Abstract: A method for adjusting a phase difference between a received code modulated signal and a replica code sequence where, in order to enlarge the control range, it comprises a step of determining measurement values representing a phase difference between a received code modulated signal and a generated replica code sequence. The proposed method further comprises determining coefficients for a loop filter operation, which coefficients optimize a predetermined function specified for current properties of the received signal. Then, a loop filter operation is applied to the measurement values to obtain an indication of a required correction of a current frequency of the generated replica code sequence, which loop filter operation utilizes the determined coefficients. Finally, the frequency of the generated replica code sequence is adjusted based on the indication of a required correction. The invention relates equally to a corresponding unit and to a corresponding system.

Abstract: In accordance with embodiments of the present invention, a receiver system is provided with a variable gain mixer circuit that is advantageous over current architectures used in wireless communication systems. The use of a variable gain mixer circuit simplifies the receiver architecture resulting in the elimination of additional circuit blocks and a reduction in complexity and cost. Moreover, one embodiment of the present invention includes a mixer circuit comprising a mixer core, a bias circuit coupled to the mixer core for providing a bias current, and a variable impedance network. The mixer core receives input signals and generates output currents that are coupled to the variable impedance network. Each of the output currents are selectively coupled to a voltage output node through a variable impedance. Variable gain is established by varying the impedance between the output currents of the mixer core and the voltage output node.

Abstract: Apparatus, and an associated method, for estimating frequency offset introduced upon symbols of a sequence communicated by a sending station to a data destination during operation of a communication system. A received sequence is rotated by multiplying the symbols thereof by offset values selected from a set of offset values. Then, for each rotated sequence, an estimation of a data sequence is made. Noise indicia associated with each estimated data sequence is calculated. And, comparisons are made of the noise indicia associated with each of the estimated data sequences. Responsive to the comparisons, selection is made of the frequency offset that has been introduced upon the data sequence.

Abstract: A receiver includes an FFT analysis result/group delay characteristic determining unit for determining whether or not a group of carrier signals of a digital broadcasting signal satisfies predetermined requirements, and delivers a requirement satisfaction determination signal indicating the determining result. When receiving the requirement satisfaction determination signal indicating that the group of carrier signals doesn't satisfy the predetermined requirements while the receiver is selectively receiving the digital broadcasting signal, a switching circuit switches to the reception of an analog broadcasting signal. In contrast, when receiving the requirement satisfaction determination signal indicating that the group of carrier signals satisfies the predetermined requirements while the receiver is selectively receiving the analog broadcasting signal, the switching circuit switches to the reception of the digital broadcasting signal.

Abstract: Systems and methods that reduce phase noise are provided. In one embodiment, a method may include one or more of the following: generating a signal at a particular frequency in which the signal may be associated with a harmonic frequency signal disposed at a harmonic frequency; and selectively attenuating frequency content disposed in a region around the harmonic frequency. The signal may be associated with a second harmonic frequency signal disposed at a second harmonic frequency. Frequency content disposed in a second region around the second harmonic frequency may be selectively attenuated. One or more non-linear operations may be applied to the signal and the applied signal may be transmitted.

Abstract: Two fixed-phase-related signals of arbitrary (unequal) magnitude are combined without incurring combining loss by use of a signal reflection technique wherein the higher magnitude signal is phase-synchronously reinforced along its path through the combining system. In a specific embodiment, two signal sources are fed as equal phase signals through respective counter-rotating circulators to a four-port first combiner, wherein the first output port of the combiner is provided with a one-eighth wavelength phase delay to a termination and the second output port is directly terminated, so that reflected signals as seen at both input ports return exactly in phase and of equal magnitude to one another. Thereupon the reflected signals are directed by the respective circulators as phase-synchronized signals to a second combiner which combines the phase synchronized signals into a common output signal. The resultant output is the sum of the inputs irrespective of relative magnitudes of the inputs.

Abstract: Embodiments of the present invention relate generally to receivers. One embodiment relates to a digital FM receiver having multiple sensors (e.g. antennas). In one embodiment, the digital receiver includes a baseband unit having a channel processing unit. In one embodiment, the channel processing unit is capable of calculating or estimating a phase difference between the incoming signals prior to combining them. One embodiment uses phase estimation method for diversity combining the signals while another embodiment utlizes a hybrid phase lock loop method. Also, some embodiments of the present invention provide for echo-cancelling after diversity combining. An alternate embodiment of the channel processing unit utilizes a space-time unit to diversity combine and provide echo cancelling for the incoming signals.

