Reporting Full signal and no signal at the same time? - AVS Forum
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post #1 of 16 Old 10-08-2009, 05:02 PM - Thread Starter
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I'm having a strange issue with an RCA DTA800B1 converter box, and I can't tell if it is the box itself or if it's just a signal issue.

I live in a rural area of the UP of Michigan (just south of Houghton), where I can only get two channels (two sub-channels on a single frequency). I've been having an issue where the channel will stutter, then freeze followed by the box reporting "No signal". The problem is, while the box is reporting that it is not receiving signal on either channel, it is also reporting 75%+ signal, and will detect the channels on a rescan. The box shows an individual signal bar for each channel, and these bars indicate strong signal as well.
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post #2 of 16 Old 10-09-2009, 04:53 PM - Thread Starter
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I think the issue is ingress. There is a radio transmitter not far away and about 180 degrees to line of sight to the tv tower. I noticed that I also get a lot of ingress on other FM stations from it.

Does anyone have a suggestion for a directional antenna?
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post #3 of 16 Old 10-09-2009, 06:27 PM
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Are you sure you don't have an overload problem?

This sounds more like an issue that would be best resolved in the antenna forum or your local DMA forum.
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post #4 of 16 Old 10-10-2009, 10:49 PM
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Quote:
Originally Posted by mbeals View Post

I think the issue is ingress. There is a radio transmitter not far away and about 180 degrees to line of sight to the tv tower. I noticed that I also get a lot of ingress on other FM stations from it.

Does anyone have a suggestion for a directional antenna?


What kind of antenna setup are you using?
Has this problem "just started".. Or have you just got the box?
Do you have a friend that has a spare box you could borrow?

Go to tvfool.com to see what stations are transmitting. This should give you info you will need when visiting antenna forums.

(This will not tell you FM station info- If you indeed have a powerful FM station in your area best to ask the guys on the antenna forums for suggestions on that ! FM Trap?...)


Here's one such site:

http://www.digitalhome.ca/forum/forumdisplay.php?f=186



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post #5 of 16 Old 10-14-2009, 04:31 PM - Thread Starter
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I'm just using set top bunny ear antennas....nothing fancy at all.

What is odd is that the the problem is very intermitent. I had no tv for two days, the one morning it was working fine.

Last weekend I started getting digital artifacts and when I turned on the box on monday morning it now has 0 signal and cannot locate any channels.

I'll check out some antenna forums, but could an overload burn out the tuner over the course of a week or two?
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post #6 of 16 Old 10-14-2009, 05:39 PM
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Quote:
Originally Posted by mbeals View Post

I'm just using set top bunny ear antennas....nothing fancy at all.

What is odd is that the the problem is very intermitent. I had no tv for two days, the one morning it was working fine.

Last weekend I started getting digital artifacts and when I turned on the box on monday morning it now has 0 signal and cannot locate any channels.

I'll check out some antenna forums, but could an overload burn out the tuner over the course of a week or two?


Has this problem "just started".. Or have you just got the box?


Q: you say you only get (2) channels, sub channels on the same freq. Do you mean you're only getting two channels on the same station?


Anyhow... It is quite possible:

1: Station is having problems
2: Box is dying
3: Box is crap (Do you have a friend that you could borrow a box from?)
4: There are atmospheric conditions working against you.
(At least in Michigan this time of year there shouldn't be many leaves on the trees.)

I'd go to http://www.tvfool.com search for the stations...

THEN POST a LINK to the info TVFOOL shows..

You may find instead of LOS, you are getting signals 1Edge, 2Edge, or Tropo.


Another suggestion is to take box OUTSIDE, do a scan.

Another course of action is to take the box to say a friends house, or take a little "trip"....hook up to a portable tv at other location to see if the box is "working".


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post #7 of 16 Old 10-14-2009, 05:53 PM - Thread Starter
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I just installed the box. It worked 2 days before having issues. The two channels I do get are from the same station. They are channels 5.1 and 5.2 (KBKP). I've attached the radar plots for TV and FM stations.

the full link (if it works) is:

http://www.tvfool.com/?option=com_wr...03fb86ca784ce5
LL
LL
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post #8 of 16 Old 10-14-2009, 07:57 PM
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post #9 of 16 Old 10-15-2009, 12:08 AM
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Quote:
Originally Posted by mbeals View Post

I just installed the box. It worked 2 days before having issues. The two channels I do get are from the same station. They are channels 5.1 and 5.2 (KBKP). I've attached the radar plots for TV and FM stations.

the full link (if it works) is:

http://www.tvfool.com/?option=com_wr...03fb86ca784ce5


Box worked for (2) days before having issues points to box itself is bad. Then again the station may be having problems.

Take the antenna OUTSIDE.... try that. Try another box....

