Abstract: A multimode wireless receiver circuit (10) includes multi-receiver control and interference detection logic (50) and least two separate receivers: a first receiver (20) associated with a first radio access technology and a second receiver (30) associated with a second radio access technology. The multi-receiver control and interference detection logic (50) simultaneously controls the second receiver (30) to detect an interference blocker signal (100), while the first receiver (20) receives at least a portion of the wireless signal (80) and the interference product signal (90). In response to the second receiver (30) detecting the interference blocker signal (100), the multi-receiver control and interference detection logic (50) adjusts at least one operating condition of the first receiver (20) such that the interference product signal (90) received by the first receiver (20) is reduced.

Abstract: A wireless communication receiver that is able to lessen the effect of noise that accompanies gain change by programmable gain amplifiers. The receiver includes an AGC controller which controls the timing at which the programmable gain amplifiers make gain change, using a terminal counter and a sequencer. The receiver prevents gain change noise signals during the reception of control signals and other signals that are susceptible to noise. By the timing control feature, the programmable gain amplifiers make gain change while reducing noise impact.

Abstract: A band edge amplitude reduction system changes the filtering characteristics of a receiver based on the amplitude of signal(s) adjacent to an edge of the operating band of the receiver and/or of signals not under the power control of the receiver. For example, the receiver measures the power level over a bandwidth at the band edges of the operating band of the receiver. If the signals adjacent to the operating band are strong enough relative to the signal power within the operating band, overload protection circuitry changes the filtering characteristics of the receiver to improve the attenuation of the signal(s) from the adjacent band(s). In certain embodiments, the overload protection circuitry switches in filter(s) with a narrower bandwidth to attenuate the signal(s) from adjacent band(s) at the edge(s) of the operating band of the receiver, thereby preventing interference with or the overload of the receiver by signals from outside the operating band and/or not under the power control of the receiver.

Abstract: A receiver, implemented with low noise and low distortion, to process an input signal containing signals of interest and unwanted interference signal. In an embodiment, the receiver contains a mixer which generates an intermediate signal in the form of an electric current, and a filter which filters the unwanted interference signals from the intermediate signal. The intermediate signal is centered around a lower frequency compared to a carrier frequency of the input signal. Due to the current mode interface between the mixer and the filter circuit, low noise and low distortion may be attained.

Abstract: A full-duplex transceiver using a method immunizing itself against self-jamming. The transceiver includes a receiver and a transmitter. The receiver includes a frequency immunization converter and a high pass IF filter. The transmitter transmits a TX signal. The receiver receives an RX signal and simultaneously receives a portion of the power of the TX signal as an undesired TX jamming signal. The frequency immunization converter uses the center frequency of the TX signal for downconverting the RX signal to an IF signal and simultaneously downconverting the TX jamming signal to near zero frequency. The high pass IF filter passes the IF signal and blocks the signal at near zero frequency. As a consequence of the downconversion using the TX frequency, a second LO frequency is controlled for avoiding image frequencies.

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

Abstract: The present invention provides a technique for cancellation of jammer signals in a radio frequency receiver. A radio frequency signal contains both a desirable signal and an undesirable jammer signal. The combined signal is processed with a filter (104) to extract only the undesirable jammer signal. The jammer signal is then added (104) back to the combined signal to effectively cancel the jammer signal. The system may be implemented using a feedforward approach or a feedback approach. The resultant clean signal is processed in a conventional manner.

Abstract: A Radio Frequency (RF) receiver includes a low noise amplifier (LNA) and a mixer coupled to the output of the LNA. The gain of the LNA is adjusted to maximize signal-to-noise ratio of the mixer and to force the mixer to operate well within its linear region when an intermodulation interference component is present. The RF receiver includes a first received signal strength indicator (RSSI_A) coupled to the output of the mixer that measures the strength of the wideband signal at that point. A second received signal strength indicator (RSSI_B) couples after the BPF and measures the strength of the narrowband signal. The LNA gain is set based upon these signal strengths. By altering the gain of the LNA by one step and measuring the difference between a prior RSSI_B reading and a subsequent RSSI_B? reading will indicate whether intermodulation interference is present.

