Frequency shift keying (FSK) is a form of FM that, with minor exceptions. The modulating signal is a digital voltage (code 1’s and 0’s) that will key the carrier to shift between only two distinct, fixed frequencies. In this case, the low frequency represents a digital 1(mark), and the higher carrier frequency is a 0 (space). The second variation from standard is that the carrier is not much higher in frequency than the frequency of a encoded message signal.

This trainer is a demonstration unit. In this trainer, the signal to be modulated namely Sine, Square or any other signal in the range of 100Hz to 2KHz with 1-2 V Peak to Peak is applied as input to the modulating input terminal. The built-in clock generator provides the required sampling rate. It is possible to change this clock frequency by patch cording necessary RC combinations. Thus the signal to be modulated is sampled now. The FSK modem converts this into series of pulses as output after locking takes place. This signal is further processed and a Frequency Shift Keyed output is available at the demodulating output terminal.

This FSK signal is further processed through a signal reconstructor circuit and the actual signal is available at the output terminals for observation.

Thus various waveforms namely modulating signal, sampling clock, FSK modulated signal, Demodulated signal, reconstructed signal can be viewed on an external Oscilloscope for measurements.

This trainer is assembled in an ergonomically designed cabinet, with necessary power supplies, test points for observations. This require an external function generator and an 20MHz oscilloscope for measurements.