Can you help me interpret this 2.4GHz WiFi spectrum analysis noise plot
that I just ran from my Ubiquiti Rocket M2 rooftop antenna?

I'm trying to debug why I have -88dBm of noise at my rooftop radio.

My Rocket M2 rooftop radio is on channel 10.
My home broadband router inside the house is on channel 1.

Here is the "waterfall" plot:
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

Here is the "channel" plot:
http://farm8.staticflickr.com/7310/1...e93b109b_o.jpg

Here's a site survey:
http://farm6.staticflickr.com/5484/1...32590c4f_o.png

And, here's a view of the rooftop radio signal to noise strength:
http://farm8.staticflickr.com/7380/1...0692ea50_o.png

Any observations with respect to the source of the -88dB noise?
(I don't really know how to interpret this stuff.)

So what's the problem?
How much noise would you consider normal?
Thermal noise is -174 dBm per Hz
What's the bandwidth and noise figure of your receiver?
Mark

On Tue, 17 Dec 2013 18:42:50 -0800, makolber wrote:

So what's the problem?
How much noise would you consider normal?
Thermal noise is -174 dBm per Hz
What's the bandwidth and noise figure of your receiver?
Mark

Q: What's the problem.
A: It's my understanding that every dB of noise reduces the dB of signal
by that amount. The less signal, the slower the Internet speeds.

Q: How much noise do you consider normal?
A: I have no idea. That's why I'm asking! Googling, I find you "should"
have about 20dB of headroom between noise & signal. My signal is about
-52dBm and my noise is -88dBm, so I'm within that range, but, my
signal to noise ratio is -52dBm - -88dBm = 36

Q: What's the bandwidth & noise figure of your receiver?
A: Googling for the "Rocket M2 bandwidth gain specifications", I find
this datasheet for a "RM2" receiver & "2G-24" 24dBi dish reflector:
http://www.balticnetworks.com/docs/rm_ds_web.pdf
Which says, on page 6:
Rocket M2, Operating Frequency 2412-2462 MHz
2.4 GHz RX POWER SPECIFICATIONS
llg = 1-24 Mbps = -97 dBm min +/- 2 dB
11g = 36 Mbps = -80 dBm +/- 2 dB
11g = 48 Mbps = -77 dBm +/- 2 dB
11g = 54 Mbps = -75 dBm +/- 2 dB
11n = MCS0 = -96 dBm +/- 2 dB
11n = MCS1 = -95 dBm +/- 2 dB
11n = MCS2 = -92 dBm +/- 2 dB
11n = MCS3 = -90 dBm +/- 2 dB
11n = MCS4 = -86 dBm +/- 2 dB
11n = MCS5 = -83 dBm +/- 2 dB
11n = MCS6 = -77 dBm +/- 2 dB
11n = MCS7 = -74 dBm +/- 2 dB
11n = MCS8 = -95 dBm +/- 2 dB
11n = MCS9 = -93 dBm +/- 2 dB
11n = MCS10 = -90 dBm +/- 2 dB === this is my channel
11n = MCS11 = -87 dBm +/- 2 dB
11n = MCS12 = -84 dBm +/- 2 dB
11n = MCS13 = -79 dBm +/- 2 dB
11n = MCS14 = -78 dBm +/- 2 dB
11n = MCS15 = -75 dBm +/- 2 dB

Given that my Rocket M2 is 11n MIMO, and on channel 10, I'd say
the receiver sensitivity is from -88 to -92 dBm.

Hmmm... I just noticed, that this is the same (essentially) as
my noise figure. But, I'm not sure what that tells me.

On Wed, 18 Dec 2013 02:21:53 +0000 (UTC), hh wrote:

only guy who can do this is gone, Jeff Liebermann

Rumors of my demise might be a bit premature. I'm buried in projects,
work, Christmas Chrisis', ladyfriend, and trying to untrash my house,
office, and vehicle. Incidentally, this is what I've been doing for
"fun".
http://www.learnbydestroying.com/jeffl/antennas/dish-move-project/

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

On Tue, 17 Dec 2013 19:32:34 -0800, Jeff Liebermann wrote:

Incidentally, this is what I've been doing for fun".

