Losing signal during middle of the day...sun? heat? gremlins?
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Losing signal during middle of the day...sun? heat? gremlins?


This is a discussion on Losing signal during middle of the day...sun? heat? gremlins? within the DTV | HDTV Reception and Antenna Discussion forums, part of the Over-the-Air (Antenna TV) category.


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  1. #1
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    Losing signal during middle of the day...sun? heat? gremlins?

    A little background here. I put this antenna up over the winter to replace my Metrostar omni antenna, in hopes to pick up one specific channel (KRBK). It worked fine over the winter. Once all the trees bloomed out, I again had difficulty picking up that channel, I did without for a while, but finally decided to pick up an Antennacraft 10G201 pre-amp in effort to pick it back up (I could still see a faint signal, but not enough to watch).

    Now then, since Ive added the amp, everything works great....except from about noon-6pm or so. Im hoping you all can provide me with some insight. I know its been a while since the trees bloomed out, but the last few months I havent been watching much TV at all, so Im just now noticing it.

    Ill try to describe my setup as best I can:

    My antenna: I have no idea what brand it is, its probably 40 yrs old, and it was free, so I cant complain about it much. The best I can do is provide a picture.


    Yes, that is duct tape in a place or two, some of the prongs were broken, and I did my best to keep their original shape. The antenna is mounted maybe 15 feet in the air?

    Im using a Digitalstream converter box, and less than 100 feet for sure of RG6 cabling. Not sure of exact length.

    Now then, TV Fool is acting up for me as I type this, so Ill include a report that I had saved from an earlier time.


    The channel Im after is KRBK, despite being the closest to me, its also seemingly the hardest to get. Their transmitter is located roughly 20-25 miles away from me. I point my antenna toward the southeast and I also receive KMOS, KYTV, KOZL, KSPR and KOLR with the sides of the antenna. The meter on my box reads from the mid 60s to low 80s on most channels. With KMOs and KOLR occasionally dropping into the 40s. When KRBK works, its usually mid 50s/60s but stable.

    Sorry for the long post, Im just trying to give as much info as possible.

    As I type this, Im receiving everything except KRBK with my antenna pointed in the usual spot. The weather has been hot, sunny, and humid lately. Im also pointing into several large trees. BUT this apparently isnt a problem at night, I came home last night and watched Cops on KRBK from 11pm to midnight.


    Any theories? Im sure my antenna isnt the greatest, but it does work quite well when it works. I would just like to know why it doesnt work.

    I should add that therre is signal present from another KRBK transmitter if I turn the antenna more straight south, but its not enough to watch, talking low 20s at best. I do know that my meter measures signal quality, not strength, but its the only way I have to express what Im getting.

    Im considering doing some tree trimming if it would help. But I would think if trees were the problem they would still be a problem at night. But ill bet if I check it out tonight itll be just fine.

    I think it has something to do with my location or my antenna, my parents live about 100 yards away, and they have a different kind of antenna, and a much more open view in that direction and they pick up KRBK with high 40s/low 50s signal without a pre-amp. Even in the middle of the day.

  2. #2
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    Update: I did go to my parents house today right after I posted to check their TV out and lo and behold they had no reception on that channel either.

    So, why are we BOTH losing signal during the middle of the day? Ill check it out again later tonight and see what I come up with. I asked them the other day when I first noticed the issue and it was working for them, but my how times have changed.

    I guess its possible they may be having transmitter issues, I have not contacted KRBK as of yet.

    Update: At around 5:30PM it was like someone flipped a switch and everything started working again. My home and my parents home immediately began receiving signal as usual.

    Is it possible that the station goes "low power" during the day on weekdays, and then dials it up once people start getting home from work, primetime, etc? My dad was telling me that some radio and TV stations used to do that about 30-40 years ago, but is it still done?
    Last edited by littlehoov; 06-28-2013 at 03:20 PM.

