Using the "138MHz-4.4GHz USB SMA Source/Signal Generator/Simple Spectrum Analyzer" for TV/CATV/SAT

[jeallen01]

vma

Got my s/a unit working on the o/p socket of my TM today (and I did use the DC blocker!) - very interesting info about what signals are on various sats.

For example, on 8W and others, I saw some signals (at the lower end of the frequency range) that appeared to vary enormously from second to second - IIRC, there was something like a +/-20db (or more!) variation from the average displayed "background" levels around those frequencies.

Data feeds, or what, but why then did they it dip so far BELOW the average either side?

Anyway, very useful device, and I think that I'm quite glad I bought it.

Pity that I did not get another dual-tuner Rx, instead of the Vu+ Solo2, that has those o/p's from both tuners because that Rx is the one that drives the steerable dish for the weaker signal sats.

 

[vma]

Thanks VMA, I now have the latest version installed, with the AUTO button.

Have fun!

Cheers,
vma

 

[jeallen01]

Tomorrow, I hope I will remember to post some very "interesting" images of some things I found today when I ran the s/w today.

 

[John]

... apologies if iv'e missed this in the blog or forum but should the program run ok on W10. Ta.

 

[jeallen01]

John

Seems to run fine on my W10 Pro ACER N2601 netop - no problems noted.

 

[John]

John

Seems to run fine on my W10 Pro ACER N2601 netop - no problems noted.

Ok , thanks for that. Loaded the latest version onto a Vortex V10 tablet, activated with the code from Vitor, loaded up some LOF's and different bands etc and saved. The screen only shows the actual spectrum view but does not show the right hand menu section for some reason. I'll do a bit more digging.
Edit: looks like this

 

[blademedia]

I had a similar issue with smart dvb. could not see any channels, turned out I had to drag the screen back

 

[vma]

Hi,

My software only supports screen resolution of 1280x800 or higher.

It will not rescale/adjust for lower resolutions - sorry!

The reason is that the main graphic screen uses 1000x500 pixels and it wouldn't make sense to use less. Add a few controls and you're at 1280x800 (with some GUI design challenges).

Perhaps you can setup a higher interpolated screen resolution. Some tablets or netbooks allow that.

Regards,
vma

 

[John]

Hi,

My software only supports screen resolution of 1280x800 or higher.

It will not rescale/adjust for lower resolutions - sorry!

The reason is that the main graphic screen uses 1000x500 pixels and it wouldn't make sense to use less. Add a few controls and you're at 1280x800 (with some GUI design challenges).

Perhaps you can setup a higher interpolated screen resolution. Some tablets or netbooks allow that.

Regards,
vma

Ok thanks Vitor, problem sorted now. Resolution of the tablet was running at 1280 x 800 but the screen text size was set to a higher level for easier readout and this was stopping the full program content screen.
Many thanks.

 

[jeallen01]

Good afternoon

I've taken another close look at that "anomaly" on 8W High Band, and I now pretty certain that this is not an LNB issue because the s/a show that there are three distinct frequency bands - the upper and lower ones are about 2MHz wide and the centre one varies between 15 & 20MHz


That distinct feature must be related to the transmission methods because I can't imagine that limited but fairly precise bandwidth and pulse repetition rate would be LNB-related. OTOH, the sampling rate does make a difference to what I see - and if I raise it to 1000, then I get this


And, if I were able to raise it further then the display would probably become even more stable - it's still very odd in respect of the way that the "peaks" dip so far below those of the surrounding frequencies, but I am beginning to suspect that this is a feature of the way the frequency conversion circuits in either the LNB or the S/A work rather than of the transmission themselves.

 

[battenfan]

Does your Technomate have a lock an a transponder? Maybe it's trying to recalibrate and toggle power to the lnb.

 

[jeallen01]

Does your Technomate have a lock an a transponder? Maybe it's trying to recalibrate and toggle power to the lnb.

Just done a check with the TM and it's locking up France 3 on 11591V with no problem, and that's just at the top end of the lowest of the 3 weird bands that were around there earlier today - BUT NOT NOW because I have just done another S/A scan and they have moved up the band by about a couple of hundred MHz, but the trace pattern is very similar to those I have seen before!

The only way I can possibly put this down to anything else but what is happening either "up there" or in the s/as itself might be to query the LNB - that's the only Inverto Single Black that I've currently got installed, as all the rest of the singles on the dishes are 3xr TM Golds or (would you believe it) 4x 10yr old Coship/Lidl Silvercrest ones. None of those seem to be exhibiting anything like the same effects (but they are not pointed at 8W).