Abstract: An image-rejecting antenna apparatus includes an antenna unit for receiving or transmitting a wireless signal and an image-reject unit for removing an image component signal having a predetermined frequency from among signals received from the antenna unit. In an image-rejecting antenna apparatus that receives a predetermined signal and provides a processed signal to a RF circuit unit for performing a predetermined function may also include an impedance matching unit for matching an impedance of the antenna unit with an impedance of the RF circuit unit and for providing the signal from which the image component signal has been removed to the RF circuit unit. A noise component of an image frequency that is transmitted to a subsequent circuit can be minimized or removed by including an image-reject unit when designing an antenna and a matching circuit, thereby improving the image-rejecting capabilities of an entire receiver.

Abstract: The present invention reduces the degradation in performance of one or more radio signals that are co-transmitted with a first radio signal from the same transmitting antenna in the same frequency channel and received by the same antenna due to multipath or other shared interference, where the one or more radio signals can be separated from the first radio signal.

Abstract: An external noise intrusion prevention device preventing intrusion of external noise into a central conductor of a trunk cable in an up signal frequency band is provided. A first filter circuit 3 letting a signal in frequencies of 54 MHz or higher pass is provided between an input terminal 1 and an output terminal 2. A front filter circuit 4a and a rear filter circuit 4b, which constitute a second filter circuit 4, are provided on both ends of the external noise intrusion prevention device, respectively. A noise elimination circuit 6 formed by cascading two connection transformers 6a and 6b is also provided. The two connection transformers 6a and 6b are connected to each other while being arranged in a line symmetrical manner.

Abstract: A receiver window design algorithm (210) is developed which minimizes the noise power of the demodulated multicarrier signal. The windows are effective on a variety of different channels and noise sources. Receiver windowing is a computationally efficient technique for reducing noise spreading in multicarrier communication systems.

Abstract: Provided is a signal processor including a band-pass filter and a low noise amplifier, which are covered with a vacuum insulation layer and cooled by a refrigerator. Further, a getter material where a heater for activation is built therein is installed in the vacuum insulation layer as a mechanism to control increase of gas pressure inside the vacuum insulation layer. The getter material is heated and activated by the heater when activating the refrigerator, and thus the gas pressure inside the vacuum insulation layer is reduced by operation of the getter material and status of vacuum insulation can be improved when the refrigerator is activated after the refrigerator has been stopped due to a power outage or the like.

Abstract: A radio receiver (100) has an equalizer (500) that operates in the time domain to remove residual interference that is not removed by an IF filter (200) operating in the frequency domain that is caused by an adjacent interfering FM station. The equalizer (500) includes a modified constant modulus algorithm (CMA) to generate a tap update signal from the output of the equalizer (500). The equalizer (500) uses the modified CMA to reduce an amplitude fluctuation of the received signal caused by the adjacent interfering station. The CMA is modified to use an infinite impulse response (IIR) filter (540) to generate the tap update. The IIR filter (540) also speeds up a convergence of the modified CMA to provide better performance.

Abstract: A wireless receiver including a receive chain, a synchronization processor, a memory, a combiner and a soft decision processor. The synchronization processor determines a frequency response of the wireless channel using synchronization data transmitted in the wireless channel. The memory stores a compensation vector indicative of a frequency response of receive chain filtering. The combiner combines the compensation vector with the wireless channel frequency response to provide a compensated frequency response. The soft decision processor uses the compensated frequency response to evaluate data decisions. The compensation vector is based on measurement or estimation of the frequency response of the receive chain. The combiner may be based on multiplication or addition. The wireless receiver may include an FEQ. The synchronization processor generates FEQ coefficients for programming the FEQ taps.

