Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4G... - Page 2

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Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)

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Yeah, but what else?  Drilling through a nail stopper is difficult but
not impossible.  However, someone mentioned that all the metal
hardware is on the inside of the framing, which might eliminate most
of the framing hardware.  He might have hit a bolt head used to secure
the collar ties.  Maybe earthquake retrofit hardware.  Maybe someone
decided to use steel beams.  The house is new enough that it should be
detailed on the plans.  In any case, whatever he's drilling is
probably not going to be suiltable for attaching an antenna, unless he
goes all the way through the wall with a through bolt.

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It depends on the disk.  If the feed projects above the edge of the
dish, as in a nearly flat dish, then there's going to be plenty of
side lobes.  If the feed is buried under the edge of the dish, as in a
deep dish, then there will be substantially fewer sidelobes.

Looking at the photos of the NanoBridge M2, the feed projects well
beyond the dish edge, so it's going to have some side lobes.  How bad
is difficult to guess without a proper model or a test in an RF
anechoic chamber.  The data sheet shows a few at -15dB, but nothing
really serious.  As usual, I don't believe the data sheet.
<http://dl.ubnt.com/datasheets/nanobridgem/nbm_ds_web.pdf

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

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Wed, 01 Aug 2012 18:58:32 -0700, miso wrote:

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Four holes! Drilled about 4 inches apart up/down and about 6 or 7 inches
apart side-to-side.

I can't imagine what it is - but there is no way my drill bits were
making 'any' headway. I was on a ladder, so I couldn't use 'all' my
strength, but I've drilled enough to know that I was hitting hard steel.

I didn't even see any metal chips coming out, although they could have
been lost in the inch of stucco as I was pulling the bit out.

At the moment, I can only think that there is some kind of earthquake tie
of some sort since I'm very near the fault line.

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Looking at the Ubiquiti Nanobrdige M2-18 datasheet at:
http://dl.ubnt.com/nbm2_datasheet.pdf

The lobes don't look too bad:




Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Tue, 31 Jul 2012 07:31:40 +0000 (UTC), "Vinny P."

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Looking at the data sheet, it appears that you're looking at about a
10 degree beamwidth:
<http://www.ubnt.com/downloads/datasheets/nanobridgem/nbm_ds_web.pdf
Take a protractor and a piece of paper and draw 10 degree angle.
That's your alignment accuracy.  Trying to bore sight aim that antenna
is not going to work.  You'll have to rock it back and forth to find
the maximum signal point.  From the screen shots you've posted, I
don't think your antenna is aimed at their AP.

Looks like you have it mounted vertically polarized.  Is that what
RidgeWireless is using?

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Probably a nail stopper protecting the area where Romex crossed over a
2x4.
<http://www.strongtie.com/products/connectors/ns-nsp-pspnz.asp
Consider yourself lucky that you didn't continue as you would
eventually have drilled through a power line.  Next time you drill,
use a stud finder to find the stud, but also use an AC voltage
detector to make sure you're not drilling into a power line.

Please remember that you have only one life to give for your
connectivity.

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Ummm...  you're on AirMax ISP firmware 5.3.5.  Version 5.5 is out. Ask
your ISP before upgrading:
<http://www.ubnt.com/download#NanoBridge:M2

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Client Connection Quality.  Basically, it's the ratio of how an ideal
radio would be expected to act, divided by what you're really seeing.
The Ubiquity definition is kinda vague.  This is from Mikrotik and
hopefully should apply to Ubiquiti.

  Client Connection Quality (CCQ) is a value in percent that shows
  how effective the bandwidth is used regarding the theoretically
  maximum available bandwidth. CCQ is weighted average of values
  Tmin/Treal, that get calculated for every transmitted frame,
  where Tmin is time it would take to transmit given frame at
  highest rate with no retries and Treal is time it took to
  transmit frame in real life (taking into account necessary
  retries it took to transmit frame and transmit rate).




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

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Tue, 31 Jul 2012 08:51:18 -0700, Jeff Liebermann wrote:

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Funny you should ask that.

I wasn't sure which way to mount it so I simply followed the instructions
that came with the radio.