Hi Jeff,

Ooooh. Yours is bigger than mine!

That looks like a neat project.

Well, I'm here in the Santa Cruz mountains, just trying to figure
out what my noise plot is trying to tell me (I'm on channel 10):
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

On Wed, 18 Dec 2013 03:32:31 +0000, Danny D'Amico wrote:

Q: What's the bandwidth & noise figure of your receiver?

Here's a better screenshot of the bandwidth numbers, without the
text formatting that went on by my newsreader client:
http://farm4.staticflickr.com/3816/1...d8e8f5a1_o.png

Since my Rocket M2 radio is on channel 10, it looks like the
sensitivity is from -88dBm to -92dBm.

The 24dBi antenna has specifications he
http://www.balticnetworks.com/ubiqui...h-antenna.html
Which say:
€¢ Frequency Range: 2.3-2.7 GHz
€¢ Gain: 24 dBi
€¢ Hpol Beamwidth: 3.8 deg. (Rx Dish) / 6.6 deg. (Tx Dish)
€¢ Vpol Beamwidth: 3.8 deg. (Rx Dish) / 6.6 deg. (Tx Dish)
€¢ F/B Ratio: -50 dB (Rx Dish) / -65 dB (Tx Dish)
€¢ Max VSWR: 1.6:1
€¢ Polarization: Dual Linear
€¢ Cross-pol: Isolation 35 dB min

The Rocketdish RD-2G24 datasheet is he
http://www.balticnetworks.com/docs/rd_ds_web.pdf
which shows these specifications:
http://farm4.staticflickr.com/3777/1...327f43fb_o.png

So, in summary, the 24dBi dish has a narrow bandwidth of 3.8° to 6.8°
degrees, and the receiver has a sensitivity of -90dBm ±2dB.

I don't know how to translate those facts into an interpretation of
the spectrum analysis noise charts provided in the OP though.

Danny D'Amico wrote:
On Tue, 17 Dec 2013 18:42:50 -0800, makolber wrote:

So what's the problem?
How much noise would you consider normal?
Thermal noise is -174 dBm per Hz
What's the bandwidth and noise figure of your receiver?
Mark

Q: What's the problem.
A: It's my understanding that every dB of noise reduces the dB of signal
by that amount. The less signal, the slower the Internet speeds.

Q: How much noise do you consider normal?
A: I have no idea. That's why I'm asking! Googling, I find you "should"
have about 20dB of headroom between noise & signal. My signal is about
-52dBm and my noise is -88dBm, so I'm within that range, but, my
signal to noise ratio is -52dBm - -88dBm = 36

Q: What's the bandwidth & noise figure of your receiver?
A: Googling for the "Rocket M2 bandwidth gain specifications", I find
this datasheet for a "RM2" receiver & "2G-24" 24dBi dish reflector:
http://www.balticnetworks.com/docs/rm_ds_web.pdf
Which says, on page 6:
Rocket M2, Operating Frequency 2412-2462 MHz
2.4 GHz RX POWER SPECIFICATIONS
llg = 1-24 Mbps = -97 dBm min +/- 2 dB
11g = 36 Mbps = -80 dBm +/- 2 dB
11g = 48 Mbps = -77 dBm +/- 2 dB
11g = 54 Mbps = -75 dBm +/- 2 dB
11n = MCS0 = -96 dBm +/- 2 dB
11n = MCS1 = -95 dBm +/- 2 dB
11n = MCS2 = -92 dBm +/- 2 dB
11n = MCS3 = -90 dBm +/- 2 dB
11n = MCS4 = -86 dBm +/- 2 dB
11n = MCS5 = -83 dBm +/- 2 dB
11n = MCS6 = -77 dBm +/- 2 dB
11n = MCS7 = -74 dBm +/- 2 dB
11n = MCS8 = -95 dBm +/- 2 dB
11n = MCS9 = -93 dBm +/- 2 dB
11n = MCS10 = -90 dBm +/- 2 dB === this is my channel
11n = MCS11 = -87 dBm +/- 2 dB
11n = MCS12 = -84 dBm +/- 2 dB
11n = MCS13 = -79 dBm +/- 2 dB
11n = MCS14 = -78 dBm +/- 2 dB
11n = MCS15 = -75 dBm +/- 2 dB

Given that my Rocket M2 is 11n MIMO, and on channel 10, I'd say
the receiver sensitivity is from -88 to -92 dBm.

