Abstract: The present invention is characterized by that, at a reception section of a base station in a CDMA system including a reception antenna, a radio section and the number of demodulators corresponding to the number of users where spreading codes of a plurality of spreading factors are available, an algorithm diversity controller and a selector are prepared, information concerning spreading factors of spreading codes utilized by users and others are applied to the algorithm diversity controller, algorithm diversity controller instructs the number of demodulators prepared corresponding to the number of users and the selector, and when signals transmitted by a user utilizing a spreading code of a low spreading factor, i.e. signals with high symbol rate, are received, by demodulating signals with different reception methods or different parameters at demodulators leftover because of the low spreading factor, the demodulated signals of the best quality are selected.

Abstract: A frequency diversity system for use in mobile reception of television and RF signals in the meter or decimeter wavelength, such as for use with a mobile television having a first receiver, an additional receiver and a control and analysis circuit. The additional receiver detects all incoming frequencies corresponding to a preset program and switches the main receiver to an incoming frequency of a higher quality. The receiver is able to identify the frequencies corresponding to the desired program through a transmitter identification code, which is added to each signal. This code is usually a VPS identification signal. The control and analysis circuit compares the incoming frequencies to the frequency of the signal transmitted by the television receiver to determine the highest quality signal. In order to accelerate the process, the system processes local position coordinates of the television so that the frequencies analyzed are only those expected within the coverage area of the television.

Abstract: In a wireless communications system having a transmitter that transmits a transmit diversity signal using multiple antennas, a channel quality metric is computed by measuring a first and second diversity branch signal quality for first and second diversity branches in the receiver. Thereafter, the channel quality metric is computed in response to a difference between the first and second diversity branch signal qualities. The first and second diversity branch signal quality measurements may be signal-to-noise measurements. In one embodiment, the channel quality metric is computed by taking a square root of a product of signal-to-noise ratios of the first and second diversity branches in the receiver.

Abstract: A demodulator 1 obtains demodulated data in a plurality of channels. Estimating portions 2a and 2b estimate and output the numbers of erroneous symbols and error locations thereof in the demodulated data. A data comparator 3 compares the demodulated data corresponding to the error locations with the demodulated data in the corresponding locations in other channels to determine whether the error location is correct, and it outputs a decision signal in response to the determination. A data selector 4 selects one of the demodulated data in the plurality of channels on the basis of the numbers of erroneous symbols and the decision signals and outputs the data as selected data. It is then possible to maintain the reliability of error detection even when a less redundant short error detecting code is used, and also to accurately select a channel of good quality even when the demodulated data in all channels contain the same extent of errors.

Abstract: A receiving antenna system for vehicles that eliminates interference in receiving signals. The interference detector is disposed within the receiver and generates and transmits an indicating signal, or a signal derived therefrom. Such signal can be formed in several different ways, and in the site of the antenna installation, it can be converted into a switching signal that only effects the switching condition in the antenna installation having a controllable switching circuit.

Abstract: A demodulator and demodulating technique is provided which automatically switches modes according to the flat-fading or multipath channel status of an incoming signal. If an incoming signal has delay spread in addition to fading a standard Maximum Likelihood Sequence Estimator (MLSE) equalization is selected as an optimum demodulation mode. If the incoming signal is only flat-fading a symbol-based demodulation mode is selected. The Maximum Likelihood Sequence Estimator (MLSE) equalizer mode is thus integrated with the symbol based mode. Channel status is first identified in order to do mode selection in the demodulator. A dual-mode receiver for demodulating both flat-fading and multipath signals in a communications system (FIG. 1) comprises a Baseband Digital Signal (DSP) Processor further comprising a Channel Identification Processor, the Channel Identification Processor computing a Maximum Likelihood Sequence Estimate x=(x.sub.0 x.sub.1).sup.

Abstract: A radio receiver receives a plurality of 4-ary FSK signal replicas and detects a four-level detected signal from each 4-FSK signal replica. The four-level detected signal is sampled by an AD converter. When a first signal replica is received before a second signal replica, a first distance between a first sample value and an input center level of the AD converter and a second distance between a second sample value and the input center level are calculated. The first sample value corresponds to the first sample value in the first and second signal replicas, respectively. One of the first sample value and the second sample value is selected depending on which one of the first and second distances is larger than the other.

