One channel issue, high VHF
 

Here is my TVfool: http://www.tvfool.com/?option=com_wr...8e03701cb62a56

Fmfool:

http://i61.tinypic.com/1ftrb5.png

I'm up in North-Western Midland county Michigan, surrounded by 85-90' trees, and I've got all the OTA local channels in the Flint-Saginaw-Bay City DMA locked and working pretty well, with the exception of WJRT-12 VHF, which is only about 39 miles away from me.

I want to dump Dish Network and go OTA (Roamio Tivo), plus some streaming. I'm using a separate Y10-7-13 VHF antenna JUST for WJRT-12 and that's up about 35'~, into a (Holland) uvsj with a HDB91x UHF antenna (91xg clone) into the other side of the uvsj. That runs down to an MCM Electronics FM filter, and then into a Kitztech kt-200-coax amplifier. Installing the fm filter brought UP the signal on WBSF 46 by 15 points! Not sure why it would do that for so high of a UHF station, but it did.

Without that Kitztech amp, I lose half the stations. My Tvfool is posted above, though my signals are probably far less than what that shows, due to the heavy tree cover this time of year. For instance, WJRT-12 averages only 18-19db, which isn't much above the minimum. Channel 5 and 19 are by FAR my strongest signals, I wish all were as good as those two.

Ok, I'm in the woods, and surrounded by 85-90' trees, including pines. I have no hope of getting above or around the trees anywhere on my property. I have very strong FM stations fairly close, in fact WPRJ is only about 6 miles away, and is pretty much at the exact opposite magnetic heading that my VHF antenna is pointed at. So that station is trouble for sure without that FM filter, as my antenna is probably picking that up from the back and it's a harmonic for VHF 12. Though once again, this reception issue is completely random, and doesn't happen 100% of the time.

Anyway, something still is going on with my reception of VHF 12 (even with the FM filter), and I'm just not sure what it is. It's NOT 100% of the time, it doesn't seem to happen only when the trees move in the breeze, and I just am not sure what's left to try. The video and audio breaks up and pixelates at random. My TIVO Roamio basics diagnostics, shows RS Uncorrected errors, and that climbs higher at these times. My LG tv set (which runs off the same antennas, split through a high quality 2-way splitter) shows the "quality" jumping up and down from 100% to maybe 45%, then maybe 14%, then back up to 100% at the same time that the Tivo is showing errors and pixelating. However, the "strength" never varies more than 3 points up or down at this same time. This could go on for hours, or suddenly quit for a while.

The other day (Friday 8/7) was pretty bad, but then the rain started later in the evening, and the problem settled down and got better as the night went along and the signal level came up 5-8 points. It just beats me as to what's going on here. I'd think if it was some sort of multipath, that it wouldn't be quite so intermittent. But, maybe I'm wrong and it is simply multipath.

Anybody have any ideas? I did try TWO FM filters in series, (I did also even try an LTE filter) but it didn't seem to make a difference. I thought about some sort of electrical issue, but if it's that, I don't know what could be doing it, and why it would be intermittent. I don't have access to a spectrum analyzer that could check this, though I wish I did.

I can probably get my antenna UP at least another 5-10' or more, but that's pretty much the limit. Even then, it's still going to be behind trees.

Move the antenna, try again. Repeat as needed.

My guess is electrical interference from power line noise, which is worse on VHF than UHF.

I have a VHF-Hi channel that is marginal. I can receive it sometimes when the SNR is 15-16 dB. When the noise level is higher, I can't receive it because the SNR is less than 15 dB. I am able to measure the signal and the noise in an adjacent unused channel, and my Sony TV gives me the SNR in the Diagnostics Screen. My old SLM (signal level meter) has an AM detector for the audio so I can hear the signal and the noise. It's the meter on the left; the newer meter on the right can also measure noise and signal.

http://forum.tvfool.com/attachment.p...1&d=1439220373

I can sometimes track down power line noise using a portable AM radio. Try both ends of the AM broadcast band where there is no station. If you rotate the radio, you see a directional effect.

