Abstract: A high impedance circuit of the present invention includes an LC parallel resonance circuit for raising circuit impedance, and a diode, which is connected in parallel to the LC parallel resonance circuit, causing a loop current to flow back via the diode and an inductor in the LC parallel resonance circuit so that a counter electromotive force, due to a surge voltage, which occurs across the inductor is cancelled. A low noise block downconverter which includes a high impedance circuit having a high impedance prevents peripheral circuits from being destroyed by a counter electromotive force, due to a surge voltage, which occurs across the inductor. For this, a diode is provided to cause a loop current to flow back via the diode and the inductor so that the counter electromotive force is cancelled.

Abstract: A single chip RF communication system and method is provided including a transmitter and a receiver. The RF communication system in accordance with the present invention can include an antenna that receives/transmits RF signals, a PLL that generates multi-phase clock signals having a frequency different from a carrier frequency and a reference signal having the carrier frequency, a demodulation-mixer that mixes the received RF signals with the multi-phase clock signals having the frequency different from the carrier frequency to output signals having a frequency reduced relative to the carrier frequency, two stage amplification that amplifies a selected channel signal to a required dynamic level, and an A/D converting unit for converting the RF signals from the mixing unit into digital signals. The two stage amplification can provide the selected channel signal with sufficient gain, even when an adjacent channel signal is output by the demodulation mixer with greater amplitude or power.

Abstract: A chilled transceiver for use in terrestrial and satellite communication systems. The chilled transceiver eliminates various problems associated with transceivers which incorporate superconducting devices. In particular, the chilled transceiver is based entirely upon conventional semiconductor technology, such as heterojunction bipolar transistor (HBT) technology formed from conventional GaAs, AlGaAs and InP materials which when chilled to temperatures down to, for example, 100° K can provide a 50% improvement in noise while trimming power losses by 20% or more at the same time. In one embodiment of the invention, the chilled transceiver is formed with a chilled receiver front end which includes a frequency diplexer, a filter, a low-noise amplifier (LNA) and a mixer, formed from conventional semiconductor technology which are housed in a refrigerator typically used for superconducting circuits.

Abstract: A method (200) for protecting receiver circuitry from high radio frequency (RF) overload voltages input to the antenna by monitoring power level and received RSSI level includes detecting (209) inside the receiver any reverse RF power on an antenna (201) connected to the receiver. The detected RF power is converted (211) to a direct current (DC) voltage. The DC voltage is compared (213) against a predetermined reference voltage. A switch (205) is than actuated (219) to disconnect the antenna if the DC voltage exceeds the reference voltage. Moreover, a radio signal strength indication (RSSI) is detected (221) based upon a received on-channel signal and is compared (223) to a first reference voltage. A secondary RF attenuator is actuated (225)if either the RSSI is lesser than the first reference voltage (223) or greater than a second reference voltage(227) for reducing input signal strength from the antenna.

Abstract: A peak limiter is intended to limit the peak of a signal that has a given frequency, in an assembly comprising other signals of lower amplitude and different frequencies. The peak limiter includes a circulator inserted into a line transporting all the signals. A first branch of the circulator is connected to a line on its upstream side. Its second branch is connected to a line on its downstream side. It's third branch is connected to a reference terminal via the combination of a band-pass filter centered on the given frequency, a threshold element, and an adapted load connected in series.

Abstract: An apparatus and method for switching a GPRS (General Packet Radio Service) service class according to the heat generated by at least one specific element in a GPRS terminal during a GPRS mode of operation. A temperature sensor measures a temperature of a specific element in the GPRS terminal during a GPRS mode of operation. An A/D converter converts an analog value of the temperature measured by the temperature sensor to a digital value. A limit data register stores a critical temperature of the specific element for the GPRS service class. A controller compares the measured temperature from the temperature sensor with the critical temperature stored in the limit data register, and switches the GPRS service class to a low class, when the measured temperature is greater than or equal to the critical temperature. The controller maintains the present GPRS service class when the measured temperature is less than the critical temperature.