Abstract: A space diversity receiver for use in a radio transmission system reduces a fading effect of a received signal and generates a constant output regardless of a variation of a signal-to-noise ratio of the received signal. The space diversity receiver compares a signal-to-noise ratio of a signal received from a first antenna and a signal-to-noise ratio of a signal received from a second antenna, so as to amplify the received signal having a higher signal-to-noise ratio and attenuate the received signal having a lower signal-to-noise ratio. The amplified signal is combined with the attenuated signal.

Abstract: An integrated adaptive spatial-temporal system and method for controlling narrowband and wideband sources of interference. The system includes an N element antenna array which receives a spread spectrum signal and interference signals, each element receiving a different phase shifted version of the spread spectrum and interference signals; a spatial filter including an antenna pattern former responsive to the antenna array which combines the phase shifted spread spectrum and interference signals according to controlling weights to null N-1 of the interference signal; an adaptive narrow band, e.g., temporal filter, responsive to the spatial filter for filtering any remaining narrowband interference signals from the combined signal; and feedback subsystem responsive to the narrow band filter for adjusting the controlling weights of the antenna pattern former until the operation of the spatial filter is optimized and nulls wideband interference signals before narrowband interference signals.

Abstract: Antenna selection control apparatus for a diversity antenna system including at least two antennas. The received power strength is measured from a selected antenna and compared with a reference power level. The reference power level is adjusted depending upon the signal to noise ratio of received signals, and if the selected antenna falls below the adjusted threshold another antenna is selected.

Abstract: A space diversity, multiple-tuner radio receiver obtains substantially noise free reception under most signal conditions. The tuner outputs are mixed in proportion with the signal quality as determined by detecting noise in each tuner output signal. Long-time-delay multipath distortion, adjacent channel interference, and co-channel interference are reduced by selecting predetermined antenna pattern combinations in response to high noise levels being present from both tuners.

Abstract: A radio apparatus includes a plurality of receiving systems connected to multiple antennas providing diversity, respectively, each receiving system including an antenna terminator and a preamplifier. After one receiving system is discriminated from another receiving system based on radio signals received by the receiving systems, respectively, a controller controls the one receiving system such that an antenna terminator is inactive and a preamplifier is active and, at the same time, further controls the other receiving system such that an antenna terminator is active and a preamplifier is inactive.

Abstract: A diversity reception system for use in narrow-band radio frequency communication systems includes a plurality of receivers that each generate a detected signal from a received radio frequency signal. The diversity reception system switches between receivers to output a high quality audio signal. The system selects a receiver having the highest quality reception at any given time by using a detected signal having the highest relative signal-to-noise ratio when the detected signals have less than a preselected threshold signal-to-noise ratio and a detected signal having the highest relative signal strength when one or more of the receivers is generating a detected signal having a signal-to-noise ratio at or above the preselected threshold signal-to-noise ratio.

Abstract: A diversity receiver having a pair of receiving circuits, which is capable of disconnecting a faulty receiving circuit from its operation for preventing a communication quality from being degraded due to mis-selection of output signal of the faulty receiving circuit in a case of signal level being received is too low to discriminate between output signals of the faulty receiving circuit and the normal receiving circuit, is provided. The diversity receiver includes a first and second error rate accumulation circuits, each is coupled with corresponding receiver circuit, to accumulate error rate of each receiver circuit in a timing generated by a timing generator circuit. In combination of six judge circuits, first judge circuit to sixth judge circuits, and input of error accumulation value of each receiving circuit, it is judged whether or not there exist a fault in a receiving circuit and which receiving circuit is faulty.

Abstract: A transmission space diversity method which is effective also for a communication system wherein different carrier frequencies are used for transmission and reception is disclosed. Such reception space diversity control that a controlling signal from terminal station 10 is received by two antennas 1 and 2 and receivers 3 and 4 of a base station and the two received controlling signals are compared with each other by reception space diversity controlling signal generation circuit 6 and then that signal which exhibits a higher reception level is provided to switch circuit 8. Furthermore, the reception space diversity controlling signal is utilized for transmission space diversity control of antenna selection wherein the output of transmitter 5 is emitted by one of the antennas.

Abstract: A system and method for bidirectionally demodulating data symbols transmitted through a communication channel. The method includes sequentially receiving and storing a first plurality of known data symbols, a second plurality of unknown data symbols, and a third plurality of known data symbols. Thereafter, a first block of the unknown data symbols received nearer the first plurality of known data symbols is forward-demodulated. Likewise, a second block of the unknown data symbols received nearer the third plurality of known data symbols is backward-demodulated. The forward- and backward-demodulation of the unknown data symbols determines quality values (figure-of-merits based on at least one of signal power, noise power and a combination of signal power plus noise power) indicative of demodulation qualities of the unknown data symbols that are compared to produce a best direction indication.

