[opendtv] Re: OTA

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
  • Date: Thu, 8 Mar 2012 15:40:03 -0600

Dan Grimes wrote:

> I have only found one way to get these signals: a very wide
> (120-144" wide) outdoor antenna with line of sight.  Without
> line of site, much of the signal is coming from reflections.

Possibly, the problem in a large bowl like the Las Vegas market is that the 
direct and reflected signals are all strong and that some reflections go beyond 
the 50 usec or so limits of 5th gen receivers? It seems to me that you have 
most success when you manage to either do away with the reflections, by aiming 
a directional antenna specifically at the towers, or with indoor antennas in 
apartments, where longer lag reflections have sort of petered out in signal 
strength? Would be really nice to have a spectrum analyzer picture.

But for instance, both Mark and I are probably relying on reflected signals all 
of the time, rather than on the direct propagation path. Also Cliff, at least 
for the Philadelphia towers, doesn't have LOS, I don't think. Lives behind a 
tall hill, right Cliff?

> Those in apartments where they cannot mount an outdoor antenna
> must lose at least channel 2, sometimes others.

I suppose you would expect the longer wavelength of low VHF to have more 
trouble getting through windows.

In my case, all of the VHF woes were caused by egregiously low VHF transmitter 
power in the early days. So I've never bought into the notion that VHF, for 
ATSC, has some metaphysical problem. I think the problems are low power, 
coupled with the fact that many DTV users, on June 12, 2009, had been using 
UHF-only receive antennas.

Since then, local VHF channels 7 and 9 have both gone to 50 KW ERP, and 
reception is solid (even though I have only the two, four-bay, UHF antennas).

I actually one time did receive Ch 11 from Baltimore. A fluke. Hasn't been 
available since that one time, that I can tell.


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