Technical questions about gr-tempest

[Beezdone]

Hello!

I've been working on gr-tempest for a while now, and I have several questions. To contextualize, I don't have a USRPB200, but an ADALM-PLUTO and a HACKRF. Also, I can read the "grabacion" files without any problem. However, I don't have a readable result for HDMI.

• I know the "sample_rate" influence the quality but are there any limits that should not be exceeded?

• What is the MAX deviation ? (in "Fine Sampling Synchronization")

• Does the result depend on the fundamental frequency ? (because of my setup, the fundamental frequency that I have is not the same as the one the creator of gr-tempest have)

Thank you!

[git-artes]

Hi, Sorry for the big delay, these were some very busy weeks. Regarding your questions:

• The max sample_rate depends on your PC. Dropped samples are a problem for the current implementation of gr-tempest, so you should use the largest one that does not produce any dropped samples.
• Fine sampling synchronizations looks for maximums in the auto-correlations. Max_deviation is the largest window it will compute the auto-correlation. The largest the value, the larger the maximum sampling error it may correct, although this increases the CPU usage.
• The central frequency should be a multiplie of the pixel-rate, either for HDMI or VGA. That's where most of the energy is. Which harmonic depends on the situation, you may try different values.

Hope this helps.