Approaches to multiple 8-kHz nonuniform sampling in PCM channel banks

Methods of compensating for the nonuniform sampling resulting from the frame format of PCM channel banks, when the basic sampling rate (usually 8 kHz) is increased by an even factor , are considered. This situation arises when it is desired to provide greater than 4-kHz bandwidth channels on a PCM system by the modification of an existing channel bank. For the present 24-channel frame format, the distortion introduced is 41.9 dB below the signal power for and greater than 30 dB for . Remedies include time delays at the input (implemented by delaying sampling) and output or special output filtering. The output filter requires a Hilbert transform for , and has a phase discontinuity for . This phase discontinuity can be eliminated at the expense of allowing some residual distortion.