HD on the air

auggybendoggy wrote on 12/15/2008, 8:41 PM
Guys,
I simply do not know who to ask and searching for an answer has left me empty handed.

My Samsung DLP with a digital tuner works fine. But once in a while a channel just drops off the face of the earth. I cant add it cause browsing the channels to add has NO 7-1 (ABC in los angeles).

a few months ago 5-1 (ktla warner in los angeles) did the same thing and now that channel is present but now we lost ABC.

The timing seems ironic and makes me think my TV is defective???

The channel strenghts are strong and 7 air comes in fine but 7-1 does not???

Any help would be appreciated.

Auggy

Comments

Coursedesign wrote on 12/15/2008, 9:07 PM
Channel 7 is in the VHF band, 7-1 (aka 7.1) is in the UHF band.

Do you live in Brentwood? Your problem is common there.

Basically, you need a better UHF antenna.

When your signal is marginal, the digital channels can come and go.

Former user wrote on 12/16/2008, 5:53 AM
Yeah, isn't digital wonderful.

Dave T2
JJKizak wrote on 12/16/2008, 6:14 AM
In my area the 3.1 sometimes flops to 2.1 and sometimes 2.1 and 3.1 are both available even though they are both the same channel. Digital has a lot of problems with signal strength and path intermod and sometimes will just start going bananas with airplanes in the path or some other anomolies. (signal oscillating back and forth from nothing to something causing large blood pressure increases) Scanning during "atmospheric ducting" will cause some digital channels 100 miles away to totally interfere with the local digital channels on the same channel. (causing gutteral comments like "what the????????") When the digital switch occurrs there will be a great amount (blank) (blank) of (blank) screaming (blank) ank) (blank)
an(blank) bit(blank) pis(blank) people.
JJK
richard-courtney wrote on 12/16/2008, 6:39 AM
Checking antennaweb.org for zip code: 90028

Station KABC is expected to go back to VHF in Feb. so you might be fine since you
get analog 7 in good now.
Coursedesign wrote on 12/16/2008, 8:30 AM
I live in West L.A., about 45 miles from Mt. Wilson where the TV broadcast antennas for Los Angeles and Orange County are located.

Just using a Zenith Z-HDTV tabletop antenna pointed out the window, I get all digital TV stations from 2-69 except 24 and 30.

This is with an old Samsung SIRT-451 receiver I've been using for four years, and no antenna preamp.

Can't complain about that.

But if KABC-DT goes to VHF, I'll probably have to get a dual-band antenna. Sigh.

auggybendoggy wrote on 12/27/2008, 9:32 AM
I have an amplified antenna indoors and it does faily well.
I bought a coupler to add a second amplified antenna hoping to boost my signal to max. Is this possible?

The co. who sold me the coupler told me thats what it's for but I don't want to pay another 50.00 bucks and it doesnt work : )

Aug
richard-amirault wrote on 12/27/2008, 3:07 PM
Couplers are to add a second TV to an existing antenna .. not multiple antennas on a single TV.

That being said .. If I were you I'd try replacing the existing antenna with the amplified antenna .(forget the coupler) . but only if you are not satisfied with the existing antenna.
JJKizak wrote on 12/27/2008, 3:11 PM
There are some people who claim (AVS forum) that adding multiple antennas to one receiver does in fact work. I have not tried that myself.
JJK
richard-amirault wrote on 12/27/2008, 4:50 PM
A coupler is designed to split a signal to two receivers .. AND .. isolate the two receivers from each other (to prevent interference)

I suppose you can connect two antennas to one TV set .. but if I were doing it .. I would not use a coupler .. a coupler would actually reduce the signal getting to the TV from the two antennas.

At least that's how I understand it.
Coursedesign wrote on 12/28/2008, 12:50 AM
If you get a second identical antenna and combine the signal from the two, you get twice the signal voltage (they add up), but the splitter takes half in order to not lose the impedance matching, so you end up with the same end result (there are some things that can change that, but nothing attractive).

Better to get a bigger antenna, or a very low noise amplifier. Gain alone is not enough, because if the amp has too much self noise, you're just amplifying that with the signal and your S/N doesn't improve.

auggybendoggy wrote on 12/28/2008, 10:36 AM
can you guys point me to a good amplified antenna not the size of the hindenberg.

Aug
richard-courtney wrote on 12/28/2008, 4:38 PM
Can you tell us the channels (actual not virtual 7.1) or at least all the the call letters
of the stations you want to pickup?

Can you also give us the zip code where you live at so we can figure the distance
to the towers?

Also, how many sets will be connected? 4-way split Ok?

Finally, have you contacted a local dealer that installs antennas and/or satellite
dishes? They would have experience with your location so we don't guess.
richard-amirault wrote on 12/28/2008, 5:10 PM
can you guys point me to a good amplified antenna not the size of the hindenberg.

Hmmm ... are you looking for an *indoor* antenna or an *outdoor* antenna?
JJKizak wrote on 12/29/2008, 5:17 AM
You can use this formula: Antenna size + antenna height above sea level + antenna position + quality of lead-in + sensitivity of HDTV tuner + atmospheric anomolies + aircraft-in-signal paths=quality of received signal.
JJK
musicvid10 wrote on 12/29/2008, 7:00 AM
Looking for a CECB (Coupon Eligible Converter Box)?

