FSK MODEM
FSK MODEM
(OP)
How I can use an PLL in order to secyre my input analogue signal from the PSTN line into the two frequencies that i need from the protocol?
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RE: FSK MODEM
But why not use a special PLL designed for the job where it's all in one package? The Exar corporation have made just such a PLL demodulation device for some years(XR2212). For FSK modulation also see the FSK generator (XR2206).
The link is: www.exar.com
I have used these in several low cost modem designs which were approved by British Telecom for use on PSTN lines. Note that most PLL devices still require band pass filters to prevent false decoding on some of the harmonic tones that you can get on PSTN lines.