I do know the WISP has both polarities because he's the one that told me
I was only using half the bandwidth with my Ubiquiti Airgrid - so gaining
the other polarity is the whole reason for me buying the nanobridge.


Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Tue, 31 Jul 2012 08:51:18 -0700, Jeff Liebermann wrote:

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:)

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Tue, 31 Jul 2012 08:51:18 -0700, Jeff Liebermann wrote:

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Hi Jeff,

Here's how my friend Simon explained it to me today ... so I hope to have
more data this weekend.

... ... ... ... cut here ... ... ... ...

If you look at the antenna profile for the NanoBridge M2,
it shows you how much loss to expect if you are a few degrees off target.
If you are 15 degrees off-target, you lose about 7 dB.

15 degrees is a whole lot. The sun moves 15 degrees in an hour. Your thumb
and fist (like a hitch-hiker's signal) at arm's length is 15 degrees.

At 5 degrees off-target, you lose 2dB. That's three fingers at arm's
length. That is still quite a lot of miss. The entire mountain is 5
degrees across when looking at it from my house.

The sun and moon are each a half of a degree across. If you are off-
target by the apparent width of the moon, or even twice that, you won't
see a single dB of loss. The entire property where the antenna lies is
about a degree wide as viewed from my house.

In other words, aiming is not your problem.

We see random fluctuations in signal strength that dwarf anything like a
5 degree aiming error.

I have the tripod, and a bunch of brand-new NanoBridges. You can ride
along with me and we can set it up at different places along the road and
see what kind of signal and speeds we get, with and without the power
lines and towers in the way.

I'll be bringing it to Joe's house and Bill's house today or tomorrow,
and you can help set them up if you like, and we can get measurements
from those places as well.

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Sat, 4 Aug 2012 02:46:35 +0000 (UTC), Vinny P. wrote:
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I've yet to see anyone question the pattern/lobes/nulls
of the _transmitter_.  

Jonesy


Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On 4 Aug 2012 13:06:16 GMT, Allodoxaphobia

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Good point.  That may be the problem.  I run into it all too often.
The WISP decides to use a very high gain omnidirectional antenna.
Something like 15dBi with an 8 degree vertical beam width.  If your
house is at the exact same altitude as the WISP antenna, everything
works just great.  However, if the house is at the same distance, but
at a different altitude, the house will be outside the antenna pattern
and you'll get little or no signal as most of it will be going
overhead.

Even worse, end fed colinear antennas tend to have some uptilt in the
pattern.  A 15dBi omni (which incidentally is about 8ft long), might
have ALL the RF above the horizon if nothing is done about the uptilt.
If the house is below this omni antenna, you'll get very little
signal.

Ease of downtilting is one reason why WISP's use panel or sector
antennas with patterns like:
<http://802.11junk.com/jeffl/antennas/AMOS-7/index.html
120 degree horizontal beamwidth.  8 degree vertical.  14dBi gain.
Three of these antennas, wrapped around a pole, pointed 8 degrees
downward, put all of the signal on the ground in a wide pattern, with
very little being lost sending RF above the horizon.  Note the
adjustable downtilt:
<http://www.qsl.net/yu1aw/ANT_VHF/Amos_Ant/3InvAmosa7c.JPG

Hint:  If it doesn't work on paper, it's not going to work when
installed.

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

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Sat, 4 Aug 2012 02:46:35 +0000 (UTC), "Vinny P."

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It's a bit more complexicated than that.  Just because you can see the
other end, doesn't mean that a 2.4GHz link will be reliable.  Any
objects inside the Fresnel zone will cause problems.  Reflections off
the ground will cause nulls and peaks.  Moving objects (cars) close to
the path can cause fades.  I use Radio-Mobile software:
<http://www.cplus.org/rmw/english1.html
to produce path profiles like this:
<http://802.11junk.com/jeffl/coverage/K6BJ-to-KI6EH/K6BJ-to-KI6EH-Path-Profile-01.jpg
This one is at 420MHz and has some errors in the numbers, but gives a
tolerable idea of what can be done.  All you need to do is supply some
numbers.

