A data communications system between fixed and moving terminals wherein a
conductor connected to the fixed terminal and disposed in the travel path
of the moving terminals supports lateral guidance control information for
the moving terminals as well as two-way inductive data communications
between the fixed terminal and the moving terminals. The fixed (wayside)
terminal transmits over the conductor an alternating current lateral
guidance signal modulated in accordance with longitudinal control
information for each of the moving terminals. Each of the moving
terminals, in turn, transmits status information over the conductor to be
used for developing control information at the fixed terminal. The fixed
terminal employs hybrid transformer techniques in conjunction with
precision filtering to enable reception of low-level status information
from the moving terminals and concurrent rejection of the modulated
lateral guidance signal and other interfering signals.