  3. #3
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    TVFool has been acting up for everyone. Google no longer supports the overuse of their maps. Here's the workaround:

    Go to Google. Click on the "Maps" overhead link. Search for your address. Right click on your location (marked with an "A" on the map). Click on "What's here?". Your latitude and longitude coordinates will appear -- in that order, separated by a comma -- in the address box where your address used to be. Highlight and copy the coordinates. Go to tvfool and instead of entering your address, click on "Coordinates" and paste your lat and long into the labeled fields that appear (delete the comma, and the numbers to it's right for latitude; delete comma and numbers to its left for the longitude). Enter the approximate height of where your antenna will go, and click "Find Local Channels" to get your report. Highlight and copy the bold face link that appears near the beginning of the report. Paste it into a message here.

    If we had the link, we could click on KRBK to see the RF map. But since this is a 2edge signal at 12 dB, it seems likely it's just the heat warping the atmosphere enough to shut you down. There are no guarantees for a 2edge signal. You could try getting your antenna much higher, or much lower. Or you could wait till fall. I'm guessing things will be better when the leaves change. Or they could change any time the right breeze starts ta blow.

    I have a similar problem with channel 58 with my indoor antenna. I set it up a year and a half ago, and it was perfect all through last summer. Last few weeks -- the pits.

    Rick

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    littlehoov,

    Your picture shows your antenna mounted under the highest point of your roof, on a building with metal siding. AAaaaack! If possible, relocate your antenna as far away from anything metallic (or) at least eight or ten feet above its present location. The siding may be acting as an unpredictable signal reflector, confusing the low-level (clean) data stream you are receiving. If there is a metal roof on that structure or even foil-backed insulation in the roof, they can contribute to reception problems.

    Jim

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    Quote Originally Posted by littlehoov View Post
    Is it possible that the station goes "low power" during the day on weekdays, and then dials it up once people start getting home from work, primetime, etc? My dad was telling me that some radio and TV stations used to do that about 30-40 years ago, but is it still done?
    Many radio stations have to cut their power at sun down, due to FCC regs. Conventional wisdom says OTA TV doesn't do that, but I claim WGN in Chicago does it. I think they cut power when their signal gets TOO STRONG for receivers in the middle of Chicago, where they broadcast from top of the old Sears tower. Causes overload. But they will never tell anyone they do it. Why give competitors a clue on when to cut THEIR power? There are a dozen stations broadcasting from same tower. One (WFLD) actually lists their power as 690/1000 kW, so there ya go.

    I used to see it in Kenosha, 48 miles away, when I had a crumby antenna. I'd be watching at 7, or 8, or 10 PM and suddenly signal would go dead. Excellent signal, then no signal, always right on the hour. (Never at 7:39 and 42 seconds.) Since the signal meter is a quality meter, not a strength meter (Fringe Reception taught me that) that's all I see.

    I missed that metal in your picture. Do what Jim said ...

    R.

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    Quote Originally Posted by Rickideemus View Post
    Many radio stations have to cut their power at sun down, due to FCC regs.
    AM stations. At night, AM stations cover much wider areas, so certain stations get to keep their power turned up and the others turn their powers down or off. FM and TV are not impacted by skywave.

    Conventional wisdom says OTA TV doesn't do that, but I claim WGN in Chicago does it. I think they cut power when their signal gets TOO STRONG for receivers in the middle of Chicago, where they broadcast from top of the old Sears tower. Causes overload. But they will never tell anyone they do it. Why give competitors a clue on when to cut THEIR power? There are a dozen stations broadcasting from same tower.
    More likely are variations in atmospheric conditions. Or local interference--perhaps something on a timer.

    One (WFLD) actually lists their power as 690/1000 kW, so there ya go.
    WFLD used to hold a license for 690 kW, and now holds one for 1000 kW. They are authorized for 1000 kW, not 690 kW.

    - Trip
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  7. #7
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    Hey folks, the picture is slightly deceiving, it is above the peak I can attest to that. Its on a mobile home, so the pitch is fairly flat. The peak is just out of frame.

    I experimented with the antenna a lot when I first mounted it, and I did have it mounted higher, but it actually got worse reception on that channel. Right now its kind of underneath the heavy top branches of the trees.

