Reception Issues At Night

I am having issues at night. It's only with channels 11 and 13. During the daytime, all my channels are 100%. At night, channels 11 and 13 will "drop out" about every 30 seconds. When it drops out, it lasts about 1 second and then it's fine again. If I watch the signal strength while this happens, it goes from 100% to about 20-30%, then back to 100%.

I have read other articles discussing how pressure changes at night can affect antenna reception, but I'm not sure that this is the only culprit. Wouldn't pressure changes be affecting all channels? I know my antenna is pointed the correct direction because I aimed it using a magnetic GPS compass.



Something else that concerns me is the antenna's upward/downward angle. What should it be set? Is there a scientific approach? Or, just guess work? Like I said before, in the daytime, everything is 100% perfect all the time. At night, only 11 and 13 mess up.

Please help.

Questions:

Are 10 and 13 "actual" or virtual channel numbers?

Could you please go to TV Fool, enter your location and details, and post your results here so we can better help you.

See instructions on getting help using TVfool here: How to ask for DTV Reception Help

Just a guess, but 10 / 13 may be weak signals that are getting night time interference from distant stations on the same frequencies. But we need the TVfool from you to find out.

Like MrPogi said, your TVFool report will help us greatly.

I suspect you are seeing co-channel interference or interference from FM stations, especially if channels 11 and 13 are physical channel numbers.

Co-channel interference might be curable with a more directional antenna. FM interference may require a good FM trap.

LibertyBell,

It would also help if we knew the type or exact model antenna are you currently using and how high is it above the ground.

Jim

I atttached the results of the TV Fool. Antenna is 10' off the ground. My antenna is the Antennacraft Colorstar C290 HDTV/VHF/UHF/FM Antenna. My amplifier is the Channel Master CM-7777 (preamp and power supply). This combination works fantastic. I am receiving 100% signal except for these 2 channels. And, it's only at night.



My answer for the previous reply regarding virtual channels, etc.. I'm not sure how to answer it. My antenna is pointed south west. Its is at 227 degrees (magnetic).




TVFool.JPG

The previous reply's TV Fool listing is hard to see. Here is a larger view.TVFool.JPG

What I like about your TVfool: All the stations, all in one direction, no rotor needed! And no co-channel interference.

What I don't like: 55 miles away, 11 and 13 are VHF-hi, as well as 8. 11 is a 1-edge signal, and I suspect that 13 may well be too. And What is on 4? That's VHF-lo, 16 miles away... Perhaps you can post a LINK instead of just the image, there is more info in the report than the image can show (you can follow links in the original report to get info on specific stations)

The antenna looks to be good enough, and the pre-amp is just about the best there is. But 10 feet up? Is there a reason you can't get it higher?

So my first and best suggestion is to get that antenna up in the air, WAY UP. Put it on the roof, or extend the mast. Ideally, you should try to get up about 20-25 feet.

Try raising it up and tell us how that works for you.

Ignore 4, it's not on the air. Even if it was, there's nothing interesting on it.

- Trip

Thanks again, Trip!

I was just at your site trying to figure this out, seems he is near Beaumont, TX, shooting to Houston. It appears that the towers are on the other side of the city, and buildings in the path may be part of the problem.

But, really, at 50 miles you need to be more than 10 ft off the ground.

It's only 10' high because it's inside my attic. This location shouldn't matter, though because I have 100% signal strength. This only happens when the sun goes down. In the daylight, it NEVER messes up. Only at night. This concludes that the antenna is positioned correctly and the amp is properly working.

Here is the rest of the reporttvfool2.JPG

Does something happen at night that causes problems? Like I stated at the beginning of this post, I have read that drops in pressure can affect signal. Is this true? What else can be causing the problem?

At 50 miles, the antenna doesn't need to any higher if the signal strength is 100%! Ta-da

Real Channels are the Radio Frequency Channel that the station broadcasts on. A virtual channel is the channel as it appears on your television. For analog they were the same, for digital they may be different. (.i.e. my channel 2, KWGN Denver, broadcasts on real channel 34) In your case Channels 11 and 13 are both real and virtual, which means that they are both in the high VHF band, as is channel 8. The fact that those two are close together in the same band may explain why they are effected while your other channels (most of which are UHF) aren't. It may be caused by a cancelling multipath caused by atmospheric cooling, and solving the problem may be as simple as moving the antenna up or down a few inches (or feet) on your mast. Digital reception can be kind of a black art, which most of us are still learning.

Your response aligns with what I was thinking. This is something that I may not be able to control. Now, does this mean that in the winter when the days and nights are both cold, those two channels will poor all the time? Or, does it mean that since the atomosphere doens't have pressure drops, the problem will be obsolete in the winter?

Anyone have any ideas on what I may be able to do to correct this?

Here is the HDTVprimers article on fading. I do believe that it will depend on the time of year.

Glossary A to F

Are you getting 100% signal on 11 and 13 at night?

I suspect (refer to primer) that you are getting a 1-edge signal on both channels, which would explain why you loose it as you loose daytime refraction and your signal goes out of phase.

If it fades then getting it out of the attic should help... it will help you eliminate the edge effect.

I would also try moving it around the attic first, even a few feet can make a difference. (change in location, as well as up/down)

Thanks, Dan.

That is true MrPogi, a change in location horizontally may be a fix, anything that changes how the various signal paths reach the antenna.

Wow! This is fantastic! What a great answer! Fading... I have learned so much. I will try to adjust the horizontal position when the problem is occuring and see if it resolves it.

What's strange to me is that I suffer from it at the opposite times of the day. Mine is great in the day, and poor at night! haha.

Thanks again!

LibertyBell,

The others here have covered the bases very well. Moving your antenna may be the trick. I receive one local channel within a 20" 'window' about 14 ' above my roof. If that antenna is either higher or lower than 'the sweet spot', I have no useable signal.

This summer I tested several antennas and I discovered I could receive two unanticipated channels, but only one at a time: if I raised my antenna 4" one channel disappeared and the second one appeared. Lower it 4" and reverse happened. At that location (a fixed mast) there was not a 'sweet-spot'.

Since you have no issues with other channels, you could leave your existing antenna exactly as it is. Add a high-band VHF Yagi to the system connected to the same coax using a UVSJ. The UVSJ should block the VHF signals your current antenna is seeing and the new Yagi could be 'walked' into a sweet-spot.

Jim

Thanks for an alternate solution, Jim.

(Jim in Seattle, king of "MORE ANTENNAS", LOL)

Mr Pogi,

I always look for alternatives, such as my Dow-Key idea. For the record, I'll only have 5 or 6 TV antennas in the air when I finalize my system. Is that a lot? LOL

Jim