I tried looking on the net about using arduino and AFSK to achieve MDC1200 projects, but there are almost no related projects. Has anyone done a similar project? I want to try to complete the decoder and encoder~ Thank you all
I used AFSK modulation to send/receive telletype on ham radio back in the 1960's. Your problem is the Arduino and all other processors will send square wave signals, not nice sine waves with coherent changes from one frequency to the other. Same on receiving AFSK. They are sine waves and will have to be either squared up into square waves or the frequencies determined by time between zero crossing.
I guess you could use two sine wave oscillators and have an Arduino switch between the two.
What is your ultimate project?
Open source Arduino 1200/2400 Baud AFSK modem here: GitHub - markqvist/OpenModem: Powerful AFSK modem platform
Arduino modem code here (error rate is a bit high): GitHub - cstroie/Arabell300: Old school Arduino modem, Bell 103 compatible, at 300 baud
I want to make a MDC1200 decoder and encoder based on arduino, because usually the price of radios with MDC1200 is not low, so I want to develop a low-cost device that can send and receive.
Yes, some of the local police agencies use those Motorola radios and you can hear the data bursts on a standard FM scanner radio.
However you still will need devices to create the AFSK audio tones and devices to decode the AFSK audio tones. As explained, those tones are SINE waves, not DIGITAL signals.
The two projects linked in reply #3 use the Arduino to generate and detect sine wave signals at the appropriate frequencies.
The modem described in the second link does not use any external chips.
Yes, either one would be a good starting point, but never a comment from the OP. Of course there is much more to the system he wants to monitor. But he had better hurry before those systems are replace by full digital voice/data systems.
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