Abstract: Disclosed is a portable terminal device that, by changing the operation of a portable terminal unit based on a selective-calling reception operation, can acquire preferable pager reception sensitivity. A portable terminal device comprises: selective-calling reception means with a selective-calling reception function for determining whether an operation is a selective-calling reception operation; portable terminal mean with a portable radio telephone function to enable transmission and reception for determining whether a key has been input; and display means for, when the input of the key is detected during the operation of the portable radio telephone function, displaying the result of the detection.

Abstract: A circuit (350) for detecting simulcast channel conditions includes a symbol center averaging circuit (308) for providing a center count of excursions above and below at least a first predetermined threshold and for providing a moving average of the center count over a predetermined number of symbol periods and a symbol edge averaging circuit (310) for providing an edge count of excursions above and below at least a second predetermined threshold and for providing a moving average of the edge count over a predetermined number of symbol periods. Finally, the circuit further includes a comparison circuit (360) programmed to receive and compare the moving average of the center count and the moving average of the edge count to provide a control signal (380) for simulcast detection.

Abstract: A method and apparatus for continuously calibrating the modulation sensitivity of a voltage controlled oscillator (VCO) within a modulator of a transmitter. In accordance with the present invention, the transmitter is coupled to the receiver in order to loop back the transmit signal. The present invention includes a baseband signal generator which generates a reference baseband signal of known amplitude during periods when no other baseband information is being applied to the transmitter by the user. A Signal and Reference Comparison Circuit (SRCC) receives the output from the demodulator and determines whether the VCO within the transmitter has the proper modulation sensitivity. If the modulation sensitivity of the VCO is not within a desired range, then a signal generated by the SRCC is applied to a baseband level control circuit to adjust the level of the baseband signal that is applied to the VCO.

Abstract: For use in a system having a received signal path therein, the signal path including a mixer that modifies a carrier frequency of an information signal propagating through the signal path, an apparatus for, and method of, reducing an overall power consumption of the system and a radio device employing the same. The apparatus includes: (1) a received signal strength indicator ("RSSI") circuit, in communication with the signal path, that provides an RSSI signal that is a function of a power of the information signal and (2) a power reduction circuit, coupled to the RSSI circuit, that reduces a current draw of the mixer when the RSSI signal exceeds an upper threshold level, the overall power consumption of the receiver thereby reduced.

Abstract: A radio communication apparatus uses an intermediate frequency section to convert a signal from a receiver into an intermediate frequency signal. The intermediate frequency signal is filtered in a filter section, and then demodulated. Matching circuits with variable circuit constants connect the filter section with the intermediate frequency section and the demodulator. A control section supplies a transmitter with an input signal which is then transmitted to the receiver, converted to an intermediate frequency, filtered, and demodulated. The control section adjusts the variable circuit constants in accordance with the input signal and the demodulated signal. Thus, inappropriate circuit constants are adjusted so that the radio apparatus has a high receiving sensitivity without a mismatch.

Abstract: A communication system is provided for increasing communication range between at least two radio communication devices without increasing the output power of transmitted radio signals from the devices, and without increasing the antenna gain of the received signals. Each radio device includes an oscillator for generating a carrier reference signal, and an SATPS receiver which receives at least one standard timing reference signal from at least one SATPS satellite. The received standard timing reference signal is used to continuously adjust the timing and synchronization of the oscillator to improve the accuracy of the carrier frequency signal. The improved accuracy in the carrier frequency signal may then be used to reduce the bandwidth of the modulated carrier frequency signals generated by the radio device to thereby increase the effective communication range and sensitivity of the device.

Abstract: The present invention relates to the extension of the RSSI range of a radio transceiver, in which the RSS value is monitored continuously during reception by a limiter circuit (1). This extension is performed by switching into the operating state of attenuation components (3, 4) which are already present in the receive path of the radio transceiver and in addition to an attenuation function have at least one further function required for operating the radio transceiver. Furthermore, a method is specified by means of which the additional attenuation of such a component (3, 4) which can be switched over can be established and stored in the radio transceiver.

Abstract: An automatic gain controlling circuit and a high-definition television signal receiving apparatus includes an input terminal for receiving a signal including first and second signal components creating interference, a first automatic gain controlling amplifier for amplifying the received signal and providing an amplified output signal, a filter for selectively passing a signal portion in a predetermined band of the amplified output signal from the first automatic gain controlling amplifier, and a second automatic gain controlling amplifier for amplifying the signal portion passed by said filter and providing amplified output signal portion.