Abstract: An input protection circuit for an RF circuit has an input switch that decouples a RF input signal from the circuit path when the power level of the input signal is greater than a preselected threshold. An isolation device receives the input signal from the switch and couples a first portion of the signal to a switch control loop. The switch control loop includes a level detector that generates an output proportional to the average power of the input signal. The output of the detector is coupled to a comparator that also receives a reference signal for comparison with the detector output. The comparator generates an output signal that energizes the switch when the detector output exceeds the reference signal. The switch couples the input signal directly to ground or through a load to ground. A reset command resets the input switch to re-couple the input signal into the RF circuit.

Abstract: The invention relates to an electronic device having a housing (1) which has a housing wall (5) with openings (7) for control elements (8) and/or display elements (9, 10). Attachment means (11) for detachably connecting to the housing (1) an external wall element (14) which at least partially covers the housing wall (5) being present on the housing (1), the external wall element (14) having openings (7′) which are aligned with the openings (7) in the housing wall (5). As a result, by using different external wall elements (14) the external appearance of the electronic device can be easily modified.

Abstract: A transceiver is disclosed for use in a wireless handset. The transceiver includes a switch for connecting an antenna, one at a time, to a receiver or to a transmitter. In a reception sub-frame, a limiting circuit switches the switch to an attenuated mode when an output signal of the receiver, such as a logarithmic RSSI signal, exceeds a predetermined value. The limiting circuit includes a comparator for comparing the logarithmic RSSI signal with the predetermined value. In addition, the limiting circuit also includes a transistor which shunts to ground a first control input of the switch when the RSSI signal exceeds the predetermined value. The limiting circuit further includes a shunt circuit to maintain the attenuated mode during a transmission sub-frame to reduce the level of a signal from the transmitter.

Abstract: The present invention relates to a novel use of cryoelectronic equipment to implement an extremely sensitive and stable receiver front end for UHF, microwave, and millimeter wave applications. The invention is particularly applicable to base station receivers in mobile radio systems, where the range and capacity of the systems are typically limited by the base station receiver sensitivity.

Abstract: The present invention relates to a novel use of cryoelectronic equipment to implement an extremely sensitive and stable receiver front end for UHF, microwave, and millimeter wave applications. The invention is particularly applicable to base station receivers in mobile radio systems, where the range and capacity of the systems are typically limited by the base station receiver sensitivity.

Abstract: A transceiver is disclosed for use in a wireless handset. The transceiver includes a switch for connecting an antenna, one at a time, to a receiver or to a transmitter. In a reception sub-frame, a limiting circuit switches the switch to an attenuated mode when an output signal of the receiver exceeds a predetermined value. The transceiver further includes a disabling circuit which disables the limiting circuit in response to a disabling signal provided to the disabling circuit when the transceiver is in a traffic mode. In addition, a disabling switch is provided which is activated in the traffic mode to provide the disabling signal. The disabling switch includes a light emitting diode, or is included in a controller of the transceiver. The disabling circuit may include a resistive network, an AND gate, a multi-vibrator, or a timer for disabling the limiting circuit in response to the disabling signal.

Abstract: A reception circuit for a cellular telephone according to the present invention shares the use of a code division multiple access system and a frequency division multiple access system, comprises: an amplifier circuit at the forefront stage; a bypass circuit connected to the amplifier circuit at the forefront in parallel therewith, having lower gain than the amplifier circuit at the forefront stage; and a common processing circuit connected to the latter stages of the amplifier circuit at the forefront and the bypass circuit, and when the level of a received signal is not higher than predetermined voltage, induces the received signal to the processing circuit through the amplifier circuit at the forefront while when the level of the received signal exceeds the predetermined voltage, the received signal is induced to the processing circuit through the bypass circuit.

Abstract: The present invention relates to a novel use of cryoelectronic equipment to implement an extremely sensitive and stable receiver front end for UHF, microwave, and millimeter wave applications. The invention is particularly applicable to base station receivers in mobile radio systems, where the range and capacity of the systems are typically limited by the base station receiver sensitivity.

