'Equipment used at Marley Hill Depot to check the main schemes. This if I remember correctly consisted of a tuneable VHF receiver which could be set to the centre frequency of the scheme required using Shumandle test equipment. The IF of the receiver was taken to an Edison HF receiver where the correct spacing could be checked on the oscilloscope by tuning the HF receiver across the IF bandwidth of the VHF receiver. Using this method the depth of modulation could be checked on each main transmitter in the scheme in question.'