Abstract: Techniques for inner/outer loop tracking that is stable and provides desirable loop convergence characteristics are disclosed. In one aspect, the contribution from any one inner loop to the tracking function of the outer loop is limited, to prohibit any one received signal component from dominating the outer loop. In another aspect, the rate of outer loop tracking variation is controlled to provide inner and outer loop stability. Various other aspects are also presented. These aspects have the benefit of providing stable inner and outer loop control, as well as efficient convergence and tracking by the various loops, resulting in reduced frequency error and improved communication performance.

Abstract: A circuit configuration for the frequency conversion of an oscillator frequency into a carrier frequency includes a mixer, to which a signal with the oscillator frequency can be fed unchanged in its frequency at an input and can be fed divided-down in its frequency at a second input. The frequency division is, in this case, preferably a frequency division by four. The present circuit configuration has a particularly small area requirement, a particularly low current consumption, and is largely independent of fabrication tolerances. The present circuit configuration can be used with preference in mobile radio transceivers.

Abstract: Amplitude phase distortion adding sections are provided for the power amplifiers on the antenna arrays greater in amplitude weighting while amplitude distortion adding sections are provided for the power amplifiers on the antenna arrays smaller in amplitude weighting. Due to this, because a required amount of distortion compensation is made based on each antenna array, there is no bad effect upon the adjacent other antenna array, suppressing the deterioration in beam control accuracy. This, also, reduces the size of the apparatus and improves the power efficiency on the array antenna apparatus overall.

Abstract: Disclosed is a method and apparatus for removing DC offsets in a ZIF radio device, the method including the steps of converting a signal to digital samples, calculating a DC burst by capturing an entire burst and a portion of the adjacent channels, removing DC offset from the digital signal, rotating out frequency error from the digital signal, and performing channel filtering of the digital signal. The system includes a digital DC offset removal circuit, which includes an analog to digital converter, a channel filter connected to the converter, and a rotator system that is connected to the channel filter input and output. The rotator system includes a DC estimator connected to the channel filter input, a DC offset removal component connected to the DC estimator, and a rotator connected to the DC offset removal component, the output of the rotator being connected to the channel filter input.

Abstract: An automatic gain control circuit that maximizes front-end signal attenuation is disclosed. The automatic gain control circuit comprises a keyed automatic gain control circuit and an intermodulation detector. The intermodulation detector detects signal interference and generates an intermodulation detection flag. The keyed automatic gain control circuit uses the intermodulation detection flag to control front-end signal attenuation. A method for maximizing front-end signal attenuation for the automatic gain control circuit is also disclosed.

Abstract: A system and method for combining the downlink signals from at least two transceivers to increase the power of the downlink signal. In-phase down link signals from at least two transceivers are combined to produce a downlink output signal having an output power level greater than the power level of any single downlink signal. Detector means, which samples the downlink signals to identify a phase difference is coupled to control a phase controller which adjusts the phase of at least one of the downlink signals to be in step with the phase of the other downlink signal. The phase controller maintains the downlink signals in phase by shifting the phase of at least one of the downlink signals relative to the other.

Abstract: K sub-carrier components from an FFT circuit 101 are output to a sub-carrier demodulating circuit 102. The sub-carrier demodulating circuit 102 demodulates the k sub-carrier components and outputs a transmitted information bit to an output terminal 104. Further, the sub-carrier demodulating circuit 102 outputs distortion correction coefficients C(1)-C(k) that are used during demodulation of each sub-carrier, each of sub-carrier components S(1)-S(k) in which distortion is corrected, and determination signal points R(1)-R(k) for each sub-carrier to a phase estimating circuit 103. The phase estimating circuit 103 receives C(1)-C(k), R(1)-R(k) and S(1)-S(k), and outputs a phase error signal to an output terminal 105. The phase error signal output to the output terminal 105 is integrated by a loop filter and so forth, and is fed back to a local oscillator, and thereby, phase tracking is conducted.

