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http://forum.tvfool.com/attachment.p...1&d=1474464195 I will not post the coordinates for your antenna without your permission. Try it for yourself here: http://www.heywhatsthat.com/profiler.html enter transmitter coordinates and click on Find: http://forum.tvfool.com/attachment.p...1&d=1474467002 click on 3983 ft and add transmitter antenna height AGL of +151 feet in pop up window and click OK. Height AGL is found here: http://www.rabbitears.info/tvq.php?r...ms&facid=46728 http://forum.tvfool.com/attachment.p...1&d=1474467653 enter your coordinates, click Find, and add your antenna height http://forum.tvfool.com/attachment.p...1&d=1474469959 |
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Most respectfully, I think the topographic data in this case is flawed or there is at least a difference of interpretation. Having walked through those woods to the north-west of my house, the ground is all very flat, with maybe a five-to-ten foot change in elevation at most through there. The tree-tops however are about 50-feet tall, and I think that is what the google-earth data are showing at point "B".
In fact, the Google 3D-view shows evidence of this. There is a small clearing in the middle of the woods 1/4 mile away along the signal-path that shows as a depression in Google-3D. That is definitely not the case. See the attached picture: |
What you say is certainly possible. Elevation used to be measured on the ground using bench marks. It is now often done by aerial survey which probably includes tree height. In any event, the ground clutter is messing with the signal.
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I will try aiming the antenna up a bit, walking the roof, and then possibly stacking antennas. |
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The Longley-Rice plots from www.rabbitears.info indicate about a 100-foot shift in the reception morphology for WCAX, relative to WPTZ. The shift puts my house right on the edge of a WCAX deadzone. I'm guessing this is a frequency effect, (473 MHz vs. 521 MHz) since the general reception pattern in the vicinity of my house is quite similar between each signal.
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The computer simulations for the tvfool report, the Longley-Rice coverage map, and the terrain profile, give the impression of accuracy that exceeds reality. Look how I was fooled by the elevation profile. I don't expect anything better than a location specified to an accuracy of a football field length or two. Quote:
Your tuner will take all factors into consideration that affect signal strength and signal quality (as defined by SNR and uncorrected errors), and tell you if the signal is good enough. When I aim an antenna, I go for max signal strength, then readjust for max signal quality. They are not always at the same azimuth because of multipath reflections. |
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That being said, can you guys recommend a TV brand or maybe even a particular model that has additional signal quality measurements other than just signal-strength? Both of my current TV's only have a signal strength meter. Since I'd like to get a third TV for the basement anyway, I might as well get one that has additional signal diagnostics (SNR, uncorrected errors, etc.) to assist in my current effort. Generally, those kind of capabilities seem hard to find on TV spec-sheets; and blue-shirts generally don't know much about the OTA capabilities of the TVs they sell. Also, is there a particular brand or model that is thought to have higher-quality OTA receivers than competitors? |
I have been very happy with my Sony KDL22L5000 and KDL32R400A.
KDL22L5000 Bad signal with picture freeze, SNR below 15 dB, and uncorrected errors: http://forum.tvfool.com/attachment.p...6&d=1438807158 Good Signal http://forum.tvfool.com/attachment.p...7&d=1438807179 KDL22L5000 calibration chart http://i496.photobucket.com/albums/r...psmz94qqxv.jpg My KDL32R400A has an even greater range of readings; the screen is similar. Here is its calibration chart: http://i496.photobucket.com/albums/r...pstasl68zu.jpg So, when I bought the 32R400A, I was getting a TV and a signal level meter for the price of a TV. KDL32R400A screen with TV connected to cable; readings are similar to OTA readings: http://i496.photobucket.com/albums/r...psqjqurwtl.jpg One of thee days I'll connect an antenna to the 32R400A and do another screen shot. You will want to make sure the model you choose has a Diagnostics Screen. For my 32R400A: Menu > Settings > Setup > Product Support > Signal Diagnostics I think the smallest model now is 40". They do make a few 32", but most are Multi-System which doesn't have a tuner for ATSC. |
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Which splitter/joiner should I select? I only seem to find ones with 3.5 dB insertion loss. Wouldn't that result in a net loss? |
Don't FOR GET THE amp channel master 78/7777,or the newest one by channel master
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However, when used as a combiner and everything is phased properly, that combiner loss disappears as if by magic (it's actually math**) leaving only the loss caused by power dissipation and inefficiency, typically somewhere from 0.4 up to a dB or so. Using a 1/2 dB as a planning factor is usually good enough. ** See http://www.hdtvprimer.com/ANTENNAS/ganging.html for a tutorial. |
Ballasted roof mount?
Does anybody have experience with ballasted antenna mounts? I found an old Dish Network ballasted roofmount for free on the side of the road. I'm wondering I could use it to mount my 2x HDB91X's + a VHF, as opposed to buying a tripod that screws into the roof. The roof is about a 3/12 pitch and the ballast mount has room for 8 cinder blocks. Obviously, the wind loads are my main concern. My house is situated in a relatively windy area, especially in winter.
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I've used non-penetrating mounts several times. Usually a couple of cinder blocks or sand bags is all it takes but it's going to depend a lot on the footprint of your "found" mount, the mast length involved, the relative wind load of the antenna, and your roof's particulars (slope, composition, etc).
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Antennas: two HDB91X's + Stellar Labs 30-2476 VHF
Mast height is 6-feet 3/12 pitch, Asphault shingles Mount base area= 36"x36" (Holds 8 cinder blocks 33 lbs each = 264 lbs) My gut check says that 264 lbs is a lot, so that this ought to work... |
You may need more capture area on UHF and no yagi design will give you that and their gain tends to be on higher channels which you don't need
An 8 bay bowtie design may give you what you seek And the channel master hd4228 is the best UHF antenna on the market as a direct result of massive capture area If the 4228 won't pick it up then nothing will |
The 4228 is probably the next thing I'll try if the 2x HDB91X's don't work, plus with walking the roof to hopefully find a better spot.
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I tried combining two HDB91Xs together, and the performance did not really improve, infact, it gets a little worse. Questions on this:
1) How close to "exactly the same length" do the feed lines need to be. I'm using two 3-foot lenghts, and they vary by about 1/4". Is this too much? 2) Will it be worth fiddling with the separation? I tried 39" as a first cut, per Tigerbangs suggestion. 3) I'm guessing the antennas also need to be "perfectly parallel". Its kind of hard to ensure this exactly unless I add another cross-piece. Seems like this might be worthwhile. Thoughts? Thanks guys! |
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