A simpler version is just the path loss.
<http://wireless.navas.us/index.php?title=Wi-Fi#Link_Calculations
that simply calculates the fade margin, which directly translates to
reliability and uptime.  I'm fairly sure you're close enough that
there are no path loss issues.  I'm not so sure about obstructions
along the path.

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6dB loss is the same as cutting your range in half at the same signal
levels.

Another way to think about it is how much of your dish antenna can you
cover in order to produce a -6dB loss?  Well, covering half will be
-3dB loss.  Another half will be -6dB.  So, how well does your dish
work with a dish only 1/4th the size?  

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Probably true.  Something else is wrong which might be indicative of
defective equipment.  The easy way to determine that is to compare
with a similar piece of hardware.  

Did you ever settle on vertical or horizontal polarization?

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Random fluctuations as in fades and nulls is exactly what you get when
there are multiple reflections and objects in the Fresnel zone.

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Great idea.  Do it.

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Even better.  Remove your Nanobridge and bring it along.  Compare
signal levels.

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

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
It isn't the signal strength as much as the waveform fidelity. If you
are off a bit, you get more reflections of the transmitted signal.

When I use a rather fat beamed antenna, I move it from side to side and
note where the signal begins to drop. then pick a spot in the middle.
This is something like direction finding, where null are easier to
detect than peaks. In this case you aren't using the null, but rather
you reach the edge of the main lobe and the signal falls off rapidly.


Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
Vinny P. wrote the following on 7/31/2012 3:31 AM (ET):
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You probably hit a metal framing hanger (or framing metal hanger) in
that first area.

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--
Bill
In Hamptonburgh, NY
In the original Orange County. Est. 1683
To email, remove the double zeros after @

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Tue, 31 Jul 2012 12:40:14 -0400, willshak wrote:

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Whatever it is, it's big because the two bracket holes are a good four
inches apart, and I drilled four of them, about six or seven inches
apart, so the impenetrable object is (at a minimum) four inches by six
inches large.

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Wed, 1 Aug 2012 02:48:45 +0000 (UTC), "Vinny P."

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Do you have a wall safe, by chance?

Jeff suggested it might be a nail stopper, but that's not it. Those
things are much too small to fit your description and they're
installed on the inside edge of the wall framing, not the outside
where you're drilling.

It's not framing hangers, either. Those are also small and located at
the ends of the framing members, so you wouldn't have hit 4 of them.
Besides, hangers are almost never used on vertical walls.

Random thought, are you in a designated earthquake zone? Some builders
do all kinds of things under that umbrella that would be weird and
unheard of elsewhere.


Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Tue, 31 Jul 2012 22:27:54 -0500, Char Jackson wrote:

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I'm very near the Loma Prieta fault line so maybe that's it.


Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Tue, 31 Jul 2012 00:18:03 +0000 (UTC), "Vinny P."

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WDS will work, but has a bit of overhead.  

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Same as client bridge mode.

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Same as transparent bridge mode.  MAC addresses are preserved through
the bridge.  If you connect an ethernet switch (not a router) to your
Nanostation ethernet port, and then connect more than one computah to
the switch, the MAC address of each machine will appear on the
ethernet port of the ISP access point.  With just station (client
bridge) mode, all the traffic looks like it's coming from the MAC
address of the client bridge radio.  A major advantage of this mode is
the ability to talk between two wireless routers.

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Ordinary access point.

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Ordinary access point plus store and forward WDS repeater.  Ordinary
user machines (such as laptops, PDA's, and cell phones) can connect to
the access point, which then repeats the traffic to the central access
point.  Other WDS access points can also pass traffic through the same
path.



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

Re: Please help me interpret noise in the Santa Cruz mountains (roughly -75dBm across the 2.4GHz spectrum)
On Mon, 30 Jul 2012 22:41:24 +0000 (UTC), "Vinny P."

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Similar, but not the same:
<

<

The antenna gains are roughly the same (18dBi verus 19dBi).  The
radios are the same boards but different power levels (100mw
Nanostation M2 versus 600mw overkill Bullet M2).  You should get
roughly the same performance and signal levels.  The dish will
probably be more difficult to aim than the panel antenna due to
slightly narrower beamwidth.



--
Jeff Liebermann     jeffl@cruzio.com
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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