Abstract: A receiver (100), transmitter (200) and transceiver (400) in accordance with the present invention overcome the disadvantages of applying adaptive antenna array technology to multi-channel communication systems. Multi-channel radio frequency (RF) signals received via an adaptive antenna array (102) are converted from an analog form to a digital form prior to splitting and processing to recover communication channels contained therein. A number of digital communication signals are digitally combined into a multi-channel digital signal and converted from the digital form to an analog radio frequency form prior to transmission from the adaptive antenna array.

Abstract: A land mobile radio system (110) includes a plurality of receive antenna (120) for receiving RF signals transmitted from mobile units. Each receive antenna (120) is connected to a transform matrix (133) which divides each received RF signal into a number, N, of transformed signals, each transformed signal containing an equal power level part, 1/N, of each received RF signal. Each transformed signal is provided to an amplifier (135) for amplification thereof, and the amplified transformed signals are provided to an inverse-transform matrix (138) which recombines the equal parts of each amplified transformed signal into amplified received RF signals which are provided to an RF signal processing section (125). The amplified RF signals are thereafter provided to corresponding radio channel units (127).

Abstract: The invention involves a method of transmitting a control signal that is synchronized in time with a radio program signal. The control signal may be used, for example, in a receiver to restore dynamic range reduction that occurred at the transmitter. The method includes the steps of forming a first supplemented signal by inserting the control signal and a first time-reference signal into a data stream of a radio data signal such as an RDS signal. A second supplemented signal is formed by adding a second time-reference signal to the radio program signal. The first and second time-reference signals are correlated in time. The first and second supplemented signals are transmitted.

Abstract: A mobile-link system for a radio communication system including a first mobile-link assembly, a second mobile-link assembly, and a satellite feeder-link assembly located in a satellite; and an earth feeder-link assembly located in an earth station. The first mobile-link assembly receives mobile uplink signals including zone-one uplink signals transmitted from mobile stations located in a first zone of a coverage area and zone-two uplink signals transmitted from mobile stations located in a second zone of the coverage area, and outputs received zone-one uplink signals and received zone-two uplink signals. The second mobile-link assembly receives mobile uplink signals transmitted from mobile stations in the coverage area, and outputs received zone-two uplink signals and not zone-one uplink signals. The second mobile link assembly also transmits mobile downlink signals to at least the first and second zones of the coverage area.

Abstract: An FM radio receiver, particularly for mobile receivers, reduces the effects of multipath distortion. It selects either an adaptive process (constant modulus algorithm or CMA) or a antenna diversity process depending on the circumstances of the instantaneous reception. The receiver reduces both the decline of the level of received signals with the diversity process and waveform distortion with the CMA process.

Abstract: A number of demodulators receive a signal transmitted from a certain base station and propagated via different respective propagation paths. Each demodulator generates a demodulated signal by examining the correlation between the received signal and a pseudo-noise (PN) spread code. A system time managing counter has a count value that is initialized at the timing of the forefront of the spread code in the modulator when at least one of the demodulators starts the demodulating process after power-on or after a reset operation. A signal combiner combines the demodulated signals that are adjusted to coincide in timing with each other from the demodulators at a timing determined by a system time managing counter after initialization and provides a combined demodulated signal.

Abstract: A rake-type CDMA base station receiver equipment, including a plurality of correlators each having a received signal as its input, a plurality of diversity combiners for respective receiver branches, and a measurer for measuring the quality of the received signal. To reduce the number of correlators and diversity combiners, the receiver equipment further includes switches for switching the correlators to the different combiners, and controllers for controlling the switches on the basis of data sent from the measurer for measuring the quality of the received signal or on the basis of the capacity loading of the base station receiver equipment.

Abstract: A system for receiving a radio signal representing a radio program comprises at least first and second radio receiver units. Each receiver unit receives the radio signal at a respective frequency and produces a respective radio program signal. All of the radio program signals represent the same radio program. A decoder decodes a control signal, such as an RDS signal, from each of the radio program signals. A control device processes the control signals to determine the delay between the radio program signals. The control device uses the delay information to modify a a variable delay in the signal path of at least one radio program signal until the radio program signals are synchronized. The synchronized radio program signals are combined, e.g., by fading the signals together, to produce a resultant radio program signal.