Hmmm... I just noticed, that this is the same (essentially) as
my noise figure. But, I'm not sure what that tells me.

Hi,
First do you understand what decibel means in the context of voltage,
current or power? Can you calcualte receiver sensitivity of -92dbm
comes out (?) volts? On what modulation mode are we talking about?

On Wed, 18 Dec 2013 03:44:39 +0000, Danny D'Amico wrote:

I don't know how to translate those facts into an interpretation of the
spectrum analysis noise charts provided in the OP though.

Googling, I can make a guess that my transient noise (blue line) is very
high at channel 10 of -40dBm, but that my average noise (green line) is
very very low at -90dBm.

The receiver sensitivity that someone asked me to look up is at about
my average noise level, at -90dBm ± 2dB for 802.11n signals.

So, the question I ask, without having the experience to know what "good"
transient noise and average noise levels are, is whether or not these
numbers are "good" or "average" or "bad"?

Also, I have no experience whether a peak instantaneous noise of -40dBm
(which is admittedly high) has any detrimental effect on my radio
performance (even as the average seems very low, at -90dBm).

I just don't know. Do you?
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

On Tue, 17 Dec 2013 21:19:40 -0700, Tony Hwang wrote:

First do you understand what decibel means in the context of voltage,
current or power? Can you calcualte receiver sensitivity of -92dbm
comes out (?) volts? On what modulation mode are we talking about?

I (think I) do understand decibels, at least at a rudimentary level.
Here's my simple summary of how I organize my thoughts around decibels:

1) Every 3 decibels is a doubling (or halving) of power.
2) A halving of power would be if it went from -87dBm to -90dBm.
3) My radio is transmits at 27 decibels (compared to the mW reference).
4) When I want to convert dBm to Watts, I google "dbm to watts".
5) The first hit is always the best dbm-to-Watts converter.
6) http://www.rapidtables.com/convert/p...Bm_to_Watt.htm
7) So, 27 dBm is 1/2 Watt (Note: 30 dBm would be 1 Watt, & so on).
8) The receiver is sensitive to -90dBm at 802.11n channel 10.
9) That means it can pick up a signal strength of 1 picowatt.
10) The signal to noise headroom needs to be around 20dBm.
11) That means I need signal to be 1/10 Watt greater than noise.
12) The transmitter is claimed to be 28dBm±2dB at channel 10.
13) So, the transmitter (without antenna) is 6/10ths of a Watt.
14) However, the Rocketdish reflector & antenna add another 24dBi.
15) A dBi is relative to a fictional spherical-radiation pattern.
16) So, my effective isotropic radiated power is 28+24=52dBm!
17) An EIRP of 52 dBm is a whopping 158 Watts!
18) The FCC only allows me an effective power of 4 Watts
19) Googling for "watts to dbm", the first link is the best.
20) http://www.rapidtables.com/convert/p...att_to_dBm.htm
21) That 4 Watts is 36dBm
22) Even though the equipment is capable of 52dBm, it's toned
down to that legal limit of 36dBm.

So, given all that, my average noise is rather low, on channel 10,
of about -90dBm or 1 picoWatt (which is the green part of the bottom
graph below).
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

However, my instantaneous noise is rather high, at -40dBm or
10 microWatts (which is the blue line in the bottom graph above).

So, I guess my question is how much will my radio be adversely affected
by 10 microWatts of instantaneous noise, when the average noise is only
1 picoWatt?

I have no experience with what noise levels are good, and which ones
are bad - so I have no background to interpret the spectrum analysis.

REFERENCE:
Transceiver datasheet (Ubiquiti Rocket M2):
https://www.discomp.cz/img.asp?attid=88929

Antenna (Ubiquiti Rocketdish RD-2G-24):
http://dl.ubnt.com/datasheets/rocketdish/rd_ds_web.pdf

On Tue, 17 Dec 2013 21:19:40 -0700, Tony Hwang wrote:

Can you calcualte receiver sensitivity of -92dbm
comes out (?) volts?

