HOw can LOS be tested using a balloon ?

[coursekec]

I've heard that LOS path can be verified using balloons. Has anyone used it ? If yes then could you please name me the type of balloon and it's related accessories ?

thanks in advance..

[chiku]

Hi

Ballon come in Big trailer.it is really huge and there is seprate company who does that.You can google it.

Ballon thread is marked with meters and it is raised from one end.From other end person try to locate that ballon and once it is visible he communiactes to other party and meters on rope is note down.

make sure you on other side from ballon try to stand on tall building or high amsl point.

[byja]

Used it, and it turned out to be a good idea.
Last time we bought 4 big balloons in an ordinary shop (standard balloons for parties, about 0.7 - 0.8 m in diameter). If you could get a hold of a weather balloon it would be far better. Balloons were filled with helium at the shop we bought them, so one of the problems we had was getting them into the car. :)
It is extremely important that you choose balloons of different colours. Combine blue/yellow/red colours because at greater distances you'll have a problem spotting them, unless they are in sharp contrast with background. Always avoid green, and in rural areas red can be either excellent choice (against green fields) or bad choice (against roof tiles). Blue is also bad if you expect to spot it with sky in the back.
So, at 10 km distance (it was a very clear day, right after rain), at a downwards looking angle, and with a help of a 45x60 spotting scope (don't use 8x50 or 10x50 binoculars) it took us less than one minute to find location and determine LOS. Even better, we had determined minimum tower height for this location.
But there's one limiting factor to this - wind. 10 meters off the ground and you probably have wind even if it's calm on the ground level. Wind will cause rope to tilt (even less than 45 degrees) and unfortunately it's always moving it left and right, so you can not "catch" height right away.

Even better method is attaching flashing light to the balloon, and performing this during nighttime, but I haven't tried this one yet.

And the best part of this method is... once you're done with LOS survey, you end up with a great gift for kids/girlfriend/friends. :D

[byja]

And here are some pictures taken during this survey:


1. Preparing balloons for survey:

http://tesla.rcub.bg.ac.rs/%7Evmarko37/baloni/baloons1.jpg


2. Close up on the balloons:

http://tesla.rcub.bg.ac.rs/%7Evmarko37/baloni/baloons2.jpg


3. Some 3 km away from the site you could spot the balloons with naked eye:

http://tesla.rcub.bg.ac.rs/%7Evmarko37/baloni/baloons3.jpg


And don't forget, the far end site was 10 km away from balloons.

[phunghm]

Used it, and it turned out to be a good idea.
Last time we bought 4 big balloons in an ordinary shop (standard balloons for parties, about 0.7 - 0.8 m in diameter). If you could get a hold of a weather balloon it would be far better. Balloons were filled with helium at the shop we bought them, so one of the problems we had was getting them into the car. :)
It is extremely important that you choose balloons of different colours. Combine blue/yellow/red colours because at greater distances you'll have a problem spotting them, unless they are in sharp contrast with background. Always avoid green, and in rural areas red can be either excellent choice (against green fields) or bad choice (against roof tiles). Blue is also bad if you expect to spot it with sky in the back.
So, at 10 km distance (it was a very clear day, right after rain), at a downwards looking angle, and with a help of a 45x60 spotting scope (don't use 8x50 or 10x50 binoculars) it took us less than one minute to find location and determine LOS. Even better, we had determined minimum tower height for this location.
But there's one limiting factor to this - wind. 10 meters off the ground and you probably have wind even if it's calm on the ground level. Wind will cause rope to tilt (even less than 45 degrees) and unfortunately it's always moving it left and right, so you can not "catch" height right away.

Even better method is attaching flashing light to the balloon, and performing this during nighttime, but I haven't tried this one yet.

And the best part of this method is... once you're done with LOS survey, you end up with a great gift for kids/girlfriend/friends. :D
Yup BYJA, we should take the wind into account when determine the min LOS height by balloon method. It seems that the flashing light to the balloon is impossible way. I think we can mark the distance stages on the rope, and measure the gradient angle (rope to tilt). Then, proposed Min LOS Height will be the result of multiple rope length and cosine of gradient angle.
http://i31.tinypic.com/2r6z7a1.jpg

[chiku]

This is good idea.but works well if there is less wind.


But in practice ballons used are very big and heavy to countrer act windy condition.

But good to know alternate method

[byja]

It seems that the flashing light to the balloon is impossible way.

Flashing light is not used to determine height, but to help easily locate balloon at even greater distances. You can spot a balloon depending on it's size up to certain distance. But in nighttime you can spot flashing light even further.


But in practice ballons used are very big and heavy to countrer act windy condition.

I don't know about your part of world, but winds here, especially on mountain peaks can rip appart radomes, even towers. Moving a balloon, no matter how big, is not a problem. :)

[Cost_Reducer]

@byja
the left green car on 1st picture is it yours? :D:D

@all

I check LOS with flash light,binocular and a good digital camera. I use a CANON binocular with image stabilizer and CANON EOS 450 with a 28-300 objective. With the flash light we had determined LOS over 34km. The guy`s at remote site had the flash light with on the tower and aligned the light to my site. If i see it through the binocular they climb down the tower for e.g 5m and i also. Step for step we goes downstairs the tower until we can`t see the light. So we have the maximum LOS.
With this binocular & cam i had checked LOS at a 45km link in the bavarian alps / germany. It was a fucking cold day but very clear air. It snows during the night and in the morning the sun rising up. It was fantastic weather and good view :) for this adventure (round about 1m snow and only a material cable car to the top of the mountain)
On roofs i use a tripod for the cam otherwise you get not exact pictures.

Cheers ,

[byja]

@byja
the left green car on 1st picture is it yours? :D:D

I wish. It's a gas guzzler as any other military truck, but I bet it can climb (or at least it could in it's younger days) where my Nissan (the one with all the doors open) can't. :)


The guy`s at remote site had the flash light with on the tower and aligned the light to my site.

That's nice, but what if there's no tower on the remote site? And that exactly is what I did with the balloons - determining necessary tower height to meet LOS conditions, so I can place an order to build new tower there.

It's the worst possible task you can get, since mistakes can be very expensive. Towers more than 40m tall are usually designed as - is, with no possibility of adding few more meters to it's height. So, if you make a mistake and say place an order for 50 m tower, and later on you find out you need 60 m tower, you must build everything from scratch, including even concrete base for tower.

Last time I did this in plains (flatlands), I placed two orders, one for 36 m and another for 45 m tower based on my survey and analysis. Other (older) engineers argued that we should build towers 60 and more meters high, but I was in charge.

Towers were built, antennas were placed and alligned and both links worked just as planned (one link is 82 km, the other is 73 km over flatlands). Never got a cent from the money I saved them, only worries till they alligned the antennas.

[Cost_Reducer]

Hi,

it`s gas guzzler...nice. Few years ago into GDR (East-Germany) the russian army had also such vehicles like trucks that called "URAL" or "KRASS"...fine ;)

Ok, back to the LoS Checks....If i must do a Path Survey on a site without an existing tower, i hire a plattform for lifting me up. In the most cases it works properly and they reach the places where i need them. If there no chance to reach this place you can do a path survey where you determine the height from obstacles along the path. This takes lot of time but it is very accurate.


P.S It seems there are a children party with the balloons ;)