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Kim Mortensen kimfmx at gmail.comHi, Would someone happened to have a sample file containing I/Q data from a DQPSK signal. The content is not important, as long as its DQPSK - Preferably in wav format. Best Regards Kim Mortensen Den lør. 15. feb. 2020 kl. 09.33 skrev Kim Mortensen <kimfmx at gmail.com>: > Hi, > > Thanks for the add, I have been hinted this place, and im looking forward > to digging deeper into the realm of TETRA / DQPSK. > > What im trying to do is write a C# program for demodulation of TETRA. and > have come so far as to be able to view the IQ vector run around on the > unity circle, but it appears a bit distorted. I think its due to a crude > low pass filter i used on the I/Q signal causing this. From reading books > and sites i find that I should probably used a raised cosine filter to keep > the signal form beeing distorted (ISI). am i correct in my assumption? and > do you have the open source code i can inspect, regardless if programming > language. > > I know there is tons of programs out there that can decode and even > produce audio from TETRA DQPSK signals, and I have one installed, but i > want to have an edge to this, i need to understand and learn first hand. It > may take time, but thats how it is. > > I have what is required regarding programming skills and radio knowledge - > I am radio Amateur, and 20 years ago i did have Digital communication > classes at Engineering college - But thats 20 years ago, and the equations > in the books are kind of far away in my head.. but the theory sticks. > > Please help me get up to speed in decoding DQPSK, im not expecting to do > this quickly, but will be in steps when i have time, and will lead to > questions. But at some point i could be on your frontier digging into TETRA > as a whole. > > Best Regards > Kim Mortensen > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/tetra/attachments/20200217/9cf9b326/attachment.htm>