Hi, Electrical Engineer, graduated 20 years ago, have been developing software ever since, using a varity of different languages. This field is something i recently fond interesting, and want to dig deeper into. I want to be able to decide DQPSK using a C# program, so i want to do all the steps by code. I have come far, but needs assistance in some crutial areas regarding processing the raw IQ data. Best Regards Kim Mortensen

Re: Sampling and using the data

Reply posted 2 months ago (03/20/2020)
1) yes, its the spectrum of the signal, the light gray box encapsulating the signal is the bandwidth of 25Khz.2) The signal is pi/4 DQPSK Signal so its Phase shift...

Re: Sampling and using the data

Reply posted 2 months ago (03/18/2020)
Good to know that people are willing to help. Eventhough these questions seems basic for those who work with it all day, Its not so easy for someone who is in another...

Re: Sampling and using the data

Reply posted 2 months ago (03/18/2020)
To sum the questions above:The sampling application SDR# (SDRSharp), and its sampling at 1.92Msps, so that should be enough to be on the safe side of the nyquist.SDR#...

Sampling and using the data

New thread started 2 months ago
Hi,I have been looking through Google, and have not gotten much wiser, so i turn to the experts.I have a Signal lets say at 393.000 Mhz that has a bandwidth of 50KHZ,...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/18/2020)
I spend a lot of hours last night working with the filters, and came to reduce the tabs, and the tab count i used distorted the signal. 255 is too much, i used 5-15,...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/18/2020)
Ok, Just realized that there are multible threads in here, and i dont know if everyone is getting all the messages, or it only to whom i reply.But thanks, ill have...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/17/2020)
Ok. And can i map tabs to samples.So if i place the raised cosine over the signal. Centre of cosin at center of a peak in the signal. The side lobes zero crossing...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/17/2020)
Is there some more analysis i can do on the raw sample to get more information that can be used.I am very sure that im sampled TETRA. Which is DQPSK. According to...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/17/2020)
Ok. It makes very much sence.. if the signal fits the raised cosine form its energy wil be preserved and that is the waveform at that sample point that is the value. phi(k)...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/17/2020)
Nice info you are giving me...Im using the raised consine, that should be perfect for eliminating ISI. When you say Filter Kernal, is that how i calculated the...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/17/2020)
Hi,The differnece between DQPSK and QPSK should not be vissible to me at this point, as demodulation would be the same. the Differential part will be apparent later...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/17/2020)
That is funny, because that was exactly what I was doing prior to the last reply. I have the I and Q in seperate arrays, so when plotting the constellation i could...

Re: DQPSK - New t this, and want to learn...

Reply posted 3 months ago (02/16/2020)
Hi,Thanks for responding. The syncronisation is a whole big topic i will be looking after i master this part. But after i Filter the signal properly, I assume I...

DQPSK - New t this, and want to learn...

New thread started 3 months ago
Hi,Happy that i found this forum, it seems like a good gathering of knowledgeable people.I also fall into the category of persons who recently discovered SDR. I...

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