Log in Register FAQ Memberlist Search pcHDTV Forum Index
pcHDTV Forum

pcHDTV Forum Index -> Installation/Setup -> HD-5500 Won't Pick Up Two Channels That Another HDTV Will
Post new topic  Reply to topic View previous topic :: View next topic 
HD-5500 Won't Pick Up Two Channels That Another HDTV Will
PostPosted: Sat Nov 15, 2008 10:39 pm Reply with quote
mance
 
Joined: 15 Nov 2008
Posts: 5




am running MythBuntu (hardy heron) and a Streamzap remote. Entire system works great, just as advertised, plug n play install.

however there are two channels I cannot get.

I had an installer come out today and he put an antenna on my roof and ran coax so that it serves two TV's, a normal 32" LCD TV upstairs (everything comes in great!), and my Mythbuntu box going to a 42" plasma downstairs. The two channels in question show up on the LCD TV no problem. He put an $800 scanner on the split going to the mythbuntu box and showed that the two channels were coming in nearly perfectly. The Mythbuntu box however was saying that one was at 70% and the other at 55% and refused to tune either in (it would just freeze on those channels). The installer said he's seen varying behavior from different tv tuners from different makers side by side before. but the LCD TV is two years old and this HD-5500 is brand new.

his suggestion was to try another tuner for mythbuntu and see. so I'm going to have to get a USB tuner or a Silicondust Homerun or some such thing.

so my question is, how do I know if this is a defective tuner or not?

I'm hoping you guys have some suggestions so I don't have to throw this new HD-5500 away and try something else. I get the impression I cannot return it (bought it a couple of months ago; it's taken me this long to get the antenna guy out here after rounds of indoor ones didn't work).
View user's profile Send private message
PostPosted: Sun Nov 16, 2008 10:03 am Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




He is correct about the differences in tuners, but the 5500 has (had) one of the latest and best tuners in it.

There is an option somewhere in MythTV as to what signal strength is considered good. I don't recall where I saw it, but you could try changing it.

If the card gets other stations, then it is not defective. You may need to rotate the antenna some to get a better signal. Go to antennaweb.org to find the correct orientation for an antenna in your location. Give your address for more exact direction help.

http://www.antennaweb.org/aw/welcome.aspx

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
View user's profile Send private message
PostPosted: Sun Nov 16, 2008 7:57 pm Reply with quote
mance
 
Joined: 15 Nov 2008
Posts: 5




it's oriented correctly. I paid the guy hundreds of dollars to provide and install the rooftop antenna, split and run coax to these two locations (the LCD TV and the Mythbuntu TV), and scan it for both strength and quality. he was awesome. regarding orientation, he and I were on walkie talkies, him on the roof me watching the signal meters on the LCD TV's menu, going over the toughest channels to get the orientation and height on the mast the most optimal. we started this process with antennaweb to know where to point. hours later we had all aligned and excellent signals. the LCD TV upstairs using the same antenna feed gets everything. I'm in line of sight, on high ground, and within 8 miles of all of these antennas.

is this normal to not be able to receive some channels even though they are being fed to the card with optimal signal strength and quality?

his website is

www.satproatlanta.com

if you want to check his credentials. he was like a jedi of reception.
View user's profile Send private message
PostPosted: Sun Nov 16, 2008 9:17 pm Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




I'm not questioning the qualifications of the installer. If you are happy with his work, then that's all that matters.

I was wondering if the broadcast towers, of two troublesome channels, are in a different location. This would explain some of the problem. I have one channel that is 90 degrees away from the others. So I have a rotor to turn it in that direction to watch it. The difference between the TV and the PC card could be the tuner sensitivity. If you feel that you may have a bad card, you should send pcHDTV an email.

Have you tried using a different application to scan for channels? Give dvbscan a try, and see if you get different results.

http://www.mythtv.org/wiki/index.php/Dvb_Apps

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
View user's profile Send private message
PostPosted: Mon Nov 17, 2008 11:38 am Reply with quote
mance
 
Joined: 15 Nov 2008
Posts: 5




thank you. that's very helpful. I will give that a try when I can. I also still have to find the right custom timing so that Mythbuntu will talk to my plasma with the right resolution Wink it won't do 1368x768 out of the box.

tuner sensitivity does seem to be at the heart of it. if the signal comes in okay and with excellent strength according to a handheld scanner, then shouldn't the HD-5500 be able to pick it up?

if the antenna needed rotation, wouldn't that have shown up as a weak signal?
View user's profile Send private message
PostPosted: Mon Nov 17, 2008 5:02 pm Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




There seems to be no standard on how to measure signal strength. That is why different methods or devices will give different results. You mentioned that you used the TV's signal meter. That may not be completely reliable, but OK for most cases.

