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Progress Report 11

March 1st, 1997

CHANGE, CHANGE, CHANGE

The biggest change came to Alamosa, when Rocky Mountain Internet made a realestate move, that has affected our operations.

Ken Sweinhart, owner of the RMII franchise in Alamosa has had his business increasing to the point US West could not support his requirement for new lines in his Carver House location. So he bought a commercial building on Main Street in October of 1996, a few blocks from the old location, and prepared to make the move.

US West took over 3 months longer than they had promised, to extend a T-1 connection to his new premises, as well as additional dialup lines. He left our equipment in place at the Carver House until he simply had to make the move, and in one hurried weekend, without our involvement, moved his 56Kbs DSU/CSU and router, our router, radio, and rooftop antenna system to his new building. This also required new routing codes by RMII, Denver to his server, to serve us.

The link to Monte Vista, since that time, has been unreliable, going out almost daily. Just the move of two blocks, but at the same distance to Monte Vista, has, for a possible variety of vegetation reasons, changed the characteristics of the path. So it is a marginal link as of this writing.

But as part of the plan of the move, we were prepared to pay for a 60 foot tower (from ground) on his building, so we would have the best possible link the 30 miles to San Luis - a long way for a 1 watt radio.

So, with building permits required, as of this writing the new tower is not in operation yet, but is expected to be by the end of March.

SAN LUIS TOWER

In the town of San Luis, Blanca Phone Company, owns a 180 foot cellular phone tower looming above the town, near the school, and with fully 100 feet of it in view of Alamosa, 30 miles away. It is the ideal tower upon which to place a small yagi antenna that will be the relay from the Alamosa POP and radio to the school.

But the owners of Blanca Telephone, who themselves are beginning to show a business interest in bringing commercial wireless as well as forms of Internet service to the valley - refused the school's request to put the test antenna on their tower.

Short of building a seperate tower, or going to extremes to place the relay on Mount Blanca, with solar power, the second best solution was to use the much shorter Costilla County tower, on which both Sheriff's Department and the School bus-contact radios reside.

It was not clear from simply standing on the ridge between the County tower and the long 30 mile valley view toward Alamosa, whether the top of the tower would clear the ridge for an absolutely necessary line of sight shot to Alamosa. The County tower sits down on a shelf overlooking the town, but not near the crest of the 9,500 foot high plateau and ridge stretching to the west. I was pretty sure we would have to extend the County Tower, so got a quotation from the main Valley tower installers, Spectracom just in case.

Then on a chilly, windy February morning, I rendevoused with Mark Luchetti, Land Surveyor, at the base of the hill mass, and we proceeded in his 4 wheel up through light snow and across sage fields to set up his theodolite to make the measurments which would tell us how much higher the County tower would have to be raised. First Mark placed, and re-placed the theodolite tripod until it was on the exact vertical line between the tower and the center of mass of the part of Alamosa which could be seen in an opening between low hills about 10 miles away. Then he found that the declination from where we were, on the highest point between the tower and Alamosa, was 21.5 minutes of arc. He then flipped over the instrument and sighted 21.5 minutes above level in the direction of the tower, making the theodolite, standing 5 feet above the surface, on a precise line between tower and the aiming point in Alamosa.

To my suprise and pleasure, it intersected the tower about 10 feet below its top, and not in space above it! Which meant a yagi antenna placed at the very top of the County Tower and aimed at Alamosa, would clear the ridge by more than 5 feet, and give the necessary 'line of sight' for the 30 mile link, without extending the tower's height.

I wished, as we made the calculations, and rechecked several ways that we were right, that a group of San Luis school math students could have been there to make the critical determination in the field, with theodolite, hand calculator, pencil and paper, that the tower was either high enough, or exactly how many feet higher it would have to be extended to be high enough to get a clear line of sight to Alamosa. It would have been an excellent demonstration of the practicality of geometry.

And the risks of using even good quality HP Calculators outside in very cold weather. (for a while we were not sure it was operating properly, from the cold.)

That tower determination cost us $100.

In the suceeding month we gained permission from the County Commissioners to put the yagi on the tower, run a 100+ foot RF cable down it, to the radio using wall power in the radio shack.

We will do that as soon as the 60 foot tower is completed in Alamosa, and we have a carefully aimed yagi antenna mounted on it, and can have three persons - one on the top of the tower, one in the radio shack, and one at the radio in Alamosa get, and fine tune a digital link to the relay site. If that proves to be a solid link, the third radio at the school should be easy, for it will only be a third of a mile between the relay radio on the tower and the school mast antenna.


Dave Hughes

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