Tips for outdoor link

Hello

I'm a newbie in need of some suggestions. I have a couple of Pheenet WL-
522BA access points (just in case anyone recognises them) linked to 14dB
directional yagi's roughly pointed at each other with a gap of less than
200 metres.

I'm having loads of trouble getting a reliable signal. How precisely will
these need to be pointed at each other? If one is pointing slightly
downwards and the other isn't, will this kill the signal? If an N
connector wasn't crimped absolutely tightly, how much difference would
that make (the outer shield, not the pin)?

I'm considering attaching a laser pointer to one of the antennas and
looking for the spot on the opposite wall and then following it up the
mast. Would this work or is there a better technique for alignment?

TIA
Tim

Tim Sampson wrote:
> Hello
>
> I'm a newbie in need of some suggestions. I have a couple of Pheenet
> WL- 522BA access points (just in case anyone recognises them) linked
> to 14dB directional yagi's roughly pointed at each other with a gap
> of less than 200 metres.
>
> I'm having loads of trouble getting a reliable signal. How precisely
> will these need to be pointed at each other? If one is pointing
> slightly downwards and the other isn't, will this kill the signal? If
> an N connector wasn't crimped absolutely tightly, how much difference
> would that make (the outer shield, not the pin)?
>
> I'm considering attaching a laser pointer to one of the antennas and
> looking for the spot on the opposite wall and then following it up the
> mast. Would this work or is there a better technique for alignment?
>
> TIA
> Tim

It really all depends on the antennas (which I see you didn't list), most
high DB increase directional antennas have to be aimed very closely, can't
even imagine why you have those, I use em for 5-10 Kilometer links, not a
lousy 600-700 FT (sorry, 200 meters). Seems to me you are doing a way
overkill antenna situation. A Semi directional (very cheap/small, don't need
masts, and usually only has to be aimed within 5 degrees, those high gain
yagi's usually have to be aimed within a degree or so) work extremely well
and are very cheap for shorter links.

On Wed, 19 Jan 2005 16:03:29 +0000 (UTC), Tim Sampson
<(E-Mail Removed)> wrote:

>I'm a newbie in need of some suggestions.

Ok. I'll try not to be insulting. I really do wanna vent my wrath as
I'm having a truly rotten day, but I'll try to be nice.

>I have a couple of Pheenet WL-
>522BA access points (just in case anyone recognises them)

You can help if you supply the URL.
http://www.pheenet.com/pheenet/produ...product_id=215

>linked to 14dB
>directional yagi's roughly pointed at each other with a gap of less than
>200 metres.

That's probably overkill for only 200 meters.

>I'm having loads of trouble getting a reliable signal. How precisely will
>these need to be pointed at each other?

Look up the data on your 14dBi yagi antennas and dig out the -3dB
beamwidths. My guess(tm) is that it's about 30 degrees. From
experience, I found that about half the beamwidth is necessary for a
reliable signal. Therefore, you can miss by about +/- 7.5 degrees at
each end.

You'll be surprised how little 7.5 degrees is. Make two lines on a
piece of paper with a 7.5 degree angle, and see for thyself. Aiming a
fairly short base antenna, without a boresight, on top of a pole, to
within +/- 7.5 degrees is not easy.

>If one is pointing slightly
>downwards and the other isn't, will this kill the signal?

How much downward? If over 15 degrees downward, you won't have any
signal. Also, such sloppy installations tend to move around, usually
for the worse. My guess(tm) is that the U-bolts that came with your
antenna are too large for the small pipe you have it mounted. Take a
piece of steel (not aluminium) angle or C-channel, cut to about 6
inches, and jam it between the u-bolt and the pipe to increase the
effective diameter.

>If an N
>connector wasn't crimped absolutely tightly, how much difference would
>that make (the outer shield, not the pin)?

Today, probably no effect as there's enough surface area between the
connector and the shield to make a tolerable connection. However,
such an air gap is an invitation to water incursion. You'll have
fatal problems after the next rain. Worse, your unspecified coax
cable could be ruined by the water, or may need to removed to bake out
the water. LMR-400 crimping tools are about $40 and a good investment
as I've seen far too many sloppy crimps.

