signal noise reduction system comprises a noise detecting circuit 11 for detecting a noise from an audio signal and outputting a detection signal indicating a start time and an end time of a noise period of the noise, an LPF 12 for extracting a low frequency component of the audio signal, an HPF 14 for extracting intermediate and high frequency components of the audio signal, a polynomial interpolation circuit 13 for polynomial-interpolating the noise period of the low frequency component being extracted, a mute circuit 15 for muting an output level of the noise period of the intermediate and high frequency components being extracted, and a signal synthesizing circuit 16 for synthesizing the low frequency component whose noise period is polynomial-interpolated and the intermediate and high frequency components the level of whose noise period is suppressed to thus output the audio signal.

Abstract: A radio transmission apparatus for performing radio transmission by use of a plurality of carrier frequencies, including signal processing systems for respective channels. Each signal processing system includes a transmission signal generator that modulates transmission data with a predetermined carrier frequency signal to generate a transmission signal, an amplifier that amplifies the transmission signal, and a variable band-pass filter connected to the output of the amplifier. The outputs of the signal processing systems are combined with a radio transmission signal. At least the center frequency of a pass band of the variable band-pass filter can be changed, with the pass band determined based on the carrier frequency signal of the channel. The apparatus also includes a fault detector configured to detect a fault of each variable band-pass filter.

Abstract: A method, system and computer readable medium for a wireless radio communication processing unit capable of, when setting or changing a communication frequency to be used in one of base station wireless radio units, setting a frequency which does not interfere with communication frequencies being used in other base station wireless radio units. In the wireless radio communication processing unit, when a power supply is turned on, when the unit is reset, or a fault detection section detects a fault resulting from an interfering wave or the like in a communication area of the base station wireless radio unit, a station information requesting section inquires for a channel being used in a base station wireless radio unit that a different wireless radio communication processing unit manages.

Abstract: Distortion due to transmission characteristics of a transmission medium is corrected by measuring leakage in a signal orthogonal to a received signal. The frequency response of an equalizer is adaptively adjusted until the measured leakage is at a local minimum.

Abstract: There is provided an improved receiver unit for wireless microphone system. The receiver unit accomplishes desirable mute control in accordance with state transmitting conditions of electric wave from a wireless microphone.

Abstract: The fixation of a coaxial cable between a GPS receiver and a receiver antenna mounted in a vehicle to an earthing conductor allows the elimination of influences due to noise and the improvement of reception even if the GPS antenna and the receiver antenna are mounted on the same mounting board due to reduction in the size of the device.

Abstract: A receiver portion of a telephone includes a differential amplifier stage with a single output, an electroacoustic transducer connected between the output, via a capacitor and ground and a unit for controlling switching on/off, connected to the differential stage for the activation or deactivation thereof. To prevent annoying noises in the transducer upon switching on and off, the differential stage includes an operational amplifier having a first capacitor and a second capacitor in series with the inverting and the non-inverting input terminals. A third capacitor is connected between the inverting input and the output of the operational amplifier. A fourth capacitor is connected between the non-inverting input and a first reference-voltage terminal. A first switching capacitor is alternatively connectable between a second and a third reference-voltage terminal, or between the first input and the output of the operational amplifier.

Abstract: An automatic squelch is provided within an intercom to control the gating of a microphone signal path. The automatic squelch includes an analog-to-digital converter coupled to receive an analog microphone input signal which is configured to convert the analog microphone input signal into a digital input signal. A peak detector is further provided to maintain a peak value indicative of peaks in the digital input signal. The peak value maintained by the peak detector reacts relatively quickly to changes in the digital input signal. In one implementation, when the digital input signal is larger than the peak value, the peak value is set at the level of the digital input signal. When the digital input signal is less than the peak value, the peak value is “decayed” or reduced at a relatively fast decay rate. A background noise detector is further provided for maintaining a background value indicative of background noise in the digital input signal.

Abstract: Radio receivers which switches the received voice signal according to a supervisory signal used for supervising the condition of the propagation path through which the voice signal is transmitted are known. However, if the reception level of the radio wave received by a conventional radio receiver is low, the level of the supervisory signal becomes lower while the level of the noise accompanying the supervisory signal becomes higher, whereby the noise acts like the supervisory signal so as to provide a voice signal containing a lot of noise to the user of the radio receiver. To solve this problem, the radio receiver according to the present invention compares the level of the supervisory signal and the level of the noise accompanying the supervisory signal, so as to control the outputting of the voice signal according to the comparison result.