I went with the RCA (the top pick on CNET) and I am entirely satisfied.
Simple, functional remote, good fringe reception, very good picture, and a usable program guide make this an excellent first choice.

I also have ordered a Channel Master with SVHS / Composite outputs for my set-top DVD recorder and TV. Will let you know how it works out.
John_Cline wrote on 12/29/2008, 7:35 AM
I've evaluated quite a few of the CECB receivers and found the Zenith 901 (made by LG) to be very, very good. I also have the Channel Master CM-7000 receiver and it's pretty decent as well. I got it mainly because of the S-Video output (not SVHS, that was a higher resolution VHS videotape format.) As expected, the S-Video output looks slightly better that the composite output.
musicvid10 wrote on 12/29/2008, 8:23 AM
You're right, I should have said S-video.

Since you have the Channel Master, John, let me ask a couple of questions:
-- Can the S-video and composite outputs be used simultaneously, or are they switched?
-- How is the sound quality? The RCA specs say Dolby Digital quality, the CM says Stereo. (I know none of the CECB's output 5.1).

Thanks for sharing your impressions.
Coursedesign wrote on 12/29/2008, 8:24 AM
When I switched between the DVI/HDMI, S-Video, and component video outputs on my Samsung SiRT-451 ATSC tuner, there was a world of difference with the digital signal.

A different league frankly, and well worth pursuing if you have a TV with digital inputs, either DVI or HDMI.

John_Cline wrote on 12/29/2008, 9:21 AM
The CM-7000's S-Video and composite outputs aren't switched., I've never tried using both at the same time, but I assume that they both work simultaneously. I'll try it later.

The audio quality is fine on both the Zenith and the Channel Master. Both units decode the ATSC Dolby Digital audio and output it as analog stereo. None of the CECB tuners have digital output for decoding with an external audio receiver. I haven't done any critical listening to either of them as I just have the boxes for a couple of nice analog CRT SDTVs that I don't want to get rid of just yet.

I have ten other HDTVs that have ATSC tuners built-in and the difference between a good SD TV with a box and real HDTVs is night and day. Nevertheless, those SDTVs have never looked as good as they do being fed with the boxes, but since the HD is being downconverted to SD, it's still just exceptionally clean looking SD television.
plasmavideo wrote on 12/29/2008, 10:31 AM
Boosters, amplifiers, etc on indoor antennas can be your worst nightmare!

Typically the problem with digital reception is NOT the strengh of the signal, but how much multipath problems you are having. In analog, multipath showed up as ghosting and scratchy audio. In digital, you don't see ghosting, but the multipath interference gets to a point where the error correction in the receiver is totally overwhelmed, and you get pixelation. More multipath and interference will cause the receiver to not even attempt to decode the signal, and you get a blank screen. Boosters amplify not only the main signal, but all of the mulitpath and noise as well, compounding the problem. Indoors, you are probably getting lots of reflected signals, especially at UHF, hence the mess.

We've run lots of tests on this very thing, and a lot of times I've had our viewers remove the "booster" and suddenly they get all of the stations clearly.

Also as mentioned, be sure to have an antenna that covers both UHF and VHF, as a lot of stations are going back to VHF after the February cutoff.

I have seeveral PDF docs I've put together regarding these issues. They also cover a variety of other issues as well, and our viewers have said that they were very helpful. Some of the FAQs relate specifically to here in central Virginia, but a most of the information is general in nature.

I have no way to host them at the moment, but if anyone would like copies, I would be glad to email them to you as soon as I get back to work.

Tom
auggybendoggy wrote on 12/30/2008, 4:59 AM
plasmavideo,
I would truly appreciate it. Perhaps that is my problem. It is an indoor amplified antenna and I just have to always change it's position.

I do leave about 4 miles south of Ontario Airport (california) so perhaps that lends to the drop in signals.

Anyhow I'd appreciate it.

Aug
richard-courtney wrote on 12/30/2008, 8:24 AM
The bulk of your channels come in due West and are around 32 miles away.

30 KPXN is NW

24, 24.1 KVCR and 25 KBLM-LP due East

69 K69CO and 31.1 KVMD-DT NE

Antennaweb shows recommended antennas are the yellow and green
marked boxes and do NOT recommend amplification.

Also antennas with build in amps such as Terks can be overdriven from nearby
FM stations. If you feel you must amplify the signal use an FM trap before the
amplifier. For the stations not coming in from the West, I'd use a device called
"jointenna" tuned to your alternate channel or use an antenna selector switch.
Coursedesign wrote on 12/30/2008, 11:51 AM
Try the Philips PHDTV1 successor to my Zenith indoor antenna.

It is legendary for a reason, easily beat my amplified antenna, and even beat a bulky multiple bow tie antenna.

plasmavideo wrote on 12/31/2008, 6:42 AM
Auggy,

I don't have access to your email address. You don't have that set up in your profile.

You can email me from my profile, and I'll reply to you with that info.

Tom