Eric Seifert sent in some information on creating a home brew radio modem using a standard PC sound card, an iPod FM transmitter, and an FM radio. He has his current revision working at 9600 BAUD for distances in the neighborhood of hundreds of feet.

The sending side outputs an amplitude encoded data stream to the sound card, which is connected to the FM transmitter. On the receiving end, an FM radio receives the transmission, and outputs it to the receiving soundcard’s line-in, where it is then decoded. The hardware set up is extremely simple. It’s the software for reliably encoding and decoding the data (and handling error conditions) that’s the tricky part.

Eric released some example encoding/decoding software on his site, so you can start with that and take a swing at improving its error handling ability. You’ll need a Linux box with the ALSA and SDL libraries to compile it.

Radio Modem – Link

6 thoughts on “HOWTO – DIY radio modem

  1. Years ago, when I have also used dual boot configuration there was great TotalCommander plugin that was giving full access to linux partition on hard disk. For people which hates explorer, like me, it was great option…

  2. PLEASE note that this allows any Windows action or program to overwrite files on the ext2/3 filesystem. This could include system root files.
    The EXT2 IFS also does not continue journaling an ext3 filesystem.

    A better solution for longterm filesystem sharing between Linux and Windows is FAT32, and even the ntfs-3g driver for Linux is stable enough for use on NTFS partitions.

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