What kind of house do you live in?
Basement apartment?
Aluminum siding
Reinforced concrete?
Antenna has a clear LOS to transmitter?

5.1 and 5.2 (WBKP). VHF, chan5, (5.1) ABC, NM(db) 68.1, Pwr(db) -22.7, Path=LOS, Distance 6.5 miles.

PS#1: You should be getting UHF channel 27 at 1.0 miles away from you...

PS#2
Quote:


Does anyone have a suggestion for a directional antenna?

http://www.digitalhome.ca/forum/forumdisplay.php?f=186


(WBKP). 5.1 and 5.2 are VHF Low, so keep that in mind when buying /building a antenna. VHF-LO channels the signals tend to suffer interference worse than VHF-HI and UHF channels. During the transition to digital TV across North America, the use of VHF-LO channels is being phased out and the frequencies reassigned to other uses than television.

http://www.digitalhome.ca/forum/showthread.php?t=41102



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post #10 of 16 Old 10-15-2009, 05:25 AM - Thread Starter
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My initial thought was that the box was bad too, but I wanted to make sure there wasn't intermittent interference from those close by transmitters or even that strong signal damaging the receiver.

I live in an old wood framed, asphalt shingled house. The antenna is set top on the first floor (so about 5' off the ground). I am tree shrouded, but nothing in the foliage has changed matching the drops in signal.

I'll try bringing the antenna outside today.

One thing I do find odd is that I cannot receive UHF 27. Since that is an analog station, shouldn't it have been shut off months ago anyway? The second attachment to my last post was the FM radio radar plot, which shows several FM stations with very high power along the line of sight of channel 27 (or 180 to channel 5).
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post #11 of 16 Old 10-15-2009, 05:45 AM
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Reception of VHF (high or low band) is seldom reliable indoors. There are just too many noise sources in the house, And the larger wavelength radio waves don't travel through walls nearly as well as UHF. An outdoor antenna may help. To test, connect a piece of coax to your rabbit ear dipole antenna and take it outside.

Also suspect FM interference or the crappy RCA box, which are know to die, sometimes within days after installation. If you can borrow a decent box (Artec, Zenith/Insignia or DTVPal Plus), that would quickly rule out the box problem.
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post #12 of 16 Old 10-15-2009, 05:45 AM
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Strong signal cannot damage the receiver, the receiver simply "closes its eyes" until an overload goes away.

Is your antenna amplified or not? If amp'd, try a non-amped antenna since strong stations + amplifiers usually equals problems.

Low-V, as mentioned, is terribly sensitive to EMI. You may need to start turning electrical stuff in your house off (unplug it) to see what may be radiating and causing interference.

Channel 27 is an ANALOG channel - the CECB has to pass it through (if capable) and its transmissions cannot be tuned by the CECB. However, it still may be a source of problems for the CECB.

Your initial symptoms are of strong signal overload, multi-path, or interference.
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post #13 of 16 Old 10-15-2009, 06:23 AM
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I've had good luck with the DTA800B1 CECB. It's signal meter leaves a lot to be desired though. When the DTA800B1 reports about ΒΌ or 1/3 reading, my Sunkey SK-801ATSC reports much higher levels.

To watch analog stations on the DTA800B1, you'll need to power the unit "OFF" and it only works through the RF connection.

You say you're in the trees. Does this mean that you don't have any open sky around you? With lots of trees and using an indoor antenna, your losing a lot of signal before it ever gets to your antenna.

Have you tried creating different lengths on the antenna rods or different angles, while you try differnt positions?
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post #14 of 16 Old 10-15-2009, 08:17 AM - Thread Starter
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even with the antenna straight into the TV (no box), I don't get analog 27...not even faintly (which I think I should for a transmitter that close...even with trees).

I do have open sky directly above me and 90* to LOS of the transmitter. I'm not ruling out the possibility of tree attenuation, but I find it funny that signal levels can drop from 75% to 0% suddenly with no range in between.
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post #15 of 16 Old 10-15-2009, 12:17 PM
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Since it's VHF on an indoor antenna, anything might be causing the problem. And the signal strength drop from 75 to 0 is not unusual at all, if there is interference, multipath or overload. IS the antenna amplified, or just regular unamp'd rabbit ears?

The suggestion to unplug/turn off EVERYTHING else in the house is a good idea, to rule out indoor interference from other electrical devices.

Based on other RCA boxes I've seen that started acting weird, I still suspect it may be part of the problem.
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post #16 of 16 Old 10-28-2009, 10:50 AM
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Quote:


The two channels I do get are from the same station. They are channels 5.1 and 5.2 (KBKP). I've attached the radar plots for TV and FM stations.

At almost a 70 NM, I would think your problem is simple overload. Try a paper clip antenna instead of the rabbit ears.
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