Whats DiSEqC users SNR ?

[aabs]

It would be a great help if members could supply a little data of SNR when fed through DiSEqC.

Location/ Size of Dish / LNB / Satellite would help us identify if the DM800 tuner is as bad as they really say.

Location : Northwest UK
Dish : Facarro Penta 85cm
LNB : Titanium TSG 2nd Edition Universal Single LNB
DisEqC : STab 100

28.2 east .....BBC HD SNR= 19%
19.0 east .....Premier Direkt Portal SNR= 18%
0.9 west ......DigiTV test channel SNR= 19%

Taken at 21:10 hrs BST

[loveman]

Location : Midlands, UK
Dish : Gibertini 85cm
LNB : Inverto Silvertech 0.2db twin LNB
DisEqC : Super Dark Motor Metal Gears

19.2 east .....Digital+ Fox = 13.8db

Taken at 23:00 hrs BST

Sorry, but gemini image with glassline skin doesn't give a % fromwhat I could see.

tbh, I think the dm800 tuner is quite good, as can get some signals from focussat on 1w quite well, which dm500 tuner could not get!

[Killjoy]

@aabs

The signal readout is in dB not %, the figures you have quoted are perfectly good.

KJ

[loveman]

not quite true from what I've seen. In some images, they give you a % which differs from the dB... So I think that it's been tried to give a %, but it just doesn't work properly... Hence why dB readings are a more accurate indication...

[Eugenie]

All images for DM800 support both % and S/N (although as mentioned, the % value is strangely calibrated), it is supported by the main application. Whether or not you get % or S/N ....or both depends on your skin.
You can modify your skin.xml to show which ones you want;
For dB
<convert type="FrontendInfo">SNRdB</convert>
For %
<convert type="FrontendInfo">SNR</convert>
You will also in most cases need to alter a few other values to have a proper display of the values.

The true signal quality measurement is the bit error ratio (BER). Unfortunately, the Dreamboxes simply present a bit error count without putting it into context.
The best way to display BER is in exponent form (ex 0.0E-2 - 0.0E-8).
If the value presented is the post viterbi (p V BER), in other words, after the error correction has taken place, then it is easy to see just how good the quality is and how much tolerence you have before reaching the quasi error free state (QEF).
QEF state is reached at 2 errors /10.000 bits (p V BER 2E-4). With more the 2 uncorrected bits per 10.000 bits you will start to see interruptions on your tv screen. The good thing about the QEF limit is that it is always the same value no matter what error correction (FEC) is used. Other measures will differ. No matter if the FEC used is 1/2 or 7/8, the QEF limit is the same.
If you have an instrument presenting both p V BER and CBER (channel bit error rate value which is measured before the error correction) you can also see just how much the error correction corrects the data.

As for measuring a signals ratio to noise, that should always be done in dB, not in %.

By the way, how will it help to see what S/N people get when they use different dishes, different lnb's, different diseqc switches...all in different locations? About any loss in signal using a diseqc switch, the actual loss should be declared on a sticker or given were ever information about the switch can be found (manufacturers or resellers web page). I find that a good quality switch will not impact your signal quality very much, in fact, hardly at all.

My opinion is that the general sensitivity of the DM800 tuner is good.

[aabs]

It happens that I posted the SNR because there were slight differencies in the readings. If I was to quote the db it would of been 6.3 for each bird.

The reason I ask for data is I disagree that the tuner on the 800 is good.
I get 11db when I bypass the Diseqc from the 800.
But if connect my samsung dsr9500 which is reported to have a bad tuner I get 11db through the diseqc and between 11db and 15.5db when direct to LNB.

Another thing which worries me about the tuner in the 800 is the amount of tuner failed messages it gives and zap up then down the channels sorts it.

It would be easy just to take the box back and say its faulty so I wanted to see others readings to confirm tuner faulty or tuner to be okay.

I think that I will be able to conclude even if SNR or db readings are given.

PS I also have an MTI lnb which gives slightly worse readings and I have metered the dish for optimum position.

[loveman]

Well, as stated, I think the tuner on the 800 is pretty good. My dm500 doesn't lock on on some channels as the signal is too weak, but the 800 can just about lock on!

Of course, my tm5400 could lock on better, but that's a different story, as it's known to have more sensitive tuner!

On hotbird, as long as all is set up ok, then you should easily get 11, even up 13db... Are you using the same cable on the 800 as on the dsr9500? As maybe you have a badly made cable? Maybe try remaking the cable eitherway?!

[aabs]

Yeah, same cable (PF90) same dish and lnb.
Strange that im getting better readings tonight in the rain!!