Applying noise signal to transmission line for testing - generating noise current and noise voltage such that ratio of voltage to current equals transmitter input impedance

摘要

A noise signal e.g. white or pink noise, is introduced via two coupling points located between a transmission line (2) carrying a useful signal, and a transmitter (1), e.g. a telephone exchange. A noise current (Ir) is produced between the coupling points, and a noise voltage (Ur) is produced at at least one of the coupling points. The ratio of the noise voltage to the noise current is equal to the input impedance (Zp) of the transmitter. The noise signals are produced by a noise generator whose output is applied to the primary winding of a transformer. The secondary winding is connected to the couplig points of the transmission line (2). USE/ADVANTAGE - For simulating noise when testing noise immunity or measuring S/N ratio of transmission line coupled to telephone exchange. Transmission line does not affect applied noise signal.