Detector for Amplitude Shift Keyed Signal
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-27
Digital information is carried by an amplitude shift keyed, or off-on keyed, signal through the presence or absence of a particular carrier frequency waveform in successive intervals of time, or time slots. Detection of the amplitude shift keyed (ASK) signal may be accomplished by heterodyning the ASK signal with a local oscillator signal to produce an intermediate frequency signal, which is then detected. Two such detection circuits are the subject of this article. In the first detector (Fig. 1), the received ASK signal E1 and the local signal E2 are multiplied together to form a signal E3. The signal E3 is passed through a low pass filter to produce a signal E4 including a signal component at the difference frequency between the received signal E1 and the local signal E2.