[mythtv-users] HDHomerun signal strength required

[Brian Wood]

backuppc at sundquist.imapmail.org wrote:

> 
> Right now I have a single pcHDTV 5500 card which works OK except when
> the weather is bad and the weather is often bad.  

Yeah, ever since they put the government in charge of the weather bureau 
things have gone to pot :-)

TV broadcast signals cab be affected by rain fade, but the effect is 
minimal (it is more pronounced the higher the frequency, thus UHF 
suffers more than VHF, and the higher channels have more potential trouble).

Often when your TV signal fades in the rain it is due to a microwave STL 
(studio transmitter link) used by your local station, or a microwave 
path used to get network programming to the station.

Microwaves are vastly more affected by rain than broadcast signals, 
especially the 13 Ghz. band that's often used for STLs. The rain drops 
approach the size of a wavelength at those frequencies. At 18 or 23 Ghz. 
the problem is even worse, and those frequencies are in fact used in 
some places.

A properly engineered microwave path will have a fade margin built into 
it sufficient to handle most weather, but not all paths are well 
engineered (and fade margin costs money in higher power transmitters or 
larger dishes).

Satellite signals operate in the same general band (Ku, 12-13 Ghz. 
downlink), thus they are affected as well, sometimes even when the 
weather is clear at your site, as you might have a thunderstorm cell 
between your antenna and the satellite. There is generally a lot less 
fade margin in a satellite path than a terrestrial microwave path. 
C-band satellite signals (3.7-4.2 Ghz. downlink) are less subject to 
rain fade, but those are not used by consumers much anymore.

True rain fades are rarely very long though, 20 minutes is a long fade.

If your signal gets poor in bad weather for much longer periods, your 
problem might be poorly weatherproofed connectors in your antenna feed, 
Trees in the path becoming laden with water, snow building up on your 
antenna and other factors only indirectly related to the bad weather.

Obviously long paths are more prone to problems than short ones, and 
even broadcast signals can be affected if the range is long and the 
weather really bad.

beww