Abstract: Disclosed is a transmission envelope detector referred to a squelch detection circuit for effectively detecting an element of transmission data in a high speed serial data transmission system. The squelch detection circuit of the invention includes a differential input level shifter, a first reference voltage generator, an amplifier, a second reference voltage generator, and a comparator. The squelch detection circuit can detect whether the transmission data is a noise or signal element even at a cross point of the transmission data, resulting in achieving stable data transmission.

Abstract: A receiver in an audio distribution system provides graceful degradation of audio quality as transmission quality decreases by dynamically adjusting the volume of audio output as a function of transmission quality. The receiver estimates the rate of transmission errors in a transmission link on which the audio signal is distributed by detecting errors in known information embedded in the audio signal. As the rate of transmission errors increases, the receiver increasingly attenuates the volume of the audio output. The receiver dynamically adjusts the volume relative to the rate of transmission errors applying a smoothing function to avoid disruptive rapid fluctuations in audio output volume.

Abstract: A mobile communication receiver generates an audio signal from a radio signal received on a communication channel, detects conditions on the communication channel, mutes the audio signal according to a first rule when the channel conditions are bad, and un-mutes the audio signal according to a second rule when the channel conditions are good. The first rule is more stringent than the second rule; as a result, sporadic muting and choppy muting are avoided.

Abstract: Squelch circuitry for narrow band audio receivers which uses a sub-audible tone or coded signal to modulate the intermediate frequency in accordance with the presence of a desired broadcast signal and then detects the sub-audible tone frequency or coded signal in the modulated IF frequency to control the audio output of the receiver to an off condition when there is excessive noise.

Abstract: A noise reducing AM receiver has a receiving stage for receiving an AM signal of carrier frequency separated from that in an adjacent channel by a predetermined spacing and that may have a noise component. A detecting stage is coupled to the receiving stage for detecting at least a first portion of the received AM signal. A filter is coupled to the detecting stage for extracting a spectral component from at least a first portion of the received AM signal. A noise detector is coupled to the filter for detecting the presence of a predetermined amount of noise in the spectral component and for providing a blanking control signal in the presence of at least the predetermined amount of noise. A first noise blanker is responsive to the blanking control signal to process at least one portion of the received signal in response to the control signal to reduce the audibility of the noise component.

Abstract: A local communication system in which a modem in a portable computer communicates wirelessly with the base station in a conventional portable telephone which is attached to a telephone land line. The computer may attach to the handset of a portable telephone via a jumper cable connection that is provided in the handset. Alternatively, the computer modem uses a wireless transceiver to communicate with a matching transceiver in the portable telephone base station. In another alternative configuration, the modem in the computer has an integral modem/transceiver that is used to directly communicate with the portable telephone base station. In addition to portable computers, the phone interface can be used by any communications device to communicate with a portable telephone. Alternative land lines such as coaxial cable networks or fiber-optic networks can be used in place of conventional telephone land lines.

Abstract: A digital noise reduction for a radio frequency receiver communication systems that is field programmable to function with a large variety of signaling schemes or waveforms. The noise reduction arrangement includes circuits to convert the mulit bit digital signal (including noise impulses therein) into logarithmic form and uses exponential averaging to determine the presence of noise and the magnitude thereof. Various threshold circuits, the exponential averaging circuits and an exponential decay circuit are responsive to digital commands to set the thresholds for noise detection and control when the noise should be blanked and the duration of blanking.

Abstract: A noise reducer generates a gate signal by detecting noise in a demodulated signal, and changes the lengths the gate pulses indicating the presence of noise according to the electric-field strength of a radio signal from which the demodulated signal has been obtained. The demodulated signal is modified during intervals indicated by the gate pulses, to reduce the noise. The amount of change of the gate-pulse lengths is preferably increased as the electric-field strength decreases. Noise can then be removed satisfactorily under even weak electric-field conditions.