Abstract: The present invention provides a diode limiter device in which a first penetration hole is formed on a wall surface of an H surface; the PIN diode is supported by the PIN diode mounting side of the post with the PIN diode being electrically connected to the waveguide at the first penetration hole; a second penetration hole is formed on the other wall surface opposite to the wall surface; a second conductive boss which grasps the PIN diode with the post is electrically insulated and supported with respect to the second penetration hole; a wiring substrate with the detection diode and the resistor mounted thereon is installed; and the wiring substrate is supported in the second penetration hole by a third boss, thereby improving productivity and reducing cost.

Abstract: In a radio display pager, a memory has message fields and corresponding attribute fields. When a message is received, it is stored in one of the message fields which are vacant. A message stored in one of the message fields is then displayed in response to the operation of a manual operated key. A protect indication is stored into the attribute field of the displayed message if the key is not subsequendy operated within a predetermined time interval. If the key is operated within that interval, a protect indication, if present in the attribute field of the displayed message, is deleted. If a new message is received when the message fields are already full, an unprotected old message is discarded to vacate a message field in which the new message is stored.

Abstract: At least the power portion of the transmitter and the front end of the receiver of a base station of a wireless communication system are advantageously co-located with the antenna (or antennae), typically atop a tower or other elevated feature. Such co-location however exposes the electronics to lightning damage. This is avoided by placement of the electronics and antenna into lightning protection apparatus that is transparent to rf radiation during lightning-quiescent conditions but is a Faraday cage during a lightning strike, reverting to the transparent condition at the conclusion of the strike. This is achieved by placement of the electronics and antenna inside a housing that comprises a dielectric chamber filled with ionizable gas in contact with electrodes selected such that, during a lightning strike, current can flow between the electrodes.

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: The method and apparatus of the present invention improve the immunity to interference of a radio receiver. The power level of a received signal is detected. If the power level meets or exceeds a predetermined power threshold, the low noise amplifier is by-passed, thus increasing the intercept point of the receiver components.Alternative embodiments include the use of an RF power detector to control the front-end gain as a function of jammer power. In lieu of a switchable RF gain block, several methods of continuous gain control are proposed. Continuous gain control allows the interference suppression and sensitivity of the receiver to be adjusted at lower signal levels than the switchable gain block.

Abstract: A radio receiver is disclosed. An arbitrary receive signal received through an antenna is amplified by an input amplifier. The signal amplified by the input amplifier is converted into a predetermined frequency by a mixer. The signal frequency-converted by the mixer is shaped in waveform by a band-limiting filter. The signal thus shaped in waveform is amplified and amplitude-limited by a limiting amplifier. The signal limited in amplitude is demodulated by a demodulator. In order to prevent the mixer circuit from generating a distortion due to an excessive input, another amplitude-limiting circuit operated at a level not saturating the mixer circuit is arranged in a stage before the mixer circuit.

Abstract: The present invention provides for a low power receiver protector and stepped attenuator for conditioning a received input signal within a microwave receiver front end. The low power receiver protector includes a detector for generating a surge signal in response to the received input signal exceeding a predetermined threshold, a delay line for delaying the received input signal for fixed duration, and a limiter for reducing the voltage of the received input signal in response to the generation of the surge signal. The stepped attenuator includes a plurality of cells each having an attenuation transmission path which includes an attenuator for providing a predetermined amount of attenuation of the received input signal. Each attenuation transmission path, bypass transmission path and delay line comprise a high temperature superconductor to provide minimal loss and reduced size.

Abstract: The method and apparatus of the present invention improve the immunity to interference of a radio receiver. The power level of a received signal is detected. If the power level meets or exceeds a predetermined power threshold, the low noise amplifier is by-passed, thus increasing the intercept point of the receiver components.Alternative embodiments include the use of an RF power detector to control the front-end gain as a function of jammer power. In lieu of a switchable RF gain block, several methods of continuous gain control are proposed. Continuous gain control allows the interference suppression and sensitivity of the receiver to be adjusted at lower signal levels than the switchable gain block.

