CHANNEL CHECK TEST SYSTEM

摘要

When the setting of the compression/expansion rules of an encoder or decoder contains an error, it causes a problem that even when it should be judged that a channel is electrically connected, a misjudgement is made. A channel check test system comprises a transmission-side DCME for inserting a nonlinearly-quantized input test pattern into a channel to be tested and a reception-side DCME having an adder for adding an offset value to the output value or a linear converter, a code extractor for extracting a code from the output signal of the adder, a delay unit for delaying the extracted code, an exclusive-OR circuit for performing an exclusive-OR operation of the extracted code and the output signal of the delay unit, a counter for counting the number of events that the output value agrees with a predetermined value, and a comparator for comparing the count with a threshold and outputting the result of the comparison. Thus it is possible to check the electrical connection of a channel under test, including the check of an error of the setting of the PCM compression/expansion rules in either the transmission-side DCME or the reception-side DCME.