If you have a radio with an AM detector for VHF (like an aircraft band) that can also hunt noise. Using an FM radio doesn't work, because FM rejects noise.

MFJ makes a power line noise detector.
http://www.mfjenterprises.com/Produc...ductid=MFJ-852
http://www.arrl.org/files/file/Technology/HANDSON.pdf

The power line noise could be coming from inside your house from LED or CFL lamps, or switchmode power adapters; try cutting off circuit breakers.

Is the coax grounded with a grounding block? That helps reject interference.
Good; that's from fundamental overload.

Powerline interference is usually worst during dry weather (low humidity) from my experience. As humidity rises the interference tends to lessen, especially when raining.

Ok, I did find heavy interference (buzzing) on AM band at 530. It starts as I drive into my 220' long driveway, and stays as I get into my garage. This parallels the power line wires going to my house.

Anyway, I read on Denny's antenna site (he's only about 35 miles from me) about another person that unplugged a "power tender" charger, and got rid of the interference. I also have a $20 Harbor Freight power tender charging a battery in my garage. I unplugged it, and the AM interference stopped IMMEDIATELY! http://www.harborfreight.com/15-amp-...ner-99857.html

My wife is watching tv right now, so I can't check VHF 12 to see if this did anything for that issue. However, since my car radio could pick this up from over 200ft away, I'm betting (I hope!) it might now be cured.

Does/can interference like this actually BROADCAST itself along the incoming utility power cables?

It usually radiates from the insulators due to dirt causing them to arc. I can routinely see the noise for up to several hundred yards on the spectrum analyzer.

Looks like rabbit73 gave you a good tip. Let's see how things turn out over time.

We have thunderstorms and heavy rain going on the last couple of hours, but in the lulls of heavy rain, I can already see that the signal level for VHF 12 has come UP to 60+%, and is over 25db on my Roamio (that was only around 18-19db earlier, before the charger was unplugged) My tv set's tuner is showing 65-66% signal strength, with locked 100% quality.

I think that's a good sign that the charger was causing the worst of it, but we will see as the next few days go by. I might still have to get the VHF antenna up a little higher just in general. Gotta have good fade margin with woods like these surrounding me.
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Edit: Well, it's 3 am here now, and I have now also discovered that my Dell Latitude E6410 90watt 19volt laptop power brick ALSO causes the VHF "signal quality" level to vary up and down from 100% - 0% and all points in-between at random. It only does this when plugged into the laptop, AND when the laptop is turned on. If I unplug the brick when that quality level is varying, it immediately jumps back to 100% and stays there with no fluctuation! At the same time, my Tivo Roamio stops throwing off RS errors. The laptop and power supply are in my living room, and the power outlets are on the same circuit.

So, guess I'll be getting a new power supply, and hope they all don't cause this same issue. If so, then I can take further steps to cure it, or I won't leave it plugged into my laptop all the time

Thanks for the report with positive results. I'm glad that I was able to point you in the right direction to make the tests.

You made my day, Mike.

Thank YOU!, I appreciate you bringing up, and getting me to re-evaluate the whole thing,

I had thought about power-line interference, but couldn't think of what I had here that might cause it. I looked around a little, but never thought about that charger, OR the laptop power supply that's been running in my living room for years! (I wasn't using OTA tv much during that time)

I just didn't realize how INSIDIOUS power-line interference could be with digital tv.

Now, if I can only calm down the multipath on windy days. I'm going to try some things now to get my signal levels higher. That should help.

Does the "planar reflector" he built and added on the back of the Y10713 antenna here: http://www.antennahacks.com/hacks/myy10-7-13v.htm help with multipath?

Try moving the VHF antenna up or down a few feet.

Moving DOWN, even by a foot (which is the easiest) lowers the signal and makes it permanently worse. It'll be sometime in the next week before I can mount it higher. I have a few logistics that need to be worked on for that, and changing out the mast pipe for a longer one.

