Hi Philip,
On 29-05-12 09:27, Philip Crump wrote: > Hi All, > > I am a second-year Electronic Engineering student with an Individual > Project being ~30% of my next (third) year. > > For this Individual Project I had the idea of designing a VHF packet > stream for Codec2. The general idea is for it to be similar in > functionality to D-STAR, but redesigned from the ground up to attempt (...) > improvement over D-STAR (particularly in SNR margin), probably still > using GMSK though for compatibility. The project would consist mainly > of simulation (MATLAB, GNUradio) and comparison of options (modelling > 4800 baud + lots of FEC against 2400 baud, differing interleaving > intervals with burst QRM, etc), with the plan of conducting > software-radio RF real-path testing for validation towards the end of > the project. The end result would be a tested and validated protocol > specification. No hardware implementation would be designed, leaving > that up to the community if they wish and allowing for further > development of the Codec2 bitstream to not interfere with the project > or vice versa. This would be very interesting. I think an experimental and a more "academic/theoretic" approuch are not necessairy contrairy to eachother. E.g. I am interesting a number of things: - 4800 bps GMSK vs. 4800 C4FM/4FSK (half bandwidth). (or. better S/N ratio due to half bandwdith vs. higher S/N ratio demands because of 2 bits/symbol vs. 1 bit/symbol) - 2400 baud GMSK (FEC of 2/3) and 4800 baud C4FM/4FSK (FEC of 1/3). Does using a FEC of 1/3 make sence? Is the S/N gain because of a better FEC completely linair, or is there an upper-limit after which adding more FEC-bits does not produce a better S/N ratio anymore? > I am aware there has been significant development on a VHF modem > recently, but having already been allocated a relevant Supervisor and > received the offer of some fancy equipment, I think I will probably go > ahead with this project anyway, just as an academic exercise for > myself and some marks on my degree. Well, for me. The specifications and implementations we are doing now ar there "to get something in the air" and allow people to experiment. I would prefer to use current implementation as a testbed so we can see what makes sence and what does not. With the experiments and your more theoretical and mathimatical approach, we should be able to draw a better "1.0" specification is -say- a year from now. So any input you have is quite usefull. > Phil Crump > M0DNY Kristoff - ON1ARF ------------------------------------------------------------------------------ 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
