dBuV 44 Mer 11/12 BER 6 x 10 e4 Help!

M

mikysylv

Member
My Satellite Setup
60cm facing Atlantic 5Deg W + Fransat receiver + 10 element antiference facing Dover (grrr!) all into an old fraccarro 12 Way mutiswitch.

Home network with Naz Win7 SSD etc. etc.
My Location
Hythe Kent UK
Hello,

I have an issue (possibly) with the above. I'm a casual installer doing Terrestrial down here in Kent and I normally don't do IRS systems, but I have a problem with my first one.

The system is 8 flats located in east London all with Sky and Sky+ plus Freeview/DAB/FM. I speced a 78cm Triax, Quattro LNB connected to a Delta 16way multiswitch fed via 30m of WF100 Coax.

The figures above are the best I can Achieve measured at the LNB Vertical Low with no obvious LOS issues. My test kit is a Swires Digiscan 007 and the BER is Pre Viterbi.

On the Swires I'm using a "Favorite" for Astra 28.0Deg East Freq 11778 I think this is the Centre Freq or am I talking more B***ocks?

I would be expecting somewhere around 70/80 dBuV or am I talking B***ocks?

Thanks for listening

Mike
 
6 x e-4 pre viterbi won't give you any problems but 44dBuV might be an issue.

Are you measuring the correct LNb port?

11.778 isn't low band.....
 
Satelliteman, thanks for the reply,

The figures quoted, were measured on the connector marked V/L (I suppose Vertical low?). Oh the LNB is a MTI Supreme line Quattro AP84-XT2BL. I'm back up there tomorrow so I'll take some pics and post them on the forum.

Mike
 
So if on your meter you are asking for 11778 with a Local Oscillator of 10600, it will have an IF of 1178, so apply that to a 9750 Local Oscillator which you have on the Vertical Low output of the LNB and your transponder will have a frequency of 10928 which doesn't exist, hence your low signal strength.

Use the spectrum to find a signal peak and measure from there.
 
Thanks for the reply,

It's obvious from your post the problem was staring me in the face (what a Muppet I am!). To be honest the Digiscan isn't the best piece of kit to setup an IRS but I'm comfortable with the Terrestrial bit of it so it's just the sat bit.

thanks to both you and Satelliteman for your replies

Mike
 
also another way to look at it is, and to confuse you, if your using the meter to measure 11.778 (being 1178Mhz) which is in the high band and your connected to the V/low port of LNb, the preset Tp 11.778 on your meter will not be seen at 1178Mhz but at 2028Mhz.
 
OK,

you've got me going I'm getting my old BT course notes out now! LOL bit of revision methinks

Mike
 
What you can always do is line up the dish with a standard LNB, then change over to the quatro and re-tweak, on my ST-4 Rover meter I have four transponders set up for basic alignment, one on Vertical low, one Horizontal low, one Vertical high and one Horizontal high, plus one now set up for 12560 H Setanta Sports, a known problem frequency.
 
rolfw said:
What you can always do is line up the dish with a standard LNB, then change over to the quatro and re-tweak, on my ST-4 Rover meter I have four transponders set up for basic alignment, one on Vertical low, one Horizontal low, one Vertical high and one Horizontal high, plus one now set up for 12560 H Setanta Sports, a known problem frequency.
Click to expand...
I have a spare televes I'll give that a go and let you know tomorrow. Cheers once again for the tips and direction.

Mike
 
I took the advice, RolfW and Satelliteman gave me.

I looked on the Spectrum analyser and the peaks are all about 46 dBuV and the Signal quality is good MER =13 BER 1x10e-5.

I spoke to an old collegue a SKy guru been in the game for 20 odd years and he was stumped.

During the conversation I mentioned that in the LOS there is a railway with 25KV overhead power lines and he suggested that this might be the problem, as he had the same issue with a job in Birmingham. anyone heard of this?

Mike
 
I guess that it's possible and if it is the problem, then the only solution may be to move the dish. Have you tried moving the meter well away from the dish and railway line?
 
The overhead catenary for the railway line is about 50 metres away but in the LOS on the Dish as for the meter I could make up a 3 metre lead and try that.

I'll need network rail's permission to move the railway ....

I suppose moving the dish and raising it higher is a possible solution
 
I was thinking more of moving the meter 30m away, to see if the radiation is affecting the meter reading.
 
Just to add,

BER & MER are ok, so just an issue with the low dBuV measurement here.

Is any part of the system working? (not mentioned anywhere in the thread)

Are all transponders below 50dBuV in all bands?

dBuV not dBmV (although the conversion is way off)?

Have you tried another LNb?

Try aligning the dish onto another satellite and see the results.

Something to go on, lol :D
 
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