Has anybody tried this Stellar Labs 30-2475 VHF antenna yet? It seems to have specs that should make it a little better than the AntennaCraft Y10-7-13 antenna. Also, it has a built-in 75 ohm balun, instead of the old-school balun you have to add for the AC antenna.

http://www.mcmelectronics.com/produc...ductid=30-2475

It would appear that MCM is importing this item from China and selling it under that part number: http://www.qiaohua.com/products/v-9h.htm That's the same Chinese company that supplies the rest of their house brand antennas.

I'd find it pretty unlikely that it would outperform the AC Y10-13. A general rule of thumb is that antennas with similar configurations will perform in similar manners. Given that the MCM offering is short a few directors and it's a lot shorter overall, it's likely to be several dB below the AC in forward gain. The two extra reflector rods would improve the F/B ratio, but wouldn't do much for forward gain. Most likely, the Chinese company is quoting gain in dBi as opposed to the dBd that AC used. Neither MCM or the Chinese company provide that information.

I agree with ADTech's evaluation of the MCM antenna.

This is just crazy! So, the main issues above have been cured by unplugging the Harbor Freight charger, and changing the Dell laptop power brick for an upgraded unit that works fine.

So, with slightly bad weather and fluttering trees, the Tivo Roamio has still at times been throwing off some RS Uncorrected errors now and again on Wjrt-12. Even with a higher signal level, which I figured could be normal due to weather conditions. At those times, the signal level might vary from 47-52, or 18-21db.

So, I haven't done anything else to my antennas as of yet, and we have 24mph GUSTY winds right now with 84 temps and sunny, and the trees in front of the antennas are fluttering, and waving around to beat the band. NO ERRORS are showing on the Tivo, even with the signal level still varying from 18-21db, or 47-52 signal level. I have to assume the changing levels are due to the wind moving the trees.

I'm happy there's no RS errors and the picture is staying locked, but, how come no errors right now? You'd think if I was going to get them, those conditions would cause it.

Just when I thought I had this figured out, lol...

Not too crazy, it's the nature of the beast.

Many things can cause errors in the digital stream. The BER (Bit Error Rate/Ratio) can be increased by a weak signal, multipath reflections (Static or Dynamic), and by electrical interference, as you found out. Any or all can be present at any time.

The FEC (Forward Error Correction) can correct a limited number of errors in the digital stream. Once that limit is exceeded, you reach the Digital Cliff, where you experience pixelation, picture freeze and finally dropout.

Forum member mulliganman was having an unacceptable number of uncorrected errors with his TiVo Roamio. This is his Diagnostics Screen readings before improvements:
and this is after improvements:

Thanks Rabbit, I will read/study through that thread again to see If there's any ideas I can implement for myself. I know my antenna configuration is not 100% set in stone as of yet, there's many things I can try to tweak it a bit better.

For what it's worth, the Tivo Roamio is incapable at present of showing Corrected RS errors at any time, so that field will ALWAYS be 0.

That's what I have gathered after a search on Google from various sites. Perhaps Tivo company will put out a revised firmware sometime that will fix this issue, but I'm not holding my breath.

My problem (when it happens) also is seen on my tv set tuner hooked right next to my Tivo, so it's an inherent antenna reception issue, NOT just a Tivo issue. Not withstanding the fact of course that the Tivo has a built-in 4 way splitter and 4 tuners, which of course would explain signal % level differences between Tivo and tv set.

As a test, I removed the Kitztech KT200 pre-amp, and reinstalled my CM7777 preamp with an external FM trap, and the internal FM trap turned ON. So there is two FM traps installed on the input of the CM7777.

I see very little difference in the signal levels on my Tivo between the two pre-amps. The VHF levels on Wjrt-12 are exactly the same. Some of the UHF channels went a little bit higher.

Kitztech kt200 is supposed to be 24db for both, with .4db noise. Does anybody know (for SURE) what the CM7777 pre-amp is for db and noise level? I think around 2db noise, but not sure on the signal level.

As for getting my antennas up higher, I'm still working on the preliminaries. I have to manufacture a swivel bracket for the bottom of the new 21' mast pipe, so I can swing it up by myself without the possibility of dying or dropping the antennas with the old way I have the shorter one mounted.