Abstract: Distortion is reduced in a radiocommunications system in which a radio signal is received with a carrier frequency with a group antenna. The group antenna includes at least two receiver channels with an antenna element and components for amplifying and processing the respective signal. A first phase shift by a predetermined value is performed directly after reception of the signal in the respective channel. A second phase shift by a value is performed which corresponds to the first phase shift but in the opposite direction. In this manner, distortion which arises as a result of, for example, non-linearities in an antenna array, is reduced.

Abstract: A null-pilot symbol assisted fast automatic frequency control (AFC) system for coherent demodulation of carrier phase modulation (CPM) includes (209) a pilot clock driven phase differentiator (252,253,255) for operating once every pilot clock cycle to determine the difference between the phase at a current pilot symbol location and the phase at a previous pilot symbol location. A frequency offset selector (256) is then used for choosing the most likely frequency offset from amongst a set of all frequency offsets that give rise to the same phase difference.

Abstract: A dual mode transmitter for GSM and UMTS operation is provided. The GSM and UMTS paths share an oscillator and an intermediate frequency stage. Also, with the exceptio of the final stage of power amplification, the transmitter is provided as an integrated device.

Abstract: This invention addresses itself to the task of securing excellent narrowband transmission quality when transmitting audio signals such as voice and music, or various kinds of multimedia signal, by means of unidirectional or broadcast communication systems. Excellent demodulation characteristics are obtained by reducing the required transmission bandwidth by using SSB modulation technology, and by performing RZ SSB demodulation at the receiving side. The sideband and the carrier component are transmitted at a sufficient distance from one another in the frequency domain so that even if frequency stability in the transmitting and receiving circuits is not very high, there is little likelihood of quality deterioration due to frequency instability, and so that the receiving circuit is easier to implement, since less sharply selective bandpass filters are required.

Abstract: Angle-modulated signals are transmitted in a communications system, in which coding information has been inserted into the transmitted data at regular intervals. The coding information is phase-modulated together with the transmitted data. This coding is used for pulse shaping, so that the receiver can recover the digital transmitted data with less implementation complexity and without carrier phase control by using appropriate signal processing.

Abstract: A mobile communications device is arranged to receive a modulated signal having a predetermined frequency. A frequency demodulator of the device demodulates the modulated signal, and a frequency correction arrangement calibrates the demodulation frequency of the device to the predetermined frequency by providing a preliminary difference estimation between the predetermined frequency and the demodulation frequency using a broadband portion of the modulated signal, followed by a main difference estimation (between the predetermined frequency and the demodulation frequency) using a dedicated narrowband portion of the modulated signal.

Abstract: Distortion of a received signal due to intersymbol interference as well as to frequency offset is corrected. For this reason, a frequency offset correcting circuit 21 corrects a received signal based on a frequency-offset estimated value. A first CIR estimating circuit 22 estimates CIR estimated values at a first position according to a known training sequence in the corrected received signal. Also, a second estimating circuit 24 updates the CIR estimated values with the LMS algorithm according to the corrected received signals as well as to the decision value outputted from the equalizer 13 with the CIR estimated values at the first position as initial values and obtains CIR estimated values at a second position apart from the first position.

Abstract: A properly modulated carrier signal exits transmission circuitry (201) and enters a first and a second mixer (203, 205). The modulated carrier is mixed with a first and a second function by the first and the second mixers (203, 205). The functions are generated by a first and a second signal generator (207, 209). The mixed signals exit the mixers (203, 205), and are amplified (via amplifiers 211-213), to be radiated by an antenna (211). The antenna (221) comprises two orthogonal antenna elements (215, 217), that are in close proximity with one another (although not in contact). One of the mixed signals is radiated on a first element (215), and the other mixed signal is radiated on the second element (217). The resulting signal transmitted from the antenna (221) is the original carrier signal having the plane of polarization constantly changing. Thus a reflected signal emitted an instance earlier cannot interfere with a wave currently emitted.

Abstract: A phased array spread spectrum system for maximizing signal strength of a spread-spectrum signal with multipath through the use of receiving means, delaying means, combining means, despreading means, generating means, storing means and comparing means. The receiving means receives a plurality of spread-spectrum signals and a plurality of phased versions of the plurality of spread-spectrum signals. The delaying means delays the received plurality of spread-spectrum signals with respect to the plurality of phased versions of the plurality of spread-spectrum signals by a plurality of delays. The combining means combines the delayed spread-spectrum signals and the plurality of phased versions of the plurality of spread-spectrum signals as a plurality of combined signals. The despreading means despreads the plurality of combined signals as a plurality of despread signals. The generating means generates a plurality of magnitude values from the plurality of despread signals.

