I am by no means a RF guy, I am still figuring out that side of being
a wisp myself. The one question I have is; could the interference be
through the LMR?
Ryan
On Jul 25, 2007, at 10:24 PM, Marlon K. Schafer wrote:
I thought about that. But then it's too hard to change channels.
There are other operators in the area and I need the ability to
change things around as needed.
marlon
----- Original Message ----- From: "Blair Davis" <[EMAIL PROTECTED]>
To: "WISPA General List" <[email protected]>
Sent: Tuesday, July 24, 2007 8:58 AM
Subject: Re: [WISPA] self inflicted interference
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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Blair Davis
AOL IM Screen Name -- Theory240
West Michigan Wireless ISP
269-686-8648
A division of:
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