Once I came upon the idea of using a swivel mount (I was reading about hinged towers at the time) everything CLICKED into place in my mind! So, I'm working on this, and hoping our weather soon clears up as it's been horrible the last few days.

Does anybody know of an available UHF/VHF preamp that has a higher level JUST for VHF?

You certainly don't need more amplification. What you do need is more signal AT the antenna.

How close are your antennas to each other? Can you take a pic & post it?

I would agree that I need more signal at the antenna. Yes, the antennas are maybe mounted too close right now, but I'll fix that with the new longer mast. My house is in a slight hollow, (and surrounded by woods) below the level of the houses to the South and South-East which are on a ridge probably 5-10ft higher. Even with my antenna mast at 35', I don't think the VHF antenna quite clears the roof of the house I have to aim over for vhf channel 12. Without an amp, I lose some of the channels, or they pixelate badly.

Even with my mast up another 10 feet, I will still be in the hollow and surrounded by trees. You should figure that my TvFool above shows signals more than probably almost DOUBLE of what I can actually receive.

Which 7777 do you have, the old one with separate inputs for VHF and UHF, or the new 7777 with one antenna input?
Are you talking about signal strength or SNR on the TiVo? Often signal quality as defined by SNR and errors is more important than signal strength with digital signals.
The old 7777 had a listed vhf gain of 23 dB and a noise figure of 2.8 dB; 28 dB gain and 2 dB noise figure for UHF. The new 7777 is 30 dB gain and "ultra low noise" noise figure, whatever that is. When the new version came out, they said NF ≤ 5 dB; now they don't say anything about NF.

Many of us techs were really upset with PCT when they bought out CM, closed the NC plant, and fired first grade RF engineers. But what really got us was when they redesigned the 7777, but kept the SAME model number to seemingly trade on the good reputation of the original 7777. This bothered many of us, so that we stopped experimenting with the CM preamps, stopped recommending them, and started recommending other brands. Then Winegard started shrinking and cheapening their preamp line. Then Antennacraft folded. We are left with CM, Antennas Direct, and RCA. Antennas Direct dropped their excellent CPA 19 and replaced it with the Juice, which is in short supply. There is also, as you are aware, a selection of very low noise preamps, but they have a history of sensitivity to static damage.

To answer your original question, the old 7777 figures are accurate according to my crude measurements. The new 7777 is an unknown.

Calaveras, of AVS, uses a Tin Lee 30 dB UHF MA-25U-77 preamp for his two 91XGs that he likes very much.

http://www.tinlee.com/MATV_headend.p...#AntennaPreamp
http://www.tinlee.com/MATV_headend.p...#AntennaPreamp
http://www.tinlee.com/PDF/MA-series-info.pdf

More gain for VHF?
I agree with No static at all.
You don't need more gain for VHF, you need to put the antenna where the signal is.
:eek::eek::eek: First it was the trees, and now a house?

After looking at your tvfool report, I think a simple folded dipole antenna above the trees and house would be good enough for 12.:)

The trees are 85-90ft tall. I know this for a fact, as I dropped some of them (to clear satellite arc) a few years ago, and measured them once they were on the ground. That way I knew what I'd deal with on all the rest that are left. There's NO WAY I can get my antennas above them. I will not go to the expense and trouble of installing a tower or mast that tall. My wife lets me get away with murder (I also have multiple KU and C-band sat dishes, as I am an FTA person, and post at SatelliteGuys) but she'd never allow a 100ft tower.

I have the NEW CM7777, with a single VHF/UHF input.

Yes, I mean SNR on the Tivo. As luck would have it, I was in such a hurry to swap my CM7777 back in, this time I totally forgot to write down the LG tv's signal and quality numbers just before. They've always been about 5% higher than the Tivo.

Yep, the house next to me has a HIP roof, and I was trying to eye-ball the height of it's peak compared to the height of my VHF antenna. That's not easy to do, due to the thickness of the trees right now. But I am now convinced that the house is at least a couple feet taller at the peak (than my antenna). The antenna actually aims at a bearing that's in front of the peak, but I still think the roof height might be problematical.

The taller mast I will be installing will definitely clear his roof.

