CRC-DABMOD is a DAB/DMB software modulator developed by CRC as an experimental tool to support activities in the area of mobile multimedia broadcasting (MMB). CRC-DABMOD is released under the GPL.
CRC-DABMOD is an COFDM modulator implementing the DAB specification.
The source code is available here:
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I wish to sponsor the modification of this software to allow near-zero cost, basic experimentation by eliminating the need for the supported Universal Software Radio Peripheral (USRP). This is to be achieved by writing to one of the VGA DACs (most likely via SDL) instead of using the USRP as the Digital to Analogue Converter.
The obvious limitations being that it would likely be necessary to generate the signal at a lower frequency, and the unavoidable blanking period in all known graphics cards.
Similar things have already been done for digital television ([login to view URL]) and FM Radio ([login to view URL]). I have confirmation from the author of the latter that VGASIG is Public Domain. I also have some correspondence from most of the above explaining what needs to be done to achieve this.
Project Summary:
To write a command line linux application which provides a variable frequency signal modulated by the COFDM modulator software described using the DAC of a graphics card to produce a baseband signal for experimental purposes. Several examples of how use libSDL to write to the DAC via SDL already exist in the Public Domain, and the tempest (FM version link below) code may well save a lot of work - it, like VGASIG uses the SDL library.
All code produced may be released by me under the GPL.