Explore BrainMass

Explore BrainMass

    Telephone channels and PCM analysis

    Not what you're looking for? Search our solutions OR ask your own Custom question.

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    The analog to digital converter (ADC) used in a telephone system outputs 8 bit words. The digital words are transmitted as a serial stream to form a PCM voice signal. The analog voice signal voltage always lies between -1.0 V and + 1.0 V.

    a. Assuming that ADC is linear, what is the step size between quantization levels?

    b. The PCM signal is converted back to an analog waveform. What is the quantization signal to noise ratio (SNR)?

    © BrainMass Inc. brainmass.com December 24, 2021, 9:07 pm ad1c9bdddf

    Solution Preview

    (a) Start by considering the Analog signal range (VR) which is easily seen to be

    Analog Range VR = Max V - Min V = 1 - (-1) = 2V.

    Now consider the word size required for the PCM words.

    If there are L = 8 bits per word then we can say that this gives rise to 2^8 possible binary digit

    Solution Summary

    Using data of a PCM telephone link and some ADC parameters in the question a solution is shown that determines the quantisation spacing (level spacing) and the Quantisation SNR for the system.