I'll bet those Tin Lee pre-amps are real pricy? I sent them and email two weeks ago, and still haven't received any reply at all.

Understood. Then what you are left with is small increments of improvement like modifications to your yagi that I see on DHC and clearing the roof.

Stupid question: could a CH 12 antenna be mounted in a tree?

If your CH 12 yagi uses a balun, would reducing the balun loss help? When I was doing a mod on a 4-bay antenna for CH 15, I tried about 20 different baluns and found the difference between the best and the worst was about 5 dB. They were all ferrite core baluns, but I could have made a half-wave coaxial balun with even lower loss.

Have you tried looking at the green signal lines in a satellite view of your location. I was able to make good suggestions to mulliganman for the location of his C2V so that it would clear his neighbor's roof.

http://forum.tvfool.com/attachment.p...1&d=1440199470

http://forum.tvfool.com/attachment.p...1&d=1440199470

http://forum.tvfool.com/attachment.p...1&d=1440199470

Kevin couldn't get the signals he wanted through the trees with his antenna aimed at the correct azimuth as you see in this photo. But when he aimed the antenna to the left where he is looking, he received some signals that came around the trees by diffraction.

http://forum.tvfool.com/attachment.p...1&d=1440200841

http://www.avsforum.com/forum/25-hdt...l#post17280909
http://www.avsforum.com/forum/25-hdt...l#post17297708

No, the trees aren't large enough to be stable at full height for mounting an antenna, even supposing I had a way to climb up there that didn't cost a fortune. They are tall trees, tight-together, but sway too much up there in the breeze. Even if I managed to do this, there's more trees on the other side of my neighbors lot... Our lots are 250ft wide. I'd also need at least 300' of coax for this option.

Yes, the antenna uses a Winegard TV-2900 balun right now. I'm aware there are many other choices, but I'm not sure which ones would be better. Baring buying a bunch at random and trying them, I'm still limited at the moment in dropping the mast to try balun after balun. That's very hard on my muscles, as I'm 56 years old and have had neck and back surgery. That bringing the mast down issue will change once I get the swivel hinge made and taller mast installed. Then again, the taller mast might be enough to solve the issue.

Yes, I have extensively viewed my property via satellite views to clear trees for my satellite-arc on my FTA dishes. I would have to move my antenna mast about 50' out into the middle of my front yard, and then it would have to be free-standing.

Ok, I'm going to try to post some photos, but it's later here and they might be a bit dark. Let me WARN you now, after seeing these, you may wonder just HOW the heck I'm able to get any OTA as well as I do now... Well, we are in the home-stretch of me tweaking everything over about two months now, off and on...

The VHF antenna points at 160 degrees magnetic. The 3rd photo is a back view of the antennas, and shows a bearing of directly what it's looking at. That photo also shows an open area ("V") of cleared tree branches that my UHF antenna aims through. That was opened up years ago for satellite.

The HDB91x points at about 145 degrees magnetic, which is weighted towards my weaker UHF channels, and slightly away from WNEM 5 (22uhf), and which is by far the strongest station.

http://i58.tinypic.com/px1si.jpg

http://i62.tinypic.com/2vju649.jpg

http://i57.tinypic.com/2f0eqdc.jpg

http://i62.tinypic.com/2cmrjfd.jpg

http://i59.tinypic.com/2mryyok.jpg

http://i58.tinypic.com/27wrjpl.jpg

http://i57.tinypic.com/2jdhp8w.jpg

http://i59.tinypic.com/24fg2zn.jpg

I wish to gosh I owned a bulldozer, as I'd LOVE to clear out more than 1/2 of those tree's.

I don't think we are going to be living here beyond another 4-5 years at most, as when I retire we are going to move for sure.

Next house I'm going to make sure there's not that many tree's around, I'm tired of so many...

I do have the possibility of dropping some of the tree's that are in the way, but it's fairly tight in there, so I need to plan out some careful logistics. I'd hate to drop a tree on a building.

Thanks for the photos Mike. I appreciate the trouble you went to and have a better understanding of your problem. The trees are so close; I thought they would be further away.

