New method for generating wideband spectograph’s with Radio-Sky and an RTL-SDR

Radio-Sky Spectrograph is a software application that is designed to produce waterfall displays similar to other software, but with a focus on observing radio astronomy phenomena. 

Radio-Sky Spectrograph displays a waterfall spectrum. It is not so different from other programs that produce these displays except that it saves the spectra at a manageable data rate and provides channel widths that are consistent with many natural radio signal bandwidths. For terrestrial, solar flare, Jupiter decametric, or emission/absorption observations you might want to use RSS [Radio-Sky Spectrograph].

Last year, we posted about the release of RTL_Bridge, which is a program designed to interface an RTL-SDR dongle with Radio-Sky Spectrograph. One limitation with RTL_Bridge was that it was limited to the dongles maximum bandwidth of about 2.4 MHz. Now Raydel Abreu Espinet (CM2ESP) has written a new application called RTL-WideSpectrum which allows for wideband spectral sweeps in Radio-Sky Spectrograph by using the RTL-SDR to quickly switch between frequencies and combine the outputs. It is similar to how rtl_power works.

With RTL-WideSpectrum and Radio-Sky Spectrograph, Raydel was able to capture this solar burst shown below which occurred between 28-48 MHz.

A solar burst between 28 - 48 MHz captured with an RTL-SDR dongle, RTL-WideSpectrum and Radio-Sky Spectrograph.
A solar burst between 28 – 48 MHz captured with an RTL-SDR dongle, RTL-WideSpectrum and Radio-Sky Spectrograph.
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all of these wideband scanners have these bars in between, this is because of a lower sensitivity at the beginning and end of bandwidth.
why not use only one 2 MHz portion out of the 2,4 MHz ??
must explain this:
for a scan from 20 MHz they tune from 20 to 22,4 – next would be 22,4 to 24,8 – and so on…
why not tune from 20 to 22 and use only 2 MHz, next 22 to 24 and 24 to 26 – so those 0,2 MHz at the beginning and end are forgotten ?

Raydel CM2ESP

Yes, correct, rtl_power can do it. But back then (2015) the minimum interval between scans that rtl_power could do was 1 second. And that was not fast enough for detecting fine details and rapid changing events. RTL-WidebandScanner depending of the bandwidth can go from 4 to 8 scans per seconds depending of the selected bandwidth. So sorry for taking so long to reply…

Raydel CM2ESP

Sorry for taking so many years to reply, I was not aware of this post. Thanks to rtl-sdr blog for posting it. The black banding was caused for that reason, the roll-off issue with the dongle at each scan. But it was a very first and beta version. I did later another version later which solved that problem.