Re: Tranzeo TR-6019f initial semi-review

"Ian" <ian_agerskov@xxxxxxxxxxx> hath wroth:

>I live in Canada. Right now there is no vegetation on the trees, you can see
>the other end through the trees.

Ok. So all you have is edge diffraction from the Fresnel Zone
problems. At 1.5 miles, the Fresnel Zone is 29ft. Do you have 29 ft
of clearance at midpoint including not hitting the ground? I don't
think so if you're 10 and 20 ft off the ground as you indicated.
http://www.terabeam.com/support/calculations/fresnel-zone.php
29ft clearance at midpoint would be nice, but I would settle for
perhaps 22ft. I should point out that objects in the Fresnel Zone do
not just cause attenuation by blocking part of the signal. They
create edge diffraction, which causes the signal level to vary in
peaks and nulls at the endpoints. Move a few inches one way or the
other, and the signal could easily be very strong, or very weak.

>There is one row of trees and once the
>vegetation comes back I might not be able to see through them. I ran a test
>with linksys stuff in the summer attached to 15dbi antennas and had a
>connection, but of course wanted as much margin as possible so thats why I'm
>using the Tranzeo 19 dbi units.

Tranzeo also transmits at +23dBm while most Linksys radios deliver
about +15dBm. Linksys also has the coax cable and connector losses,
which Tranzeo does not have with an integrated antenna. By all reason
and calculations, it should work.

>As far as interference goes we are in a fairly
>sparse area but a mile away I do have a 802.11 setup. The tranzeo CPQ picks
>it up as a signal 0f -94.

That's too low to have much of an effect.

>There is alot of oil field sacada equip around
>running on 400 mhz I think and the ISP here runs aironet equipment on 900
>Mhz.

Not Aironet but probably WaveRider. They use 900MHz because it goes
through the trees. It won't cause problems unless the ISP is using
2.4GHz as a backhaul from his central access point. Look for the
characteristic barbeque grill dish antennas.

A few years ago, we were having a local interference problem. None of
the 802.11 sniffers would show anything. I dragged a spectrum
analyzer and big dish around in the back of my pickup for most of day
until we found the culprit. It was a power company remote telemetry
link (SCADA) from a mountain top power switching station. For some
reason, copper data lines were not available so they used 2.4GHz
Proxim/Glenayre Lynx radios. These boxes transmit continuously even
though there is little or no data to send. They also occupy half the
2.4Ghz band in each direction (full duplex). It was difficult to find
because they had used solid dish antennas with every few side lobes. I
had to be practically under the antenna (on a 40ft telephone pole)
before the spectrum analyzer would see anything. PG&E was eventually
convinced to run some copper and replace the data link.

>I did bench test them but it was more to get familiar with the setup
>screens and to configure and test the encryption before installation. To be
>honest I do not know if the units were hunting for a connection speed. I
>like the wet towel idea.

It's difficult to simulate field conditions, but not impossible. I
like to set it up at close range and see what breaks. However, be
careful going too close. The 802.11 timing relys somewhat on the
speed-o-light time delay between endpoints. You'll need to put some
minimum distance between endpoints to do a proper test. I think about
3 ft is the minimum. Anything you can put between the antennas will
suffice as an attenuator. However, try to use absorbant material
rather than reflective. The reason I use a wet towel is that it's
easy to throw over a panel or dish antenna. Ideally, I should be
using black carbon foam, which is the same stuff used in RF anechoic
chambers.

>At the end with the trees the guy said we can cut down some brances in the
>summer if we have to.

Can you put the antenna in the trees and run a very long CAT5 cable?
I'm not sure how long a PoE CAT5 run can be with these units. The
data part of the CAT5 can be much longer than 300ft. I've done almost
1000ft without problems (using 10baseT-HDX). You can always run the
power over larger diameter copper cable such as Romex instead of CAT5.

>I think I'll try moving the CPQ closer, they are close to where I live the
>CPQ is easily accessable and it won't take long to do. Horizontal polarity
>wouldn't take very long as well.

Worth a try. Just remember that you're changing 3 things at once. The
Fresnel Zone, the folliage attenuation, and possibly the interference
pickup.

>I'll have to check if the wireless card I
>have will work with Kismet - SMC2532W-B. I purchased it because it is 200mw
>and can connect to an external antenna.

Prism2 (not sure) so it should work just fine.

>When checking for local interference
>is it best to attach an external antenna and do a sweep or just use the card
>as is?

External antenna pointed in the direction of the line of sight. You
want to pickup as much as possible. You can temporarily ignore
anything to the sides. Start at one end and point the antenna along
the line of sight in both directions. Repeat at the other end. If
that doesn't show anything interesting, find a high place nearby and
slowly spin the antenna 360 degrees. Anything that causes that much
trouble should show up with Kismet as a fairly strong signal. So, if
it really is 802.11 intereference, you should have no trouble finding
it. Don't be suprised if it's a client radio and not an access point
or repeater.

>Yeah I got them the V5 before I knew of the issues with it because I have a
>ton of V4's out there working flawlessly. Hopefully the WRT54GL will be
>better. Anyone have any comments on it? At any rate it is easy to take it
>out of the mix and try transfering files between PC's.

I've never seen a WRT54GL. It's my understand that it's a WRT54G v4
with a $20 higher price tag because Linksys had to re-negotiate the
contract with the vendor after the v5 problems.

>We are in a very sparsely populated area aprox 1 house every mile or so but
>there is one house in a direct line in between at an elevation that should
>be below fresnell problems but maybe I'm wrong. I don't think they are
>running any equipment but you never know.

Don't just consider the houses in between. Also anything that's along
the line of sight including beyond the end points. The signal doesn't
just magically stop when it hits the other end of the link.

Good luck.

--
Jeff Liebermann jeffl@xxxxxxxxxxxxxxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.

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