Abstract: Improved radio receiver designs can be used in the operational environment of wireless telephone communications. The radio receiver includes a variable attenuator, a variable-current RF signal amplifier, and a controller. The controller controls the amount of attenuation provided by the variable attenuator, and/or the current consumed by the variable-current RF signal amplifier, in response to signals received by the RF signal amplifier. The controller adjusts the variable attenuator, and/or the RF signal amplifier, to achieve a minimum symbol error rate and/or to maximize the signal-to-noise and interference ratio for a desired signal, irrespective of the levels of any interfering signals received by the RF signal amplifier. In this manner, the variable attenuator, and/or the variable current RF signal amplifier, are adjusted to obtain just the right amount of intermodulation performance for a given set of receiving conditions.

Abstract: A radio transmission system is disclosed for operating in a multipath transmission environment having improved reception, and in the case of bi-directional systems, also improved transmission. This is achieved by using at least two reception beams, corresponding to one fixed reception beam and one scanning reception beam, and by continuously evaluating the quality of these beams as to their signal-to-noise-and-interference ratios or bit-error-rates (BERs). The best beam is dynamically chosen to be the fixed beam. Alternatively, the fixed beam is updated with the best beam acquired by the scanning beam as compared to the current fixed beam. In a bi-directional system, the receiving radio apparatus applies the direction of the best reception beam for transmission to the opposite radio apparatus.

Abstract: A digital data radio receiver and method evaluates a data signal preamble received on an antenna to determine whether the antenna should receive the data signal following the preamble. The receiver determines frequency offsets from a desired frequency for each symbol in a block of symbols in the preamble, determines the variance of the frequency offsets, determines the average magnitude of the symbols in the block of symbols, where the determination of average magnitude may be performed in parallel with the determination of variance of the frequency offsets, and evaluates the variance and the average magnitude for the block of symbols to determine whether the preamble is actually noise and to assess reception quality at the antenna. In a two antenna diversity receiver system, these steps may be performed first on a block of symbols received at one antenna and then performed on the next block of symbols received at another antenna.

Abstract: A self-steering antenna apparatus for receiving and transmitting electromagnetic signals, includes a plurality of antennas for receiving and emitting electromagnetic signals and a plurality of receivers for processing the received electromagnetic signals. Each one of the plurality of receivers corresponds to a respective one of the plurality of antennas. Each receiver provides signal strength information indicating a signal strength of the electromagnetic signal received by the corresponding antenna. A comparator compares the signal strength information provided by each receiver, and determines which of the antennas is receiving the strongest electromagnetic signal. Switching circuitry switches the received electromagnetic signals and the signals to be emitted, based on the comparison performed by the comparator, the switching circuitry selecting one of the plurality of antennas to emit and receive the electromagnetic signals based on the comparison.

Abstract: In a time diversity receiver, where in time diversity is performed using the detector output, without any use of a receiving level detection circuit, thereby simplifying the receiver circuitry and reducing power consumption.

Abstract: A method and apparatus for improving the signal-to-interference ratio and signal-to-noise ratio of a signal transmitted on a reverse channel from a mobile transmitter in a land mobile communications system by using a sectored cell in which the same channel is received by each sector of the cell. Each directional antenna is coupled to a unique associated receiver tuned to the same frequency or frequencies as the other receivers associated with each other directional antenna within the same sectored cell. Depending upon the location of the mobile end system with respect to the antenna pattern of each directional antenna, each signal will typically be redundantly received over more than one, but less than all, of the antennas. In accordance with the present invention, only one of the received signals is to be communicated from the base station to an intermediate system and all others are to be discarded.

Abstract: Herein disclosed are a radio receiving apparatus and a receiving system switching control method used in the radio receiving apparatus. The radio receiving apparatus has an active receiving system and a standby receiving system including respective equalizers, and a changeover switch for performing a switching between the active receiving system and the standby receiving system. The radio receiving apparatus further includes an alarm predicting information predicting means for detecting alarm predicting information in each of the equalizers and a switching control means for controlling a switching condition of the changeover switch on the basis of the alarm predicting information detected by the alarm predicting information detecting means, where the alarm predicting information as internal information of the equalizers is monitored to predict a malfunction of a receiving circuit to switch the circuit before the circuit is hit. It is therefore possible to reduce a hit rate of the circuit.

