Data transmission using a transparent tone-in band system.

摘要

In transparent tone-in band (TTIB) systems the transmitter and receiver may include complementary circuits, such as modems, which require reference signals in order to operate. This problem can be solved by using those circuits in the transmitter (a mixer 63, and oscillators 33 and 36), which determine the width of the notch in the TTIB spectrum, to derive the reference signal. Thus the output signal of the mixer 63 is passed to a multiplier 64 and used as the reference signal for a transmit modem 62. In the receiver the required reference signal is derived from circuits whose output can be used to derive a signal dependent on notch width; for example the oscillators 38 and 43 and the mixer 66. Thus the output signal of the mixer 66 is passed by way of a phase shift circuit 67 to a multiplier 68 and used as the reference signal for the modem 65.