[mythtv-users] Poor Signal Strength

[Andre Newman]

On 18 Mar 2010, at 16:10, Devin Heitmueller wrote:

> On Thu, Mar 18, 2010 at 11:56 AM, Andre Newman
> <mythtv-list at dinkum.org.uk> wrote:
>> I did some research a year or two ago with several DVBS & S2 cards, the receiver sensitivity was pretty poor compared to a modern decent make set top receiver.
>> The Nova S+ was around -65dBm which is as bad as the old QualiTV receivers from an age ago or the newer cheapo Fortec Star Passion.
>> The HD-S2 & HVR-400 was a little better at -72dBm but still nothing like a decent stb receiver, better than -78dBm is common now.
>> TT3200 was -68dBm.
>> 
>> So yes, most PC sat cards need more signal than a good modern stb, I'd like to know if the recent cards are any better or maybe worse but I don't have access to a calibrated signal source anymore.
>> You'd need a significantly bigger dish to make up the difference between -65dBm and -78dBm!!
>> 
>> Of course there are lots of other factors especially inside a PC and sensitivity varies greatly across the frequency range, all the same I overspecced our communal sat feed system here to ensure I wasn't going to have loads of glitchy recordings.
>> 
>> Andre
> 
> It's not just the hardware.  For the most part, the driver developers
> do "just enough" to get the board basically working, with very little
> time spent on fine-tuning the performance.  Fine tuning the driver is
> a huge investment in time, whereas most people will never notice the
> difference.

I had suspected as much, not that there seems to be that much better fine tuning in the manufacturers Windows drivers in some cases!

Let's be thankful for forward error correction and mpeg stream fault tolerance...

> 
> It's an unfortunate reality, but there are so many products out there
> that need support we cannot even keep up with just making them
> basically work.
> 
> There are exceptions of course, such as cases where some commercial
> party needs a particular board to work very well, and pays a developer
> to take the time to do the optimization work.  Finding a developer
> willing to burn forty or fifty hours doing such for no compensation is
> a bit of a challenge though.

So am I likely to find out which cards get any extra attention by lurking on the lkml? I believe there isn't a separate v4l-dvb list any more.

And if I ever get the project that I was testing DVBS cards for off the ground I'll know where to ask around to fund some driver TLC.

Andre

> 
> Devin
> 
> -- 
> Devin J. Heitmueller - Kernel Labs
> http://www.kernellabs.com
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