| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve the problem of a conventional voice channel test unit that has had to device the configuration of the test unit because a correlator is required for testing a voice channel and a product sum arithmetic unit of the correlator requires many logic elements. SOLUTION: The voice channel test unit testing a voice channel through which a companded voice signal is transmitted, is provided with a de-packet circuit that converts a packet in the voice channel into a continuous signal, an expansion circuit that expands the continuous signal, a voice channel test circuit that takes correlation between the expanded signal and a voice signal sent as a test signal and outputs a test result, a voice compression circuit that compresses the transmitted voice signal, and a packet circuit that assembles the compressed signal into a packet and outputs the packet to the voice channel, and the voice channel test circuit is provided with a quantization decoder that receives the test signal and quantizes the signal, aΣΔmodulator that applies differential integration to an output of the quantization decoder in the unit of 1-bit, a correlator that takes correlation between an output of theΣΔmodulator and the transmitted voice signal, and a comparator that compares an output of the correlator with a prescribed threshold value and the acceptance of the voice channel is discriminated on the basis of the result of comparison.</p> |