Abstract: Improved radio receiver designs are disclosed that can be used in the operational environment of wireless communications. The radio receiver includes a signal input terminal, a variable-current RF signal amplifier, a demodulator, and a controller. The variable-current RF signal amplifier has an input terminal for accepting RF input signals, an output terminal for generating an amplified version of the RF input signals, and a current control terminal for controlling the current consumption of the RF signal amplifier. The signal input terminal is coupled to the input terminal of the variable-current RF signal amplifier, the output terminal of the variable-current RF signal amplifier is coupled to the demodulator, and the current control terminal is coupled to the controller. The controller is also coupled to the demodulator. A received signal, including any noise and/or interference, is coupled to the signal input terminal.

Abstract: A system and method are provided for reducing perceived distortion in an output audio signal derived from an amplitude modulated compatible digital broadcast signal having an analog portion and a digital portion. The digital portion of this signal is demodulated to produce a demodulated digital signal and the analog portion of the signal is demodulated to produce a demodulated analog signal. The noise in the demodulated digital signal is measured and an estimate of the signal-to-noise ratio is derived. This estimated signal-to-noise ratio is compared with a threshold level which is set at the minimum acceptable signal quality for the digital signal. Based upon the estimated signal-to-noise ratio, a switch directs either the analog derived audio output or the digitally derived audio output as the system output signal.

Abstract: A selective diversity apparatus in which a predetection diversity system is used and branches can be switched without generating a signal error, etc., even at the time the reception of a communication physical slot having a short preamble signal zone, and a control method thereof. When a control physical slot is received in which a preamble signal zone contained in a burst received is sufficiently longer than the time necessary for selecting and switching the branches, judgment and switching of the branches are executed in the preamble signal zone, and when a communication physical slot not having a sufficient time is received, judgement of the branches is made during reception of the burst and switching of the branches is made in a guard time immediately before the burst after one frame.

Abstract: A diversity receiver respectively receiving signals in two branches includes two demodulating sections for producing respective amplitude and phases of received signals at a unit of symbol. The receiver includes a memory access section for producing an amplitude ratio of the amplitude of the received signals and a phase difference between the phases of the received signals. The receiver further includes a storage section for storing at least one relative phase difference between a phase of a vector-combined signal combined based on the received signals and one of the phases of the received signals for an address given by the amplitude ratio and the phase difference of the received signals. The phase of the vector-combined signal is previously calculated based on the amplitude ratio, the phase difference, and the one of the phases of the received signals.

Abstract: Diversity reception apparatus includes a number of receivers each having a distortion detector. There is a common output channel. A comparator compares the signals detected by detectors and provides a control signal to a selector or switching circuit that couples that receiver having the preferred received signal to the common output channel.

Abstract: A base site (100) employs a method and apparatus for selecting two of a plurality of antennas (101-106) from which to receive a communication signal. A first signal quality metric is measured for a communication signal received from a first antenna (102) and a second signal quality metric is measured for the communication signal received from a second antenna (103). When the first signal quality metric differs from the second signal quality metric by a threshold, a signal receiver (113) is coupled to a third antenna (e.g., 101) and a third signal quality metric is measured for the communication signal received from the third antenna (101). Based on the three signal quality metrics, a primary antenna and a secondary antenna are selected from which to receive the communication signal.

Abstract: A signal quality detector (206) and analogous method thereof for operation on a signal having at least one predetermined frequency, the detector including a symbol detector (209), coupled to the signal, for providing a maximum discrete time Fourier transform value for a time period, the maximum discrete time Fourier transform value corresponding to one of the at least one predetermined frequency, an energy detector (217) for providing an energy estimate corresponding to a energy value of the signal over the time period, and a combinatorial logic (219) for combining the maximum discrete Fourier transform value and the energy estimate to provide a signal quality estimate or signal power or noise power.

Abstract: Band-pass filters BPF1, BPF2, and BPF3 correspond to the reception frequency band for FDD, the transmission band for FDD, and the band for TDD, respectively. An antenna A1 is used in common for transmission and reception in the FDD and TDD systems. Another antenna A2 is used for diversity reception in the FDD system. A controller 20 controls switches SW1 through SW4. When the FDD system is selected, the reception signal is sent from the antenna A1 or A2 through the filter BPF1 to a reception amplifier RA, and the transmission signal is sent from the transmission amplifier TA through the filter BPF2 to the antenna A1. When the TDD system is selected, the reception signal is sent from the antenna A1 through the filter BPF3 to the reception amplifier RA, and the transmission signal is sent from the transmission amplifier TA through the filter BPF3 to the antenna A1.