Abstract: A block radio design is disclosed that prevents the primary analog-to-digital converter from saturating and thus prevents the introduction of intermodulation products into the multi-carrier signal. The block radio comprises a strong signal suppressor that selectively suppresses any carrier signal in the multi-carrier signal before the multi-carrier signal is digitized by the analog-to-digital converter, thus preventing the possibility that the analog-to-digital converter can be saturated. Furthermore, the strong signal suppressor attenuates the stronger carrier signals without affecting the weaker carrier signals.

Abstract: A diversity reception device which weights in proportion to the reception level and combines a plurality of reception signals, includes a phase demodulator for demodulating the phase of the reception signal, a converter to output the sine and cosine elements of the reception signal, a sine element adder to add up sine element of each reception signal, and a cosine element adder to add up cosine element of each reception signal. The converter fetches and outputs predetermined values on sine and cosine elements of the reception signal upon input of the reception signal's reception level and phase data that is sent from phase demodulator. Therefore, the present device does not require expensive electronic circuits and can be made of small digital circuits suitable for IC including a memory.

Abstract: A space diversity receiver apparatus receives signals by two spatially separated antennas, controls the phase of the signal received by one of the antennas by a phase control circuit, combines the phase-controlled signal and the signal received by the other antenna by a combiner and outputs the combined signal. A digital detector digitally detects the center frequency level and the levels on high- and low-frequency sides of the center frequency of the combined signal. Phase is controlled in such a manner that the center frequency level will coincide with a set level and a deviation between the levels on the high- and low-frequency sides of the center frequency will become zero.

Abstract: The contact error of a contact section which is brought into contact with an IC card is detected reliably. The level of a reset signal which is supplied to a reset terminal (RST) of an integrated circuit (21) mounted on an IC card (20) through a contact section (11) is controlled to be low and also, the level of a clock signal which is supplied to a clock terminal (CLK) of the integrated circuit through the contact section is controlled to be low. After that, power for the integrated circuit (21) is supplied to a power supply terminal (Vcc) of the integrated circuit (21) through the contact section (11). At that time, the voltage which is outputted from an I/O terminal (I/O) of the integrated circuit (21) through the contact section (11) is compared with a predetermined reference level by a comparator (16). When the voltage is lower than the predetermined reference level, it is judged to be contact error of the contact section.

Abstract: Various methods for terrestrial transmission of digital broadcast signals as DVB, HDTV-T and DAB signals are known. One of these methods is the OFDM method, where the transmitted signal includes a multiplicity of modulated carriers. These carriers are separated in the receiver by means of a Fast Fourier Transformation (FFT). Before being transposed in the frequency domain by the FFT, the analog signal must be sampled. For this purpose a local oscillator controls the timing in front of the FFT. Oscillator imperfections like jitter and frequency offsets can degrade the accuracy of the sampling operation and therefore introduce intercarrier interferences after the FFT. A feedback loop combining the AFC and CPEE process has been designed in order to correct frequency deviations and to reduce jitter of the signal without introducing significant phase noise.

Abstract: An apparatus for automatic gain control (AGC) of a digital QPSK demodulator is disclosed. The apparatus for automatic gain control of a QPSK demodulator comprising a variable gain amplifier for controlling an amplification gain of a QPSK-demodulated signal by a predetermined gain control signal comprises a signal magnitude estimator for estimating the magnitude of I and Q-channel signals in the QPSK demodulator by using the equation S.sub.mag =MAX.vertline.I.vertline.,.vertline.Q.vertline.)+1/2MIN(.vertline.I.vertli ne.,.vertline.Q.vertline.), and a control signal generator for generating a gain control signal according to the magnitude of the input signal outputted from the signal magnitude estimator, and outputting the gain control signal to a variable gain amplifier.