Abstract: A receiver and a method for controlling a receiver, the receiver being implemented on the RAKE principle and comprising a number of correlators (30a-30d) which are able to synchronize with a received signal. To effectively utilize the correlators of the receiver, the operation made of the correlators in the receiver is changed dynamically in the method of the invention between the received signal tracking and acquisition modes according to the need.

Abstract: A radio frequency (RF) antenna switch (136) and associated method of operating the same is provided for switching between a first antenna (109) and a second antenna (111). A first mixer (125) has an input terminal 124 coupled to the first antenna (109) and has an output terminal 126. A second mixer (129) has an input terminal 128 coupled to the second antenna (111) and has an output terminal 130 coupled to the output terminal of the first mixer (125). The first mixer (125) and the second mixer (129) are alternatively enabled responsive to the state of an antenna select signal (141). Additionally, the common output terminals 126 and 130 of both the first mixer (125) and the second mixer (129) are matched to a first intermediate frequency stage (131). The RF antenna switch (136) advantageously provides low loss and low current drain.

Abstract: A device for filtering wide-band signals at radio frequencies is usable either in a base station cellular telephony system or separately. The wide-band signal occupies a total frequency band comprising frequency bands allocated to that signal and a central frequency band extraneous to that wide-band signal. Within the device, the wide-band signal is mixed with a heterodyne wave to translate the signal from RF to IF. The signal at IF is then filtered by two surface acoustic wave (SAW) band-pass filters which have respective pass bands which correspond at IF to the allocated frequency bands of the wide-band signal, and which the SAW filters have the filtering effect of passing with low attenuation signals in those allocated bands while substantially attenuating signals and/or noise in the central extraneous frequency band between those allocated bands.

Abstract: The invention relates to a baseband signal combiner and to a sampler typically used in radio relay systems and also in generic communication systems. In order to avoid temporary failures in the free space links, space and/or frequency diversity techniques are used, which consist in the use of two suitably spaced receive antennas or of two transmission frequencies. By suitably combining the signals thus received, the failures in radio links can be redued. The invention provides the use of a particular algorithm of the type CMA (Constant Modulus Algorithm) which, being independent of the combined signal phase, does not interact with the carrier recovery circuits. Moreover, by also applying the same algorithm to the sampler, the cooperation of the two circuits for the optimization of the output signal is obtained.

Abstract: An object of the present invention is to provide a soft decision circuit by which the reception accuracy can be improved. Each of first and second receivers of the soft decision circuit includes a phase amount detector for detecting a phase amount of a receive signal, an I table and a Q table for converting the phase amount into orthogonal I/Q signals, an A/D converter for converting a receive level signal of the receive signal into a digital value, a log linear table for converting an output of the A/D converter into a squared value of a true value, and first and second multipliers for multiplying outputs of the I table and the Q table with the output of the log linear table to weight the outputs of the I table and the Q table.

Abstract: A method and an apparatus for adaptively canceling an interference signal in any D/U ratio is disclosed. The method and apparatus are directed to being implemented in a two-branch space-diversity system having an array of first and second receivers assigned to a first diversity branch and a second diversity branch, respectively. The feature resides in the ratiow.sub.2 /w.sub.1 =(m.sub.1 g.sub.1 m.sub.2 g.sub.2 *) / (m.sub.2.sup.2 g.sub.2 g.sub.2 *),wherein w.sub.1 and w.sub.2 are the weights by which a first branch signal and a second branch signal, respectively, are to be multiplied, m.sub.1 and m.sub.2 are the gains of the first and second receivers, and g.sub.1 and g.sub.2 are the transmission coefficients of the interference signals received by the first and second receiver, respectively.

Abstract: This invention relates to apparatus and a method for provision of diversity in reception in a communications system such as the GSM cellular radio system. A received call of low quality is received through a first of two antennas (15, 16) and through first of a plurality of receivers (10-14). A spare receiver that is not required for receipt of a call is identified and the spare receiver is switched to receive the call through the second antenna. The spare receiver is tuned to the frequency of the call of low quality and the calls are diversity combined through the first receiver and the spare receiver.

Abstract: In a diversity reception communication system (200), a method is provided for recovering data symbols (213) from a transmitted signal. Multiple signals representing the transmitted signal are received via corresponding multiple reception paths (201, 202). For each reception path, values are determined for noise (206), channel quality (207), and for a weighting factor (209) as a function of the channel quality. The signals are processed using diversity combining (212) which includes the weighting factor (209) for each reception path, to provide a resultant signal that more likely represents the transmitted signal than any of the received signals alone. The data symbols (213) are recovered from the resultant signal.

