Hi all,
This is part 2 of the "how to help codec2 initiative" thread. With codec2 now providing a 900 bps version, the codec and modem is now moving into the VHF/UHF range using off-the-shelf FM-radios. Althou it has already been possible to use FreeDV over VHF/UHF using SSB- and designs using specialised SDR radio are being developed, the possibility to run codec2 over FM -either using AFSK, GMSK or any other modulation-sceme- is something that looks to be "to interesting to be ignored". However, for this to be done successfully, more information is needed about the typical characteristic of an FM channel. This applies both for "normal" FM channels and radios using the "9k6 discriminator" port. Some elements that need to be determined are: - (for normal FM): attenuation and delay of a typical FM channel - (when using the discriminator-port): is there any low-pass filtering done on discriminator-port of an FM radio. Can this impact the codec2 stream when running at lower bitrates. We need as much as information as possible about this using different brands of radios and using different reception levels. For this, we would like to make an appeal to the community. We need somebody that can take the lead in a project to do the following: - determine, create and distribute audio-files that can be used to determine the characteristic of a FM-channel - write and distribute a simple "how-to" document that descibes how people can do a test to collect data to determine the characteristics of their rig - set up a website to collect audio-files + additional data uploaded by users. It would be interesting if this data would also contain information like the brand of the radios used, as this should provide us an indication how much the characterists of an FM channel differ per brand of radio. I would propose to use the "open data" model for this: - All information provided by the public should also be made available to the community (after removing any privacy-related information, of-course) unless the user asks not to do this - Once sufficient data has been collected, the FM channel characteristics data dermined on the collected data will be made available to the community. I would like to point to the work done by Jimmy KG4SGP last year on this topic: https://groups.google.com/forum/#!topic/digitalvoice/YEvJdzUM3Ts 73 Kristoff - ON1ARF ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