Abstract: In a radio selective call receiver for lowering a radio signal level in accordance with the state where reception of a sync signal is enabled/disabled, an amplifier 53 amplifies a radio signal fed from a base station. A frequency converter 54 shifts a frequency of the radio signal amplified in the amplifier 53 to a first frequency band and a second frequency band. A demodulator 55 converts a radio signal shifted to the second frequency band by the frequency converter 54 into a base band signal. A level detector 56 outputs a direct current voltage relative to an electric field intensity level of the radio signal shifted to the second frequency band by the frequency converter 54. A comparator 57 compares the direct current voltage output from the level detector 56 with a predetermined voltage.

Abstract: A pager includes a radio frequency (RF) attenuator which is initially rendered inoperative and which initiates attenuation of an incoming RF signal in response to a control signal. An amplifier is coupled to amplify the output of the attenuator. A signal level monitor (24, 26), coupled to the amplifier, determines if the output of the amplifier exceeds a predetermined level. A demodulator (16) is coupled to reproduce a base band signal from the output of the amplifier. A controller, following the demodulator, attempts to establish bit sync during each of a plurality of conventional and intermittently executed preamble searches. If bit sync is not established in a given preamble search and if the level monitor indicates that the output of the amplifier exceeds the predetermined level, the controller applies the control signal to the attenuator for activating the attenuator.

Abstract: A continuous wave (CW) integrator is employed within a compressive receiver to improve the sensitivity of the compressive receiver to CW signals. The CW integrator circuit partitions the bandwidth of the compressive receiver into a series of contiguous bins and integrates any signals residing within these bins over many sweeps of the compressive receiver bandwidth. By sampling and integrating CW signals present in the compressive receiver bandwidth, the CW integrator circuit improves the sensitivity of the compressive receiver by a factor approximately equal to 10 log .sqroot.N, where N is the number of integrations performed.

Abstract: Enhanced detection of an FM signal is provided through the use of a coded pattern signal which is processed at a receiver (120) non-linearly to facilitate pattern detection. The received signal is conditioned to limit signal amplitudes according to a particular noise threshold (530, 540, 550). The conditioned signal is then processed to determine the presence of the coded pattern (560). In this manner, the probability of detecting signals in weak signal conditions can be enhanced, while maintaining a particular detection falsing rate.

Abstract: An anti-saturation circuit controls the gain of a variable-gain element in the front-end section of a receiver, responsive to a desired signal strength indicated by an indicator signal. The gain of the variable-gain element varies monotonically over a certain range, being reduced as the desired signal strength increases, in order to avoid intermodulation of the desired signal with an interfering signal. If the receiver also has an automatic-gain-control circuit, the automatic-gain-control signal is adjusted to compensate for the changing gain of the variable-gain element.

Abstract: A radio receiving apparatus has a main receiver (10) and a diversity receiver (12). The main and the diversity receivers are linked by a mute logic (34) which is capable of applying a mute signal to either receiver in order to reduce the sensitivity of that receiver. Receiver sensitivity is reduced in order to prevent a comparatively strong received signal causing ringing (persistence of vibration) in the receiver filter.

Abstract: In a receiver of the present invention, a local oscillator frequency, used as a basis for a reception unit to demodulate a received signal, is generated by a local oscillator based on a reference frequency, which is generated by a voltage-controlled oscillator whose oscillation frequency is adjusted by a control voltage applied thereto. The control voltage is prescribed by a decoding unit which monitors a reception electric field intensity (RSSi) or an error rate in the reception unit. The control voltage is adjusted in a manner to increase the reception electric field intensity (RSSi) or reduce the error rate. When the local oscillator frequency experiences a large deviation and the signal cannot be received with good reception sensitivity, the decoding unit generates a control voltage in a manner so as to eliminate the deviation and applies the generated control voltage to the voltage-controlled oscillator for automatically adjusting the local oscillator frequency to a level having a reduced deviation.

Abstract: A technique and apparatus for developing AGC voltage in a receiver capable of receiving VSB signals that do not have the average magnitudes of the data symbol levels and the sync symbol levels related so as to produce the same average level. One technique eliminates the sync symbols from determination of the AGC voltage. A preferred technique corrects for the different symbol levels of the sync by multiplexing in an offset at the proper time or multiplying the sync symbols by a compensating factor.

Abstract: The performance of a radio receive system such as a trunked or non-trunked land mobile multi-channel receiver site is optimized to maximize coverage area and receiver dynamic range while minimizing the potential for intermodulation distortion. A noise test receiver including a noise receiver and a spectrum analyzer measures ambient noise and strong ambient signals. A computer analyzes the resulting spectral information to determine likely intermodulation distortion products and associated amplitudes. The computer compares the measured noise and intermodulation product results with system characteristics to arrive at an optimum variable attenuator setting that maximizes receiver sensitivity and dynamic range while protecting against intermodulation distortion. In one example, the optimized performance parameters are computed dynamically and used to dynamically control the value of a programmable attenuator, thus yielding maximum system performance under varying conditions.