Abstract: A method and apparatus diversity-combine radio signals received from a plurality of branches (108, 214). Each radio signal comprises a plurality of subchannels (806). The radio signal from each branch (108, 214) is digitized (904) into digital samples that are converted (908, 910) into frequency domain signals (702, 712). Each frequency domain signal (702, 712) corresponds to a subchannel and a branch (108, 214). A weighting factor is determined (916) for each branch (108, 214) and each subchannel (806) from instantaneous signal energy and noise power calculated (912, 914) from the frequency domain signals (702, 712). The frequency domain signal (702, 712) corresponding to each branch (108, 214) and each subchannel (806) is multiplied (918) by the weighting factor therefor to produce weighted frequency domain signals corredponding to each branch and each subchannel.

Abstract: Several emitter stations (MS1-MS4) are allowed to transmit call set-up packets in random access channels and user information packets in traffic channels to a receiver station (BST) which is provided with an array of N sensors (A.sub.l -A.sub.N) and with a receiver (RM) adapted to simultaneously acquire N-1 packets from the emitting stations and to derive therefrom N-1 distinct array output signals (X.sub.1 -X.sub.N-1). During a random access channel (RACH) channel, the identity of the emitting station (MS) as well as the direction of arrival (.theta.) and the power (.sigma.) of its signal are stored in a parameter data base (PDB) together with its weigh vector (W) calculated (WVG) therewith and a traffic channel (TCH) channel allocated (CHC) thereto. During either a RACH or a TCH channel, the weight vectors of a emitting station are provided by the data base and are applied to multipliers (M.sub.1 -M.sub.N-1) which produce the N-1 array output signals.

Abstract: A method for communication of information is described. The method provides for a much greater number of communication channels than available with conventional technologies. The number of communication channels that can be obtained is of the order of n.sup.2, where n is the number of physical channels available. Further, the method provides robustness in the presence of noise, interference, path delays, and other adverse environmental conditions. It is also compatible with a number of privacy insuring methods, and has an inherent resistance to casual prying.

Abstract: A radio communication unit for a digital communication system is provided in which an input information signal is protected from transmission errors by forward error correction encoding the information signal. In addition, the communication unit enhances subsequent processing of a transmitted form of the information signal by a hard-limiting receiver by inserting a predetermined synchronization sequence into the information signal. Further, a corresponding radio communication unit is provided which includes a hard limiting mechanism for removing the magnitude of each sample in a group of data samples of a signal received from over a radio communication channel. In addition, weighting coefficients of the hard-limited group of data samples for maximum likelihood decoding and diversity combining are generated by comparing the hard-limited group of data samples to a known predetermined synchronization sequence.

Abstract: In a combining diversity apparatus for a digital multi-valued modulation RF signal, at least first and second receiving antenna units having a space diversity relationship, first and second frequency conversion units for converting the RF signal into first and second IF signals, a combining unit for phasing-combining the first IF signal with the second IF signal, and determination units for determining whether or not the first and second IF signals are interference signals, are provided. When the first or second IF signal is an interference signal, the first or second IF signal is shut off or attenuated by a first switching unit or a second switching unit.

Abstract: A signal combiner for use in a space diversity radio receiving system. The signal combiner accepts two signals which have been received at physically diverse locations and which have been converted from radio frequency to intermediate frequency. Each of the signals is checked for signal strength and for amplitude versus frequency dispersion. Each signal is run through a separate amplitude slope equalizer which removes amplitude slope. Each signal is then run through a separate squelch circuit which either attenuates the signal, or passes it on undiminished. The squelch circuits are controlled by a control circuit which selectively activates one or neither of the squelch circuits based on the difference in signal strength between the two received signals and the signal dispersion of each of the signals. The outputs of the squelching circuits are then combined to create a composite signal which is comprised of one or both of the equalized signals.

Abstract: At least two receiving branches receive incoming signals corresponding to a transmitted data sequence. Each branch includes an equalizer for producing an estimate of the transmitted data sequence, and providing for each data element a reliability information signal representing a computed probability that the data symbol or value for that element is correct. The receiver selects as a most probable estimate the symbol or value having the highest sum of the reliability information signals from the receive branches. Preferably, for a binary system, each branch provides a single numerical value whose sign identifies the symbol (e.g., 1 or 0), and whose absolute value is its probability. The single numerical values from the branches are simply added to determine the best estimate for that element.

