CommsLinkTestSheet2

A two page test report for the transmission links for a two-way radio system. The links joined the track-side base stations and the control centre. The system is no longer in use. This is used for checking the links shown here: www.ipernity.com/doc/grahamh/24117033

E&M signalling over copper pairs in Australia was done using the 4W (1 pair each direction for the audio signal) circuit, ie no additional conductors. This is done in a similar manner to that used in feeding DC power to a condenser/electret microphone in a public address or studio sound system. The direct current for the signalling flows one way equally on both wires of a pair with the earth being used as the return conductor.