No data decoded, but in fact there is?

[EricFROL]

Hi. I've set up r2cloud in a rpi, using the image. Looking at the waterfalls I noticed that there's signal, but r2cloud is not decoding it. I share here some waterfalls, where no data had been decoded: https://i.imgur.com/cdx5Mw2.png https://i.imgur.com/kdFqy7y.png https://i.imgur.com/wp8PQxG.png https://i.imgur.com/7c0uy16.png

[dernasherbrezon]

Hi,

There are several reasons to this:

• Signal is not strong enough. Even if it is visible on the spectrogram doesn't mean it is decodable. For example the first waterfall has strong signal but also strong interference. Most of signals on amateur frequencies are AX.25 which is not designed for space communication and require good SNR
• Small dynamic range of your rtl-sdr. For example second waterfall has very strong signal on right right that deafens satellite signal.
• Incorrect satellite configuration. This can happen to the newly added satellites when they transmit on unknown baud rates or switched to unknown framing/modulation.
• Bug in r2cloud reception. Some edge-cases from ~50 supported framings/satellites can yield missed frames.

There are several ways to improve that:

• Wait couple of days. Maybe satellite was passing on the very low elevation and your antenna wasn't able to pick it up. More observations required.
• Install band pass filter with LNA right after the antenna. This should reduce interference from FM or other strong sources.
• Select loud satellites such as FUNCUBE-1 or AAUSAT-4