For waterproofing, I suggest you find some 1" wide teflon tape. Wrap
the tape around the connector(s) with about 50% overlap. Then cover
the TFE with Scotch 66 or Slipknot Grey electrical tape. The TFE will
cold flow into a good seal, prevent capillary action from sucking in
water, doesn't make a mess, and is easy to remove.

>I'm considering attaching a laser pointer to one of the antennas and
>looking for the spot on the opposite wall and then following it up the
>mast. Would this work or is there a better technique for alignment?

No. A laser pointer is very difficult to aim if you cannot see the
target dot on the other end. If you can, then by all means, use it.
However, I prefer a cheap rifle telescopic sight, a USB camera, or
both, for alignment. Also, buy a bubble level and use it to get the
vertical elevation correct.

Incidentally, I built an electronic inclinometer using an electrolytic
tilt sensor. It's very handy when I have to adjust the elevation of a
highly directional antenna on a tower, where I have to be both behind
the antenna for adjusting the bracketry, and simultaneously in front
of the antenna, for viewing the level.
http://www.sensorsmag.com/articles/0500/120/main.shtml


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

On Wed, 19 Jan 2005 13:14:37 -0800, Jeff Liebermann
>>I'm considering attaching a laser pointer to one of the antennas and
>>looking for the spot on the opposite wall and then following it up the
>>mast. Would this work or is there a better technique for alignment?
>
>No. A laser pointer is very difficult to aim if you cannot see the
>target dot on the other end. If you can, then by all means, use it.
>However, I prefer a cheap rifle telescopic sight, a USB camera, or
>both, for alignment. Also, buy a bubble level and use it to get the
>vertical elevation correct.

You might take a look at the new green laser pointers. I bought one
awhile back from here:

http://www.thinkgeek.com/gadgets/lights/5a47/

This is the most visible beam I've ever seen from a handheld unit. The
beam itself is visible off-axis in low light. The reflected spot from
buildings can be seen in the daylight for at least a quarter mile and well
over a mile at night. Reflected from reflective film such as on street
signs, the beam is visible literally as far one can see the reflector.
I've used it to shoot a locating beam from a mountaintop to an observer on
the receiving end over a path length of almost 10 miles.

I bought this thing primarily as a long distance aiming aid and it works
beautifully. All past impressions of handheld lasers go out the window.

>
>Incidentally, I built an electronic inclinometer using an electrolytic
>tilt sensor. It's very handy when I have to adjust the elevation of a
>highly directional antenna on a tower, where I have to be both behind
>the antenna for adjusting the bracketry, and simultaneously in front
>of the antenna, for viewing the level.
> http://www.sensorsmag.com/articles/0500/120/main.shtml

Nifty. Lowe's has a commercially made version available. Some stores
carry it, others special order. I have one. I think it was about $60.
The display resolution is 0.1 degree. I have no way to measure the
accuracy.

John
---
John De Armond
(E-Mail Removed)
http://bellsouthpwp.net/j/o/johngd/
Cleveland, Occupied TN

On Wed, 19 Jan 2005 19:49:52 -0500, Neon John <(E-Mail Removed)>
wrote:

>You might take a look at the new green laser pointers. I bought one
>awhile back from here:
>
>http://www.thinkgeek.com/gadgets/lights/5a47/

Hmmm... $100/ea. Can you really see the beam as a line? If so,
targetting should be fairly easy. Thanks for the er...ah pointer.

>I bought this thing primarily as a long distance aiming aid and it works
>beautifully. All past impressions of handheld lasers go out the window.

Well, actually I did have a way to use an IR laser. I have a night
vision scope with an IR filter. If conditions were perfect (fairly
dark, lots of dust, smog, or fog, and no nearby lights, I could see
the beam out to about a 3km. Projected dots were good to about 5km.
Not great, but still useful.

>>Incidentally, I built an electronic inclinometer using an electrolytic
>>tilt sensor. It's very handy when I have to adjust the elevation of a
>>highly directional antenna on a tower, where I have to be both behind
>>the antenna for adjusting the bracketry, and simultaneously in front
>>of the antenna, for viewing the level.
>> http://www.sensorsmag.com/articles/0500/120/main.shtml

>Nifty. Lowe's has a commercially made version available. Some stores
>carry it, others special order. I have one. I think it was about $60.
>The display resolution is 0.1 degree. I have no way to measure the
>accuracy.

