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majortom

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Reply with quote  #1 
to capture an iqplot from a narrow band on 107W,
Looks like ~ 3892 V ~890 QPSK 1/2 according to the Prof, which won't lock such a low SR
plus I think there is more than one in this vicinity, and I haven't bothered calibrating the sdr...
kinda cool... Not great, but proof of concept...


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Perfect 10 7.5' mesh Chapparal C/Ku Co-Rotor feed, Norsat 8115 CBAND, Norsat 4106A Ku Thomson Saginaw Actuator, Vbox positioner,
Home Brew Polarotor683 Servo circuit. Openbox S9, Prof7500, v4l-updatelee linux drivers installed.
ricardo's geo-orbit archive: https://web.archive.org/web/20071202191450/http://www.geo-orbit.org:80/sizepgs/tuningp2.html

photoman76

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Reply with quote  #2 
I can lock it with the TBS 5925.
Here is what I'm seeing:
AnikF1R.jpg 

There is a similar signal at 3895 V 861.

boblop

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Reply with quote  #3 
Some times I miss this being in a hurry but I see 4 separate narrow signals here around 3892 to 3898.

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majortom

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Reply with quote  #4 
yeah I was seeing like 12 db SNR on that guy, but the prof won't lock it, so can't really trust the SR
it reports until it does. acm/vcm makes more sense as to why it wouldn't lock on the prof.

I was just happy to see a QPSK constellation on the homegrown program I am hackin around with,
If ya know of any other skinny signals (say less than SR <= 1M or so) let me know and I will look there too.
103 W might be a good candidate in the vicinity of 11720 MHz.
I might try and sniff around near some beacons as well.


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Perfect 10 7.5' mesh Chapparal C/Ku Co-Rotor feed, Norsat 8115 CBAND, Norsat 4106A Ku Thomson Saginaw Actuator, Vbox positioner,
Home Brew Polarotor683 Servo circuit. Openbox S9, Prof7500, v4l-updatelee linux drivers installed.
ricardo's geo-orbit archive: https://web.archive.org/web/20071202191450/http://www.geo-orbit.org:80/sizepgs/tuningp2.html
majortom

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Reply with quote  #5 
try 3896 V 930 see what tbs reports when it locks it, prof says..
QPSK 8/9


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Perfect 10 7.5' mesh Chapparal C/Ku Co-Rotor feed, Norsat 8115 CBAND, Norsat 4106A Ku Thomson Saginaw Actuator, Vbox positioner,
Home Brew Polarotor683 Servo circuit. Openbox S9, Prof7500, v4l-updatelee linux drivers installed.
ricardo's geo-orbit archive: https://web.archive.org/web/20071202191450/http://www.geo-orbit.org:80/sizepgs/tuningp2.html
boblop

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Reply with quote  #6 
This morning I see 3896.9 V 861 DVB-S2 QPSK2 8/9 AMC 13.3 db.
At around 3894 it says FEC is 1/2.

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majortom

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Reply with quote  #7 
Thanks bobplop, here is another low symbol rate QPSK lookin signal, on 103W H, Ku...

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Perfect 10 7.5' mesh Chapparal C/Ku Co-Rotor feed, Norsat 8115 CBAND, Norsat 4106A Ku Thomson Saginaw Actuator, Vbox positioner,
Home Brew Polarotor683 Servo circuit. Openbox S9, Prof7500, v4l-updatelee linux drivers installed.
ricardo's geo-orbit archive: https://web.archive.org/web/20071202191450/http://www.geo-orbit.org:80/sizepgs/tuningp2.html

photoman76

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Reply with quote  #8 
Quote:
Originally Posted by majortom
Thanks bobplop, here is another low symbol rate QPSK lookin signal, on 103W H, Ku...



I'm not seeing any signals at 11739 H or V on 103 W at this time.
wejones

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Reply with quote  #9 
Quote:
Originally Posted by majortom
Thanks bobplop, here is another low symbol rate QPSK lookin signal, on 103W H, Ku...



I'm curious re what program is displaying your constellation?
Is that done via the GNUradio Companion thing?
I'm too dumb to figure out how to use that thing.  I tried to follow some samples, dragging sources and filters over to the left and connecting them, but got stuck when I couldn't find the things used in the samples.   Of course I'm using the windows version.  Maybe the linux version is different.
Anyway, if it did come from the GNUr companion, what items did you connect together?
If the program isn't from the companion, where did you find it?

merkin

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Reply with quote  #10 
check out this new software for airspy:
http://www.rtl-sdr.com/spectrum-spy-new-spectrum-analyzer-software-for-the-airspy/

also a "mini" version of airspy is now available for preorder:
https://airspy.com/airspy-mini/

makes a cheap spectrum analyzer..the refresh rate seems fast enough over 500mhz.
wejones

