Mark, Did you try switching frequencies?
-RickG On Sat, Feb 27, 2010 at 1:45 PM, MDK <rea...@muddyfrogwater.us> wrote: > On Thursday, I set about to fix a link that's performing badly. It was > just re-pointed and working really, REALLY bad. Somewhat intermittently, > but still REALLY bad. I had already tried new radios at each end. So > far, no luck. I tried a new pigtail on the low end, as well, still... No > luck. I replaced the whole board and radio setup at the low end, no luck. > > After much watching what it did and when, I came to the conclusion it was > self interference. Not on the same frequency, but I noticed that way up > the pole was another antenna with the same polarization and it was almost > exactly the same aim and polarization - I'm thinking I'm overloading the > radio with signal. So, I decided that I'd switch from Hor to Ver, on this > link, figuring it would reduce the self interference. > > So, I went to the low end (down in the valley, 4 miles) and installed a new > antenna, pointed it right, and real quick, switched the cable over to it. > After a slight re-pointing, it worked fine, slightly better than the old > antenna, which is an ancient Equinox. Cool. But no fix for the link's > issues. So, I pulled the antenna down, switched it over to Vertical and > put it back up. It was a clear, 55 degree day, sunshine. Could see > perfectly. > > Drove to the hill site, put a mount on the pole, and installed another > antenna, about 3- 4 feet below the original, other side of the telephone > pole it's on, and in Vertical, as well. > > Doug got on one end, me on the other and synchronized over the cell phone, > we switched the antenna cables over. > > No signal. > > Now, it was brilliant daylight, crystal clear air, sunshine, and we can > literally SEE the building and pole from the other end. I re-aimed my end, > swapped again. No signal. > > Doug changed the dipole at his end, to one I had JUST REMOVED from a working > antenna (took the antenna apart, but the antenna had been working 3 hours > before). No signal. > > I changed the dipole on my end. No signal. > > I changed the whole antenna. No signal. > > Doug changed dipoles yet again to a new one off the shelf. No signal. > > Original antennas are fine ,and the signal is around -64. I grab another > grid - one I had JUST REMOVED from service (replaced it with a higher gain > panel), HAND HOLD it while standing on the ladder and point it to the other > end. -89 is the best we can get. So the other end is the problem, right? > > Check the antenna taken off the far end. Works fine. > > Mind you, we're 4 miles apart. We can see the other end standing on the > ground. We can see it in great detail through binoculars. There are no > buildings, trees, bushes, or other obstructions. The land slopes away > from the hill end, and other end is 16 feet off the ground, angle uptilt is > about 1 degree. There is NO possible fresnel zone encroachment at either > end, even if you're standing, holding the antenna at chest height at the > hillside end. > > So, what's wrong? I don't know, and I can't figure it out. Nobody has > stuff pointed at the higher end. The other end is 270 degrees shielded by > heavy trees, metal roof buildings, hills, etc, and has always showed zilch > for noise, though the hillside shows some. There's nothing but sky > behind the hillside site. Nothing to point to. No reason for anyone to > build a high gain beam pointing its way, and certainly there's nothing for > at least 9 miles aside from my own customers that could possibly be pointing > that way. I have twice checked to make sure both are Vertical. They are. > > Each time, we put the cables back to the original antennas and the link > comes up. I moved the low end accidently, and we gained slightly. But, > the antennas are obvious visually aimed. And the replacement on the low > end is HIGHER than the original. Almost 4 feet higher. The low end > antenna is now the one I had working in Hor polarization. The upper > antenna was new, and I replaced the dipole with another new. And then I > replaced the whole antenna with a used one I had just removed the day > before, from a working customer's site. > > I've gotten the link to work reasonably well, by reducing power on the short > link (far end) and reducing power on the NEAR end (other link, 2.5 X > longer), and using Star-OS thresholds, so it ignores the higher level, but > out of band signals it sees. So, my self interference diagnosis is pretty > much correct. > > So, which one is bad? Yes, I lowered the hillside end, but it's 8 feet > up, and the ground slopes downward starting at the pole. There's no chance > we're even within 2X the fresnel zone to the ground, which is dirt and a > little wheat stubble. The handheld one didn't work lower or higher, so I > doubt it's a height issue. Tilt has been checked and re-checked, and is > NOT off any significant amount. > > I've been trampled by the rats and I can't get up... HELP! > > > > > > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