Yes, but the digital contractors levels all have the same problem. I
can't see the display while I'm aiming the antenna because it's on the
other side of the dish or panel. The one I build uses a seperate
electrolytic tilt sensor, about 20ft of wire (setup as a Kelvin
bridge), and a home build instrumentation (balanced) opamp. Output is
on whatever DVM I can find. Calibration in degrees is by a simple
lookup table. I'm usually not interested in exactly how many degrees
of incline, as I am trying to get something exactly horizontal.

One really nasty problem I run into often is that many dish and yagi
antennas do not have their major lobe aligned exactly with the
boresight. They can be off as much as 5 degrees. That's due to
construction asymmetry, lack of a balun, coax radiation, or just plain
sloppy assembly. With panels, it can be caused by phasing errors
between patches. A yagi with the elements mounted on the side of the
center boom, instead of going through the middle of the boom, will be
misaligned. I use a conventient RF source on a nearby mountain top to
test the boresight alignment and tag my antennas with any
discrepancies. That saves considerable guesswork during installation.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

On Wed, 19 Jan 2005 19:01:04 -0800, Jeff Liebermann
<(E-Mail Removed)> wrote:

>On Wed, 19 Jan 2005 19:49:52 -0500, Neon John <(E-Mail Removed)>
>wrote:
>
>>You might take a look at the new green laser pointers. I bought one
>>awhile back from here:
>>
>>http://www.thinkgeek.com/gadgets/lights/5a47/
>
>Hmmm... $100/ea. Can you really see the beam as a line? If so,
>targetting should be fairly easy. Thanks for the er...ah pointer.

:-)

The actual beam is visible at night. It can be seen for some distance in
overcast conditions if one looks practically down the boresight of the
pointer. The spot is so bright, however, that even in direct sunlight,
one can aim the beam at something close below the target and then walk it
up to the target. I can do that by hand up to about a quarter mile.
Beyond that I have to mount the thing on a viscous head video tripod and
slowly pan up.


>>>Incidentally, I built an electronic inclinometer using an electrolytic
>>>tilt sensor. It's very handy when I have to adjust the elevation of a
>>>highly directional antenna on a tower, where I have to be both behind
>>>the antenna for adjusting the bracketry, and simultaneously in front
>>>of the antenna, for viewing the level.
>>> http://www.sensorsmag.com/articles/0500/120/main.shtml
>
>>Nifty. Lowe's has a commercially made version available. Some stores
>>carry it, others special order. I have one. I think it was about $60.
>>The display resolution is 0.1 degree. I have no way to measure the
>>accuracy.
>
>Yes, but the digital contractors levels all have the same problem. I
>can't see the display while I'm aiming the antenna because it's on the
>other side of the dish or panel. The one I build uses a seperate
>electrolytic tilt sensor, about 20ft of wire (setup as a Kelvin
>bridge), and a home build instrumentation (balanced) opamp. Output is
>on whatever DVM I can find. Calibration in degrees is by a simple
>lookup table. I'm usually not interested in exactly how many degrees
>of incline, as I am trying to get something exactly horizontal.
>

Slick. I like that idea. I bet one could take one of the commercial
units and tap the analog signal before it goes to the A/D and bring that
out to a connector that could connect to a voltmeter. That would be a way
to do it without having to build from scratch. If I can find mine, I
might just give it a shot.

John

---
John De Armond
(E-Mail Removed)
http://bellsouthpwp.net/j/o/johngd/
Cleveland, Occupied TN

"Peter Pan" <(E-Mail Removed)> wrote in
news:(E-Mail Removed):

> It really all depends on the antennas (which I see you didn't list),

Sorry, it's the 14dB one here: http://www.solwise.co.uk/wireless-
outdoorantenna-24.htm#24YAGI

> most high DB increase directional antennas have to be aimed very
> closely, can't even imagine why you have those, I use em for 5-10
> Kilometer links, not a lousy 600-700 FT (sorry, 200 meters).

Oh dear, seems I was badly advised.

