I know the s/n value was strange but it was only when I had HIGH% signal that I was getting pixelation and sound "pops". I'm about 40-50kms from the transmitters and have always had a "noisy" analog signal.
I would love to see what the true signal strength is but I dont have access to any antenna test gear.
I mainly tried the experiment so I could work out an antenna distribution design for my network which will have a rack of 1 master and 6 or 7 secondary backends coupled to 3 or 4 remote frontends. With three boys, 19,10,8, the wife and myself we record/timeshift a hell of a lot.


> Joe Votour <vulturej@vulturesnest.net> wrote:
> 
> Quoting noelcollins@optusnet.com.au:
> 
> > Does anyone know how or what the OSD signal % means?
> >
> > I am using the current release of Mythbuntu (7.10) with a Leadtek   
> > DTV2000H card receiving Free to Air DVB-T ( all VHF freq ) in   
> > Sydney, Australia
> >
> > Last night I was playing around with the antenna system which has a   
> > masthead amp and got the following readings
> >
> > 1) Lead direct to wall ***Signal 50% - S/N 4.8 db - BE 0 - Lock OK
> > 2) 10db attenuation ***Signal 55% - S/N 4.8db - BE 0 Lock OK
> > 3) 20bd attenuation *** Signal 60% - S/N 4.8db - BE 0 Lock OK
> > 4) 2 way splitter *** Signal 75% - S/N 4.8db - BE 0 Lock OK
> > 5) 3 way splitter *** Signal 100% - S/N 4.8db - BE 0 No Lock
> > 6) 4 way splitter/Amp +12db *** Signal 35% - S/N 4.8db - BE 0 Lock OK
> > 7) 2 piggy backed splitter/amps ***Signal 20% - S/N 4.8db - BE 1000 No 
> Lock
> >
> > From this I am getting the idea that the % is inverse to the actual   
> > signal strength and that below 20% I am actually overloading the card.
> 
> Disclaimer: I'm a QAM/DVB-C guy, I don't know much about DVB-T.
> 
> The numbers come from from the Video4Linux driver, and there are some  
> drivers that are known to give incorrect numbers (the driver for the  
> DViCO Fusion Lite back when I used it).  A 4.8DB Signal-to-Noise ratio  
> is horrendous, and would not actually give a usable signal (at least  
> not in a DVB-C/QAM world).
> 
> It's been over a year since I've done any V4L work (not driver  
> development, just a simple QAM capture program), and I found that the  
> API for fetching the signal level at that time *suggested* a return  
> value from 0-65535 for signal strength (0 being 0%, 65535 being 100%),  
> but not all drivers necessarily honor that.
> 
> I would say that direct to the wall is probably your best signal, 20DB  
> is some serious attenuation.   However, you may very well have to do  
> things by trial and error.
> 
> If you really need to know the signal levels, then you'll either need  
> a different DVB-T card (where the numbers are implemented correctly),  
> or use another OS/piece of hardware that gets it right.
> 
> -- Joe
> 
> 
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