A photo-telegraph transmitter-receiver utilizing sub-carrier frequency modulation

摘要

The equipment described is designed for the transmission and reception of pictures by sub-carrier frequency modulation, the same mechanical and optical system being used for transmission and reception. All mechanical, optical and electrical parts and all testing equipment required for normal operation are contained within a single console. The mechanical system is of the normal drum type rotating at the standard speed of 1 r.p.s. The drum diameter is 3.52 in and is scanned at 100 lines per inch, giving the standard index of co-operation of 352. Speed control is from a crystal oscillator. Provision is made for alternative positive or negative photographic reception. The f.m. swing is adjustable both in magnitude and sign, the final standards adopted being 2300 c/s for black and 1500 c/s for white.