Abstract: A reception clock signal used for a data sampling unit to sample received data is generated by a reception clock generator based on a reference clock signal, which is generated by a reference clock generator based on a reference bit rate frequency. The reference bit rate frequency is produced by a reference oscillator which is controlled by a control voltage. The control voltage is generated by a phase difference-to-voltage converter depending on the phase difference, detected by the reception clock generator, between the timing of a change in the received data and the reference clock signal. If good reception sensitivity is not available due to a phase difference, then the phase difference-to-voltage converter generates a control voltage in a manner to eliminate the phase difference, and applies the generated control voltage to a variable capacitor connected to the reference oscillator for automatically adjusting the reference bit rate frequency.

Abstract: A radio receiver has an antenna circuit, a high-frequency amplifier, a tuned circuit, a mixer for generating a first intermediate frequency signal, and an AGC circuit applied with an output signal of the radio receiver for controlling a gain of the receiver. An intermodulation predicting circuit is provided. The intermodulation predicting circuit has a high-frequency amplifier applied with an output of the radio receiver, and a mixer for generating a second intermediate frequency signal. The intermodulation predicting circuit has a dynamic range smaller than that of the radio receiver. Therefore an intermodulation prediction signal based on a received broadcasting signal is produced earlier than a response to the received broadcasting signal at the radio receiver.

Abstract: In a radio-frequency receiver, a received RF signal is converted to an intermediate frequency (IF) signal and band-limited by a first IF filter to a channel bandwidth. The level of the output of the IF filter is detected by a detector and compared with a threshold to produce a first and a second output when the detected level is lower or higher than the threshold, respectively. A switching circuit applies the output of the IF filter to a demodulator via an IF amplifier in response to the first output and directly applies it to the demodulator in response to the second output. To prevent interference from adjacent channels, a second intermediate frequency filter is connected between the band-limiting IF filter and the detector. The second IF filter has a passband corresponding to a center frequency portion of the passband of the band-limiting IF filter.

Abstract: A method and multicoupler for a receiver at a base station in a cellular/PCS radio communication system includes a cooled container that is mounted on an antenna tower at the base station. The container is mounted on the antenna tower adjacent an antenna and contains thereinside a preselector filter, a highly linear amplifier, and a directional coupler that are cooled to a temperature less than 175.degree. K. and greater than 100.degree. K. A power splitter is connected between the output from the container and the radio system receiver, and is located at a ground station near the base of the antenna tower. Cooling the components inside the container, particularly the amplifier, to a temperature of about 150.degree. K. reduces the noise from the multicoupler so that base station range is extended, building penetration is improved, and subscriber transmit power may be reduced.

Abstract: A distortionless receiving circuit used in a radio receiver to reduce degradation of the receiving sensitivity in case of a relatively lower receiving electric field. The circuit has a radio frequency amplifier, a mixer for frequency conversion, a variable attenuator interposed between the radio frequency amplifier and the mixer, an intermediate frequency amplifier disposed on the output side of the mixer, a detector and a control block. The control block generates a control signal in accordance with the intensity of the output signal of the intermeddle frequency amplifier. The attenuation amount of the variable attenuator is controlled by the control signal in a stepwise manner.

Abstract: A receiver for being mounted on an automobile telephone or similar mobile station which is included in a cellular mobile radio communication system. The receiver has a high frequency amplifier for amplifying a received input wave, and a mixer for converting the received input wave to an intermediate frequency. The gain of the amplifier or that of the mixer is changed on the basis of the level of the field strength of the received input wave and whether or not the mobile station is communicating with a base station. The receiver enhances the reception sensitivity characteristic at locations where the reception field strength is low or the intermodulation distortion characteristic at locations where the field strength is high and intermodulation distortions occur.

Abstract: A controller for AGC recognizes a signal level broader than an AGC control output from an AGC circuit and also recognizes a signal level (a desired station signal level) in a narrow-band by an output from an S-meter. No interference, or the occurrence of 2-signal interference or inter modulation interference can be detected from a change ratio of the desired station signal at the time of the alteration of attenuation values of these two signal levels and an RF signal. In consequence, a proper regulation of the RF signal attenuation value can be carried out in accordance with the presence or absence of the interference and the kind of interference, whereby the suitable receive of the signal can always be achieved.

