Multifrequency signalling system test unit - has signal generator controlled by computer in accordance with program

摘要

The test unit generates signals with different frequencies, levels, waveforms and durations, and a receiver analyses the signals with respect to the above parameters, and returns them to the computer for processing, or feeds them into a data store. Switching means and a set value store for manual setting of test frequencies are provided. The frequency ranges accessible are typically 440 Hz to 4400 Hz in 5Hz steps. The pulse signals are emitted according to codes specified by the CCITT. Circuit elements include a linear amplifier, overlap circuit oscillator a filter element and a mixer.