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 data receiver (110) for processing multiple signals includes a receiving circuit (120) for demodulating at least first and second signals and a selector (125) coupled to the receiving circuit (120) for comparing the at least first and second signals to estimated peak and valley values. The selector (125) generates error values associated with the at least first and second signals and selects a data symbol associated with one of the estimated peak and valley values based on the error values. A timing circuit (140, 150) activates the selector (125) at predetermined times, and a controller (140) coupled to the selector (125) and the timing circuit (140, 150) recovers information in accordance with the data symbol and other data symbols.

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 radio communications system (100) has multiple receive sites (210, 250) for providing signal diversity for a common source signal. At a receive site (210), data is received on a wireless communication channel (208), and associated signal quality determined for the data received. Coefficients of a time domain function defining the signal quality are determined and transferred, along with the data, to a central site (110). At the central site (110), the data transferred from multiple receive sites (210, 250) is weighted according to the corresponding time domain functions to recover the source signal.

Abstract: A method and apparatus for measuring a characteristic of a fading signal received using a two or more branch diversity receiver is presented. This fading characteristic is generally proportional to the speed of the user. In a first embodiment the number of times the antenna branches change in a selection diversity process is counted, and the result is scaled for imbalance between the branches. The output of a fading quality estimator, indicative of the fading and generally proportional to the speed, is thereby obtained.

Abstract: A system for digital selection diversity includes receiving different versions of a signal sit different antennas (222, 226) of a receiver (210), and processing the different versions on separate branches each having a digital downconverter (224, 228) and filter (232, 236). The filters are controlled by a diversity switch selector (250) so that one acts to filter (the active branch), and the others decimate, their respective input signal versions, based on detected signal quality. The diversity switch selector also controls a demodulator (240) to demodulate the filtered signal. The decimated signals are used to provide both signal quality information, and phase history when a branch becomes active.

Abstract: The present invention provides a system and methods for coding and decoding digital data to improve the subjective quality of a voice signal. According to the invention, a sampled voice waveform is compressed by an ADPCM algorithm resulting in a sequence of samples. The sequence of samples are formed into an array and coded into parity bits. Row and column checksums are preferably performed on the parity bits to form row and column vectors. The samples and row and column vectors are transmitted to a receiving unit preferably having a diversity capability. The receiver processes each diversity block by generating row and column vectors from the received samples and comparing the generated row and column vectors to the row and column vectors received. Then based on the comparison, the samples of the best diversity block are used to reconstruct the voice waveform on a sample-by-sample basis.

Abstract: The present invention provides a wireless communication system which employs Butler matrix combiners and circuit switching at transmitter and receiver antenna arrays to provide directive beamwidth capabilities. Such narrow beamwidths permit the communication system to determine and select the transmission path having an optimum signal quality. The antenna arrays are integrated in a multilayer construction which reduces power consumption, increases the coverage range, improves the efficiency of the antenna array, and which has lower fabrication costs.

Abstract: A radio link for a digital radio transmission system having spatial and/or angular diversity is optimized in real time by searching for a minimum of the analog BER function BERn(.phi.), by analyzing the minimum to determine if it is an "absolute" minimum that will result in an optimal radio link, and if not, searching for another minimum until the absolute minimum is located. Once the relative phase .phi. corresponding to the absolute minimum has been thus determined with both channels having the same nominal attenuation level, the relative attenuation level T of the two channels may then be varied in order to optimize the dispersion Ban.sub.n (T) of the recombined data spectrum while holding the relative phase at its previously optimized value.

Abstract: Electric field intensity of a signal corresponding to a plurality of receivers and received through antennas are converted into direct currents. The converted direct currents thus converted are fed to an electric field level detection circuit. The electric field level detection circuit detects the electric field level on the basis of the direct currents of respective receivers and feeds a detection signal to a control portion. The control portion compares the electric field level corresponding to the direct current value in said controller with a predetermined electric field level to make judgement that the received electric field is a strong electric field and stable. Then, a command is issued to keep one of the receivers, at which the higher electric field level is detected and to turn off other receiver.

Abstract: A high frequency power amplifier is implemented by a GaAs FET and is supplied with a positive and a negative power supply. The amplifier amplifies the power of an input signal and delivers the amplified signal to a high frequency switch. The high frequency switch is supplied switch control voltages in the form of the positive and negative voltages. Since the switch control voltages are implemented as the positive and negative voltages, a great difference in level between the switch control voltages is achievable which improves insertion loss. While the high frequency switch may also be implemented by GaAs FETs, the insertion loss will be further reduced if the negative voltage is applied to the high frequency switch only during transmission. In this case, current consumption will also be reduced if the generation of the negative voltage is controlled at the negative voltage source side.

