| 摘要 |
In a digital communication system using a switching device as a detector-discriminator, information about the amplitude of the input signal is lost. As a result, there is no way to adjust the threshold of the switch as a function of signal strength to achieve minimum error rate. This problem is resolved by transmitting, along with the data, reference pulses whose amplitude is intermediate that of the data "0" and "1". Automatic threshold level control in such a system is provided by means of a coincidence circuit (13), which gates out any of the reference pulses that are detected by the detector-discriminator switch (11), and an integrating circuit (14) which averages the detected pulses over a period of time. The output from the integrator is used to bias the switch in a manner to optimize the threshold level.
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