Keying circuit for radio transmitter - uses information presence or absence to key carrier on and off

摘要

The keying circuit for a radio transmitter, uses presence or absence of information for transmission to switch the carrier wave on and off respectively without loss of information. The information (N) is applied to the input of a first filter with rectifier (1) and to the input of a delay line (2). the delay line output is passed to a second filter with rectifier (3). The two filter with rectifier circuits remove noise and allow only the largest amplitude information signals to pass through. The outputs of the two filter and rectifier circuits are connected to the inputs of a gate (4) whose output is used to operate the transmitter keying relay.