Abstract: Apparatus for demodulation of a signal which is frequency-modulated with a data symbol sequence {dk}, having a zero crossing detector (1), a generator (2) for production of a sequence {zi}, with zi being calculated from zero crossings ti and ti+1, and having a unit (3) for reconstruction of the data symbol sequence {dk}, which is characterized by a minimum Euclidean distance between the sequence {zi} and an auxiliary sequence, with each sequence element in the auxiliary sequence being formed from convolution of the data symbol sequence {dk} with a sequence {hi,k} relating to the index k, and with the sequences {hi,k} being functions of the times ti.

Abstract: When data bursts are transmitted between a base station and a mobile receiver, a changeover is made between a plurality of modulation methods during an existing radio link for modulation of the data. For resynchronization of the receiver in the event of the changeover, synchronization information items are determined from a first part (ET) of the data burst modulated by a first modulation method, and are used for synchronization with a second part (ZT) of the data burst modulated by the second modulation method.

Abstract: In a method for avoiding transients during switching processes in integrated circuits, a module (2.1, 2.2, 2.3) of the integrated circuit (1) is switched from a first operating state to a second operating state, a load change occurring. In this case, it is ensured that the occurring quotient of load change and time duration for the transition from the first operating state to the second operating state does not exceed a limit value that is predetermined or can be predetermined in a targeted manner.

Abstract: The possible number of zero crossings in the interval [kTb,(k+1)Tb] is determined for each time (k+1)Tb based on hypothetical subsequences, on the basis of a model for frequency modulation, and a trellis diagram is constructed, based on the model. In a first selection step, those paths in the trellis diagram are then excluded whose number of zero crossings in the stated interval does not match the number of detected zero crossings in the received subsequence in this interval. In a second selection step, the path metrics of the paths which still exist are extended by the new branch metrics based on the Viterbi algorithm which is known per se. If two paths meet one another at a node point then only that path which has the lower path metric is continued.

Abstract: A detector (1) for zero crossings and a counter (2) which is connected to it are used to determine the time intervals between the zero crossings of the received signal or of an intermediate-frequency signal which is produced from the received signal, and for detection of the digital signal data. In this case, a sequence of determined zero crossing intervals can be stored in digital form in a shift register chain (3), and can be compared in a classification device (4) with previously stored interval sequences. Furthermore, a frequency offset can be determined by averaging the zero crossing intervals and can be compensated for by suitable selection or modification of the previously stored interval sequences, in which case the latter can also be used during the synchronization phase. The synchronization process may, furthermore, be assisted by payload data identification.

Abstract: A data transmission system contains at least two stations between which data bursts are exchanged via radio. A frequency hop is provided between the first channel mid-frequency which is used for the transmission and the second channel mid-frequency which is used for the feedback transmission, the height of the frequency hop corresponding to the intermediate frequency. Therefore, the local oscillators must not be tuned to new frequencies between the transmission and the feedback transmission.

Abstract: In a method for demodulating a CPFSK-modulated signal, the n−1-th substitute symbol an−1 which occurs in the linear approximation of the CPFSK is estimated in order to determine an n-th input data symbol dn on which the CPFSK modulation is based. The n−1-th substitute symbol an−1 is in this case estimated on the basis of the previously determined n−1-th input data symbol {circumflex over (d)}n−1.

Abstract: A data transmission system has a base station and at least one mobile station. Data packets are interchanged between the base station and the mobile station using a time slot method. In this case, first measures are used for transmission of a first part of a data packet at a predetermined first symbol rate and at a first transmission frequency, and second measures are used for transmission of a second part of the data packet at a second symbol rate and at a second transmission frequency.

Abstract: A data transmission system transmits first data bursts from a base station to mobile stations. The first data bursts at least in some cases contain two or more data blocks that are intended for different mobile stations. The data transmission system furthermore transmits second data bursts from at least one of the mobile stations to the base station and produces guard time intervals between successive data bursts.

Abstract: A receiving device for angle-modulated signals performs the channel selection in a digital manner rather than an analog manner. A receive signal is preferably initially converted to an intermediate frequency band, filtered and A/D converted. The receive signal is subsequently converted to the baseband and channels are selected in a digital manner through the use of a digital complex multiplier before the receive signal component of the selected transmission channel is demodulated and the corresponding symbols are detected through the use of a differential demodulator.

Abstract: Channel selection of a received signal is first of all carried out, in the process, by way of an analog channel selection filter. The signal is then converted to a digital discrete-time and discrete-value signal. Finally, the continuous-time and continuous-value signal profile is determined on the basis of a mathematical reconstruction using the zero crossings {ti} and the phase values {&phgr;(ti)=ki·&pgr;/2, ki&egr;N0}, with a mathematical reconstruction algorithm using a function system {&phgr;(t−k)}.

Abstract: A receiver circuit of a cordless communication system has an analog signal processing section with a channel selection filter and a digital signal processing section which is connected downstream of the latter and has a group delay equalizer. The group delay equalizer is used to equalize the digital distortion caused by the channel selection filter.

Abstract: A receiver circuit for a mobile radio receiver has a controllable amplifier with a variable gain level, an analog-digital converter stage, a digital filter configuration for the purpose of channel selection and a signal strength estimator. The signal strength estimator is connected downstream of the filter configuration in the signal path and has the purpose of determining the signal strength in the selected user signal. The amplifier is controlled in dependence on the user-channel signal strength determined by the signal strength estimator.

Abstract: In a method for demodulating a CPFSK-modulated signal, the n−1-th substitute symbol an−1 which occurs in the linear approximation of the CPFSK is estimated in order to determine an n-th input data symbol dn on which the CPFSK modulation is based. The n−1-th substitute symbol an−1 is in this case estimated on the basis of the previously determined n−1-th input data symbol {circumflex over (d)}n−1.

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: For the offset compensation of a digital signal, particularly of a communication signal transmitted in a cordless digital communication system, a recursive digital filter is used. The recursive digital filter has at least one filter coefficient that is varied in a time-dependent manner. In this way, the filter can be adapted differently for the access information and the actual user information of a burst of the communication signal.

Abstract: A receiving device for angle-modulated signals performs the channel selection in a digital manner rather than an analog manner. A receive signal is preferably initially converted to an intermediate frequency band, filtered and A/D converted. The receive signal is subsequently converted to the baseband and channels are selected in a digital manner through the use of a digital complex multiplier before the receive signal component of the selected transmission channel is demodulated and the corresponding symbols are detected through the use of a differential demodulator.

Abstract: In the use of a transceiver based upon frequency modulation for signals coded by a method for spreading spectrums, a series of first data symbols having a valence M is used as a basis for assigning a series of L second binary data symbols to each of the first data symbols. In this case, the L-element series of second data symbols correspond to chip sequences used for the spectrum-spreading method. A signal containing the sequence of second data symbols is used by the transceiver for the frequency modulation.

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: In a method for estimating a sequence of input data symbols of a CPFSK-modulated data signal transmitted via a faulty channel, in the course of an ACS operation for calculating a transition metric value, an estimated value is determined for the replacement symbol occurring during the linear approximation of the CPFSK. That estimated value is considered in calculating the transition metric value.