By John W. Oades, GTE Lenkurt Incorporated
Microwave radio relay equipment capable of carrying up to 1800 FDM telephone channels on one RF carrier over 4000- mile routes are presently being manufactured in North America. Plans call for capacities of 2100 or 2400 channels in the near future. Radio systems with capacities of 2700 channels are now being operated in Europe.
The baseband of a typical 1800 channel microwave radio link extends from 300 kHz to 8.2 MHz. To transmit this traffic load with minimum distortion, the useable bandwidth of such a radio will extend to over 12 MHz.
The standard 525 line video signal has frequency components that extend up to approximately 4.2 MHz. Thus a radio designed for 1800-channel operation has excess baseband capacity when carrying one video signal. It would seem reasonable that this excessive capacity could be used to carry additional telephone channels or an additional video signal, if a suitable multiplexer was available. This paper describes such a multiplexer, the GTE Lenkurt 46V.