One practice used to improve service on circuits that are conducted through cables is to splice short lengths of
twisted pair wire to certain pairs in the cable. The purpose of this procedure is to:
provide continuous loading for the cable.
filter and reduce inductive coupling.
filter and reduce undesirable noise.
provide capacity balance between the pairs.
Assume that there are generators and battery chargers causing noise and humming on the transmission line. This
disturbance can be reduced by installing:
The ground-return telephone circuit shown in figure 64 is very seldom used in present military communications.
One of the disadvantages that limits its use is the:
complexity of the installation.
high initial cost of construction.
possibility of excessive noise from poor ground connections.
The circuit shown in figure 68 is providing two channels of communication. The voice currents of the simplex
circuit are not heard in the metallic circuit because:
repeating coils transfer the emf in only one direction.
because voice currents go through the ground in a simplex circuit and not over the wire.
voice currents divide equally at the secondary center top thus inducing no emf in the secondary.
Voice currents in the secondary cancel the emf in the ground path.