Abstract: An original signal, different portions of which are captured by two or more different receivers, is reconstructed from the outputs of the various receivers. In a first embodiment, signal reconstruction is achieved by first converting the analog receiver outputs into digital signals and then shifting the frequency of at least one of the digital signals such that a frequency difference is introduced between at least two of the digital signals. Thereafter, each digital signal is processed through a corresponding filter (38, 40) to derive filtered signals. These filtered signals are combined to derive a primary output signal which is a representation of the original signal. After the primary output signal is derived, it is passed on to an error determiner (44) where an error component is computed. This error component is used to adjust the parameters of the filters (38, 40) in such a manner as to reduce the error component.

Abstract: In a combining circuit comprising first and second frequency converting sections (20a, 20b) for frequency converting first and second received signals from two independent antennas (10a, 10b) under the control of a control circuit (30) into first and second frequency-converted signals, first and second preliminary amplifying sections (60a, 60b) preliminarily amplify the first and the second frequency-converted signals under the control of the control circuit (30) to produce first and second preliminary amplified signals having first and second output levels, respectively. The first and the second preliminary amplified signals have first and second noise power levels, respectively, which are equal to each other. First and second main amplifying sections (40a, 40b) mainly amplify the first and the second preliminary amplified signals by first and second amplification degrees in proportional to the first and the second output levels, respectively.

Abstract: A communications system is disclosed for spectrum sharing of a microwave point-to-point system and a PCS system. The invention comprises a microwave communications system. This system includes a transmitter for transmitting a first signal and a second signal. The first signal and the second signal are oppositely circularly polarized electromagnetic waves within a predefined frequency range. The system also includes a receiver for receiving the first and second signals. In the preferred embodiment of the present invention the receiver may further include a first microwave receiver for receiving the first signal. It would then include a second receiver for receiving the second signal. The receiver would also include signal combining circuitry for combining the first signal and the second signal to generate a composite signal. It would then include a signal comparator to generate a comparison signal by comparing the average value of the amplitude of the composite signal with a predetermined value.

Abstract: Open loop phase estimation methods and apparatus for coherent combining of signals on mobile channels using spatially diverse antennas are disclosed. In accordance with the method, the signals from each of two antennas are demodulated using inphase and quadrature components of a local carrier oscillator to provide RF demodulated inphase and quadrature components of the output of each antenna. These components are simultaneously sampled at a sample rate and digitized to provide the digitized components of the two signal vectors. A phase estimator vector having a phase equal to the difference in phase between the two signal vectors of each successive sample time is determined. An average phase estimator vector for a group of successive signal vectors is determined, and is used as the estimated phase difference between the signal vectors at the middle of the group of successive signal vectors to align the respective signal vectors prior to the same being combined into a single signal vector.

Abstract: A radio system having a master station including a wideband receiver, an A/D converter and a digital signal processing module for each of a plurality of space diversity antennas, the digital signal processing module converting the digitized samples into the frequency domain, weighting and combining the frequency domain signals from each of the antennas and separating the signals into signals corresponding to those transmitted from the remote stations.

Abstract: A digital radio communications system employs a digital information source for providing digital information such as message bits, a transmitter for transmitting encoded digital information into data symbols in a radio-frequency (RF) signal to a plurality of antennae which sense the transmitted RF signal. A post detection measure of signal quality, the signal-to-impairment ratio, (SIR), is utilized by the receiver to perform post detection combining of signals received by a plurality of antennae. The antennae are coupled to a receiver which for each received signal: digitizes the signal, determines phase angles of the digitized signal, converts the signal to unit vectors, determines a signal-to-impairment ratio (SIR) estimates .gamma..sup.j of the digitized signals. The SIR estimate .gamma..sup.j is weighted by combining weight computation element and multiplied by each unit vector to provide an in-phase is component and a quadrature component for each signal.