Abstract: A portable telephone communications system has a portable telephone terminal (300) and a repeater unit (100), and a remote receiver unit (200), wherein the repeater unit (100) includes a main power supply control device which includes detection means triggered by a signal from the telephone terminal arising on receipt of an incoming call, and including infra-red transmission means for transmitting the signal as a frequency-modulated signal to the remote receiver unit; the remote receiver unit (200) includes an infra-red receptor, demodulation means (205) and means for outputting the demodulated signals as audible voice signals, and further comprises a noise level comparator (209d) which compares the voltage of noise generated when no infra-red signals are received with a predetermined level and delivers an output signal when said voltage exceeds the predetermined level, and a time counter (210) which outputs a reset signal when the output from the noise comparator has been generated for a predetermined time i

Abstract: The pulse-shaping look-up table with transient suppression (530) avoids hard turn-on and turn-off transients by modifying word segments of initial and final digital words during transmission of a digital data sequence. A controller (570) sends a mode signal and a digital data sequence to the pulse-shaping look-up table with transient suppression (530). A mode buffer and command block (560) uses the mode signal to control the creation of initial and final digital words created by a data buffer and control block (550) from the digital data sequence. The digital words are used by a look-up table (540) to create a sampled digital output waveform sequence. The pulse-shaping look-up table with transient suppression (530) provides an accurate output waveform sequence with reduced spectral emissions even during start-up and shut-down of digital data transmissions.

Abstract: A problem in hearing aids or other audio/acoustic amplifier circuits is that external sources of EM energy may be coupled into the electronics of the hearing aid so as to contribute to the acoustic output. The invention provides a circuit for removing the effects of EM interference. A separate reference generator is used to detect the external EM energy. This is fed into an interference canceller which may be adaptive, which effectively removes the unwanted component in the hearing aid signal, leaving only a signal representative of the desired acoustic output.

Abstract: A receive squelch circuit detects a pulse width of an input data signal to prevent errors from occurring during detection of received data. The squelch circuit adds a function of detecting a pulse width to an input side to detect normal and abnormal pulse signals of received data and adjust the squelch circuit operations. The squelch circuit includes a plurality of current sources for each supplying a predetermined amount of current in accordance with a supplied power and a plurality of MOS transistors for detecting a pulse width of an input differential data signal. A plurality of voltage comparators compares the detected pulse width of the input differential data signal with a standard value and judges whether the detected pulse width is normal.

Abstract: A radio receiver operates primarily in a first operating mode to process received signals (410). When a carrier signal detect is triggered while in the first operating mode (415, 420), the receiver temporarily operates in a second operating mode which has receiver parameters selected to reduce carrier detect falsing when compared to the first operating mode (430). Preferably, in the second operating mode, the receiver's frequency and time response characteristics are modified to facilitate carrier squelch detection. Carrier squelch is performed if a carrier signal detect is triggered while the receiver operates in the second operating mode (440, 450, 460, 470).

Abstract: An improved squelch circuit which utilizes a phase-locked-loop (PLL) arrangement to track the carrier signal and identify when audio communication should be curtailed. The lock detect circuit of the PLL is used for a signal-to-noise monitor. As the loop locks and unlocks, the lock detect line pulses. These pulses are integrated to give a direct current (DC) level. This DC level is proportional to the signal-to-noise ratio of the carrier signal. The signal-to-noise level is monitored by the squelch gate until a threshold is passed. Falling below the threshold results in a squelching of the audio, when the ratio exceeds the threshold, then audio is commenced. The circuit is enhanced by the ability to automatically adjust the threshold level once the PLL has locked onto the signal.

Abstract: Detection of in-band noise in a radio communications voice channel is provided by mixing a signal having a known frequency into a radio signal containing a voice channel signal in an in-band range, thereby translating the voice channel signal out of the in-band range. The in-band range is thereafter examined for the presence of noise signal energy whose presence can be indicative of in-band noise. Squelching of the voice channel is provided in the event that in-band noise energy exceeds a predetermined threshold.

Abstract: In a portable telephone, a voice filter is connected to an antenna through a receiving circuit. A filter is connected to the voice filter through a switching circuit and filters the voice signal from the voice filter to produce a filtered voice signal. The filter has a first cut-off frequency when the filter is supplied with a first clock signal. The filter has a second cut-off frequency smaller than the first cut-off frequency when the filter is supplied with a second clock signal. A telephone receiver is connected to the filter through an amplifier. A clock generating circuit is connected to the filter and generates the first clock signal when is supplied with a first frequency control signal. The clock generating circuit generates the second clock signal when is supplied with a second frequency control signal.

