Waveguide Tests by Means of Error Rate Measurements at Different Clock Rates of 640, 320 and 160 Mbits/s

For determining the transmission properties of waveguide links, an experimental repeater for one channel with variable bandwidth was designed for error rate measurements at clock rates of 160, 320 and 640 Mbits/s. The length of the experimental waveguide link used at present is 5.65 km. The transmission frequency is 38 GHz, the modulation procedure being two-phase differential coherent phase shift keying (DCPSK). The error rate measurements are based on the theoretical error probability and distinguish between errors caused by the regenerator, the repeater itself and the waveguide. Results of error rate measurements are given as a function of the carrier-to-noise ratio, the repeater input level and the bit rate. It was found that the waveguide allows pulses to be transmitted at clock rates up to the order of 640 Mbits/s and that the pulses are increasingly affected by delay distortions at rising bit rates. However, definite statements require a longer experimental link, which is under construction.