Abstract: A wireless communication handset and system having improved antenna performance. The system includes a handset body (300) and multiple housing portions with different antenna loading characteristics, for example different materials or shapes, interchangeably mounted on a common portion of the handset body. The handset body (300) includes electrical communications circuitry coupled to an antenna (314), which is adjacent the interchangeable housing portions. A discrete or integrally formed antenna loading feature compensates for the different antenna loading characteristics of the different housing portions to provide optimal antenna performance regardless of the housing portions mounted on the handset body.

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

Abstract: A receiver performs DC offset correction by preliminarily using an unused LNA with a terminating resistance to determine a base level DC offset. Once the DC offset is determined, a DC offset correction may be calculated and applied to an active LNA output. When determining the DC offset, the active LNA is disabled.

Abstract: A method for biasing signal-to-interference ratio (SIR) to generate channel quality indicator (CQI) includes measuring the packet error rate (PER) of a received signal and comparing the PER to a to the target PER to generate a correction term. The correction term is combined with the SIR estimation of a reference channel to generate a CQI. The CQI is reported to a transmitter to adjust signal configurations, such as code rate, modulation type, number of codes, power offset.

Abstract: A method and apparatus for mitigating co-channel and inter-channel interference in an antenna array system. It is determined by a base station or other transmitter employing an antenna array that transmission of at least a first downlink signal will generate a co-channel or inter-channel ghost signal at at least one location that may be susceptible to such ghost signal (e.g., as interference). As such, a weight to be applied to the at least first downlink signal is adjusted to reduce mitigate the undesirable effect of the ghost signal at the location before transmission of the at least first downlink signal.

Abstract: A mobile communication system is provided with a system for frequency correction in a reception apparatus which has a first control system, device or loop for detecting a frequency discrepancy in received signals and for appropriate correction of the frequency supplied to a mixer stage, and a second control system, device or loop for detecting a frequency discrepancy in received signals and for subsequent computerized correction thereof on the basis of the CORDIC algorithm.

Abstract: The present invention provides a dummy low noise amplifier (LNA) and an associated resistive network. Prior to DC offset correction, the primary LNAs are deactivated and the antenna is decoupled from the receive path leading to the inputs of the primary LNAs. A resistance is selected to provide a load at the input of the dummy LNA, wherein the load emulates the input load resistance seen by the primary LNA, which will be used to receive the incoming signal. Thus, the output of the dummy LNA emulates the performance of the primary LNA used to receive the incoming signal to allow accurate DC offset correction.

Abstract: A transmitter circuit improves a noise margin for decoding a common mode signal at a receiver circuit. The transmitter circuit includes a common mode signal transmitter and a noise margin enhancement circuit coupled to a transmission line. The common mode signal transmitter transmits a control message using a common mode signal. The common mode signal has a first voltage level and a second voltage level higher than the first voltage level, and the control message corresponds to a portion of the common mode signal having the first voltage level. The noise margin enhancement circuit raises a voltage level of the common mode signal to a third voltage level higher than the second voltage level for a specific time period from a rising edge of the common mode signal from the first voltage level.

Abstract: In a receiving apparatus according to the present invention, a shield plate, which is made of metal, is mounted above IF amplifiers and output terminal mounting parts of a circuit substrate, thereby decreasing adverse effects caused by a back lid with unstable earthing. This produces a stable earthing condition, and further, changes a condition where signals are reflected in a space produced in the apparatus, resulting in the improvement of its isolation characteristic.

