[mythtv-users] What does ATSC poor signal look like? or isthePCnot up to it?

[Andre Newman]

On 16 Apr 2009, at 22:06, Misty P wrote:
>
> Yup yup, if you're getting UNCs then you have a signal quality  
> issue.  I get UNCs (and BERs) when the winds *really* pick up around  
> my place and blow about 45 MPH...  it starts the tree across the  
> street rocking and my tuners lose their mind trying to compensate.   
> Once the wind dies down below 40 or so, the tuners all happy-dappy- 
> doo again.

Makes sense, I was fooled into thinking everything would be simple  
being so close to the transmitter, might even be he's got too much  
signal and it's bouncing around everything in the house. I know DVBT  
thrives on reflections but I don't think ATSC behaves the same. I used  
to be a radio ham and worked in TV with radio cameras in the analogue  
days so I've chased enough strange signal situations along the way,  
one studio job we did only worked if we ran the transmitters are very  
low power 1 to 3 mw with high gain antennas, needed to keep the  
bounces off the studio walls outside of the FM capture effect.

Strangely enough most of the old tricks still help when dealing with  
digital gear!

RF used to be a big black art, the mobile phone people have turned it  
back into a science but TV people are still in the art rather than  
science camp most of the time!

>>
> Haha, yeah you pretty much have to slay the elephants in order; if  
> the signal isn't rock solid nothing else can be.  The good thing is  
> that myth leaves the tuners tuned even when it's not really 'doing'  
> anything (I think that's a configuration option somewhere), which is  
> super handy for antenna futzing.  (Don't have to worry about the  
> dreaded 'There was an error displaying video' message!)

Found that out from playing with VLC and Xine, if you have active EIT  
off and set the capture for "on demand" use then you can use the tuner  
while MythTV doesn't need it.
>>
>
> I think I can beat that! http://www.avsforum.com/avs-vb/showthread.php?s=e2246271565759ce11b582385f2413b6&p=15892034#post15892034
>
You didn't invert the pringles can wifi antenna by any chance ;-P

I've been to a few of those kind of setups, as an engineer it's  
possible to spend days and never work out how that particular  
combination works at all much less works well! I dread to think how  
you arrived at that!!
We get situations in Europe where the best results are by pointing  
antennas at walls (or mountains) in totally the wrong direction,  
usually it's to reduce the high power analogue TV signal and the  
robust digital signal sorts it's self out.

Sounds like the trees are a functional part of your antenna! There was  
a wood close to where I grew up in which all radio signals  
disappeared, growing on an iron ore deposit supposedly, even police  
high powered transmitters stopped working in there, maybe your trees  
are related....
>>
> No problem.  I am noting that the output from femon on the different  
> model cards is completely non-comparable; your signal numbers are a  
> few orders of magnitude higher than I get with my internal cards.   
> (My signal strength tops out at 0127!  And the status line is  
> *completely* different.  I know, I know, it comes with source...)

I ignored that totally, working with domestic satellite receiver  
systems one manufacturers 70% signal strength is another's 12% I  
quickly learned that ber is the only thing to trust and usually that  
is cooked up into "signal quality" which might as well be measured in  
Elephants to the furlong cubed. Even the mega expensive broadcast  
receivers vary madly between manufacturers, there are standards to  
adhere too but as always with standards there are so many to choose  
from! I'm sure it's no fault of the driver authors, they will only be  
passing along what the hardware reports.

Cheers