Four wire carrier frequency system - converts four specified CCITT quaternary groups into frequency of fundamental quinternary group using given carrier

摘要

The 4-wire carrier-frequency system, for 3600 voice channels with the same frequency plan for the incoming and outgoing bands, can be converted by a carrier into the frequency of the fundamental quinternary group of an 80 MHZ CARRIER system such that when this is switched to another system also using the 80MHz carrier that system's filters can continue to be used. (These filters suppress the unwanted second sideband). This is achieved by making the fundamental group from the 4CCITT quaternary groups 22.812-26.684 MHz, 27.212-31.084 MHz, 31.612-35.484 MHZ, and 36.012 - 39.884 MHz and converting it into the 1-18 MHz line transmission band using a 41 MHz carrier.