Abstract: A system is provided which combines the advantages of Adaptive Antenna Arraying and Adaptive Locally-Optimum Detection, as well as Adaptive Filtering, signal processing techniques and achieves the capabilities of all these techniques. The present invention represents the first successful integrated system for performing signal processing techniques associated with an Adaptive Antenna Array (AAA) system and an Adaptive Locally-Optimum Detection (ALOD) system. The system automatically distributes interference signals among Adaptive Antenna Arraying and Adaptive Locally-Optimum Detection sub-systems according to which sub-system's algorithms can provide a more optimum suppression of the interference signals. The system permits an adaptive antenna array with a given number of antenna elements to effectively suppress a larger number of interferers than it otherwise could, and to adapt more quickly to a rapidly changing interference scenario.

Abstract: A communications receiver includes a baseband signal recovery circuit which uses a low-IF architecture for data reception. The baseband signal recovery circuit uses a full-analog implementation for channel selection and filtering. Thus, the overhead placed on the design of analog-to-digital converter is greatly relaxed and most of hardware can be re-used for multi-mode applications with only a slight modification.

Abstract: A device (10) for reducing vibration effects on position measurement includes a receiver (12) for providing position signals (13); and a vibration control circuit (18) operative to control position information generation based on the position signals (13), to prevent position information generation during mechanical vibration of the device (10). A method for reducing vibration effects on position measurement includes receiving position signals through a receiver; and controlling position information generation based on the position signals to prevent the position information generation during mechanical vibration of the device.

Abstract: Multi-channel self-interference cancellation is provided in relayed electromagnetic communication between a first device and one or more other devices on one or more shared frequency channels. Specifically, near signals are generated at the first device and transmitted to a relay station. A composite signal is received at the first device from the relay station containing relayed versions of the near signals and relayed versions of remote signals transmitted from the one or more other devices, the composite signal having frequency channels including the one or more shared frequency channels, each shared frequency channel occupied by at least one of the relayed near signals and one of the relayed remote signals. One or more cancellation signals are selectively generated, each having a frequency band corresponding to one of the shared frequency channels. The cancellation signals are combined with the composite signal to produce a desired signal representing the relayed remote signals.

Abstract: An improved noise reduction system (20) is provided for a radio frequency audio processor having one or more weak signal processing components for generating one or more corresponding control values (36a, 36b) for controlling characteristics of the audio output from the processor, and a blanking pulse generation component (10) for generating a blanking pulse signal (18) in relation to an impulse noise signal imposed on the radio frequency signal. The improvement (20) can include at least one detector (30a, 30b) for determining a state value of the blanking pulse signal, such as the pulse density or frequency. At least one alignment function module (32a, 32b) is provided that is operable on the state value to generate at least one corrected control value corresponding to one of the weak signal processing components.

Abstract: This invention provides a method and system for increasing the bandwidth and distance of communication links by enabling noise from unwanted background radiation to be effectively eliminated. This is achieved by taking advantage of the fact that background radiation has much broader frequency spectrum than information signal carriers. Spectrum of interest is divided into multiple partitions. Reference signals are constructed over the spectral partitions according to defined selection criteria so that these reference signals can be used to reduce in-band noise of desired information signal through common mode noise elimination. Using differential signaling schemes further reduces noise from non-background radiation sources in addition to noise from background radiation sources. This method is applicable to both analog and digital systems.

Abstract: A direction for a desired radio signal arriving at a receiving station is determined from a plurality of estimated signal medium response coefficients for a ray of the desired radio signal. According to an aspect of the present invention, the estimated signal medium response coefficients for the ray are generated according to an interference rejection combining (IRC) process. According to another aspect, a direction of arrival for a ray of the desired signal is determined and used to compute a power spectral density for the ray for a plurality of directions. A direction of arrival for the ray is then determined by determining a direction for which the power spectral density has a maximum value. In addition to desired signal direction, direction of arrival for an interfering signal can be determined using an impairment autocorrelation matrix that is also generated as part of the IRC process.