> Seems to
> me you are doing a way overkill antenna situation. A Semi directional
> (very cheap/small, don't need masts, and usually only has to be aimed
> within 5 degrees, those high gain yagi's usually have to be aimed
> within a degree or so) work extremely well and are very cheap for
> shorter links.

Do you have any examples I can look at?

Thanks very much
Tim

Jeff Liebermann <(E-Mail Removed)> wrote in
news(E-Mail Removed):

> On Wed, 19 Jan 2005 16:03:29 +0000 (UTC), Tim Sampson
> <(E-Mail Removed)> wrote:
>
>>I'm a newbie in need of some suggestions.
>
> Ok. I'll try not to be insulting. I really do wanna vent my wrath as
> I'm having a truly rotten day, but I'll try to be nice.

Jeff

Thanks for humouring me. I hope it wasn't a wife or pet that got the
brunt of it instead.

I'll do my best to take your comments and suggestions on board.

Cheers
Tim

Tim Sampson wrote:
> "Peter Pan" <(E-Mail Removed)> wrote in
> news:(E-Mail Removed):
>
>> It really all depends on the antennas (which I see you didn't list),
>
> Sorry, it's the 14dB one here: http://www.solwise.co.uk/wireless-
> outdoorantenna-24.htm#24YAGI


That's funny.. the way the link above wrapped, if you click on it you get
....

The page you are looking for might have been removed, had its name changed,
been kidnapped by aliens or is temporarily unavailable.

======================================
I like the kidnapped by aliens one...

Tim Sampson wrote:
> "Peter Pan" <(E-Mail Removed)> wrote in
> news:(E-Mail Removed):
>
>> It really all depends on the antennas (which I see you didn't list),
>
> Sorry, it's the 14dB one here: http://www.solwise.co.uk/wireless-
> outdoorantenna-24.htm#24YAGI
>
>> most high DB increase directional antennas have to be aimed very
>> closely, can't even imagine why you have those, I use em for 5-10
>> Kilometer links, not a lousy 600-700 FT (sorry, 200 meters).
>
> Oh dear, seems I was badly advised.
>
>> Seems to
>> me you are doing a way overkill antenna situation. A Semi directional
>> (very cheap/small, don't need masts, and usually only has to be aimed
>> within 5 degrees, those high gain yagi's usually have to be aimed
>> within a degree or so) work extremely well and are very cheap for
>> shorter links.
>
> Do you have any examples I can look at?
>
> Thanks very much
> Tim

Unfortunately, the examples are for US stuff, and for your situation, and
looking at that same website (obviosly you can buy from them), they have two
outdoor panel antennas listed (as in stock)

NET-WL-ANT008PN 8dB Directional Panel with flush wall-mount and N type
Socket connector*
or
NET-WL-ANT010PN 10dB Directional Panel with flush wall-mount and N type
Socket connector

=============================
With any luck, by going to the same company, you may be able to get a credit
on what you already have, and trade it in for the new stuff. Chances are the
connectors etc will also be the same.. You may want to give that a try
first.

Why the difference in signal/radiation etc? Basically (not exact, but
hopefully something you can picture in your mind and understand) think of a
normal omnidirectional antenna, putting the power into radiating into a 360
deg spherical circle (think basketball).. Now use a semi directional antenna
that only radiates in 180 degrees (think basketball cut in half), the output
power is doubled into 1/2 the radiation pattern, and the range increased.
Cut it in half again (90 degrees), and you double the output power/range in
one slice.... now cut it in half again (45 degrees, smaller radiation area,
same power) and again going into a beam about 22 1/2 degrees)... etc etc etc
Remember, you are still radiating energy from top to bottom (180 degrees),
you can narrow that down too.... Finally you end up with the above
(directional panels), that focus all the power into a much smaller area, the
difference in the DB is one has a tad smaller beam/pattern/area than the
other. The yagis, are very small beams (usually 1 or 2 degrees), so you have
what is normally radiated in a sphere, concentrated into a degree or so
beam/area/smaller pattern/etc.

Again, the above is not meant to be a technical description, just a sort of
generic overview/idea.. For your needs, (between buildings) I would look at
a flush mount directional panel like listed above.. Easy to install/aim/etc,
doesn't need any fancy equipment, and easily gives you the power you
want/need.