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Reply with quote  #11 
Thanks. Very interesting.  I didn't realize that I already had that program on my computer.  It came with the newer version of the SDR# program, although it wasn't part of the older version that I had been using until I recently tried a newer version.
    My biggest complaint with the $15 dongle I use is that it only has a 2 MHz bandwidth, and even the edges of that 2 MHz show significant dropoff, plus you get false images of other signals showing up at the edges.  So for satellite signals, I'm limited to signals with very low SRs, less than 2000 Msps. 
   I looked at several other SDR receivers that had wider bandwidths. I think the Airspy is about 6 MHz, and I've seen some other ones that are up around 18-20, and one that's up above 40 MHz, however the cost of the higher bandwidth receivers goes WAY up with the higher bandwidth. 
  I tried to run the program, and it came up, but said that it couldn't find an Airspy receiver, so I guess it won't work with other generic SDRs.
  But from what I see in the link (which I have been at before, but didn't read very carefully), this, and some other software must extend the range of the scans by piecing together a bunch of the 2 MHz sections (or 6 MHz for the Airspy).  On playing a couple of the videos on the link, it looks like it works pretty well. Obviously slower than with more expensive receivers, but fast enough to tune dish aim and watch for intermittant signals showing up, and would give you the ability to scan the whole satellite while moving your dish across the arc while looking for new satellites, etc.  Definitely makes me think that the mid priced Airspy with that program might compete with the more expensive SDR receivers.
   On the other hand, the link mentioned a couple other programs that do similar things. I don't know to what extent these other programs can be real time, but I think I'll check them out.  But you've got me leaning a bit back away from the more expensive units now. 

  





TheSatBible

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Reply with quote  #12 
Quote:
Originally Posted by majortom
Looks like ~ 3892 V ~890 QPSK 1/2 according to the Prof, which won't lock such a low SR
plus I think there is more than one in this vicinity, and I haven't bothered calibrating the sdr...


I have locked SR's of 285, 740, and 900 with the prof 7500 but I can't lock the 3892V signal in this thread with my prof 7500.

what utility do you use to come up with a SR to try?  There are quite a few signals in the arc that I wonder might be lockable in dvb or dvb-s2 with a prof card but crazyscan (the best program I know of to use or try to lock low SR signals) doesn't seem to get them all (one of the signals I had to find on a webpage -- crazyscan would not find the SR on its own.  When I put that SR in crazyscan and unchecked "blind scan", it would get a lock).

I have a SDR dongle but I don't know what utility would be needed to analyze the signal to try to come up with its modulation and symbol rate in order to try to lock with a prof or other cards.



majortom

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Reply with quote  #13 
the prof can't lock an acm/vcm signal (see photoman's plot from his tbs5925). But I can usually get it to report parameters using updatedvb or tune-s2 when acm/vcm. You can't rely on all of them when it won't lock, but is usually close enough to tell something is there, specially when it's a strong signal.  I haven't used crazyscan in years but I am guessing it behaves similarly?

That's kinda why I was playing around with the low bandwidth signals there. Not gonna be much of interest to me. But with low bandwidth signals it's something to possibly learn from.
I am not a programmer or software developer, just seems like something to hone in on with some cheap hardware and free tools.
I am always lookin to learn something. Albeit sometimes it takes someone to hit me on the head with a hammer to get something to sink in.


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Perfect 10 7.5' mesh Chapparal C/Ku Co-Rotor feed, Norsat 8115 CBAND, Norsat 4106A Ku Thomson Saginaw Actuator, Vbox positioner,
Home Brew Polarotor683 Servo circuit. Openbox S9, Prof7500, v4l-updatelee linux drivers installed.
ricardo's geo-orbit archive: https://web.archive.org/web/20071202191450/http://www.geo-orbit.org:80/sizepgs/tuningp2.html
TheSatBible

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Reply with quote  #14 
Quote:
Originally Posted by majortom
the prof can't lock an acm/vcm signal


had a brain fart about that last night when making my post.

the low ones i mentioned are DVB-S or DVB-S2 CCM that i've locked with the prof.  

so both utilities you mention are linux, right?  It would be great to use a windows utility to be able to come up with SR less than 1000 for signals on G16 C and AMC8 C and SES3 Ku because I have a feeling a lot more radio networks may be using DVB-S or DVB-S2 CCM with really low SR that a prof could lock if you can get an accurate SR since blind scanners miss them.






wejones

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Reply with quote  #15 
Quote:
Originally Posted by TheSatBible


I have locked SR's of 285, 740, and 900 with the prof 7500 but I can't lock the 3892V signal in this thread with my prof 7500.
....



I'm curious re where the 285 SR transponder was, and if it's still there.   I've never been able to lock one that narrow, and would like to try it.  When you posted that, I thought it must have been an ACM/APSK transponder that was confusing the PROF with the trick APSK enabled, but if it's CCM and regular QPSK or 8PSK as suggested by last post, that's interesting. 


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