Abstract: In accordance with the preferred embodiments of the present invention, a method (400) and a base station (140) for providing phase-shift transmit diversity in a wireless communication system are described herein. The base station (140) phase-shift modulates a first signal with a reference signal to produce a first phase-shift modulated signal including a first phase shift. Further, the base station phase-shift modulates a second signal with the reference signal to produce a second phase-shift modulated signal including a second phase shift. The second phase shift is distinct from the first phase shift such that the second phase-shift modulated signal is diverse relative to the first phase-shift modulated signal. Accordingly, the base station transmits the first phase-shift modulated signal via a first antenna and the second phase-shift modulated signal via a second antenna to a plurality of mobile stations.

Abstract: Methods and devices for sending, transmitting and/or receiving information by means of waves, in which an information signal of a carrier wave is impressed, whose frequency is continuously changed to form at least one carrier sweep in a predetermined time interval and in which the information signal is filtered to separate multipath components after being received in the frequency range or is cleaned of noise portions and then evaluated with respect to the information-bearing signal parameters.

Abstract: A system and method of identifying the source of uplink and downlink interference in a disturbed cell of a wireless telecommunications network. Initially, call events occurring in offending cells are recorded. In conjunction, the disturbance events occurring in the disturbed cell of the telecommunications network are recorded. The recorded call events with recorded disturbance events are then correlated. A distribution of disturbed and offending cells within the telecommunications network as a function of time is computed to obtain a statistical correlation of call events in offending cells and subsequent disturbances resulting in the disturbed cell to identify the possible source of disturbances that caused the sealing of the sealed device with in the disturbed cell.

Abstract: A process for operating a cordless TC final apparatus with a device for compensating acoustic echoes between loudspeaker and microphone comprises the following steps:

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

Abstract: A system for reducing internal interference in a radio-frequency (RF) receiver includes providing a plurality of time slots within a frame where the receiver is configured to receive external RF signals during a receive time slot within the frame. External RF signals are the prevented from reaching a front-end portion of the receiver and the receiver is activated, and a predetermined period of time is permitted to elapse to permit the receiver to settle. An interference data collection is performed during a period of time prior to a predetermined receive time slot where the data collected represents internally generated interference signals. The data collected during the interference data collection is processed to determine a bias value corresponding to the interference signals, and the receiver is then permitted to receive external RF signals during the predetermined receive time slot so that data is collected during the predetermined receive time slot.

Abstract: RF circuit includes an amplifier and a shunt. The shunt is controlled to provide a path around the amplifier for avoiding intermodulation distortion caused by overdriving the amplifier. The shunt is formed by a diode with capacitors that match to the RF characteristics.

Abstract: A circuit for at least substantially eliminating at least one external interference signal from a radio communications signal received by a code division multiple access (CDMA) mobile phone including a receiving terminal and a low noise amplifier comprises: a plurality of damping devices operatively coupled between the receiving terminal and the low noise amplifier; a plurality of switches respectively operatively coupled between the plurality of damping devices and the receiving terminal; an interference detector operatively coupled to the receiving terminal for detecting the at least one external interference signal from the received radio communications signal; and a switch driver operatively coupled between the plurality of switches and the interference detector, the switch driver generating a switching signal in response to the interference detector to select at least one of the switches in accordance with the at least one detected interference signal in order to vary a gain associated with the received

Abstract: In a method for compensating D.C. offset in a direct conversion receiver by a signal (IF.sub.-- I, IF.sub.-- Q) received and demodulated in one of the channels of the reception frequency band of a radio communication system, a correction signal (Q.sub.control) is produced from the signals in the channels of the reception frequency band. The correction signal (Q.sub.control) is combined with the demodulated signal. The apparatus for implementing the method comprises means (12, 17, 18, 19) for producing the correction signal, and means (15, 16) for combining the correction signal with the received and demodulated signal.