I never deal with volts when I'm working with the radio.
I always deal in power. So, I don't know what the volts are,
but, I do know this about -92dBm:

0) First, I always google "dbm to watts".
1) The first hit is always a great time-saving calculator.
2) That's http://www.rapidtables.com/convert/p...Bm_to_Watt.htm .
3) So, -92dBm is about 631 femtoWatts (which is pretty small).
4) I don't know how to convert that to volts though.

On what modulation mode are we talking about?

I'm not sure if I understand the question, but, the radio operates
in the 802.11n MIMO channel 10 (with vertical & horizontally polarized
antennas) that have a 3.8° to 6.8° beamwidth (which is pretty narrow).

NOTE: The narrow beamwidth is how the antenna gets all that gain in
the first place. You can't create or destroy power, so, I'd have a
wider beamwidth with a lower-gain antenna. This is a pretty high-gain
antenna, so, the beam width is pretty narrow, but, since it's pointed
at the WISP access point a few miles away, it doesn't have to be broad.

On Wed, 18 Dec 2013 05:10:15 +0000, Danny D'Amico wrote:

NOTE: The narrow beamwidth is how the antenna gets all that gain in the
first place.

I didn't explain that one all too well.

Here's another try at my thought process:

1. If I put the legal limit of 4 Watts into an antenna with a wide
radiation pattern, it goes only so far.
2. If I then change the antenna pattern to be more narrow, the
radiated signal goes farther in the direction that it is pointed.

So, my antenna & dish reflector, having a gain of 24dBi, is pretty
narrow at around 5° beamwidth (in both horizontal & vertical planes).

Breaking out my trig (SOH, CAH, TOA), I see that I can create a right
triangle of half the 5° beamwidth, with the Adjacent being 3 miles.

Since I have the angle and the Adjacent, and I want the Opposite,
it looks like the tangent will tell me the how large of a circle is
painted on the WISP antenna 3 miles away.

1. TOA means Tangent is equal to the Opposite over the Adjacent.
2. So the Adjacent times the tangent is the Opposite.
3. 3 miles time the tangent of 2.5° is what I need to know.
4. Googling for "tangent calculator", again I take the first hit.
5. That's http://www.rapidtables.com/calc/math/Tan_Calculator.htm .
6. The tangent of 2.5° = 0.04366094 .
7. So 3 miles x 0.04 is about 633 feet.
8. The 2.5° was half the beamwidth (to make a right triangle).
9. So the beam paints a pattern twice that, at about 1200 feet.
10. This tells me that a beamwidth of 5° isn't really all that narrow!

Note: The 5° is defined, I think, by where the furthest lobe's power
is cut in half (i.e., by 3dB).

Here is a picture of that pattern from the Rocketdish RD-2G-24:
http://farm3.staticflickr.com/2890/1...854acbb9_o.png

Notice that this radio is pretty directional, but even so, I have
a catcher's mitt about 1200 feet wide to hit my access point.

Here are the Internet speeds I get by hitting that catcher's mitt:
http://farm4.staticflickr.com/3743/1...187217bd_o.png

All I'm trying to do is *improve* on those Internet speeds, by
understanding first, and then lowering my noise (or raising my
signal-to-noise levels) within legal limits of 36 decibels EIRP.

REFERENCE:
http://dl.ubnt.com/datasheets/rocketdish/rd_ds_web.pdf

Danny D'Amico wrote:
On Tue, 17 Dec 2013 21:19:40 -0700, Tony Hwang wrote:

First do you understand what decibel means in the context of voltage,
current or power? Can you calcualte receiver sensitivity of -92dbm
comes out (?) volts? On what modulation mode are we talking about?