    It was working fine today when I got home around 3pm. But it was also significantly cooler outside today. Temps in the low 80s as opposed to mid 90s, and not nearly as humid.

    Jim brought up something I hadnt thought, I do have foil backed insulation underneath the metal in that roof. I can attest that it reflects a lot of heat and sunlight, I installed it personally in the middle of the summer and it nearly killed me haha.

    But, my parents antenna is mounted probably 10 feet above their metal roof, a bit higher than mine, they also dont have foil insulation, but foamboard, and they lost it at the same time. So its hard to say.

    Ill have to keep an eye on things and experiment. Like i said it worked today, but it was much different weather, and Saturday. So a couple different theories both changed at once.

    The next time it acts up, Ill have to scurry up the ladder and maybe try raising it up just for kicks. But thanks a lot for giving me a couple more ideas.

  8. #8
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    Quote Originally Posted by Rickideemus View Post
    I claim WGN in Chicago does it. I think they cut power when their signal gets TOO STRONG for receivers in the middle of Chicago, where they broadcast from top of the old Sears tower. Causes overload.
    Is there any evidence out there that says living too close to a tv tower causes tv tuners to overload? I have my doubts because I don't believe tv stations would put their transmitting towers in heavily populated areas if that were the case. There's that and the fact that I use a CM7777 preamp to help pull in Cincinnati channels while living only 3.5 miles from the Dayton, Ohio tv antenna farm. The CM7777 works great this close to the Dayton towers and reception is worse (on Cincinnati channels) without it.

    So is there any evidence that living too close to tv transmitting towers will cause reception problems from those channels?
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  9. #9
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    You can overload a digital TV tuner, especially if you use an amplifier with your antenna in close proximity to a station.

    - Trip
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  10. #10
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    Quote Originally Posted by Tim58hsv View Post
    Is there any evidence out there that says living too close to a tv tower causes tv tuners to overload? I have my doubts because I don't believe tv stations would put their transmitting towers in heavily populated areas if that were the case. There's that and the fact that I use a CM7777 preamp to help pull in Cincinnati channels while living only 3.5 miles from the Dayton, Ohio tv antenna farm. The CM7777 works great this close to the Dayton towers and reception is worse (on Cincinnati channels) without it.

    So is there any evidence that living too close to tv transmitting towers will cause reception problems from those channels?
    Tim,

    Just like you have, I have questioned that "theoretical fact" and I have done testing using my Haier 10" ($35.00 - cheap) portable battery operated digital (sd)TV set within less than a block from four, megawatt ERP TV transmitters and there were no overloading issues. Tested again, at 1/2 mile ... no difference, so transmitted beam angle doesn't play with my results.

    On the other hand ... when I worked in AM Radio Engineering I did 'antenna proofs' that were required quarterly and annually by the FCC, for stations to keep their licenses to broadcast. I was astonished when one of our standard 'monitor points' (I took reading at the same spots for years, called monitor points) became "HOT"! No kidding - a real change from the prior quarterly readings (omni and directional).

    At a range of about five miles from the transmitter, there was over ONE VOLT of RF from this particular 50kW AM radio station at that monitor spot. Not microwatts or milliwatts, enough energy to run a flashlight's bulb. Scary to me, because the location was on an Elementary Schools' playground.

    You cannot arc-weld with one volt but this playground literally had nearly a million times the usual RF energy that "should" have been in the distance from that transmitter. We assumed the new chainlink fence around that playground just happened to be resonent to our AM frequency and that explained the ultra stong signal. Kinda like a tank-circuit and that particular monitor point happened to be there.

    I was told to keep my mouth shut.

    So, if a 50 kW AM radio stations can offer a ONE VOLT of RF at a particular location, a megawatt (ERP) TV transmitter probably does as well ... but I haven't seen an example ... yet.

    Now ... overload versus multipath? I'll bet on multipath every time. A clean WEAK signal always trumps a dirty or noisy strong signal.