Abstract: In a receiver having an antenna switch (23) which is connected between a receiving section (24) and an antenna (21) for adjusting a received signal so that the received signal has, as a current signal level, one of a first and a second signal level, a switch control section (26) controls an operation of the antenna switch by the use of a current signal level of the received signal and a first and a second reference level which are determined in first and second determining sections (27, 28), respectively. In order to detect the current signal level, a signal level detection circuit (25) is connected to the antenna switch. It is preferable that a signal level holding circuit (34) is connected between the signal level detection circuit and the switch control section and is for holding the current signal level during a predetermined time duration.

Abstract: A pair of filter units directs incoming signals from an antenna and outgoing signals to the antenna. One of the filter units blocks the outgoing signals and passes the incoming signals while the other of the filter units blocks the incoming signals and passes the outgoing signals.

Abstract: Patch antenna systems for half-duplex communications which are capable of providing a positive gain, quasi-hemispherical antenna pattern over widely separated transmit and receive frequency bands. The antenna systems according to the present invention generally comprise a patch antenna, transmit and/or receive circuit branches for tuning the patch antenna to resonate in separate transmit and receive frequency bands, and disconnection means for electrically isolating the transmit circuit branch from the antenna during periods of reception and for electrically isolating the receive circuit branch from the antenna during periods of transmission. Matching means, which preferably are implemented as part of the transmit and receive circuit branches, may also be provided for increasing the operating bandwidth of the antenna in both the transmit and receive frequency bands.

Abstract: A method and apparatus to enable high-quality digital transmissions to a satellite terminal operating in proximity to a radar source combines interleaving a sequence of channel symbols at a land station before transmission of an RF signal to a satellite, increasing the satellite's EIRP to compensate for the effects of the radar's duty factor on received signal power and code distance, detecting the radar pulses at a satellite terminal, blanking the received RF signal to prevent reception of the signal by the modem at the satellite terminal during the radar's ON time, having the modem recognize and eliminate the effect of the gap in the channel signals on its metric calculation, and de-interleaving the sequence of channel symbols. As a result, satellite terminals operating in proximity to radar sources can provide the same quality of service as if there were no radars operating.

Abstract: A digital signal processing system that produces an adaptive cancellation arrangement which nulls out all types of concurrent interference and/or jamming signals received by a Global Positioning System (GPS) or spread spectrum receiver from diverse antennas. The present invention uses a unique adaptive interference suppression technique to convert and digitize the analog input signals, and numerically modulate the data to produce effective cancellation of interference signals by nulling while preserving the multiple underlying spread spectrum signals. The invention generates digital and analog output signals which contain a reduced amount of interference. In the present arrangement, orthogonal components of the composite received signal are separated by the receive antenna arrangement and adjusted in the digital network between the antenna and receiver in phase and amplitude to optimally cancel components.

Abstract: It is an object of the present invention to provide a variable attenuator which can be produced at a low cost and can suppress production of unnecessary resonance and propagation. When the radio frequency resistance values of PIN diodes 13 and 14 are higher than a characteristic resistance value of a signal line interconnecting radio frequency signal input terminal 1 and radio frequency signal output terminal 2, the sum of voltages applied to PIN diode 11 and PIN diode 13 and the sum of voltages applied to PIN diode 12 and PIN diode 14, that is, V3, are controlled so as to be fixed.

Abstract: An antenna structure (108) operates in the presence of narrow or wide band interference and yet is able to enjoy high receiver sensitivity. This is done by steering the antenna structure (108) radiation pattern null in its near field at the noise source.

Abstract: In accordance with the present invention, an RFID system has a homodyne receiver having two outputs; the in-phase or I output and the quadrature or Q output. The modulated backscattered signal is composed of an information signal, modulated onto a single frequency subcarrier signal, generating a modulated subcarrier signal; this modulated subcarrier signal is then backscatter modulated onto the incoming RF signal. To demodulate this modulated backscattered signal, the I and Q outputs are combined using an IQ combiner. This IQ combiner introduces a 90.degree. phase shift, with respect to the frequency of the subcarrier signal, onto one of the demodulator outputs and then combines the outputs of the demodulator.

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.