How to check line channel of IKM-15 digital pulse-code-modulation transmission system

A generator of test signals is developed for checking the line channel of a digital pulse code modulation apparatus in rural telephone networks. The test signal generator consists of a relative group reference generator, a pseudorandom sequence generator and an output amplifier. The test signal generator for checking either a terminal station or an intermediate station of a line channel operates together with an interference generator, both feeding a line simulator. The signal parameters are measured at the transformer output and on the screen of a cathode ray oscillograph. All equipment is designed for an operating frequency of 1.5 MHz and operating voltages up to 10 V.