Abstract: Methods and apparatus for detecting the presence of impulse noise in a signal representing digital data and for performing a limiting or blanking operation in a receiver in response thereto are disclosed. In accordance with the present invention, to detect the presence of impulse noise, in one embodiment, the instantaneous sliced error energy for each received symbol is estimated and compared to either a predetermined threshold level indicative of impulse noise or to an adaptive impulse noise threshold level. In an adaptive impulse noise threshold embodiment, an adaptive impulse noise threshold value is generated by averaging the instantaneous sliced error energy values over a period of many symbols and by then applying a preselected gain to the averaged sliced error energy value to obtain an impulse noise threshold value.

Abstract: It is a primary object of the invention to provide a noise suppressing device in which the function to suppress or remove the noise is more improved than the conventional device. The invention comprises a tuner section which detects the radio wave and converts it to the electric signal, an antenna connected to the tuner section, a field/disturbance information-detecting section for detecting the carrier level and the like of the input signal based on the signal from inside of the tuner section, a modulation information-detecting section for detecting the modulation degree and the like based on the signal from inside of the tuner section, a noise suppression control section which suppresses or removes the noise from the noise-containing signal input from the tuner section, a noise cancel section, and a noise data-generating section; and the noise-removed signal is output to an amplifier and amplified and sent to a speaker.

Abstract: A noise blanker (400) suitable for use with a radio receiver (500) having a track and hold unit (509) includes an impulse noise detector (401), a low pass filter (404) that is coupled to the impulse noise detector, and a first amplitude threshold detector (406) that is coupled to the output of the low pass filter and to the input of the track and hold unit. In one embodiment, this noise blanker is configured in conjunction with a radio receiver to yield a radio receiver that substantially minimizes the impact of noise impulses on resulting processed audio. In one embodiment, a second amplitude threshold detector (512) and a repetition rate threshold detector (513) are additionally utilized to allow gating of the internal signal processing paths of the radio receiver in conjunction with operation of the track and hold unit.

Abstract: A noise-controlled communication apparatus reduces an annoying effect to the other speaker due to an ambient noise on the transmitting side and improves articulation of the receiving voice under noise. In a noise-controlled communication apparatus, a transmitting level detector detects a transmitting level above a threshold. Then, a mode controller enters to a transmitting mode. When the mode controller enters to the transmitting mode, a control mode switching circuit reduces attenuation of a transmitting signal. When the noise-controlled communication apparatus detects a receiving signal, the mode controller enters to a receiving mode for passing through the receiving signal. When the transmitting signal and receiving signal are not detected, the mode controller enters to an idle mode for attenuating the transmitting signal and receiving signal to half.

Abstract: A control for an FM receiver reduces multipath distortion by reducing stereo separation and high frequency response in the demultiplexed signal. The receiver includes an FM detector including a noise detector as well as the signal strength meter for introducing control signals to a separation control and a frequency response control. Unlike the direct input from a noise detector output to the separation and frequency response controls in the prior art, the noise detector output is input through a noise detection manager that generates responses to at least one, and preferably two thresholds of noise detector output. In the preferred embodiment, a stereo separation manager responds to a first threshold of noise and a frequency response manager responds to the second threshold. The frequency response control reduces the high frequency output at the stereo decoder or the audio processor.

Abstract: The present invention provides a method (200), transceiver (100), and system (900) for providing wireless communication compatible with 10BASE-T Ethernet. In the transceiver, an absence detector receives a transmitted signal, determines an absence of the transmitted signal, and passes the absence to an activity detector in order to differentiate between a reflected signal and a received signal in a half duplex system. The activity detector receives the received signal and determines an operation time signal in which the received signal is absent.

Abstract: A pulse noise canceler in which the sensibility of FM pulse noise detection is decreased when an FM wave exceeding the minimum bandwidth which is predetermined of an FM wave detector is input to the pulse noise canceler. In order to detect pulse noise from an output from the FM wave detector in an FM tuner to open a holding gate, an FM pulse noise detector is constituted by a high-pass filter, a variable control amplifier, a full wave detector, and the like. An over deviation detector is constituted by a signal meter for detecting a received field strength, an attenuator, and a high-pass filter, thereby detecting an over deviation level of the FM wave detector. This detection output from the over deviation detector is input to a bottom peak detector and becomes an over deviation signal. An over deviation signal from the over deviation detector is incorporated in the arrangement of a noise AGC amplifier in the FM pulse noise detector to influence control of the holding gate.

