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Finding Highest Signal Strength by OTA ATSC channel
http://forums.linhes.org/viewtopic.php?f=15&t=12275		 Page 1 of 1
Author:  BigBill [ Sun Oct 22, 2006 12:38 pm ]
Post subject:  Finding Highest Signal Strength by OTA ATSC channel
Is there a signal strength meter somewhere in knoppmyth I can use to help find the strongest signal for my OTA antennas? I have three antenna's pointing in the different directions required by three mountain tops with the OTA transmitters on them here in San Diego. I have gotten them pretty close using antennaweb's compass settings but I would like to fine tune them for highest signal strenght. I am sure it would be asking alot to have some pretty gui like what you get to dial in my Satellite dish... is there one for OTA using a HD5000AV-pci card?? I am able to see signal strenght when I attempt to watch live tv and there is an issue locking on the channel. I am just trying to find a way to dial in my UHF DB-2 antenna's to get the strongest signal possible.

Thanks, Bill
Author:  jzigmyth [ Sun Oct 22, 2006 1:00 pm ]
Post subject: 
Once you have an ATSC channel selected just hit F7 for a continuous signal strength meter.

This document also has many keyboard commands for Mythtv:
http://www.mythtv.org/docs/mythtv-HOWTO-singlehtml.html
Author:  BigBill [ Sun Oct 22, 2006 4:47 pm ]
Post subject: 
So I click on Watch TV then when a channel comes up I hit F7. A blue box does come up for a little while with signal strength but it seems to go away. Or am I doing this at the wrong place. PS.
Author:  jzigmyth [ Sun Oct 22, 2006 5:32 pm ]
Post subject: 
When I select Watch TV, the TV show comes on and a box comes up with the channel info and a signal strength percent reading. After a few seconds, the box with the info goes away and just the TV show is displayed.

Then I press F7 and the picture goes away and I get a black screen with a box in the upper third of the screen with the channel info, signal strength percent, s/n ratio and "lock" or "no lock". The signal strength bounces around and there is no TV show just black screen on the rest of the screen. This box stays up for ever or until I press F7 again.

I am running a stock R5D1 and my atsc card is the HD3000 (I also have a pvr500 in there, too). What card are you using? Maybe different cards display the signal strength differently...
Zig
Author:  BigBill [ Sun Oct 22, 2006 8:59 pm ]
Post subject: 
Currently I am using a test box with a HD5000AV card. The box is extremely slow with an builtin video. I may be hitting it twice or something. It sounds like the same thing occurs, just a stutter at a time on the test/proof of concept machine. It the few times I left it running and went outside to mess with the antenna's I came back and the statistics were gone. I must be hitting the keys to many times. Thanks for the input! I'm just about ready to get a faster machine to run this on, as it appears Knoppmyth can record HDTV from my antenna's.
Should the same F7 key work from a front end workstation too? It turns out my regular pc's video is also too crummy to display the hdtv signal on my sony lcd panal so I can't tell if the F7 does anything on that machine or not.
Author:  jzigmyth [ Mon Oct 23, 2006 7:07 am ]
Post subject: 
If you PC is slow you might want to think about getting an Nvidia FX5200 video card, or better. If you have an Nvidia FX card you can tell mythtv to use the hardware decoder on the video card ("Standard XvMC" setting with "BOB" deinterlacing). This allows you to play back hdtv with a lot less CPU.

I have a Pentium 2.4 Ghz (might even be a 2.1 Ghz, I'm not home now so I can't check) and it plays HDTV just fine with XvMC enabled. It stutters and pauses continuously with XvMC turned off.

The fact that your box is blue means XvMC is not enabled. When XvMC is working the on screen boxes and menus are in black and white.

I think F7 should work from a frontend only, but I have never tried it, I run a combined front and back end.
Author:  BigBill [ Mon Oct 23, 2006 9:01 pm ]
Post subject: 
Yes, I am planning on buying a good video card. I didn't realize the fx5200 had an mpeg decoder built in. That just helped me make up my mind one which one to get. I was holding out to see if I could find a card with hdmi output but that maybe some time. I will look into XvMC. I am not sure what that is yet. Dang, just noticed my old dell P4 2.5 doesn't have an AGP port just an old regular PCI. I wouldn't imagine there are any pci based cards with decoders built in..

-Bill
Author:  tjc [ Mon Oct 23, 2006 9:20 pm ]
Post subject: 
BigBill wrote:
I didn't realize the fx5200 had an mpeg decoder built in.

It doesn't. What is has is some code in the driver which uses the cards hardware to provide some acceleration, so that the GPU does a lot of (but not all of) the decoding work.
Author:  BigBill [ Mon Oct 23, 2006 11:11 pm ]
Post subject: 
Are there any cards with a hardware decoder and a DVI that will work with knoppmyth?
Author:  jzigmyth [ Tue Oct 24, 2006 6:58 am ]
Post subject: 
I appologize for passing along my misunderstanding of the Nvidia architecture. :oops:
Author:  BigBill [ Tue Oct 24, 2006 9:41 am ]
Post subject: 
In checking out the fx5200 on the internet, I keep seeing references to built in mpeg-2 decoder. Some say it has one and others make reference to speeding up mpeg-2 decoding. There seems to be a regular and an Ultra fx5200. The ultra has a faster clock and more ram. Would one be better than the other for pushing an HDTV?
Author:  tjc [ Tue Oct 24, 2006 7:46 pm ]
Post subject: 
Faster is generally better, at the very least it'll help avoid any potential bandwidth problems with HDTV at 1080i, however, the descriptions for the FX series cards are all variations of marketing speak for the same motion compensation (the MC in XvMC) and IDCT hardware assist for playing back video. A google search for XvMC would be instructive. e.g. - http://www.mythtv.org/wiki/index.php/XvMC
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