I was not going to change the Inverto, but now I think will do that tomorrow and put a TM there instead, and then see what happens.


!

 

[jeallen01]

Good morning

Looks like it WAS the bloody LNB because I changed it for a TM Gold (same LNB holder in same position) this morning, and the artefacts have now completely disappeared - see attached screen shot.

I think the "clue" that clinched it in my mind was when the frequency bands had shifted quite noticeably yesterday evening as that rather pointed in the direction of some "instability" in the LNB (nothing else having changed, and with the TM Rx locking onto France 3 in one of the "original" suspect frequency bands), and so I went out and made the change before the rain comes again.

BTW: when I took the F-plug off the bottom of the Inverto there was no sign of water ingress or corrosion, although the plug seemed to have unscrewed itself from the cable by a few mm because the core insulation was not flush with the inner mating face of the plug.

The "good news" is that having the S/A was what made me aware of the issue and helped me to sort it out, otherwise I might never have noticed the problem - thank you again, vma!

 

[vma]

Hi,

Great news! Glad you sorted it out and yes, a spectrum analyser helps a lot to "see" things like this and it still amazes me that a 60 Euro device offers so much possibilities.

Also, I feel very recomforted by the fact that my initial thoughts got confirmed in the end.

Here a small attempt to explain why I assumed it would be something like corroded cables or faulty LNB and not something being sent from the satellite itself:


The red lines show the amplitude of the interference, while the orange lines show the amplitude of the signal.

No satellite operator would be transmitting some weird signal with a stronger power than the remaining transponders.

But more importantly, the lower orange line shows the noise floor. How could the operator transmit a much lower noise floor on selected frequencies? That is not possible! Hence why I assumed that some corrosion or other failure caused some frequencies to be filtered out.

Regards,
vma

 

[jeallen01]

vma

I was feeling the same way about the noise floor issue, but I didn't know why - that was until I saw the frequency shift that occurred yesterday evening and that that almost certainly pointed at LNB circuit instability, which was confirmed by this morning's change to the TM LNB (and, yes, it did rain torrents a couple of hours after I did that!)

Another little bit of good news: bought both Invertos (one is not currently used) from Amazon in Jan this year, and so reported the problem to them before we went out shopping around 13.30, including the URL of this thread as evidence of what had happened.

When we got back around 30 mins ago, there was a reply from Amazon Customer Services that they are refunding the cost of both LNBs (OK, it's not a lot - just £7.90 - but the "thought counts") because I had said to them that I knew I had one faulty unit and that I did not trust the other not to do the same if I were to install it - still waiting to know if I have to return one or both of the LNBs, but I suspect not as that was not mentioned and it would cost Amazon more than it is worth. You never know, but I might be able to keep the 2nd one as a "freebie" (but with a big question mark written on the case to remind me of the potential problem in the future).

 

[jeallen01]

Update: Amazon have now confirmed that I don't need to return either of the Inverto's - so I get to keep the (hopefully!) "good" one.

 

[Lazarus]

I wonder if Amazon's Customer Service folks nodded sagely when reading the link ..... Surely it made a change from the usual stuff they get!

 

[John]

@Feedsat_DXer .... or anybody else. Myself and Chris (scopus) are having a bit of trouble with the program freezing when trying to use on Ka 18GHz information input. Iv'e tried two different pc's on either W10 or Win7 Pro with different past versions of vma's software, double checked and double checked again for any mistakes and still have freezing problems. Also Ctrl-Alt-Del will not clear the program, only a pc re-boot will do it.
I can get a successful frequency scan and display of the 18GHz span only if i use "Full Range" input without inputting any 18GHz details
Would you be kind enough to post us some grabs of your program "setup" screen and "Spectrum" screen showing what details you have entered to get a successful operation.
Thanks.

 

[vma]

Please post a screenshot of the crashed program and another one with it working in full span. what exactly are you doing?

Regards,
vma

 

[Anonymous_1]

No crash for me (W7 64bit) tested on 2 computers (not with a KA LNB yet but whatever the LNB, we don't care for the spectrum analyzer).

All OK for me, whatever the band in use, I've never seen any crash (yet)





Full


Even by the task manager ? with the Process off and USB unplugged: no way to fix this local crash ?