A question/request concerning SNR

[captain jack]

Hi,

As we all know, the Vu boxes do not provide a SNR value in dB but always in percentage. This is something to do with drivers.

Now, I have checked my friend's Dreambox 800HD receiver and compared the dB value and the percentage value to find a correlation. The correlation seems to be SNR dB = SNR% / 6.21 which gives a more or less accurate conversion.

So, if my SNR% on the Uno is 34%, which is a just about watchable picture, it converts to SNR dB of around 5.47dB which sounds about right. I *know* that this value shouldn't be taken as gospel and it's purely an indication etc. but I was wondering if it's possible for the VIX team to calculate the dB from the percentage SNR?

I have played around with OpenWebIF and edited the signal.py file like the following:

\t<e2snrdb> ''')
_v = VFFSL(SL,"snr_db",True) # u'$snr_db' on line 4, col 12
_v = round(_v/6.21,2)
if _v is not None: write(_filter(_v, rawExpr=u'$snr_db')) # from line 4, col 12.
write(u''' dB </e2snrdb>
\t<e2snr> ''')

After restarting Engima, my http://uno/web/signal changed from:

<e2frontendstatus>
<e2snrdb>42 dB</e2snrdb>
<e2snr>42 %</e2snr>
<e2ber>0</e2ber>
<e2acg>65 %</e2acg>
</e2frontendstatus>

to

<e2frontendstatus>
<e2snrdb>6.76 dB</e2snrdb>
<e2snr>42 %</e2snr>
<e2ber>0</e2ber>
<e2acg>65 %</e2acg>
</e2frontendstatus>

This helps for windows based apps which use this path to get signal levels but skins seem to take this information from somewhere else.... So, er.... where? skin.xml seems to look at "FrontendInfo" but I am not sure how I can use skin.xml to change values....

Any advice/ideas/criticisms?

CJ

[Rob van der Does]

STB's are no signal meters. The SNR-read out, whether in % or dB, is always just a value, not calibrated at all. Good for comparison using one and the same box when e.g. aligning a dish, but not for comparing values between boxes.
So what would be the use of using this not-calibrated value of a Dreambox to convert the percentage-read out of a VU-box?
The percentage read-out can be used for the very same purpose as any dB-read out: aligning a dish, comparing the SNR of several transponders and see if a transponder has it's usual value in case of disturbed reception. Nothing more, nothing less.

So percentages are fine; might even call them cows; its the numerical value that counts.

[captain jack]

Rob, it's nothing more than a matter of personal preference of how I want my values represented. Same sort of preference as how you want your skin to look.

All I am asking is where I can change the representation of SNR read-out on the Infobar - that's all.

[irishchris]

As far as i remember this option has already been coded into the image. Setup/system/customise off the top of my head. Will check later when home for correct location of this option for you

Sent from my GT-I9300 using Tapatalk 2

[captain jack]

Yeah, there's an option in System > OSD > Settings but it doesn't change one from the other.

[irishchris]

Correct location is menu/setop/system/osd/settings and change infobar reafout from snr to db. Reboot and should then be displayed in db in infobar

Sent from my GT-I9300 using Tapatalk 2

[irishchris]

Yeah, there's an option in System > OSD > Settings but it doesn't change one from the other.

After changing the setting , did you restart your reciever?

Sent from my GT-I9300 using Tapatalk 2

[Rob van der Does]

Yeah, there's an option in System > OSD > Settings but it doesn't change one from the other.

Correct: most drivers don't support that. so they will always show the same figures, whatever choice has been made.