simple FSK/AFSK Modulator

Posted on Feb 6, 2014

Audio frequency-shift keying (AFSK) is a modulation technique by which digital data is represented by changes in the frequency (pitch) of an audio tone, yielding an encoded signal suitable for transmission via radio or telephone. Normally, the transmitted audio alternates between two tones: one, the mark , represents a binary one; the other, the

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space , represents a binary zero. Commercial FSK (frequency-Shift-keying) modulators are bulky and need many Passive components. the circuit uses a single NOT gate (inverter), On Semiconductor NL27WZ14 into a surface mount Package, to generate continuous FSK data from the TTL level signals. the Spending of this range are compatible with the available channels. If the TTL input is low, the circuit is a continuous execution of the oscillator output about 2400 Hz (adjustable with R1). If the input assumes a high level of The oscillator frequency reduces by half with the Introduction of a capacitor in the circuit over time Q1. converter IC provides space for surgical Frequency of approximately 80 kHz. You can easily Operation of the FSK modulator at higher frequencies eg, 4800 and 9600 Hz, by reducing the values of the timing capacitors C1 and C2.

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