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daniestevez / gr-satellites

GNU Radio decoder for Amateur satellites
GNU General Public License v3.0
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Can´t Decode QO-100 #480

Closed mdmpereira1 closed 7 months ago

mdmpereira1 commented 12 months ago

Hello Folks I am doing a project to decode the multimedia beacon of the QO-100, similar to those posted here. But when I try to run it the following error occurs: Reed-Solomon decode fail (interleaver path 0); Besides that the constellation that arrives is missing the symbol for bit '0':

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I tried also to use the example posted here (qo100_multimedia_beacon_df2et.grc) to see if the problem was with my fluxogram, but the output is similar:

image

I was doing this project in GNU Radio Companion in Windows 10, but after seeing a similar issue on #217 I switched to a virtual machine (Unbuto) and did the steps provided there, but yet again the same 2 problems appeared.

The signal that I receive is downconverted to 432.5MHz, passes through a HackRF One to my computer. I am not sure if it is relevant but the system also has a QO-100 DX patrol.

Thank you in advance

Miguel

daniestevez commented 12 months ago

Hi Miguel. From a quick look, you're not correctly tuned to the signal. In the spectrum plot, the signal and its mirror image (blue and red traces) should overlap as well as possible. In that way, you can be certain that the signal is in the centre of the receiver's passband.

mdmpereira1 commented 11 months ago

Hello Daniel. Thank you for your response. I did what you suggested and is started to show the bit in the middle I think:

image image

I added 2 frequency offsets one in the order of [-300, 300]KHz and another in the order of [-100, 100]Hz int the Fir Filter but I can't get the signal correctly, although it is close.

image

I think the problem is with the phase but I don´t know how to correct it.

daniestevez commented 11 months ago

The think you now have in the spectrum plot in GNU Radio doesn't look at all like the beacon signal. See this for how the spectrum should look like.

Also, it's difficult to say, since you're showing 8 MHz bandwidth in GQRX, and the beacon is only 2.7 kHz wide, but I would say that what you're seeing in GQRX is not QO-100's NB transponder, but something else.

daniestevez commented 9 months ago

@mdmpereira1 do you have updates about this or shall we close the issue?

daniestevez commented 7 months ago

Closing, since there have been no updates in months.