Abstract: A digital-to-digital sample rate converter for converting digital input signals x(n) having a first sample rate F into digital output signals y(m) having a second sample rate F.multidot.L/M, wherein L/M is an arbitrary rational fraction. The digital lowpass filter needed for sample rate conversion has a piecewise continuous linear hull curve. This allows an efficient and low-cost hardware solution, since only one multiplier is needed for the digital-to-digital sample rate converter.

Abstract: There are time-division multiplex communication systems in which digital signals which are asynchronous with the pulse frame and consist of successive blocks whose beginnings are marked with sync words are inserted into the pulse frame. The resulting jitter of the sync words ("waiting-time jitter") is reduced by a circuit which derives from the clock of the received sync words a sync signal (SY) that exhibits less jitter than the clock of the received sync words. According to the invention, the circuit contains a measuring device which measures the time intervals (N) between the sync words, a filter (F) which takes the average (N') of the time intervals (N), and a signal generator (S) which forms the sync signal (SY) from said average (N') in such a manner that the pulse period of the sync signal (SY) is equal to said average (N').