
A simple radio receiver for FSK signals is described in which the signals from the aerial are mixed in two high-gain mixers respectively with local oscillator signals in phase quadrature and at the signals' nominal center frequency. The outputs from the mixers are low-pass filtered to get the difference frequencies. The filter outputs are amplified and one applied to the D input of a D-type flip-flop to the clock input of which the other is applied. The flip-flop output gives the FSK modulation....