Abstract: A digital radio communication system includes a first demodulator, a second demodulator, a non-break switch, and a switching controller. The first demodulator receives a signal from a first antenna and outputs demodulated data and a line quality degradation signal. The second demodulator receives a signal from a second antenna and outputs demodulated data and a line quality degradation signal. The non-break switch receives the demodulated data output from the first and second demodulators and selects and outputs one of the demodulated data. The switching controller receives line quality degradation signals output from the first and second demodulators to output a switching control signal to the non-break switch on the basis of the received line quality degradation signals. The first and second demodulators output the line quality degradation signals before the demodulated data are set in an interrupt state when abrupt frequency selective fading occurs.

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: The present invention comprises a method and apparatus for selecting one of at least two antennas (202, 204) in a communication unit (200) for use in a wireless communication system (100). A signal is received by a radio frequency receiver during a receiving period from one of the at least two antennas (202, 204) currently selected by an antenna switch (206), the signal transmitted in a digital communications format comprising a plurality of bits. The quality of the receive signal is determined by a switch diversity algorithm programmed into a microcomputer (212) that bases the decision to switch antennas on predetermined thresholds established for each of: a received signal strength indicator, a phase error signal, and a recovered clock signal.

Abstract: A diversity receiver that receives modulated signals may determine signal usability of the received signals in the following manner. A modulated signal that includes a desired component and an undesired component is received in each receiver branch of the diversity receiver, wherein the desired component includes an originally transmitted signal and the undesired component includes noise and interference. Each receiver branch estimates the desired and undesired components and processes the modulated signal with a channel gain/phase estimator, a complex conjugator, and a complex mixer to produce a complex output. The complex output of each receiver branch is derived independently of the undesired component and combined to produce a diversity resultant. The diversity receiver estimates the signal usability of the diversity resultant based on the estimated desired components and the estimated undesired components.

Abstract: A method and apparatus in a data communication receiver (100) for diversity reception of a radio signal including a predictably repetitive, predetermined data bit pattern (304) comprises a processor (114) controlling (600) an antenna switch (106) to select between a first antenna feed (102) and a second antenna feed (104) as a momentary source of the radio signal during transmissions of the predetermined data bit pattern (304). The radio signal received from the momentary source is monitored by a data receiver (110) during the transmission of the predetermined bit pattern (304) to derive the data therefrom, and at least one bit error count is determined (604, 610) by the processor (114). After completion of the predetermined bit pattern (304), an antenna feed (102, 104) for the radio signal is selected (616, 620) in response to the at least one bit error count.

Abstract: A diversity receiver that receives diverse modulated signals may produce a usable signal from the received modulated signals in the following manner. Two modulated signals, each including a desired component and an undesired component, are received by the diversity receiver, wherein each desired component includes an originally transmitted signal and each undesired component includes noise and interference. The diversity receiver estimates each desired and undesired component and produces the usable signal based on the estimated desired components and the estimated undesired components.

Abstract: The present invention comprises a method and apparatus for selecting one of at least two antennas (202, 204) in a communication unit (200) for use in a wireless communication system (100). A signal is received by a radio frequency receiver during a receiving period from one of the at least two antennas (202,204) currently selected by an antenna switch (206), the signal having a plurality of bits. The receiver is capable of determining the quality of the receive signal by determining if the incoming bits transition periods fall within a predetermined time window. If it is determined by the receiver that the quality of the receive signal is below a predetermined threshold the currently selected antenna (202 or 204) is switched. The currently selected antenna remains selected when the currently selected antenna has been selected within a predetermined amount of time.

Abstract: A space diversity receiver comprises a plurality of antenna connectors, with each of which an antenna is to be connected, a signal selecting portion for selecting one of signals from the antenna connectors, a signal processing circuit block for producing an output signal based on a signal selected by the signal selecting portion, wherein a signal sampling operation through which the signals obtained from the antenna connectors are sampled for every short period to be supplied to the signal processing circuit block is performed by the signal selecting portion during a specific period so as to select one of the antenna connectors through which a signal giving rise to the best output signal of the signal processing circuit block is introduce and the signal introduced through the selected antenna connector is continuously selected by the signal selecting portion during a period successive to the specific period, the signal selecting portion being controlled to perform the signal sampling operation in such a manne