Abstract: A signal which results from cross modulation of two or more nearby received waves contained in the output of a high-frequency amplifier or mixer of a radio receiver, for example, a low-frequency signal corresponding to a channel separation frequency is extracted. The gain of the high-frequency amplifier or attenuation of a variable attenuator provided in the preceding stage of the amplifier is controlled in accordance with the level of the low-frequency signal. Alternatively, the gain of the high-frequency amplifier or attenuation of the variable attenuator is controlled in accordance with the level of the low-frequency signal when it is equal to or larger than a predetermined value. This permits normal reception of a desired wave, even if the signal receiving level is high.

Abstract: A radio pager has a variable gain adjustable to high setting for normal reception or low setting at which the strength of intermodulation products is reduced in relation to the strength of a desired signal. A sync code contained in a received signal is detected to establish synchronization and a sync-absence signal is generated if it is not detected during a time interval in which it is expected to occur. The pager is initially switched to the high gain setting. In response to a first generation of the sync-absence signal, the pager recognizes that the desired signal is severely affected by intermodulation products and switches to the low gain setting so that the signal-to-noise ratio of the desired signal is improved. In response to a second generation of the sync-absence signal, the pager recognizes that its amplification gain is not sufficient and switches to the high gain setting to resume normal reception.

Abstract: An AGC circuit comprising a first level wave-detecting circuit for wave-detecting received signals having been band-limited, having a sensitivity being particularly high for a central frequency of a desired channel and a sensitivity being low for the other frequencies, and a second level wave-detecting circuit for wave-detecting received signals before the band-limitation having a sensitivity being constant irrespective of the frequency. Since the wave-detected signals of these two wave-detecting circuits are mutually added, it is possible to set an optimum detecting sensitivity by the first level wave-detecting signal against adjacent disturbances close to the central frequency of the desired channel, thereby effectively suppressing disturbance signals taking place when the respective intensities of the electric fields of adjacent channels are similar.

Abstract: A radio receiver simultaneously achieves maximum sensitivity and minimum susceptibility to intermodulation distortion by employing wideband and narrowband automatic gain control which further selects the automatic gain control response in dependence on the detection of intermodulation distortion. An AGC signal is modified to improve sensitivity in the event of a low narrowband signal level except when intermodulation distortion is detected above a predetermined distortion level.

Abstract: A base site circuit (38) for operating in a communication system (10) having a plurality of base sites capable of allocating a communication channel for use by a communication unit (16) in response to a communication channel request from the communication unit. The base site circuit includes a receiver (34) that operates in a low sensitivity mode when there are no communication channel requests received, and that operates in a high sensitivity mode which is activated by a control signal. The base site further includes a transmitter (34) which is activated by the control signal and a control circuit (32) coupled to both the receiver and the transmitter, for controlling the receiver and the transmitter. The control circuit (32) provides the control signal to the transmitter and to the receiver, in response to a communication channel request.

Abstract: A receiver (10) is provided where an information signal (11) is received (12) and examined to determine (20) its signal strength. When the signal strength is at least equal to a threshold, an unmodulated signal (40) is added to the received signal to improve the sensitivity of the receiver.

Abstract: An RF signal received by an antenna is amplified in an amplifier circuit and is then tuned in a tuned circuit to pick up a signal having a certain frequency and a certain level. Then, the picked up signal is mixed with another signal to output an IF signal and the IF signal is detected to reproduce the desired broadcasting program. An AGC circuit ensures high and low levels of the received signal to make the received signal to a certain level. Further, a damping circuit capable of switching a damping amount by a sensitivity switching signal is arranged in the rear stage of the AGC circuit. Hence, intensity of a signal for performing a detection or the like can be exactly switched based of the sensitivity switching signal in an automatic broadcasting station selection.

Abstract: A security device includes a portable transmission unit that gives an instruction to start or stop security, a sensor that detects an abnormality of a tuner which receives a signal from the transmission unit and of an automobile, a sensor circuit having predetermined characteristics for discriminating the output of the sensor, and a security control section for causing a theft prevention device like a siren to be activated after output from the sensor circuit is received, wherein the characteristics of the sensor circuit can be set by the transmission unit.

Abstract: A cellular telephone system includes a plurality of base stations which cover a plurality of cells. The system also includes a plurality of portable telephones communicable with the base station over radio frequency channels. A base station covering a given cell transmits an IM control signal indicating that there exists IM interference in the given cell. In response to the IM control signal, each of the portable telephones reduces its receiver sensitivity, so that the IM interference can be alleviated.

