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Parrothead
On 10/12/2017 at 6:04 PM, Oz Jon said:

That may well be high enough at the farm, because you said that the other end's antenna is mounted pretty high - the opposite scenario from the previous arrangement.

 

Unwise to try to guess this stuff - when I get your path profile data I'll work it all out again.

 

That's an incredibly cheap piece of kit and it works already - can't complain too much about that!

 

Cheers.

 

Howdy,

 

First, some images of the tower that broadcasts the signal:

 

tower_01.jpg

 

tower_02.jpg

 

tower_03.jpg

 

We stopped by there on the way back to the apartment today, to get a few images and to grab its GPS coordinates.

 

The tower is located at: 12.974649, 103.053851 decimal, or 12° 58' 28.7364'' N by 103° 3' 13.8636'' E

 

The farm's GPS coordinates are: 12.9867798, 103.0072846 decimal, or 12° 59' 12.4073'' N by 103° 0' 26.2246'' E

 

I still have to work on the Google Earth elevations.

 

 

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Parrothead

Not as much of a difference here, mate. What do you think? 

farm_to_tower_elevation.jpg

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Oz Jon

I need your estimate of the antenna height at the tower end to get started Paul

cya

 

ps

You saved me some work by drawing that profile, but I can't read the vertical scale Paul - even zooming-in! -  What are the 3 values?

Edited by Oz Jon

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Parrothead

I need your estimate of the antenna height at the tower end to get started Paul

cya

 

ps

You saved me some work by drawing that profile, but I can't read the vertical scale Paul - even zooming-in! -  What are the 3 values?

 

Sorry. That was just where I left the cursor, when taking the screenshot.

 

The tower land elevation is at 23 meters elevation. The land at the point I marked at the farm is at 20 meters elevation. I was surprised how close they were, actually.

 

I'm not sure of the height of the antenna at the tower, above ground level. I guess, maybe 40 meters? If I could get inside the fence, I could get a much better idea. The tower is just behind the house. It appears, with all the vehicles, that someone is living there. But, the place is locked up tighter than a drum. 

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Oz Jon

There is an easy, neat way to estimate a tower height Paul.

 

Get back a bit from the tower and sight the tower at arms length with a pencil in hand.

 

Line up the top of the tower with the top of the pencil and move your your thumb nail to also line up the bottom of the tower.

 

Now twist your extended arm 90 degrees and transfer that pencil height to somewhere convenient on the ground (at the same distance away as the tower.)

 

Now go and measure that horizontal distance copy! It's a simple technique and quite accurate.

 

Cheers

 

ps.I need to know the 3 numbers (on the far left of the height profile) - I can't read them from the image.

If that height profile was produced by Google Earth, how did you get it?

Edited by Oz Jon

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Parrothead
On 11/3/2017 at 8:31 AM, Oz Jon said:
ps.I need to know the 3 numbers (on the far left of the height profile) - I can't read them from the image.

If that height profile was produced by Google Earth, how did you get it?

 

24 meters

20 meters

17 meters

 

They the elevations that are generated by Google Earth. By that scale, the elevation at the tower is 20 meters. The farm is at 23 meters.

 

Some other information on the image is: 

 

Distance (by way of the direct line between the two locations) is 5.02 kilometers.

Average elevation is 21 meters.

Image taken 16 / Feb / 2017.

 

 

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Parrothead
On 11/3/2017 at 8:31 AM, Oz Jon said:

There is an easy, neat way to estimate a tower height Paul.

 

Get back a bit from the tower and sight the tower at arms length with a pencil in hand.

 

Line up the top of the tower with the top of the pencil and move your your thumb nail to also line up the bottom of the tower.

 

Now twist your extended arm 90 degrees and transfer that pencil height to somewhere convenient on the ground (at the same distance away as the tower.)

 

Now go and measure that horizontal distance copy! It's a simple technique and quite accurate.

 

Understood, and thanks. The problem is, the gate is secured at the compound where the tower is located. It was constructed directly behind the home. Chan knows the owners of the property. But, they are in the US. I figure the internet company probably leased the entire property, though. I doubt they will openly give us access there. 

 

 

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Oz Jon

Ok.

 

Just to get started (with a bit of guesswork about antenna heights) here is a chart showing the shape/size of the 1st and 2nd Fresnel zones (with arbitrary equal antenna heights each end). F1 is the good one and F2 the bad one, to be avoided.

 

With a high mast height at the road end and a much lower operating frequency, it's very different from the previous scenario I gave you.

 

Also drawn is the effect of a good (probably close to reality?) 42m/9m agl antenna combination.

 

That shows that you don't want the farm antenna any higher than about 9m for the best signal and least risk of fading from F2 reflections.

 

Lower antenna height at the farm is probably a better choice - very little reduction in signal, but much lower fading risk. (cheaper and simpler too!)

 

When you can give me a better idea of the antenna height at the cell-site, I'll review things.

 

Cheers

 

The site won't let me post the 128kB .jpg .... how do we get around that?

Edited by Oz Jon
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Oz Jon

wELL, MAYBE IT WILL ALLOW A JPG?

 

post-1173-0-20477200-1509697905_thumb.jpg

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Parrothead
On 11/3/2017 at 8:31 AM, Oz Jon said:

There is an easy, neat way to estimate a tower height Paul.

 

Get back a bit from the tower and sight the tower at arms length with a pencil in hand.

 

Line up the top of the tower with the top of the pencil and move your your thumb nail to also line up the bottom of the tower.

 

Now twist your extended arm 90 degrees and transfer that pencil height to somewhere convenient on the ground (at the same distance away as the tower.)

 

Now go and measure that horizontal distance copy! It's a simple technique and quite accurate.

 

@Oz Jon, I am in the city at the moment. But, I will be back at the farm all day today (Thursday), back this afternoon, then back out there Friday onward. I will finally be able to take time to work on this and will get back with you with the results I come up with. 

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