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Topic: Looking for FSK modem (Read 2034 times) previous topic - next topic

Looking for FSK modem

Anyone know any alternatives to the TCM3105 (Bell 202) FSK  modem IC? They're 7 dollars each in small QTY's and I only need about 5 but am looking for something a little bit cheaper for a project. Anyone know of anything similar? It can be a different modulation or buad rate, but it needs to be require few external parts and have the ability to work over a telephone.

Re: Looking for FSK modem

Reply #1
Easiest alternative is to replace them with MCU, and to the signal conditioning in software. I have been using bertos (with internal AFSK demod, bit altered filtering). It requires ADC/DAC to be running at 9600ksps sampling rate, 8bits.
Some features are missing e.g. carrier detect.

My experiment:
http://michaldemin.wordpress.com/2012/0 ... -afsk-tnc/

I guess that you will always need some interface to telephone line. These modems ICs do not connect to telephone line directly.

Re: Looking for FSK modem

Reply #2
[quote author="robots"]Easiest alternative is to replace them with MCU, and to the signal conditioning in software. I have been using bertos (with internal AFSK demod, bit altered filtering). It requires ADC/DAC to be running at 9600ksps sampling rate, 8bits.
Some features are missing e.g. carrier detect.

My experiment:
http://michaldemin.wordpress.com/2012/0 ... -afsk-tnc/

I guess that you will always need some interface to telephone line. These modems ICs do not connect to telephone line directly.[/quote]

Wow, awesome! I was actually using a STM32VLDiscovery board for my project, what are the chances of that?