Yes, that would be very inconvenient, no matter what your age. You could test balun loss before connecting it to the antenna with an A/B switch to make a rapid comparison with the CH 12 OTA signal. A DIY half-wave coaxial balun would have the lowest loss.


http://forum.tvfool.com/attachment.p...1&d=1440204319

Your photos are quite wide. They make all posts wide on this page. I use 125% to read the text and 75% to look at the photos. Do you have a way to resize a little smaller? I try to limit mine to about 800 pixels wide. If not, I could resize for you.

I've resized the photos. Thanks for the schematic of the balun "testing machine".

This "swivel hinge" I've mentioned a few times, will allow me to permanently have the antenna mast connected towards the middle top of that larger pipe, and be able to swing it back and down over the peak of that porch roof. That'll take all the leverage off of ME, and put it on the mechanical swing point. The 21' mast I'll install will hang past the middle of the porch roof, and I can easily make changes, and then swing it back up by walking it up to the large pipe. Then U clamp it down in two more places above the bottom swivel point.

That's such an elegant (and in retrospect, obvious) way to do it, I'm amazed I didn't think of it a month ago. I could have saved so much time and effort. Oh well, better late than never!

Thanks for the rapid resizing, Mike; much easier to read.

The "swivel hinge" is a clever solution. The Australian hams think the US hams are crazy to maket it so hard to bring the antenna down for adjustments. They use a pivot and counterweight system, for a welded pipe mast, that requires very little winch effort to go from vertical to horizontal and back.

The 2 antennas seem a bit close & may be interfering with each other.

If in your shoes I would remove the UHF antenna & lower the VHF antenna in 6 inch increments to see if you can find a better sweet spot. Concentrate on finding the best spot for VHF, then add the UHF antenna above or below it depending on where the VHF antenna ends up. Higher is not always better.

Anyone else think this is worth a try?

I think your post #18 was on target. The increase in antenna separation, and a little more height might help, but the trees are a big problem. Maybe Mike can have a few critical trees topped without having to remove them completely.
http://www.avsforum.com/forum/25-hdt...-part-1-a.html

That's already been tried (lowering). Also, I know the antennas are probably too close, however moving the UHF antenna lower kills it's signal a lot. That UHF antenna also works best BELOW the VHF antenna, and is sitting in it's sweet spot for the coordinate aim of the antenna. It's hard to tell in the photos, but the UHF antenna is also tilted UP about 5 degrees. That gave me more than 5 points jump in signal. That leads me to believe that there's a possible big "signal wave" sitting up above the level of where my antennas are right now. Or at least there is for the UHF antenna.

The VHF antenna loses signal quite badly if it's lowered at all, even a few inches. There is NO "sweet spot" lower on the pole for VHF. It doesn't have a cut or open spot in the trees anywhere towards it's direction.

I'm lucky in that the "V" cut in the tree's towards the left happens to be a sweet spot for the UHF antenna. Even though those tree's have grown higher and started filling that in since others were removed 8 years ago,

The ONLY way to go is UP for VHF.

Or to put it on it's own pole somewhere else, but that's logistically not going to be easy and still stay anywhere on my roof area. Moving it to a tripod at the very end of the porch roof MIGHT work, but even I don't think putting it there would look good. Not to mention I don't want to put holes through my roof for bolts, even with using pitch patches to limit leaks.

I might ultimately just need to settle for what I get, but since I am not quite at the quitting point as of yet (haven't been able to get antennas higher than they are now), I'm not ready to settle as of yet. There's reasons I can't just go out there and "crank it up" and get it over with. Lifting a 10' mast with antennas using my arms is hard enough, lifting a 21' mast with those same antennas is a disaster just waiting. Weather, health, and my 12 hour night-shift schedule at work are fighting me lately. I hope to have it ready to go higher in the next week, now that I thought of the "swivel hinge" idea, and am making that in my garage. That new mast will allow the antennas to go higher by over 10' more.