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: In portable terminal units each of which has a rechargeable battery and a data processing section, one terminal is used as both a terminal for charging the rechargeable battery and a terminal for connecting a data processing unit to an external data processing unit. First protective circuitry protects the data processing unit from a battery charging current and second protective circuitry eliminates loading of the rechargeable battery due to a data voltage and protects the external data processing unit from charging current for the chargeable battery.

Abstract: An amplifier arrangement includes a first amplifier (A1) having a first output terminal (5) for the connection of a first terminal of a load and having at least a first power transistor (PT1) with a main current path for carrying a first current (i1), which current (i1) is related to a first load current flowing via the first output terminal (5), a second amplifier (A2) having a second output terminal (6) for the connection of a second terminal of the load and having at least a second power transistor (PT2) with a main current path for carrying a second current (i2), which current (i2) is related to a second load current flowing via the second output terminal (6) a first circuit (M1) for generating a first signal (s1), which signal (s1) is related to the first current (i1), a second circuit (M2) for generating a second signal (s2), which signal (s2) is related to the second current (i2), a third circuit (M3) for generating at least one control signal (r1, r2), which control signal (r1, r2) is related to a sum

Abstract: A radio receiver antenna arrangement incorporating an RF pre-amplifier (5) wherein circuitry (11 to 21) is provided for by-passing the pre-amplifier when strong signals are picked up by the antenna (1) to avoid overloading the pre-amplifier.

Abstract: A diode limiter including a signal line connects an input terminal to which a high power electric pulse signal is applied and an output terminal connected to a receiver. A PIN diode conducts when the high power electric pulse signal is applied thereto and provides a low impedance connection of the signal line to ground. A directional coupler extracts a part of the high power electric pulse signal out of the signal line. A detector diode is inserted in the return direct current path of the PIN diode, a resistor is inserted into the path including the directional coupler, and a means is provided for applying the voltage generated in the resistor to the PIN diode.

Abstract: A digital differential signal transmission apparatus is provided in a transmission line connecting a device (3) requiring an explosion-proof structure with a differential driver (101) or differential receiver (102). A shunt diode-type safety device (16) is inserted in order to realize an essential safe explosion-proof structure. High impedance transmission lines, which transmit and receive a single end signal, are employed as the transmission lines. Another shunt diode-type safety device (408) is inserted in a power supply line (143) connected to transmitting equipment (405, 406) on the side of the abovementioned device.

Abstract: An overload detector for an analog-to-digital converter. A series of logic gates are connected to the output of an analog-to-digital converter for determining the presence of an upper limit and a lower limit of an overload condition. A signal indicative of such a condition is input to circuitry which extends the length of the signal so that it is visible or audible to a user. An algorithm for a computer causes a latch to be engaged when an overload condition occurs. The latch is coupled to a pulse stretching circuit which permits a visible or audible signal to be generated.

Abstract: In a programmed audio amplifier system, the volume setting when the system is turned on is conditionally related to the last volume setting, i.e., immediately before the amplifier was turned off. At turn-on the system remains at the last volume setting as long as it is less than a preset volume setting. However, at turn-on the system exhibits the preset volume setting if the last volume setting exceeds the preset volume setting.

Abstract: An automatic AC protection circuit protects a radio receiver from RF overload by shortcircuiting the overload power to ground. The circuit includes a transistor having its collector coupled to the RF input and its emitter coupled to ground and the base coupled through an inductive impedance to ground. The value of inductive impedance in parallel with the base to emitter impedance of the transistor determines the RF input level at which the transistor turns on and clamps the RF to ground to protect a receiver from overload.

Abstract: A short-circuit protected mains supply unit, especially for the screen-text component of a television receiver. A conventionally controlled unit is expanded in accordance with the invention with only a few components (T1 and T2) in such a way that it can be turned on electronically and its output is protected against short circuits.

