🚀 go-pugleaf

"Witek" <robertwi@polbox.com> wrote in message news:<9llppk$3rk$1@news.tpi.pl>...
> Hi,
> 
> I find algorithm to demodulation GSMK.

Good, well done.


> In my device i have stream from A/C
> (I,Q)

Oh, have you, well done again.

One thing I can see you are porbably doing wrong is that you mean GMSK
and not GSMK. What is A/C? Do you mean analog to digital converter
(ADC)?
The other thing you are doing wrong is missing too many words out of
sentences.
Without wanting to sound cruel, you have to structure a sentence
properly as otherwise people will not be able to answer you as they
will not understand the question.

From the above, and using some information theory error decoding I
assume you mean you are looking for an algorithm to demodulate GMSK
and in your device you have an I-Q data stream coming from your ADC.
Am I right?
I don't really know what you mean you when you say you want to find an
algorithm to do this. I would have thought you suss out the theory
first and then write the code for it. Do you understand the theory
first? If so, say exactly what you want to be answered.

Steve

Excuse me , but I do not write well in English language.
I must recover data from signal modulated GMSK.
From devices which one I possess goes out stream I&Q from analog to digital
converter.
How from this of stream to reproduce digital data?

Robert




> One thing I can see you are porbably doing wrong is that you mean GMSK
> and not GSMK. What is A/C? Do you mean analog to digital converter
> (ADC)?
> The other thing you are doing wrong is missing too many words out of
> sentences.
> Without wanting to sound cruel, you have to structure a sentence
> properly as otherwise people will not be able to answer you as they
> will not understand the question.
>
> From the above, and using some information theory error decoding I
> assume you mean you are looking for an algorithm to demodulate GMSK
> and in your device you have an I-Q data stream coming from your ADC.
> Am I right?
> I don't really know what you mean you when you say you want to find an
> algorithm to do this. I would have thought you suss out the theory
> first and then write the code for it. Do you understand the theory
> first? If so, say exactly what you want to be answered.
>
> Steve

> From the above, and using some information theory error decoding I
> assume you mean you are looking for an algorithm to demodulate GMSK
> and in your device you have an I-Q data stream coming from your ADC.
> Am I right?

Yes, you have 100% right.

"Witek" <robertwi@polbox.com> wrote in message news:<9lmo8i$rep$1@news.tpi.pl>...
> Excuse me , but I do not write well in English language.
> I must recover data from signal modulated GMSK.
> From devices which one I possess goes out stream I&Q from analog to digital
> converter.
> How from this of stream to reproduce digital data?


If you have a coherent detector, for both I and Q branches you
demodulate, low pass filter, integrate then add the two outputs of the
integrtors. I am just writing this from looking at a diagram. It is on
page 266 of Wireless Communications by T. Rappaporte. There are a few
timing phase shifts: obviously the pi/2 phase shift to the Q branch
with respect to the I branch. There is a pi/2 phase shift from the
output of the symbol timing recovery circuit to the input signal of
the loop filter for carrier recovery, this pi/2 is multiplied by the
output of the product of the two carriers. There is a pi phase shift
for the Q branch with respect to the I branch for symbol sample timing
from the symbol timing recovery circuit. And that's about it. I would
draw a diagram if I were you but I wouldn't guaruntee my description
has been that good so if you can get the book I mentioned I would get
that.

Steve