A new design of digital multifrequency signal receiver by using the method of decimation of digital signal is proposed in this paper. With this method

the filter bank for seperating frequencies can be operated at lower sampling rate and the volume of computations required for processing can be reduced considerably. The filter bank of this method is implemented with polyphase network in connection with DCT and DST. The outputs of DCT and DST are orthogonal to each other

thus

meet the requirement for detection. The multifrequency receiver designed with this method has the property of lower rate of processing and high calculation efficiency.