Book
Premium
join:2004-05-24
Shepherd, MI
| Any tricks for determining los?
I need to set up a 11.6 mile link that I'm a little worried about line of sight or fresnel zone impingement. Point A is a building. Point B, the proposed sight is a farm on a hill overlooking a village and about 200' higher above Sea Level than Point A. I've have been up in a 90' bucket truck at point B with a telescope trying to see point A but couldn't distinguishably make it out. Since Point B is 200' higher above Sea Level, Point A doesn't stick up over the trees on the horizon from that vantage point. I'm pretty sure it's there (los) but can't see it. I can see other references like nearby Water Towers and so forth but I was just wondering if anyone had any other tricks I could try other than firing up some radios (which would involve erecting a tower at point B) and hoping for the best. Thanks in advance
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Anav
Sarcastic Llama? Naw, Just Acerbic
Premium
join:2001-07-16
Dartmouth, NS | You might consider a point in between that can effectively see both ends, with vertical room to spare. |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp | reply to Book
Coordinates of both locations?
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A is A |
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Book
Premium
join:2004-05-24
Shepherd, MI | reply to Book
Point A
43' 22.763 N
084' 39.540 W
elev 733
Rooftop roughly 122 and of course we can go up some.
Point B
43' 37.391 N
085'00.485 W
elev 1014
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
 ·CenturyLink
| Using these coordinates, I arrive at a much greater distance than you indicate.
I also notice that the elevation of Point B is less. There is a hill located SE of that location that has the proper elevation, though.
If you could double check...!
Thanks!
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A is A |
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jebz
join:2002-05-19
·OptusNet
| reply to Book
said by Book  :I can see other references like nearby Water Towers and so forth but I was just wondering if anyone had any other tricks I could try other than firing up some radios (which would involve erecting a tower at point B) and hoping for the best. Using a large 12"x12" mirror for a mirror to flash is the best low tech method to determine line of site. The mirror flashes stand out very well. Use a close object inline with the target and move the mirror up and down and across in small zig-zags watching the flash on the close object. |
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ejd91717
join:2001-01-10
Summerville, GA
1 edit | reply to Book
It does not look like you have LOS Between the two site. About 18KM out you have a hill that is killing your Fresnel zone. Take a look at this Map. |
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ejd91717
join:2001-01-10
Summerville, GA
| reply to Book
Sorry Hit post too fast
I would advise a Relay at the following location.
43'39'53.4N
084'59'48.4W
At 10 meters |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| reply to John Galt
These are the two locations that I get based on a "cut-and-paste" from the coordinates given in the post...
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A is A |
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Book
Premium
join:2004-05-24
Shepherd, MI | reply to Book
Sorry Guys.
Proper coordinates for Point A
43'36.308 N
84'46.690 W
elev 855 |
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Book
Premium
join:2004-05-24
Shepherd, MI | reply to Book
And Yes, their is a huge hill (for this neck of the woods) to the Southeast. I'm worried about the North slope. The link is "around" 11 miles. I drew a line with Map Point and am using what it indicated for miles. |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| reply to Book
New locations...
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A is A |
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Book
Premium
join:2004-05-24
Shepherd, MI | Yes John, these are correct. |
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ejd91717
join:2001-01-10
Summerville, GA
2 edits | reply to Book
With about 20 meters/65 feet on the B side you can make it work. The good news is you have about 21db of play space
There is the data the Link is based off of.
Distance between Point B and Point A is 14.8 km (9.2 miles)
True North Azimuth = 107.2°, Magnetic North Azimuth = 113.0°, Elevation angle = -0.1440°
Terrain elevation variation is 49.9 m
Propagation mode is line-of-sight, minimum clearance 0.2F1 at 8.2km
Average frequency is 2440.000 MHz
Free Space = 123.6 dB, Obstruction = 0.2 dB, Urban = 0.0 dB, Forest = 0.0 dB, Statistics = -0.1 dB
Total propagation loss is 123.8 dB
System gain from Point B to Point A is 145.0 dB
System gain from Point A to Point B is 145.0 dB
Worst reception is 21.2 dB over the required signal to meet
50.0% of time, 50.0% of locations, and 50.0% of situations
This is based off the the Legal 802.11b limits minus 2 DB of power |
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ejd91717
join:2001-01-10
Summerville, GA | reply to Book
A flare gun always works at night BTW |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| reply to Book
said by Book :Yes John, these are correct. The black line indicates the height of the building that you are going to mount your equipment on.
It looks like you have a problem close to Point 'B'...maybe you could PtP to the hill and distribute to other subs in the area...?
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A is A |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| reply to ejd91717
said by ejd91717 :A flare gun always works at night BTW Good free advertising on the local nightly news..."a large fire was caused last night by a local wireless operator looking for a building..."
People will be calling right and left!
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A is A |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| reply to John Galt
This obstruction is actually only one foot less than the Point "B" elevation...
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A is A |
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DaDogs
Semper Vigilantis
Premium
join:2004-02-28
Deltaville, VA | reply to Book
You will be using 5.8 GHz for this link? |
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Book
Premium
join:2004-05-24
Shepherd, MI
| reply to Book
Yes, we were planning 5.8 radios for the link.
Great stuff John, what tower height did you plug in for the "b" side? What height would I have to go on "b" side to make it work?
ejd91717, I don't think you punched in the coordinates correctly. Thanks for trying to help though, I appreciate it. |
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