steven n fettig's Jitterin' Thoughts

    Well, the project has begun and I feel good. We have a link up between the supply facility and the center-point. I had the fantastic help of an old, old friend. I plan on taking a few pictures to post tomorrow. One thing I debated was whether I would set up a detailed map of the node locations, but due to the concerns about privacy of the end-users and worries about node hijacking (something extremely remote, but possible), I am going to simply take pictures of the antenna installations. The center-point antenna was the craziest installation I have ever done - at one point, my buddy was riding the silo like the guy from Dr. Strangelove who rides the bomb to the end yelling yee-haa the whole way... And that was one of the more tame moments of us trying to get the antenna up while battling the 25-30 mi/hr winds (plus my insane fear of heights).
    I had been watching the weather all week to see whether it would be possible to do the work today or not. Yesterday would have been much more ideal, but at least it didn't rain today (other than 10 minutes around 7:30 after we had just gotten on top of the center-point). The center-point is at the top of a silo that supplies one of our facilities with raw materials for our product. I had the choice of five locations and debated the pros and cons of each by some objective and subjective guidelines:
1) Which center-point gives the greatest range of line-of-site to potential end-nodes.
2) Which center-point will have the most reliable source of power and be the easiest to maintain if something happens.
3) Which center-point will have the potential to be a bridge to other center-points - i.e. which location offers the best potential for continued growth. If the system were to grow to multiple center-points/nodes, which one would provide the most useful center-point?
4) Trying to minimize latency on a wireless network can be difficult due to reflection from natural and man-made objects. I tried to look at the surrounding buildings as reflectors - like multiple stones thrown into a pond and the ripple effects that collide. If my understanding of rf reflection is correct, then reflection can also be to your advantage. The problem is that predicting reflection versus absorption is practically impossible - at least I don't have the training to do so - nor do I have the understanding to do the calculations quickly. Plus, due to the varying heights of the buildings and different roof pitches, it would be even more difficult to figure out where the signal can and cannot go without simply relying on a line of site model.
    The silo we ended up mounting to has turned out to be better than I thought. We were able to reach some sites that I thought would be obstructed by other buildings. After finalizing the mount of the center-node antenna, we started work on the feed. The original plan was to use a tripod mount on a portion of the roof that had a 1-2 deg. pitch. Ironically, the wind that caused terror up until then, ended up becoming our saving grace - at least in the future we would have learned this to be a saving grace. Trying to mount a 10 ft. mast to an relatively small tripod base (without being able to screw it to the roof - holes in roofs eventually leak...) turned out to be all but impossible - the wind whipped around the base even with 25 lbs. weights on each of the feet. We ended up having to use a side mount method whereby mounts are attached to the side of the building. We were able to mount a 20 ft. mast using a 5 ft. standoff between the two mounts. The antenna mast ended up flexing quite a bit in the wind, but the flex proved to be a means by which neither the antenna nor mast were damaged by the wind. I will eventually replace the directional patch at the top of the mast with a mini grid antenna so that wind is less of a factor. The beam width and antenna sensitivity differences are negligible, so weather is really the issue.
    After testing the link between feed and center-node, we cleaned up and put power/surge protection in place (on the base stations and between the center-node antenna and the base station). So, the link is up and running... 8 Hrs of work and we have a functioning core. Tomorrow I'll do so more signal tests from different points and see if we need to make any further adjustments to the center-node. From here, we will start installing end-nodes and testing over-all network performance.