Cel Towers

Why don't you make the dock your leaving a favorite and use that to get back? Unless I'm missing something.

I haven't seen a specific POI file for the towers, but I think it would be a great idea if somebody gets interested in developing this. I actually am interested for a different recreational reason. I like to ride my ATV in some very rural parts of Minnesota and Wisconsin. I have often thought that if something were to happen on the trail and I had no coverage, it would be nice to know which direction the closest cell tower is. For example, if the nearest tower was 30 miles to the west, but only 20 miles to the east I could start eastbound until I was in range of the tower. I know that tower coordinates are listed in the FCC database, but it would take some time to use them to create a POI file. I suppose it could be further broken down as GSM (AT&T and T-Mobile), CDMA (Verizon and Sprint), iDen (Nextel and Southern Linc).

I have a csv file of all Canadian towers, that I downloaded from http://www.spatialdatabox.com/map-demos/cell-tower-canada-ma....
The CSV file contains over 11000 towers, and that's for Canada. Imagine the size of the US equivalent.
The referenced site is very useful in that it gives a Google map if the locations.

Does anyone make a nautical chart for Lake of the Woods? They have all kinds of nav aids listed along with their heights - towers, lighthouses, large cranes, just about anything you can see from a distance. A chartplotter is even better, but they're usually pricey.

Here we are http://www.northwestontariomaps.ca/hydrographiccharts.cfm

It's just from experience, I use the Morson Cel tower as a Visual nav aid. Last year, we were out with some friends when the boat engine, and everything that it powered (read here the GPS!) quit dead (found out later it was a manufacturing defect in the electrical system...but I digress). Some VERY nice folks stopped and gave us a tow, quite far out of their way. I happened to have my old Vista with me, but had pretty low batteries, so I cycled it on for quick position fixes, then off (I didn't have any detailed maps loaded, so it told me where I was, but little else). It was getting dark, but we managed to fix our position with the Morson tower, which guided us back to Hanson Bay, where the dock is.
As well, being a Canadian Forces Air Navigator, I learned early in my career that the best and MOST accurate navigation comes from the Mark 1 eyeball, hence the visual navigation reference earlier.

Jim1348:
Another EXCELLENT idea and potential use. The Search and Resue folks would have a far easier time if you could talk directly to them (via celphone), and give them an accurate position (via GPS).

NOW were talkin'! HOOOOAHHH!

That's not an easy task on the US side. Many cell sites are co-locations with other services, the cellular companies don't own most of the towers they are on and the fact the information would have to be gathered by carrier.

From dealing directly with many of the carriers at the national level, the location of their towers is closely held as it can be used by competitors to map out the actual coverage and signal strength for a given area. So, for the US at least the locations would be considered "Company Proprietary" and a trade secret.

Yes, the location of their transmitters is recorded in the FCC databases, but you have to know exactly what you are looking for in order to dig it out. The information is indexed to the transmit frequency so you have to know what frequencies are licensed in any given area and how they have set up their frequency reuse parameters.

a_user, knowing the FCC and the companies involved I am certain there is a concern for security as well as the issues you mentioned. With our dependence upon instant communication increasing daily, I am sure we can expect an even smaller circle of people privy to the location information.

I laugh when I observe some of the means the companies are using to disguise their smaller towers to look like lightpoles, pine trees, palm trees and other living specimens in the Phoenix and Las Vegas areas. Sometimes I think it would be better to leave well enough alone and let it be a tower rather than a fake imitation tree.

True, the fake ponderosa pine cell towers up The Hill from Phoenix are laughable.

So the next phase of this is putting in a proximity alarm such that you a good chance of communications with a specific cel tower in areas of sparse or gapped coverage.

The theoritical range is certainly power dependent, however, as a WAG (wild-a$$-guess) approximation the following formulas may help:

Cel Range in Nautical Miles = 1.23 * (sq root your height in feet + sq root of the cel tower height in feet).
So, for example, if you are at ground level (height = 0 ft) and the cel tower height is 100 feet high, the theoritical range (line of sight) is 1.23 * (sq root of 0 + sq root of 100) = 1.23 * (0 + 10) = 12.3 nautical miles.

Obviously some assumptions are made here like a clear line of sight between you and the tower etc., but the formula at least gives you an idea of range.

For Visual horizon range, the same formula is used except the first constant is 1.06 instead of 1.23.

How is this useful? If you find yourself out in an area of no coverage, by putting a theoritical range around a cel tower, you can get an idea of where the closest point is that you can expect some sort of cel reception. May be useful if you need to make contact...

We used this formula to give an idea of radio / radar horizon when flying at low altitude over water, for the most part it worked quite well, except, of course, when there were atmospheric anomalies like temperature inversions, but they only helped increase the actual range significantly...

Dark Diz

Darkdiz, looks like you are making a SWAG instead of a WAG.

Bowditch (2002) shows the factor for distance to radar horizon to be 1.22 which is close to your 1.23 for radar/radio waves, but shows a factor of 1.17 for distance to visible horizon. I am curious how you determined the 1.06 factor for the visible horizon.

Not as useful as you think. Not all cell towers are omnidirectional. Most are sectored - and only provide coverage in certain directions. Just because you can see a tower does not mean you'll be able to pull a signal from it.

Cell antennas are usually installed with down-tilt as well to limit any radiation pattern toward the horizon. That's why you won't pick up cell signals above 2500 feet.

Your signal can be strong but the bandwidth can be used up.

In West Yellowstone Montana, I had "six bars" and none of my calls ever rang through. Just too many tourists "using" the one tower.

Maybe a good old marine map of Lake of the Woods would be advisable as a backup along with the signaling devices recommended for a large body of water. Marine Radio isn't a bad idea either. Also wondering why as Bobdee suggested a Via Point of the dock. You state that you last all power and I guess assuming your GPS batteries were dead which would not allow you to use the via point but also would not allow you to use a Cell POI file. I'm puzzled.