| 摘要 |
Rapid disconnection of a receiver in response to a small signal-to-noise ratio is provided in that in the receiver there is arranged a FSK demodulator having two channels connected in parallel at the input ends and each having a band-pass filter, an amplifier and a detector whose output is connected to a voltage comparator. The output signal of the voltage comparator is fed to an input of an AND gate in the receiving arm by way of a series arrangement of a high-pass circuit, a demodulator and a low pass filter to the inverting input of a further comparator whose non-inverting input is connected to a comparison voltage by way of a variable voltage divider. The output of the further comparator is connected to the other input of the AND gate. |