Abstract: A radio receiver is disclosed having a wide filter and a narrow filter, each of which is connected with the front end and outputs an intermediate frequency signal. To the output of the filters are connected first and second detectors, respectively. A subtracter receives the outputs of the detectors and subtracts one from the other. A switch receives the output of the subtracter and directs the outputs of detectors in such a way that the switch is switched to a first position for directing the demodulated output from the first detector to a following circuit when the difference is below a reference level, and to a second position for directing the demodulated output from the second detector to the following circuit when the difference is above the reference level.

Abstract: A radio sensitivity enhancer inputs an incoming radio frequency signal into two receiver strings. The first receiver string modulates the RF signal to a frequency which is passed by a filter to produce the desired signal plus a noise component. In the second receiver string, the RF signal is modulated to a frequency outside the frequencies passed by a filter to produce a signal with a noise component but without the desired signal. The desired signal with the noise component is then subtracted from the signal with only the noise component to produce a substantially noise-free desired signal.

Abstract: In a communication system having a time base for system synchronization, there is provided a method and apparatus for controlling the sensitivity of a receiver comprising the steps of (a) receiving a signal that was predeterminally transmitted by another relative to the time base (wherein signal reception is confirmed when the amplitude of the received signal exceeds a pre-established threshold), (b) determining signal transit time from the time difference between the instant of signal reception relative to the time base and the instant of signal transmission relative to the time base, (c) controlling the sensitivity of the receiver as a function of the transit time by: (1) increasing the gain of the receiver from a minimum sensitivity at the predetermined transmission instant to a maximum sensitivity at maximum range (maximum expected transit time) and (2) nominally maintaining the receiver's gain at the level prevailing at the instant the signal is received.

Abstract: A variable frequency RF passband filter is calibrated to maximize the sensitivity of a radio receiver using reference frequencies applied based on the clock operation of a digital processor within the receiver. The reference frequency passing through the variable passband filter is mixed to the intermediate frequency of the receiver and its level is detected. A frequency counter verifies that a measureable reference frequency signal has in fact been mixed to the intermediate frequency in order to avoid errors. The correct control voltage signal for the variable passband filter corresponding to each receiver frequency can thus be conveniently and inexpensively determined and stored for use during normal operation of the receiver.

Abstract: A portable radio receiver assembled in a case. In accordance with the present invention, the case is also employed as an antenna of the portable receiver. The case is composed of a pair of parallel-opposed square conductor plates interposed therebetween a space sufficiently smaller than the wavelengths of received waves of the portable radio receiver, a frame of insulating material interposed in the space. Feeding terminals of the portable radio receiver are provided at desired positions on one pair of opposed sides of the parallel-opposed square conductor plates. Each of short-circuit elements of high-frequency-wise is provided on other pair of opposed sides of the parallel-opposed square conductor plates so that the direction of the plane of polarization of the antenna can be changed by short-circuiting any one of the short-circuit elements.

Abstract: An FM detection system receives an FM input signal containing a plurality of carrier bands, including a tuned carrier band. The tuned carrier band is separated from side carrier bands by a frequency guard band. A detected, demodulated output signal is fed back to at least one local oscillator, which generates corresponding local FM signals having a deviation which is in phase with the deviation of the tuned carried. The FM input signal and the local FM signal are inputs to a guard band expansion device. The guard band expansion device includes a harmonics generator which produces an output spectrum which is a multiple of its input spectrum. In one embodiment, the harmonics generator operates directly on the FM input signal, its output signal then being beat by a mixer with the local FM signal. In another embodiment, the operations of harmonics generation and mixing are reversed.

Abstract: An auto tuning apparatus sequentially varies the value of N, a positive integer, in the frequency-dividing ratio 1/N of a variable frequency-dividing circuit incorporated in a local oscillating circuit having a phase locked loop configuration. The apparatus detects a plurality of candidate tuning points of an intermediate frequency carrier and includes a circuit for performing a scan of those tuning points by, among other steps, changing a tuning point detecting threshold relative to the level of the received signal. A circuit is provided for determining the correct or optimum tuning point on the basis of the scan.

Abstract: A reception sensitivity control system in a sweeping receiver in which a frequency dividing ratio of a phase lock loop is instantly changed from one end of the band to the other. The number of receivable stations is counted in the period of time required for the phase lock loop to adjust. If the number of stations is less than a preset minimum, the input sensitivity is increased. Thereafter, the channels are selected.

Abstract: In a radio receiver provided with an automatic tuning circuit, a tuning sensitivity adjusting circuit comprises a buffer which extracts a signal received partially-processed from the radio circuit without substantially affecting the audio output, and a change-over circuit which receives the signal from the extracting means, selectively attenuates the signal, and supplies the signal to the automatic tuning circuit as a signal to lock the tuning circuit to a desired frequency.