Abstract: A signal quality detector (200) determines the quality of an incoming received data signal within a communication device (100). The audio output of the communication device is muted and unmuted according to the decision of the signal quality detector (200). The signal quality detector (200) allows the threshold length of an invalid bit period (210), along with the number of invalid bit periods detected (220), to be used to vary the decision sensitivity of the detector.

Abstract: In a circuit for suppressing short-lived noise phenomena in a digital audio signal, in particular during a temporary test reception of another transmitter, the audio signal is multiplied by a factor which, prior to the appearance of the noise phenomenon, is brought from a maximum value to a minimum value in accordance with a predetermined time function, and at the end of the noise phenomenon, is returned to a maximum value. The invention has special application to the Radio Data System defined by the European Broadcasting Union, and the testing of "Alternative Frequencies" in that system.

Abstract: An adaptive digital squelch system, responsive to ambient RF background noise, that automatically adjusts the receiver squelch level during intervals when no valid signal is being received. A valid signal is considered to be a signal that is greater than the receiver squelch level and which contains an audio signal at a specific frequency; otherwise, the signal is considered noise. When the invention detects the absence of a valid signal, the squelch level is periodically calculated by averaging multiple noise signal levels at multiple frequencies.

Abstract: An adaptive processor for a spread spectrum receiver utilizes an adaptive Wiener filter and an adaptive limiter-canceller in tandem and in conjunction with bypass controls. The adaptive processor derives its cancelling signals from the primary signal. The adaptive processor makes use of bypass switches connected to the adaptive Wiener filter and adaptive limiter-canceller and activated by internally generated control signals to switch the adaptive Wiener filter and adaptive limiter-canceller in or out of the signal processing path.

Abstract: A radio broadcast receiver for receiving digitally coded sound broadcasting data (DAB) includes a bit error rate measuring device. A control device controls the reproduction of the sound broadcasting data, wherein a reception quality threshold value is defined in the control device and, upon the measured reception quality falling below the threshold value, the control device alters the reception quality and/or the reproduction signals in a perceptible manner.

Abstract: A highspeed scanning type radio receiver is disclosed which prevents an erroneous interruption of a scanning operation caused by high frequency noises produced from a clock oscillator and a local oscillator circuit employed therein. The highspeed scanning type radio receiver includes a highspeed clock oscillator, a lowspeed clock oscillator, and a clock switching circuit for switching these highspeed clock oscillator and lowspeed clock oscillator to be connected to a CPU. Normally, a searching operation is carried out by supplying the highspeed clock to the microcomputer. When a reception signal is detected in a certain channel, the highspeed clock is changed into the lowspeed clock to be supplied to the microcomputer, whereby a reception signal is again detected. When no reception signal is detectable, the microcomputer recognizes that the detection of the reception signal under operation at the highspeed clock is caused by high frequency noises, and commences a searching operation of the next channel.

Abstract: Controlled by a signal level produced by a microphone (12), a noise suppressing circuit (25) supplies a first attenuator (16) with a local level which is equal to the signal level and is suppressed to a predetermined output level when the signal level is lower and higher than a predetermined input level. Cooperating with a drive level produced by a second attenuator (17) to drive a loudspeaker (13), the local level makes a comparator unit (21-23) produce a control signal for making the first attenuator give smaller and greater amounts of attenuation to the signal level with the drive level rendered by the second attenuator low and high when positive and negative values are had, respectively, by an input difference equal to the local level less the drive level. Preferably, the local level is suppressed by a level difference had by the signal level above the predetermined input level.

Abstract: An apparatus and method for discriminating and suppressing noise within an incoming signal including a first signal processor to generate a first signal representing the incoming signal; a second signal processor to generate a second signal representing the first signal; a prediction device which generates a prediction for the second signal; a logic device which determines the difference between the second signal and the prediction and generates a logic output having a first value when the difference exceeds a threshold and a second value when the difference does not exceed the threshold; and a muting device to mute the incoming signal when the logic output has one value and not mute the incoming signal when the logic output has the other value.

