[amsat-bb] A tip for Gqrx users and report of the copy of FIREBIRD-II FU3/4 19k2 FSK.

M.Sc. Pavel Milanes Costa co7wt at frcuba.co.cu
Thu Oct 15 22:02:38 UTC 2015

Hi, some users have asked for pictures of this... so I share this on the BB

Thanks to Scott (K4KDR) that put them on-line for me (I have internet 
problems here at the moment)


Partial satellite sub-band in view, it's bigger than the BW of the RTL-SDR
Tracking Cute 1.7 (sat not in range) + Gpredict control

Tracking phonesat 2.4 (no signal, end of the pass)

Tracking phonesat 2.4 wide

Tracking phonesat 2.4 wider...


Detail of two signals in the spectrum; the left is a terrestrial signal 
(commercial?: more than one TX site/signal level, always there, no 
doppler) and right is unknown...



With this I see that there are some withe spaces on the sub-band, I have 
to check the band plan of the IARU...

Enjoy, 73.

PS: antenna is a homebrew RHCP QH and homebrew preamplifier (not worth 
to name it as "LNA", it's quite noisy but do the job....)

El 14/10/15 a las 23:24, M.Sc. Pavel Milanes Costa escribió:
> I'm playing this night with my linux box and rtl-dsr + Gqrx + Gpredict 
> to see the 70cm satellite sub-band...
> And found a way to identify the sat from the spectrum at a glance in 
> 70cm using the bookmarks of gqrx... very handy feature of this 
> software... just linux here, not know if windows sdr soft has this 
> feature...
> After playing with satlist.csv (from 
> http://www.ne.jp/asahi/hamradio/je9pel/satslist.htm) and parsing it to 
> make it work with gqrx... I fire the Gqrx software, put up the antenna 
> and watch for any suspicious signal... and the bookmarks on top of the 
> signals are there, nice....
> ... (a few minutes after) ...  haja !!!!
> A packet like signal around 437.4 Mhz, zoom it.... wow, to wide for 
> normal packet... let's widen the filter to fit... ~25 Khz is enough, 
> hum... it's bigger than 9600 bauds... lets see what the bookmarks on 
> the screenm says... FIREBIRD-II FU4 19k2 FSK within the +/- 10khz of 
> doppler... bingo !!!
> Let's run Gpredict to check.... right on the spot... and also 
> FIREBIRD-II FU3 incoming on range... let's check... right...
> So if you use linux and some SDR hardware with Gqrx, you can use the 
> bookmark function to this purpose, you can actually click & zoom and 
> then read of the screen to approximate which is the satellite who tx 
> that signal... all at a glance...
> If any of you want to play with this I can send you my bookmark file 
> of the entire 70cm satellite sub-band, updated with the last info 
> from  http://www.ne.jp/asahi/hamradio/je9pel/satslist.htm just email 
> me a private msg.
> I was not trying to decode, just to prove the usefulness of this 
> feature, I use the latest gqrx & gpredict from ubuntu PPA.
> BTW, none of the FIREBIRD satellites are in the 
> http://www.amsat.org/status/ page, so I can't update it's state.
> 73 from Cuba, CO7WT
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. 
> Opinions expressed
> are solely those of the author, and do not reflect the official views 
> of AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite 
> program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb

More information about the AMSAT-BB mailing list