Abstract: A magnetic communication system includes a transmitter have a single coil transducer, and a receiver having a three orthogonally oriented coil transducers. The signal processing circuitry in the receiver adjusts the phases of the signals received by the three transducers to produce signals which are in-phase. The signals are then summed to provide an output signal from the receiver. The processing circuitry adjusts the phases of the incoming signals either serially or in parallel. Transmissions from the receiver to the transmitter are also phase adjusted in accordance with the same adjustments used in reception.

Abstract: In a communications system wherein a broadcast signal is received by a plurality of antennas each connected to a receiver, the resulting plurality of received signals are jointly subjected to automatic frequency correction (AFC) before interference rejection combining (IRC) or maximal ratio combining (MRC) processing to output an estimate of the broadcast signal. The joint automatic frequency correction processing involves computing and applying a frequency offset on a sample by sample basis to each of the received signals to output corresponding frequency corrected received signals for IRC or MRC processing.

Abstract: A receiver configured to measure phase change (.DELTA..phi.) in a signal transmitted from a microwave signal source, such as a cell site for cellular telephones, the transmitted signal including a carrier signal (F.sub.1) added to a modulation signal (F.sub.MOD), the receiver providing the phase change measurement (.DELTA..phi.) without further reference to the modulation signal (F.sub.MOD). Utilizing (.DELTA..phi.), distance from the transmitter can be calculated. The receiver includes one or more mixers for receiving the transmitted signal from the cell site and downconverting relative to an intermediate frequency signal (F.sub.IF) to produce an IF mixed signal including a sum IF mixed signal (F.sub.IF +F.sub.MOD) and a difference IF mixed signal (F.sub.IF -F.sub.MOD). The receiver then further includes components to demodulate the IF mixed signal to provide the modulated signal (F.sub.MOD) and the phase change measurement (.DELTA..phi.) with tracking of the intermediate frequency signal (F.sub.IF).

Abstract: A balanced differential radio receiver (100) has an antenna (64) operative for receiving a modulated signal. A first pair of mixers (110, 112) each having an input that receives an output (106, 108) of the antenna (64) and each of the first pair of mixers (110, 112) having an output (118, 120). A second pair of mixers (114, 116) each having an input that receives an inverse output (108, 106) of the antenna (64). A resistive adding circuit (122, 124) having a pair of inputs (118, 120). The inputs (118, 120) coupled to the output of the first pair of mixers (110, 112).

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 wireless audible indication system comprising a transmitter and a receiver. An embodiment of the transmitter includes a modulator formed by a microprocessor and a radio frequency oscillator. The modulation format employed is selectable by the user using severable jumper wires. A battery status circuit is included which verifies the status of a battery within the transmitter. The modulator transmits a low battery bit to the receiver in order to alert the user of a weak transmitter battery. An embodiment of the receiver includes a superregenerative detector which produces an intermediate signal upon receiving a radio frequency signal. A signal processing circuit, which includes an active peak detector stage and a discrete comparator stage, is used to process the intermediate signal. A microprocessor controls a sound generator circuit in response to the processed intermediate signal.

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: 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 radio link for a digital radio transmission system having spatial and/or angular diversity is optimized in real time by first varying the relative phase .phi. between the two channels to locate an absolute minimum of the analog bit error rate function BER.sub.n (.phi.) with both channels having the same nominal attenuation level, and then by unbalancing the relative attenuation level T of the two channels 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: Improved apparatus for a radio communication network having a multiplicity of mobile transceiver units selectively in communication with a plurality of base transceiver units which communicate with one or two host computers for storage and manipulation of data collected by bar code scanners or other collection means associated with the mobile transceiver units. The radio network is adaptive in that in order to compensate for the wide range of operating conditions a set of variable network parameters are exchanged between transceivers in the network. These parameters define optimized communication on the network under current network conditions. Examples of such parameters include: the length and frequency of the spreading code in direct-sequence spread spectrum communications; the hop frame length, coding, and interleaving in frequency-hopping spread spectrum communications; the method of source encoding used; and the data packet size in a network using data segmentation.

Abstract: This arrangement is formed by two receive branches (1) and (4) for receiving a wave whose frequency spectrum is practically constant in a predetermined frequency band, a combining circuit (15) for combining the waves at the output of the receive branches and a servo-control for keeping the spectrum of the signal at the output of the combining circuit constant by adjusting a phase shifting circuit (12) inserted in said branch (4). The servo-control is constituted by a frequency discrimination circuit (25) for analyzing the combined waves, an adjustable selective circuit (27) for obtaining a frequency band of the spectrum of the combined signal as a function of the output signal of the frequency discriminator and by a control circuit (29, 31) which adjusts the phase shifting circuit for optimizing the output signal of the selective circuit.

