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 | Re: Any tricks for determining los? 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 | Coordinates of both locations?
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A is A | |
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Book
Premium
join:2004-05-24
Shepherd, MI | 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
| Re: Any tricks for determining los? 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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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| Re: Any tricks for determining los? 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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jebz
join:2002-05-19
·OptusNet
| 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 | 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
| 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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Book
Premium
join:2004-05-24
Shepherd, MI | Sorry Guys.
Proper coordinates for Point A
43'36.308 N
84'46.690 W
elev 855 | |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| Re: Any tricks for determining los? New locations...
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A is A | |
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| | Book
Premium
join:2004-05-24
Shepherd, MI | Re: Any tricks for determining los? Yes John, these are correct. | |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| Re: Any tricks for determining los? 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
| Re: Any tricks for determining los? This obstruction is actually only one foot less than the Point "B" elevation...
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A is A | |
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| | | | | TalkRadio
join:2004-06-23
Valrico, FL | Re: Any tricks for determining los? John Galt - very impressive graphics all over the place there! Would you mind sharing how you created them? I geocache all the time and have never seen such maps and charts. They would certainly be useful. Thank you. | |
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join:2004-06-23
Valrico, FL | Re: Any tricks for determining los? It's probably a bit more than what I need for quick geocaches nearby the house, but spectacular nonetheless!! Thanks for the quick response and explanation. | |
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Book
Premium
join:2004-05-24
Shepherd, MI | 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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ejd91717
join:2001-01-10
Summerville, GA
2 edits | 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 | A flare gun always works at night BTW | |
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| | ejd91717
join:2001-01-10
Summerville, GA | Re: Any tricks for determining los? LOL good point. I can do it in GA when its wet outside. But maybe i need to wait for it to dry out:D | |
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DaDogs
Semper Vigilantis
Premium
join:2004-02-28
Deltaville, VA | You will be using 5.8 GHz for this link? | |
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Book
Premium
join:2004-05-24
Shepherd, MI
| 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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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| Re: Any tricks for determining los? said by Book :what tower height did you plug in for the "b" side? I calculated from ground height...no additional elevation.
What height would I have to go on "b" side to make it work? I would suggest a 60 footer, since I do not know what else is in the way, such as trees, etc. on the hill.
The calculator says that the radius at 0.5 miles (the obstacle in question) is 16 feet for 0.6 zone clearance at 5800 MHz.
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A is A | |
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| | Book
Premium
join:2004-05-24
Shepherd, MI
| Re: Any tricks for determining los? OK, I'm planning a 100' tower on the "B" Side. Thanks so much for the info people. I've tried to use some different mapping programs like Keyhole and Worldwind trying to determine this but couldn't.
Thanks for all the help John! What mapping programs do you use? | |
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rsa0
join:2003-01-25
Birmingham, AL | Re: Any tricks for determining los? Try to do a link budget before you spend the money. At this frequency your issues may be greater than only the LOS.
PM me if you need more details. | |
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tallen03
join:2005-02-02
Ozark, MO | Book: Where do you get a 90' bucket truck and how much does it cost? I looked into getting a 90' lift and it was going to be about $750/day. | |
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Book
Premium
join:2004-05-24
Shepherd, MI
| The local Paint guy has a 90' Bucket Truck that we contract for $85/hour.
According to Trango's Calculator, a panel on each end will do it. What concerns do you have rsa0? We have a 20 mile and 26 mile link that work flawlessly at this frequency however their isn't the difference in elevation that their is here. | |
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Andrew J
Premium
join:2001-11-09
Lancaster, PA
clubs: | Use a laser pointer and have the guy on the other end looking for the red beam smoke a bunch of cigarettes.
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Best Team. | |
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KevinG0
join:2005-08-08
Sykesville, MD
| RadioMobile does this sort of link calculation. Works great, and (best of all) it's free! There's a bit of a learning curve, but once you get used to it, you can do some surprising things with it.
»www.cplus.org/rmw/english1.html | |
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