Hi Kristoff, > Do keep in mind that it does make sence to have a header in front. > Certain information -like callsigns- are actually used to some device to > make descisions on it. > E.g. a repeater does routing based on information in the header. A radio > can decide to open the squelch or not based on information in the header. > If this information is not be in front of the stream itself, any > application like that will need to implement buffering.
Sure, so just send data for the first few 20ms frames, dropping (or delaying) voice packets. Not sure if you need a parallel data and voice channel. As you say, delaying the voice for a few 10's of ms is no big deal. > > 4/ Re protocol information, fwd and backward compatibility I think some > > one a few years ago mentioned an Internet database for the many digital > > data modes which seem to expand daily. > Concerning backward compatibility, one of the things I like to add is > the ability to automatically add a small fixed audio segment behind > every transmission. This would allow people to put their callsign (in > CW) in their so anybody (including the regulator) will be able to > identify the source of this "weird digital transmission". This might be > a legal safeguard for people who are experimenting with new > (undocumented) digital modes and the legal obligation that hams must > identify themselfs. That's a good idea - the modulator could send "canned" analog voice or CW at teh end of each over as an option. Cool. > Well, for me, as long as the whole "pre-stream" process is finished in > less then 0.5 seconds, I do not think this is a major issue for most people. IIRC 500ms preambles like this were a big deal for the HF guys who developed FDMDV, I forget the exact reason. Perhaps some early HF DV systems wouldn't sync if the pre-amble was lost (due to interference), or they were concerned about fast break-in operation. The approach I took for FDMDV was to make sure it can sync up fairly quickly at any time (e.g. after a fade) without a pre-amble. But I guess D-star works well enough in practice. Its probably a nicer channel than HF. Cheers, David ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