Abstract: A modularly-designed FM vehicle radio for operation in connection with a plurality of antennas is disclosed, where the summing circuit consists of a series connection of the secondary coils of the output transformers of the input stages.

Abstract: The disclosure relates to methods and apparatus for combining a multiplicity of diversely received replicas of a signal originating in the same remote transmitter. The disclosed methods and apparatus apply, in particular, to digitally modulated sinusoidal prime-carriers or subcarriers, and base the final decision about which of the code alphabet symbols is present in each bit-symbol time slot on either: a) the maximum value of a decision index for each code alphabet letter indicated in/for the same bit time-slot by parallel bit-by-bit detection of the diverse replicas of the signal, the decision index being defined as a function only of the pre-video (IF carrier or subcarrier) signal-to-noise power ratios of the various signal replicas that yield the same code alphabet letter; or on b) bit-by-bit detection of the maximal ratio combination of the video (or pre-bit-detection) bit-stream waveforms out of the prime-carrier or subcarrier exponent (i.e., phase or frequency) demodulators.

Abstract: A radio-frequency receiver employing antenna diversity is provided with a plurality of antennas and a local oscillator. Individual error signals are derived from each of respective ones of signals received from the plurality of antennas. The error signals are thereafter combined in such a way as to arrive at a combined error signal having greater reliability than any one of the individual error signals taken alone. Finally, an automatic frequency control circuit is controlled using the combined error signal. Since the effect of fading on the input signal to the automatic frequency control circuit is reduced, performance of the automatic frequency control circuit is increased and the quality of radio reception is improved.

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: In a space diversity reception system, a plurality of receiving circuits, each of which is connected to respective antenna, outputs a first type signal having a level which varies in accordance with the radio frequency signal level input to the receiving circuit. An automatic gain-controlled amplifier amplifies the first type signal so as to output a second type signal having a substantially constant level. A phase control circuit detects a phase difference between the second type signal output from each of the automatic gain-controlled amplifiers and controls the phase difference in each of the first type signals to be null. A combining circuit combines the signals, whose levels are respectively following the input radio frequency signal levels, picked up from each of an inter-stage in the receiving circuits, an output of the combining circuit is the output of the space diversity system.

Abstract: Compensation is provided for phase errors resulting from differing path lengths in a receiver system having a multi-element antenna. Variable phase shifters are adjusted to provide phase shifts to the electrical paths so that the effective lengths of the electrical paths are approximately equal.

Abstract: According to the receiving method for mobile reception has a plurality of individual receiving antennas, also known as diversity receiving method, on the individual antenna output signals an auxiliary modulation is superimposed and the antenna output signals are added to give a summation signal which as amplified selected intermediate-frequency summation signal is then demodulated in relation to amount and frequency or phase, the phase position of an individual signal in relation to the phase position of the summation signal and/or the amplitude contribution of an individual signal to the amplitude of the summation signal thereby being determined. This information is utilized for optimizing the useful signal with a view to optimum interference suppression for example in that the phases and/or amplitudes of the high-frequency individual signals are changed in dependence upon the phase position and/or amplitude contribution determined.

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: 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: The disclosure relates to methods and apparatus for combining a multiplicity of diversely received replicas of a signal originating in the same remote transmitter. The disclosed methods and apparatus apply, in particular, to digitally modulated sinusoidal prime-carriers or subcarriers, and base the final decision about which of the code alphabet symbols is present in each bit-symbol time slot on either: a) the maximum value of a decision index for each code alphabet letter indicated in/for the same bit time-slot by parallel bit-by-bit detection of the diverse replicas of the signal, said decision index being defined as a function only of the pre-video (IF carrier or subcarrier) signal-to-noise power ratios of the various signal replicas that yield the same code alphabet letter; or on b) bit-by-bit detection of the maximal ratio combination of the video (or pre-bit-detection) bit-stream waveforms out of the prime-carrier or subcarrier exponent (i.e., phase or frequency) demodulators.