Subband coding :

• In subband coding the input signal is first split into numberof non overlapping frequency bands by band pass filters.
• The output of each band pass filter is decimated or down sampled by a factor M.
• This can be achieved by retaining every M$^{th}$ sample of the filter output and discarding M-1 samples.
• The output of decimator is quantized using the technique like PCM, DPCM, etc.and transmitted.
• At the receiver and inverse sequence of events takes place.
• The subbands are demultiplezed and decoded and theneach subband signal is interpolated by inserting zeros to replace the samples discarding during decimation at the transmitter.
• The output of the interpolator is applied to band pass filter.
• All bandpass filter output are summed together to reproduce the original signal.