Abstract: A time division multiplex transmission system for time division multiplexing a plurality of information signals having different sampling frequencies and transmitting the time division multiplexed signal by one transmission path. The system includes the steps of: rearranging the plurality of information signals so as to have a format of the time division multiplexed signal by use of a reference sample signal which has a frequency obtained by multiplexing the maximum frequency or a frequency higher than the maximum frequency among the sampling frequencies of the plurality of information signals by the number of the plurality of information signals; and interposting a dummy signal into the portion where there is no available information signal.

Abstract: A frequency synthesizer includes a 1/N divider for generating an address clock signal the frequency of which is 1/N times the frequency of an input signal, a memory for storing samples in a unit sine and cosine wave which is read out in response to the address clock signal to produce a frequency deviation signal, and a quadrant modulator responsive to both of the input signal and frequency deviation signal for producing an output signal the frequency of which is the difference between the input signal and frequency deviation signal. The frequency of the frequency deviation signal is varied by digitally changing N to modify the frequency of the output signal while maintaining the continuousness of the output signal phase.

Abstract: A time division multiplexed signal demultiplexing system for regenerating original signals from a time division multiplexed signal which is obtained by time-division multiplexing information signals of N channels with mutually different sampling or clock frequencies by means of a reference clock signal of a frequency equal to N times of the highest one of the sampling or clock frequencies or an even higher frequency and inserting a dummy signal and a dummy flag bit in pairs in the portion where the information signal is lacking.