Abstract: A diversity combiner for a digital receiver receives a plurality of complex baseband signals (S.sub.1 (t), S.sub.2 (t)) each having an associated receive signal strength-intensity signal (RSSI.sub.1, RSSI.sub.2). The combiner differentially detects each of the complex baseband signals (S.sub.1 (t), S.sub.2 (t)) to produce a plurality of differential signals (RX.sub.1 (t), RX.sub.2 (t)) in accordance with:RX.sub.1 (t)=S.sub.1 (t).multidot.S.sub.1 *(t-T), andRX.sub.2 (t)=S.sub.2 (t).multidot.S.sub.2 *(t-T)where S.sub.x * is the complex conjugate of S.sub.x and T is a symbol delay. The differential signals (RX.sub.1 (t), RX.sub.2 (t) ) are processed to produce a selected differential signal R(t). The selected differential signal R(t) is converted to produce a plurality of converted signals D.sub.1 (t) and D.sub.2 (t) in accordance with:D.sub.1 (t)=R(t).multidot.e.sup.-j2.pi.fstD.sub.2 (t)=R(t).multidot.e.sup.+j2.pi.fstThe converted signals D.sub.1 (t) and D.sub.2 (t) are further processed to produce timing (.

Abstract: An adaptive receiving apparatus capable of realizing maximization of SN ratio while making multi-path signals coincident is provided. The apparatus comprises a plurality of antenna elements, a plurality of array arrangements each receiving a plurality of received signals from the plurality of antenna elements for producing an adaptive arrayed signal, a combiner for combining a plurality of adaptive arrayed signals form the plurality of array arrangements, an adaptive equalizer receiving a combined signal from the combiner for producing a decision data signal and adaptive array control means responsive to the plurality of received signals and the decision data signal for controlling the plurality of array arrangements.

Abstract: A Digital Post-Detection (Post-Discriminator) FM spatial diversity combination circuit improves performance for fading channels typical of cellular radio operating environments. A feature of this system is its flexibility. The system can be configured to use signal quality information in a manner which is appropriate for a given radio environment. Also, the weighting information can be derived from various sources and then processed to accommodate various situations. This spatial combiner has the ability to perform as a "hybrid" combiner. For example, this circuit can combine signals from various receivers based on soft weighting information, as in a maximal ratio combiner, or on hard weighting information, as in a switching combiner. The basic circuit includes a normalizing circuit (21, 22, 23) which receives the digitized received signal strength indicator samples from each of first and second receivers (11, 12) and generates first and second weighting signals.

Abstract: In a time division multiple access (TDMA) system (10), a method (50, 60) of recovering a data signal of a transmission burst commences by obtaining the frequency transmission codes for the transmitters to be monitored (52, 62). The data signal is then received in separate transmission bursts from a first transmitter in a first time period (53, 65) and from a second transmitter in a second time period (56, 65). The data signal of one of the received transmission bursts is then selected or a plurality of the data signals are combined (58, 69) to be used by the receiver as the received data signal.

Abstract: A method of estimating the quality of a communication channel from a differential phase angle between a received signal and the corresponding transmitted phase angle employs determining a signal to impairment ratio (SIR) as an indicator of channel state information (CSI). A maximum likelihood estimation procedure is employed to calculate this CSI metric as a function of the differential phase angle between be received signal and transmitted signal An alternate embodiment employs an estimation that incorporates average SIR information for a Rayleigh fading channel. Since CSI is derived from the phase angle of the received signal, and does not require signal amplitude information, it is attractive for use with differential detectors, phase-locked loops (PLLs) and hard-limited signals. The CSI provided can be used for implementing post detection selection diversity, by selecting the signal from a plurality of antennae which has the best SIR.

Abstract: An interference canceler comprises an adaptive equalizer, first and second diversity branches, and an auxiliary branch. A first correlator detects a correlation between the output of the equalizer and the output of the first diversity branch, and a second correlator detects a correlation between the equalizer output and the output of the second diversity branch. The first and second diversity branch signals are multiplied with the detected first and second correlations, respectively, and diversity combined. A phase variation component of one of the first and second correlations is detected and multiplied with the output of the auxiliary branch to produce a signal whose phase rotation is the same as that of the diversity combined signal. A weight control signal is derived by detecting a correlation between a decision error of the adaptive equalizer and the multiplied auxiliary branch signal.

