Digital speech/data discriminator for transcoding unit

Claim 1

In a transcoding unit of a telecommunication system including circuit means for respectively directing digitized samples of speech signals and of voice-band-modulated data signals from an incoming signal path to first quantization means using a lower number of quantizing bits and to second quantization means using a higher number of quantizing bits for each outgoing sample, said coders having outputs switchable to an outgoing transmission line, the combination therewith of a digital discriminator with an input stage connected to said signal path for receiving said samples in parallel with said first and second quantization means, said discriminator comprising: a first transversal filter connected to said input stage with a transfer function equal to the reciprocal of the mean bandwidth of incoming speech signals; a second transverse filter connected to said input stage with a transfer function equal to the reciprocal of the mean bandwidth of incoming data signals; a digital low-pass filter connected to said input stage; first, second and third integrating means respectively connected to said first transversal filter, said second transversal filter and said low-pass filter for accumulating output signals thereof over a predetermined evaluation period; and arithmetic means connected to said first, second and third integrating means for determining from the contents thereof a probable classification of incoming samples as speech samples, high-rate data samples or low-rate data samples; said first quantization means having an enabling input connected to said arithmetic means for activation in the presence of probable speech and low-rate data samples, said second quantization means having an enabling input connected to said arithmetic means for activation only in the presence of probable high-rate data samples.