Abstract: A power limiter circuit for a radio frequency transceiver of the type having a single input-output antenna port is comprised of an isolator, first and second three port circulators and a pair of PIN diodes. One port of the first circulator is connected to the antenna port and one port of the second circulator is coupled to a transmit/receive antenna. The second ports of the two circulators are connected together through the isolator for passing signal from the transceiver to the antenna and the third ports of the two circulators are connected together for passing signal from the antenna to the transceiver. The PIN diodes, arranged in inverse parallel relationship, are connected between the third ports and circuit ground and operate in connunction with the isolator to limit to a safe value the signal passed from the antenna to the transceiver.

Abstract: An overload protector, using a power-dissipating element for receiving and dissipating excessive radio-frequency power, can safely transfer a signal from an input to an output. The protector also has a detector coupled to the input for providing a bias current in response to an input signal in excess of a predetermined magnitude. Also included in a diverter coupled to the input, the output, the power-dissipating element and the detector. This diverter can receive the bias current and can, in response, redirect power at the input from the output to the power-dissipating element.

Abstract: Method of switching off the stand-by operation of a television receiver including a microprocessor, which includes providing the microprocessor in the form of a timer, and switching off the receiver with the timer after a given length of time, and a receiver for carrying out the method.

Abstract: A television tuner comprises a tuning circuit including a voltage controlled variable capacitance diode. The tuning circuit is housed within a shield casing. The shield casing is provided with a terminal for electrical connection to the variable capacitance diode and the terminal is supplied with a tuning voltage from a channel selecting apparatus. A Zener diode is connected between the tuning voltage terminal and the shield casing, whereby the upper limit of the tuning voltage being applied to the variable capacitance diode is restricted. A predetermined voltage determinable dependent on the Zener diode is selected such that the tuning frequency established by the tuning circuit when the predetermined voltage is applied to the variable capacitance diode may be a predetermined upper limit frequency of a desired receiving frequency band. The lower limit of the tuning voltage is also restricted so as not to become lower than a predetermined voltage.

Abstract: In a television receiver system having an antenna and a preamplifier, the antenna is chosen to receive signals from distant stations. Weak signals are amplified and applied to the receiver through an adjustable attentuator. Strong signals from near stations are held to a maximum level before amplification and before application to the receiver through the adjustable attenuator. Manual adjustment of the attenuator enables the viewer to adjust the signal to optimize the television picture.

Abstract: A radar receiver protector having high isolation and low insertion losses due to a unique microwave assembly configuration is disclosed. The receiver protector includes at least one high power input protection stage and a sensitivity time controlled multi-level attenuation which together achieve rapid switching with a non-critical bias supply and circuit configuration and develop attenuation levels which are invariant with temperature and insensitive to diode parameters.

Abstract: The passive limiter is formed by at least two parallel micro-strip lines, a slot line orthogonal to the two micro-strip lines and a pair of diodes having the same polarity and placed on each edge of the slot line facing one another, the assembly of these three lines and the diodes forming at least two micro-strip line-slot line transitions.

Abstract: A sound transmission and reproduction system including at the transmitter side means for producing a non-audible control signal indicative of a predetermined character of the transmitted sound, preferably the intensity of the sound as actually transmitted, whereby the transmitted sound may be artificially attenuated and amplified, respectively, in respective passages of high and low intensity so as to be transmittable within a restricted dynamic range. At the receiver side the control signal is detected and used for controlling the amplifier as an automatic volume control so as to effect extra amplification of the attentuated passages and attenuation of the artificially amplified passages so as to enable the reproduction to take place with the full dynamic range of the original sound.

Abstract: Tape deck adapter apparatus for radio reception, especially for reception of citizen band transmission having widely variable noise levels. The device consists of a receiver which is adaptable for use within a conventional tape deck for energization and operation; the receiver then includes an automatic squelch control circuit of the type which is particularly useful in receiving incoming citizen band transmissions. The automatic squelch control includes reactive means controlling input to the output audio amplifier, such reactance means being controlled by a DC feedback component as derived from the audio output signal, for application to control conduction of the reactance means, and therefore, the amplification of the audio output stage.