Abstract: According to this invention, a modulator modulates a carrier serving as a fundamental wave with data to be transmitted, thereby to generate a modulated output including at least the fundamental wave and double wave thereof. A transmitting antenna radiates electromagnetic waves into the air, and the electromagnetic waves include the fundamental wave and the double wave included in the modulated output generated by the modulator. A receiving antenna receives the electromagnetic waves including the fundamental wave and the double wave radiated from the transmitting antenna. A diversity section generates an output having a diversity effect on the basis of the fundamental wave and the double wave included in the electromagnetic waves received by the receiving antenna. A demodulator demodulates the output having the diversity effect and generated by the diversity section, thereby to output data corresponding to the data to be transmitted.

Abstract: A VHF radio receiver intended for mobile use, e.g. in a car, features inputs from multiple antennas. Each antenna signal is mixed with a locally-generated oscillator signal; the resulting mixed signals are added, with controllable phase position, to form a summation signal. Alternate frequencies, as defined by the Radio Data System (RDS) international standard, are stored. At periodic time intervals, momentary switchover is made to alternate frequencies to measure their reception quality and to store this parameter. Whenever the originally-tuned frequency provides inadequate reception quality, a control circuit 19 switches over to the best of the alternate frequencies, so quickly that the changeover is almost imperceptible to the listener.

Abstract: A diversity receiver includes a first antenna and a second antenna. A first receiving section connected to the first antenna serves to convert a digital modulation wave induced at the first antenna into a first intermediate-frequency signal. A first band pass filter connected to the first receiving section serves to subject the first intermediate-frequency signal to a band pass filtering process. A second receiving section connected to the second antenna serves to convert a digital modulation wave induced at the second antenna into a second intermediate-frequency signal. A second band pass filter connected to the second receiving section serves to subject the second intermediate-frequency signal to a band pass filtering process. A switch alternately selects one of output signals of the first and second band pass filters at a period equal to a half of a period corresponding to the symbol rate.

Abstract: In a cellular mobile communication system, each base station is allocated common frequencies shared with other base stations in addition to unique frequencies. One of the unique frequencies is assigned by a base station to a mobile terminal in response to a call request. The field strength of a signal from that mobile terminal is detected and one of the common frequencies is assigned to it if the detected field strength becomes lower than a threshold. The base station receives a field strength signal from a neighboring station indicating the field strength of a version of the signal at the neighboring station and compares it with a threshold, and combines the signal of that mobile terminal with the version of the signal received by and relayed from the neighboring station when the field strength of that version of the signal is higher than the threshold. At the given mobile station, a signal from the base station which assigned the common frequency is combined with a signal from the neighboring station.

Abstract: A phase combining method and apparatus for use in a diversity reception radiotelephone is described. The phase combining method and apparatus is a hybrid diversity technique which combines elements of maximal ratio combining (MRC) and level comparison selection diversity, which results in a simple and effective implementation of a diversity receiver with superior performance. The diversity receiver demodulates the received signals, extracts the phase, forming two phase signals. Then, the two phase signals are combined to form a third phase signal. One of the three phase signals is selected to be used for interpretation of a symbol in the Quadrature Phase Shift Keying (QPSK) constellation. The selection process is based on the received signal strength of the received signals.

Abstract: A diversity receiver (300) has improved diversity weighting parameter estimation. The receiver receives different versions of a signal (101) having encoded data, combines the versions and decodes the data contained within the combination. The decoded data output is then re-encoded using a similar technique as that at a transmitter which transmitted the signal (101). The re-encoded data is then used to calculate a diversity weighting parameter which is used to modify a stored replica each version. The modified versions are then combined and decoded to yield a more accurate estimate of the information contained within the signal (101) at diversity receiver (300).

Abstract: A method and device are set forth for providing improved diversity reception to a receiver system in a communication system, the receiver system having at least one receiver on each of at least a first and a second receiver branch. The method and device provide, upon receipt of signals on the receiver branches, for utilizing received signal strength voltages to determine control voltage values, utilizing the control voltage values to amplify the designated signal (the designated signal being, for example, a signal having a received signal strength (RSSI) greater than a predetermined threshold) to obtain an amplified designated signal, and generating a resultant signal in view of the at least first amplified designated signal. The control voltage values are utilized to obtain at least one weighted difference. The at least one weighted difference is utilized to obtain an adjusted amplification of the at least one designated signal in accordance with a linear approximation.