Abstract: A fast acting noise squelch control circuit for FM radio receivers samples the noise above the audio band to determine the presence of an RF carrier. The detected noise signal is integrated by a low-pass frequency gain integrating filter and compared, using a high gain differential amplifier, against a preset squelch threshold voltage to provide a signal indicative of the presence or absence of a received carrier. The output of the integrating filter is initialized at a reference voltage that is only slightly below the threshold voltage setting for the comparator to minimize integration time and increase sensitivity of the squelch. In this manner, a long time constant in the noise integrating filter can be used without having to wait for a long time to establish whether a carrier signal is present.

Abstract: An apparatus for detecting noise in communications channels in electrical power transmission systems and generating squelch signals, for transfer-trip receivers for performing protection and control functions, detects changes in a period of an analog signal and generates a signal in response to such changes. The apparatus receives an analog signal, generates zero-pulses corresponding to zero-transitions of the analog signal, generates an error pulse when an interval between successive ones of the zero-pulses either exceeds a preselected long window interval or is less than a preselected short window interval, and generates, in response to the error pulse, a squelch signal.

Abstract: An FM noise reduction circuit including a level detection circuit receiving an intermediate frequency signal. The level detection circuit rectifies the intermediate frequency signal, and outputs a rectified intermediate frequency signal. A first frequency filter passes the rectified intermediate frequency signal in a first frequency range, and outputs a first voltage responsive to the portion of the rectified intermediate frequency signal passed in the first frequency range. A first interference signal detection circuit includes a second frequency filter. The second frequency filter passes the rectified intermediate frequency signal in a second frequency range and outputs a second voltage responsive to the portion of the rectified intermediate frequency signal passed in the second frequency range. The second interference signal detection circuit includes a third frequency filter.

Abstract: An FM audio signal receiver having a characteristic control function includes a receiving circuit for receiving an FM broadcast wave, a received state analyzing circuit for analyzing a state of the FM broadcast signal received by the receiving circuit, an analog-to-digital converter for analog-to-digital converting the FM broadcast signal received by the receiving circuit, a digital signal processor for performing processing for improving characteristics of the digital-to-analog converted signal, a parameter table memory for storing parameters for the digital signal processor and a control circuit for reading out a proper parameter for realizing improvement of a characteristic of the digital-to-analog converted signal from the parameter table memory in response to result of analysis by the received state analyzing circuit and controlling the digital signal processor with the read out parameter.

Abstract: An apparatus and method for discriminating and suppressing noise within an incoming signal which provide a first signal processing unit for processing the incoming signal to generate a first iteration signal representing average difference signal level of the incoming signal; a second signal processing unit for processing the first iteration signal to generate a second iteration signal representing specified aspects of the first iteration signal; a prediction unit for generating a predicted value for the second iteration signal from earlier samples of the second iteration signal; a logic unit for determining a threshold difference between the second iteration signal and the predicted value, the logic unit generating a logic output having a first value when the threshold difference exceeds a predetermined threshold value and having a second value when the threshold difference does not exceed the predetermined threshold value; and a muting unit for muting signals which is operatively connected to receive the in

Abstract: A receiver includes a plurality of antennas, a selection switching unit for selectively switching between the plurality of antennas to output one of the respective output signals of the plurality of antennas having the largest induced voltage, and a unit for converting the selected one antenna output signal to an audio signal to be outputted as an output signal of the receiver. The receiver further includes a muting control unit for detecting the level of the induced voltage of the selected antenna output signal so as to output a muting control signal when the detected level of the induced voltage becomes smaller than a predetermined value, and a muting unit for muting the audio signal for a predetermined time on the basis of the muting control signal. The selection switching unit performs its antenna switching operation on the basis of the muting control signal.

Abstract: A digital communication device (10) comprises a signal quality detector (18) that determines the quality of the received signals and instantaneously mutes and unmutes the voice output (22) of the digital radio communication device when the quality drops below a selected level to prevent noise bursts from being heard by the user of the communication device.

Abstract: A communication device (100) having a receiver (106) and an audio output device (116) is provided. The communication device (100) includes a digital signal processor DSP (110) for measuring the level of signal energy in a first segment of the frequency spectrum of the received signal to dynamically establish a squelch threshold. The DSP (110) is also used to measure the level of signal energy in a second segment of the frequency spectrum of the received signal. The communication device (100) also includes audio gates (114). The audio gates (114) provides for the unmuting of the audio output device (116) when the signal energy contained in the second segment of the frequency spectrum of the received signal is below the squelch threshold.