Look into some high Q cavity filters.
Marlon K. Schafer wrote:
Hi All,
I just completely rebuilt a tower site. It had inconsistent speeds
and I'd hit the point that I normally change things around.
When I hit 50 people to a tower I'll sectorize it.
On this tower I had an omni at about 25' (the hill is 700 feet over
the valley) and a 15dB integrated Tranzeo ap at about 15'.
Omni was vertical, sector was horizontal.
I rented a manlift and put an hpol maxrad wisp series 120* adjustable
beam sector at about 45', a vertical at 37ish and another horizontal
at about 30. All antennas are also 6 to 8' horizontally separated.
Each on a standoff attached to the different legs of the tower.
All antennas are fed with lmr600 and the radios are right beside each
other at the base of the tower (I'm too chicken to climb so the radios
stay where I can get to them).
Here's my problem, with all of the radios on and transmitting the
speeds are worse than before for most customers.
The sector to the west has 2 customers and sits at the 30' level and
is hpol. Those two customers get around 4 megs down and up.
The sector to the north east is vertical and a customer at 10ish miles
gets .7 to 1.5 megs down and .25 to .5 up.
The sector to the south east is hpol and sits at the 45 or 50' level.
Customers get .6 to 1.5 down and .1 to .5 up.
Unplug any two radios and speeds hit the 2 to 3 meg, sometimes 4 meg
speed for all customers on that system. Plug the other one back in
and speeds drop back down.
The hpol maxrad antennas have a 30dB fb ratio. I've not yet looked at
the patterns lately, as I recall they are pretty good though. APs are
Teletronics 11-152s with metal cases.
I've had GREAT luck with ALL of these components at other sites. Just
never all at the same time and place like this. As most of you know,
most of my coverage areas are VERY low density so I tend to use a lot
of omni antennas, or am mounted on hills that have no coverage behind
them so only one or two sectors are used.
The two systems that interfere with each other the most are north east
and south east. One's hpol one's vpol. They are on channel 1 and 9.
To get things working MUCH better than they were before, I've replaced
the north east and south east radios with Tranzeo ap's. I also moved
the southeast antenna (actually put up a new one) back down to the
roof of the shack. It's also a Tranzeo ap now. It, however, now sits
in front of, though much lower than the west antenna, both are hpol
though. If the channels are anywhere near the same for west and
southeast the folks to the west get really slow speeds.
I also moved the antennas on the tower further apart, they are now at
least 5 or 6 feet apart from each other. I don't know how much that
helped as I changed one of the radios to a Tranzeo at that same time.
This helped but didn't fix the speed and consistency problem. That's
when I moved the south east system back down where I could more easily
get to it.
Things still aren't as consistent as they need to be. If one system
gets busy the others slow down. Any ideas? My first thought is to
try a REALLY high end access point or two. You'd think those systems
could sit side beside when using channels so far apart from each
other. It's like the new radios are soooooo sensitive that they will
pick up the noise close to them no matter what. OR, more likely, that
the new, cheaper, gear has really really sensitive radios but with
rotten side band isolation on both tx and rx.
Any ideas? Radios/antennas to try? Changing the radios is easy.
Getting a manlift back out to change the antennas will suck big time
(due to the stand offs it would be too hard/dangerous to change
antennas from the tower).
thanks,
marlon
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