In order to better understand your situation, I looked at some aerial photos of your area and the channel 12 signal has to cross your neighbor's roof and also two other houses. I also did some terrain profiles for the signal path from the CH 12 transmitter to your location. The transmitter is at the left end and your location is at the right.

http://forum.tvfool.com/attachment.p...1&d=1440383735

http://www.tvfool.com/index.php?opti...id=15&Itemid=1

The color code indicates signal strength.

- White is extremely strong. Beware of signal overload on amps.
- Red-yellow-green are all quite strong. You can expect reasonable coverage with an indoor antenna.
- Cyan is where it's advisable to move the antenna up to the second floor or attic.
- Blue is where it's probably necessary to install a good antenna on the roof.
- Purple is quite weak and you really have to work at it for any chance of reception.

If you look carefully you can see it's starting to turn cyan. The same colors are used for the coverage map.

http://forum.tvfool.com/attachment.p...1&d=1440379614

http://forum.tvfool.com/attachment.p...1&d=1440380665

Using another terrain profile system:

http://forum.tvfool.com/attachment.p...1&d=1440383990

http://forum.tvfool.com/attachment.p...1&d=1440384095

http://forum.tvfool.com/attachment.p...4&d=1440384336

http://forum.tvfool.com/attachment.p...5&d=1440385242

Hummm, so as I suspected, my VHF antenna for WJRT-12 is just BARELY at the very bottom of the 'wave' of signal from this transmitter. It's a wonder at the moment that I get it as well as I do most of the time!

I think that extra 10-12 feet of higher mast, might really be the thing that makes the biggest difference. Short of chopping down, or thinning out some trees.

Thanks for your work so far on this Rabbit, I REALLY appreciate it! I'm sure it'll also help others reading it to understand a bit more about their antenna situations.

In the last profile I saw a peak by the lake and wanted to do a closer profile.

http://forum.tvfool.com/attachment.p...9&d=1440543163

http://forum.tvfool.com/attachment.p...0&d=1440543188

WJRT transmitter site:

http://forum.tvfool.com/attachment.p...2&d=1440545193

The "Lake" (and I use the word loosely) is the Tittabawassee (yes, it's an American indian word) river, that's dammed up on one end with a hydroelectric dam that's been there since 1925. The dam is on the left side of your terrain pic. The river drops towards it to build up head-pressure.

Us-10 expressway crosses the lake right there, just after the supposed "peak" you show (it flows right to left). There is an outjutting (into the lake) of land there, with a subdivision of very tightly packed houses. The signal passes over that outjutting, and then is clear over the water again all the way to my subdivision.

There is no peak there that I am aware of, or that can be seen by the naked eye, certainly not to the height of what that terrain profile shows. I can't even imagine what that is showing in this case at all. There's just no chance that there's any sort of high ridge on that side of the expressway that's invisible, so I'm at a total loss here as to why it shows one.

I think the vertical scale exaggeration is misleading you.

The average peaks on your side are at 680 feet; the tall one is only 15 feet more than that average. It would be difficult to see that difference when standing there, but that peak does project into the signal path, and it can't be ignored.

That extra 15 feet probably isn't any more than the height of the trees.

Also, the resolution of the measurement data probably isn't that precise.

Sorry, didn't mean to mislead you, I was just curious to see what a close-up profile would show.

Well, if you think it's only around 15', then I'd agree it wouldn't be easy to see by eye. It then does make sense that the out jutting subdivision, which has lots of trees, could have a slight rise that could explain it.

The channel 12 signal reaches landfall on the west side of the "Lake" far above US10, because it crosses at an angle, not straight across. The terrain profile follows the green signal line; it is not an east to west profile.

http://forum.tvfool.com/attachment.p...6&d=1440553662

Ok, in that subdivision as you drive along the road ( starting at the landfall area of the Wjrt signal), that parallels the lake (UP in your pic) you go UP a hill there that's just past the upper edge of the map photo. I would have to say that hill is at least 15' higher than the normal ground level on the majority of that area.

You are certainly making me see my whole area in a different way now, lol. So much you never really "notice", even though you see it almost every day...

Thank you; glad I enlightened you a little.

Then I didn't waste my time with that investigation.

I also wanted to practice using the new (to me) profile software.:)