Abstract: A method for synchronizing switching mechanisms or program sequences to an external frame clock pulse, wherein after a given period of time the switching mechanism or program is enabled to be reset and that after this enabling the resetting takes place with the edge of an external clock pulse. Moreover, the resetting takes place immediately after enabling if the edge of the external clock pulse has appeared earlier in time and the resetting takes place in any case no later than after a further given period of time even if the edge of the external clock pulse has not arrived. An apparatus for carrying out the method is also disclosed.

Abstract: A method for simultaneously transmitting a plurality of data streams over one transmission channel with the aid of modems, wherein in order to synchronize the receiver for the purpose of device-specific modulation, a small additional modulation is applied in the transmitter, with the frequency of the additional modulation being equal to the transmitter modulation rate divided by a whole number, and the additional modulation is demodulated in the receiver by multiplying the associated values obtained from the scanning clock pulse by the difference between the associated and actual values received, and the resulting parameter is freed of interference with the aid of a band pass filter or a phase control loop.

Abstract: A method for digitally regulating the residual carrier phase error in receivers of digital data transmission systems. A comparator compares the sampled data signal or value of the carrier demodulated input signal to the receiver with the estimated value for each associated sampling time or moment as provided by a decider, to determine the deviation dk which is a measure for the phase difference between the sampled value and the associated estimated value. This deviation dk is filtered in a digital loop filter, including a proportional branch and an integration branch, and a regulating value for the demodulated input signal is obtained from a subsequently connected accumulator. A non-linear limitation on the deviation dk is included in the integration branch of the digital loop filter.

Abstract: A method for generating modem transmission signals with quadrature amplitude modulation (QAM) wherein scanned values of elementary bandpass signals are stored in digitally coded form, the elementary bandpass signals are weighted with coefficients depending on the information to be transmitted and the modem transmission signals are formed by superposition of the thus weighted elementary bandpass signals; and wherein in the case of n-PSK modulation, where n=4, 8, 12, 16 . . . , the phase positions of all elementary bandpass signals are selected such that the phase diagram is symmetrical to the axis .phi.=0, and no elementary bandpass signal coincides with the axis .phi.=0; 1/4n elementary bandpass signals, which cannot be derived from any other bandpass signal of phase diagram neither due to symmetry with the axis .phi.=0 or the axis .phi.=90.degree., respectively, nor by symmetry to the origin of the diagram, are stored in a digital memory; and the remaining, e.g.

Abstract: A method and apparatus for recovering the timing frequency in a modulated data signal receiver containing a timing frequency generator, by demodulating a received signal with the aid of carriers which are shifted by 90.degree. in phase relative to one another to form two demodulation products, forming the sum of the squares of the two demodulation products, and determining changes in the value of that sum with respect to time to provide characteristic values which determine the adjustment criterion for the timing frequency generator.