Even if the antenna is only a little bit off, it could effect the reception. You may be getting reflected signals that are interfering with reception (multipath). Some tuners are better in handling multipath than others.

I am only offering explanations, but don't really have a solution. If you decide to get a different card, you can certainly get something cheaper than a pcHDTV card. Hauppauge cards have pretty good Linux support. I would search for Linux support before purchasing anything. Hauppauge has a new lineup of cards, so drivers are still being written for some of them.

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
View user's profile Send private message
PostPosted: Tue Nov 25, 2008 8:49 am Reply with quote
mance
 
Joined: 15 Nov 2008
Posts: 5




thanks for all your help. I have not had a chance to try dvbscan yet but I plan to.

I think I'm going to send an email to PCHDTV asking them what to do. I'm on the verge of buying an HDHomerun and trying that instead.
View user's profile Send private message
UPDATE
PostPosted: Thu Dec 18, 2008 5:49 pm Reply with quote
mance
 
Joined: 15 Nov 2008
Posts: 5




I talked through email to someone from pchdtv who recommended I run a command line tool to record from the two missing channels without invoking mythbuntu, to see if mythbuntu was just scanning them improperly. I have not tried that yet, but am still willing.

however I did get an HDHomerun from Silicon Dust, plugged it into the same coax that was going into the Mythbuntu machine, and the two missing channels came in! it's a great little box, by the way. very nifty. hd on the pc on a 24" lcd is nice.

however, one of the previously missing channels that did come in does stutter. last night a lot (a hiccup every minute), and tonight not at all yet (might be weather related). but otherwise the hdhomerun is behaving just like my 32" tv upstairs that's being fed by the other end of the split off the roof antenna.

next I will take the hdhomerun upstairs and plug it into the coax going into that tv and see if the intermittent stutter goes away, since I've never seen it on that tv upstairs on that channel before. I'm trying to determine if it's the line or the device.

then I'll have to check on this hd-5500 and its command line tools...
View user's profile Send private message
Did you make any more progress on this?
PostPosted: Fri Jan 02, 2009 11:17 am Reply with quote
mcaptk
 
Joined: 02 Jan 2009
Posts: 3




I have a very similar situation. I receive my signal through Comcast. I do not have a Comcast box... just get the signal straight from the cable. My HDTV can get all of the major networks in HD (NBC, CBS, ABC, FOX). These channels come up as channels that do not exist on Comcast's line-up for my location... in fact they are sub-channels. For example, my ABCHD is channel 20-1 and FoxHD is 20-3; CBSHD is 21-1, etc.

When I take the cable out of my HDTV and plug it into the pcHDTV 5500 card (and use the PC to send the picture to the HDTV), I cannot receive CBSHD. In fact, the channels are different. Fox is 18-6 or something like that.

Does anyone have an explanation as to why the channels would show up in different locatoins between my HDTV and pcHDTV card? Thanks for your help!
View user's profile Send private message
PostPosted: Fri Jan 02, 2009 4:42 pm Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




Cable companies often have the cable box remap the channels to make them appear to be on a different channel. This is no different than what the OTA digital channels (ATSC) do.

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
View user's profile Send private message
PostPosted: Sat Jan 03, 2009 10:56 am Reply with quote
mcaptk
 
Joined: 02 Jan 2009
Posts: 3




But for my system, I don't have a cable box. I ran the cable directly to the TV, and was able to get all of the HD channels that I wanted. Then I took that same cable, unplugged it from the TV, plugged it into the pcHDTV card, scanned the channels, and could not get CBSHD. Additionally, the other channels were not at the same channel number / frequency as they were when I plugged the cable directly to the TV.

Is there any good way that I could get the exact frequencies from the TV and then use those in MythTV setup to set the card to the right channels? The whole thing seems very unusual to me... when I bought the card, I just figured I would be able to pick up all of the exact channels that I can pick up with the TV, and I was very surprised when I couldn't.
View user's profile Send private message
PostPosted: Sat Jan 03, 2009 11:53 am Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




Your TV re-maps the channels just like a cable box, that is why I said the OTA channels are re-mapped too.

You can scan for channels using the external program scandvb. It is usually found in the dvb-utils package. You can find more info on using it in another thread.

http://pchdtv.com/forum/viewtopic.php?t=7139

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
View user's profile Send private message
PostPosted: Sat Jan 03, 2009 4:11 pm Reply with quote
mcaptk
 
Joined: 02 Jan 2009
Posts: 3




Ah, now I see. Thank you for the link. I will check it out.
View user's profile Send private message
HD-5500 Won't Pick Up Two Channels That Another HDTV Will
  pcHDTV Forum Index -> Installation/Setup
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
All times are GMT - 7 Hours  
Page 1 of 1  

  
  
 Post new topic  Reply to topic  


Powered by phpBB © 2001-2003 phpBB Group
Theme created by Vjacheslav Trushkin