| 摘要 |
When there is an error in setting of a companding law of an encoder or a decoder, there is a problem of an error in judgment although it should be originally judged that the continuity of the testing channel does not exist.Therefore, a channel check test system includes a transmitting side DCME for inserting a nonlinear quantized input test pattern into a channel to be tested, and a receiving side DCME. The receiving side DCME includes an adder for adding an offset value to an output value of a linear converting section, a sign extracting section for extracting a sign from an output signal of the adder, a delay unit for delaying the extracted sign, an exclusive OR arithmetic unit for performing an exclusive OR operation of the extracted sign and an output signal of the delay unit, a counter for counting the number of times of conformity in which an output value of the exclusive OR arithmetic unit is in conformity with a predetermined value, and a comparator for comparing a counted value of the counter and a threshold value and outputting judged results.Existence or nonexistence of the continuity of the channel to be tested can be checked including an error in setting of the PCM companding law in one of the transmitting side DCME and the receiving side DCME.
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