79 days left before the end of TV.

Page 7 of 7  


Andy writes:
Here are some rules of thumb that, if you have any experience to the contrary, please take issue with me as I am eager to learn experiences of others...
A good analog signal needs about a 45 db SNR or so to make a good picture . As the SNR drops, the signal degrades, more or less linearly, down to a point where sync will drop out...or a blue screen appears, depending on the features in the set.
A good SD signal needs about a 16 db or so SNR at the decoder to lock. If the decoder is locked, the presentation will be good. As the signal SNR goes to where the decoder is dropping in and out of lock, the pixels will freeze until lock is re-established. When the decoder stays out of lock, the pix will stay frozen until the SNR goes so low that the signal detector says "No Signal".... It all happens very quickly , over a few db of SNR change, centered around 16 db or so, for a SD signal.
I don't know about HD...... I guess an interested party could google "HD SNR" and learn quickly.... (but I really ain't interested cuz I like more channels more than I like seeing sweat pores),,,, {>))
Andy in Eureka, retired comm designer from Raytheon/Texas Instruments
PS I ain't kidding about taking issue with me. I'm eager to learn if I've been doing stuff wrong for 40 years :>)))))
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
AndyS wrote:

I don't know about the actual SNR numbers; I've never looked specifically for values.
My experience in looking for the digital broadcasts via the converter box basically echoes your description above -- while up at the antenna on the lift w/ the converter box and a small set so I could fiddle w/ the antenna aiming and see what was occurring I could occasionally manage to get a frame but it was only about 1-2 in 5 minutes or so--other than that, mostly the "no signal" message.
A scan would repeatedly find enough to identify that there was indeed a broadcast channel there, but the signal strength was too low to ever indicate anything at all on the tuning sensitivity screen to be any aid in aiming as would be true in any area w/ a usable signal level.
There was, of course, no information on the converter box about it's actual performance sensitivity levels, etc.
The FCC site the the antenna web .org site all seem to think eventually there should be a usable signal from all three of these translators but so far it just ain't happening.
I'd be far happier camper to simply be able to opt out, but that's not an option of course. One can only hope they will actually increase power to the digital transmission when they pull the plug on the analog and it's the limitation of how much power they have they can spare for the digital while the analog is still the standard that is the current problem and they're not planning on drastically curtailing their energy costs w/ the transition.
--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
[snip]

I' ve already seen many of those points (and yes, that's in practice) and never seen one of those TVs that refuse to work unless the signal is perfect. Maybe that's what you get under laboratory conditions. In the real world, receiving conditions vary.
BTW, it's not "all digital" either, and can't be. If you think otherwise, don't forget the eye is an analog device.
--
21 days until the winter solstice celebration

Mark Lloyd
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mark Lloyd wrote: ...

...
You're undoubtedly not in far fringe areas where the signal strength is low enough to be questionable and analog reception is "iffy".
I've got the situation on the other end I'm talking about -- far distance, presently very low transmission power relative to VHF and the signal is, for all practical purposes, unusable.
Every once in a while (like once every 4-5 minutes) a frame would come across. When it did, it was, as expected devoid of snow and other such artifacts but w/ some level of pixel drop out. But, while some snow and other such analog artifacts, the VHF signal was, while not great, at least usable.
That's the situation I'm discussing, not whether there are some pixels missing now and then in a relatively strong signal area as most urban areas will be and it's only the passing intermittent interference problem that might cause a momentary glitch.
--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Analog reception is VERY iffy here.

--
20 days until the winter solstice celebration

Mark Lloyd
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mark Lloyd wrote:

If you're getting digital then it would indicate to me they're broadcasting at respectable power levels vis a vis the analog.
--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I expect they all do. Consider how many people use analog cable, with no box.

It'll probably be very erratic.

--
21 days until the winter solstice celebration

Mark Lloyd
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 3 Dec 2008 13:43:13 -0800 (PST), " snipped-for-privacy@aol.com"

Here, the CW station is not currently broadcasting in digital but intends to in February.

According to the DTV government site, translator stations are exempt too.
--
21 days until the winter solstice celebration

Mark Lloyd
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

What? Its changed? If they keep changing the number or days left every day or two people will really be confused.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.