The oscillator also contains a differential amplifier into which both the signal oscillation and reference oscillation are fed. The output from the differential amplifier is a 16 kHz sine wave, the amplitude of which is the difference between the signal oscillation and the reference oscillation.
After modulation the resultant voltage is fed along a 50 Ω coaxial cable to a receiver. The oscillator contains line drive amplifiers to enable up to 100m (328 ft) of cable to be driven.