    Jim
    Last edited by Fringe Reception; 06-30-2013 at 06:53 PM.

  11. #11
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    Quote Originally Posted by Trip View Post
    You can overload a digital TV tuner, especially if you use an amplifier with your antenna in close proximity to a station.
    - Trip
    No doubt too much amplification can overload a tv tuner. I've done it myself by putting two preamps on the same line and many years ago I hooked up a Blonder Tongue 55db vhf distribution amp and turned the gain all the way up. The two strongest vhf channels were bleeding into and all over the uhf band, distorted images but there they were, so yeah, too much amplification will cause overload.

    What I'm really wondering is if it's possible to live so close to transmitting towers that they screw up your television reception (without an amp) due to too much signal. I don't believe it's possible. In fact I think it's just an old wife's tale that we've all heard so much we believe it.

    'Course I could be wrong.

    Edit: Jim, ya' beat me to it gosh darn it.
    Last edited by Tim58hsv; 06-30-2013 at 06:55 PM.
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  12. #12
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    Well...I was having problems with it today, matter of fact I was losing all my stations for little spurts of time, and the only connection I could make was that everytime I looked outside the sun was shining bright. Then when it would come back on, the sun was behind clouds. Called my parents while I was in the middle of an outage, and theirs was working fine.

    So I decided to try raising my antenna up. I was only able to raise it about another 3 feet due to my mast not wanting to cooperate anymore than that.

    Raising it just that little bit did make a difference in the signal quality of every station, and made drastic reception differences in a couple PBS stations, so it was definitely worthwhile. I swear though this winter, having it higher made things worse, but maybe I found a sweet spot this time.

    Time will tell if it made a difference in my dropouts. But Im just about sold on the metal roof/foil insulation theory. I know the sun is at a different angle during summer as opposed to winter, so that would explain why I didnt have any problems during the winter, and this is my first summer with this antenna.

    So far everything is working well, Ill be sure and post back after some research when it gets good and hot again, and the sun is really beating down. IVe got a good feeling about it though.

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    littlehoov,

    Stay tuned and keep us posted!

    Jim

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    Quote Originally Posted by Fringe Reception View Post
    Tim,

    At a range of about five miles from the transmitter, there was over ONE VOLT of RF from this particular 50kW AM radio station at that monitor spot. Not microwatts or milliwatts, enough energy to run a flashlight's bulb. Scary to me, because the location was on an Elementary Schools' playground.

    So, if a 50 kW AM radio stations can offer a ONE VOLT of RF at a particular location, a megawatt (ERP) TV transmitter probably does as well ... but I haven't seen an example ... yet.

    Now ... overload versus multipath? I'll bet on multipath every time. A clean WEAK signal always trumps a dirty or noisy strong signal.

    Jim
    So basically you're saying is that living next door to a transmitting tower won't cause tv tuner overload but a fluke such as what happened with that AM station could and most likely would cause overload? That I can believe.

    Thanks!
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    Quote Originally Posted by Tim58hsv View Post
    So is there any evidence that living too close to tv transmitting towers will cause reception problems from those channels?
    I dunno, maybe not! I spent an hour trying to come up with a google search phrase that would tie poor reception to proximity to the Willis tower. Can't find a thing. If this was a real phenomenon, seems like there'd be some discussion on the internet.

    Over a year ago, when I was getting advice on an antenna setup, I was warned about overload, because of my strong TVFR. I live 37 miles from the nearest transmitter! So I always assumed this overload thing was thoroughly established. My rough calculation with the inverse square law shows that un-amped antennas within 4 miles should get about the same signal strength as what comes out of my 20 dB preamped indoor antenna. But there must be thousands of receivers within one mile of Willis tower.

    Rick
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    when is 12pm in summer the environmental temperature gets in the peak one and if the tv channel use VHF II can be affected by a effect called mirage effect where the heat and humidity acts like a mirror for those signals making that gets reflected and do not reach the antenna that signals through the air in fact in Spain when was the transition had to change all frequencies to UHF because many cities got without signals due this effect, before they had signals on VHF II

 

 

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