tvfool vs. antennaweb which is right?

[R0ss]

I recently put up an OTA, solved all the issues that I posted in another thread. Anyway I used tvfool to find the coordinates for aiming my antenna. Just happened to take a look at antenna web and noticed that the listings there are a degree off from tvfool. Ex WBZ is listed at 134 on tvfool and 135 on antennaweb. Tvfool has WUTF at 159 and antennaweb at 164.
Tvfool says the info is from the fcc abd antenna web is a government site so why thw difference?

Ross

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[jayn_j]

Likely a rounding error where you were near a boundary between the two angles. The true angle was likely closer to 134.5.

Did you give both your exact address? If not, it needs to guess based on the center of the zipcode. That can make a difference as well. They also use one of the mapping programs to get lat/long of your address. They may use different mapping programs, so the error could come from google maps vs bing maps vs mapquest vs yahoo maps.

The real point is that both are sufficiently accurate. I dare you to point an antenna within 5 degrees of a given azmuth. Even 10 degrees is non-trivial.

 

[boba]

Both are equally accurate for normal usage. I would lean to TVfool over antenna web, but remember those are starting points you need to fine tune any installation to maximize signal.

 

[jayn_j]

It's that old adage: Measure with a micrometer, mark with a rusty nail, cut with an axe.

I spent 30 years in the electronic test industry and customers always carried way too many digits in their measurements, just because they could. For example, if you are measuring a battery voltage, a resolution of 0.1V may actually be overkill. Measuring to 1.4625937 V will just cause confusion and generally rejecting perfectly good batteries.

This relates to antenna pointing because as Boba mentions the heading is just a starting point. The actual azmuth can be affected by ground effects, multi-path, adjacent channel interference, or a myriad of other causes.

 

[R0ss]

All makes sense. And yes I used address. I do need to go back out and fine tune a bit just haven't had time. Just seemed like there was a significant difference between the two sites eapecially when hou se 4-5 degrees

Ross

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[boba]

All makes sense. And yes I used address. I do need to go back out and fine tune a bit just haven't had time. Just seemed like there was a significant difference between the two sites eapecially when hou se 4-5 degrees

Ross

Sent from my rooted DROID RAZR Maxx using SatelliteGuys

Antennas have reception patterns called polar plots, they have front lobes side lobes and a back lobe. The front lobe is your main reception area it might have a 40 degree reception area so being off 5 degrees will still produce a signal even 40 degrees off may work that is why it is a starting point and you fine tune from there. You might have a 20 degree wide area that produces virtually the same signal strength that is why satellite signals are easier to peak.

Try a google for antenna polar plot.

 

[R0ss]

Antennas have reception patterns called polar plots, they have front lobes side lobes and a back lobe. The front lobe is your main reception area it might have a 40 degree reception area so being off 5 degrees will still produce a signal even 40 degrees off may work that is why it is a starting point and you fine tune from there. You might have a 20 degree wide area that produces virtually the same signal strength that is why satellite signals are easier to peak.

Try a google for antenna polar plot.

Thanks that would also explain why I am receiving one channel that is 30 degrees off from the rest. Its spanish language and none of speak spanish so we didn't care if we received it or not.
Ill try the polar plot and see what I get

Ross

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