Abstract: A combiner circuit employs the maximum power method, in which the phase of one of the signals is varied such that the power of the aggregate signal (main and diversity) is varied such that the power of the aggregate subsequently formed is optimally high. In order to improve this combining method that becomes less and less efficient with increasing bandwidth and number of steps of signals, particularly given selective fading, it is provided that the combiner circuit contains a control circuit for the combination phase, the control circuit being composed of a maximum power control circuit and of two preceding, supplementary circuits for varying the amplitudes of the main and diversity signals.

Abstract: In the diversity receiver which switches between receiver branches to receive phase modulated signals, this invention can achieve a diversity effect with a circuit of simple construction which by switching between receiver branches based on relative modulation phase error, and can attain diversity effect not only against fading but also against any factor which might affect the transmission lines.

Abstract: A selection system in a space diversity system of a mobile receiver combines the ultra high frequency signals after they have been frequency shifted to an intermediate frequency. The system combines the intermediate frequency signals depending on the ratio of the magnitudes of these signals. If the ratio of the magnitude of the received signals is equal to or greater than a preset magnitude level, for example, 5 db, a control unit selects only the received signal having the largest magnitude. Otherwise, the control unit linearly combines both received signals Specifically, if the absolute value of the difference in received phase signals is less than 90.degree., the output of a phase detector causes the control unit to pass both received signals to a summer that linearly combines them prior to demodulation. Otherwise, the control unit inverts the phase of one of the received signals prior to passing both received signals to the summer.

Abstract: Signals in synchronizing sequences and data sequences are transmitted over a fading channel to a Viterbi-receiver. The signals are received by antennas and sampled to received antenna signals (s.sub.in,r (k)). Part channel estimates (h.sub.est,r) for the individual antennas are formed. For Viterbi-analysis, assumed input signals (s.sub.a,r (.DELTA.T.sub.ij,k)) for the data sequence are produced with the aid of the part channel estimates (h.sub.est,r). Part metric values (m.sub.r (.DELTA.T.sub.ij, k)) are formed as a difference between the received antenna signal (s, .sub.in,r (k)) and corresponding assumed input signals (s.sub.a,r (.DELTA.T.sub.ij, k)) for Viterbi state transitions (.DELTA.T.sub.ij). For one state transition there is formed a metric value such as the sum of a metric value ((M(T.sub.j, k-1)) for an old state (T.sub.j) at a preceding sampling time point (k-1) increased with a weighted (K.sub.r) sum of the part metric values (m.sub.r (.DELTA.T.sub.

Abstract: A receiver for processing signals transmitted through a dispersive medium which receiver provides received signals at a plurality of diversity channels and uses adaptive equalizer circuitry for providing an adaptive weighted equalizer output signal. An error signal is derived at an error circuit in response to the equalizer output signal and to a reference signal, the error signal being correlated at a correlator with the adaptive weighting signals at each weighting section of the adaptive equalizer circuitry to generate weighting factors for use in such weighting sections. Scale factor circuitry responds to a signal having an amplitude which is a reliable estimate of the amplitude of the adaptive equalizer output signal and to the reference signal to provide a scale factor by which the reference signal is multiplied at a multiplier prior to its use in deriving the error signal.

Abstract: A combiner for a radio receiving signal which receives signals having various signal paths of a digital radio transmitter, particularly a mobile transmitter. The combiner is designed so it allows maximum power gain in broadband systems and can also be used in systems which have pulse or discontinuous transmission. A correlator is provided at the receiver in every signal path. Frequency converters are also in each signal path. Following the frequency converter and following each of the correlators there is provided a metric table in each path which had been calculated in accordance with the respective line model obtained at the receiver. The output values formed from the metric tables and individual signals are combined and supplied to a Viterbi demodulator which produces the corrected output signal.

Abstract: A method for implementing diversity reception to counteract effects of channel fading on a transmitted information signal. In diversity receive paths, estimates of complex channel gain are computed based upon pilot symbols inserted from time to time in the transmitted information symbol stream. Phase corrected and weighted samples from the diversity paths are summed prior to the decision process. The squared magnitudes of the diversity path channel gains are summed to provide the proper threshold adjustment.

Abstract: A diversity receiving system for a differential phase shift keyed digital signal having symbols occurring in successive time periods comprises at least one antenna and a plurality of receiving branches. Each receive branch operates on a different version of the digital signal and detects different type prescribed components of the phase difference between successive symbols of the branch version. A detected prescribed component of the phase difference of each type is formed for each successive time period by processing the same type detected prescribed phase difference component signals from the receive branches.