A Frequency Modulation Telegraph Terminal Without Relays

Frequency-modulated carrier telegraph equipment provides advantages in transmission efficiency which have led to its extensive application. This paper describes a frequency-modulation telegraph terminal from which relays have been entirely eliminated so that the over-all circuit between ultimate operating positions is completely electronic. The circuits employed are described in detail, design considerations are discussed, and application information is given. The results of various performance tests also are included. In the development of this system, significant economies have been effected by reducing equipment complexity to a minimum, thereby saving space and simplifying maintenance.