I (think I) do understand decibels, at least at a rudimentary level.
Here's my simple summary of how I organize my thoughts around decibels:

1) Every 3 decibels is a doubling (or halving) of power.
2) A halving of power would be if it went from -87dBm to -90dBm.
3) My radio is transmits at 27 decibels (compared to the mW reference).
4) When I want to convert dBm to Watts, I google "dbm to watts".
5) The first hit is always the best dbm-to-Watts converter.
6) http://www.rapidtables.com/convert/p...Bm_to_Watt.htm
7) So, 27 dBm is 1/2 Watt (Note: 30 dBm would be 1 Watt, & so on).
8) The receiver is sensitive to -90dBm at 802.11n channel 10.
9) That means it can pick up a signal strength of 1 picowatt.
10) The signal to noise headroom needs to be around 20dBm.
11) That means I need signal to be 1/10 Watt greater than noise.
12) The transmitter is claimed to be 28dBm±2dB at channel 10.
13) So, the transmitter (without antenna) is 6/10ths of a Watt.
14) However, the Rocketdish reflector & antenna add another 24dBi.
15) A dBi is relative to a fictional spherical-radiation pattern.
16) So, my effective isotropic radiated power is 28+24=52dBm!
17) An EIRP of 52 dBm is a whopping 158 Watts!
18) The FCC only allows me an effective power of 4 Watts
19) Googling for "watts to dbm", the first link is the best.
20) http://www.rapidtables.com/convert/p...att_to_dBm.htm
21) That 4 Watts is 36dBm
22) Even though the equipment is capable of 52dBm, it's toned
down to that legal limit of 36dBm.

So, given all that, my average noise is rather low, on channel 10,
of about -90dBm or 1 picoWatt (which is the green part of the bottom
graph below).
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

However, my instantaneous noise is rather high, at -40dBm or
10 microWatts (which is the blue line in the bottom graph above).

So, I guess my question is how much will my radio be adversely affected
by 10 microWatts of instantaneous noise, when the average noise is only
1 picoWatt?

I have no experience with what noise levels are good, and which ones
are bad - so I have no background to interpret the spectrum analysis.

REFERENCE:
Transceiver datasheet (Ubiquiti Rocket M2):
https://www.discomp.cz/img.asp?attid=88929

Antenna (Ubiquiti Rocketdish RD-2G-24):
http://dl.ubnt.com/datasheets/rocketdish/rd_ds_web.pdf

Hi,
When you talk about noise there are many different kinda noise.

On Wed, 18 Dec 2013 00:21:46 -0700, Tony Hwang wrote:

When you talk about noise there are many different kinda noise.

In the case here, it's all 2.4GHz signals which are not coming
from the access point that I'm connecting to, yet, which the
rooftop antenna sees.

On Tue, 17 Dec 2013 22:40:14 -0800, miso wrote:

First things first. I'm guessing your WISP picked channel 10 and you can't
change that. Is that the case?

Yes.
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

A waterfall is just time dependent sniffing. If your WISP wasn't spraying
you with wifi on channel 10 (again, my guess), you would examine the
waterfall display and find the area with the least activity. Now the
waterfall is useful if someone burps wifi at you, as in a telemetry
application. If the band was crowded, you would pick the channel with the
occasional belch of wifi rather than one that is busy all the time. [If
you were doing SIGINT, you would look for patterns in the occasional wifi
belch. This is knows as traffic analysis.]

It's rare to see time on the Y axis, so I see how it's time-dependent
sniffing. I guess it also looks like a waterfall, since it's columnar
but in layers. Blue seems to be where I'd want to be, if I wasn't
constrained to be on channel 10, which is my access point channel.

My next guess is you WISP provider has a customer on channel 2 at the same
location that feeds you. [It could be another WISP from a different
vendor.] The WISP provider has a beam antennas at the transmitter site.
One beam for you on channel 10, another beam for somebody else on channel
2.

You are correct. The same WISP is feeding two different neighborhoods with
two antennas, both at the same mast, one on channel 2 and the other on
channel 10.

I can now see the waterfall is yellow'er on those two channels, as are the
power levels bluer, and the real-time view greener.

That person may live near you since you are seeing the signal, but
there are no red blobs in the waterfall, so the antenna isn't pointed
directly at you. [And why would it be?] Red means a strong signal. The
WISP on channel 2 is only 7 db less than your signal, but channel 2 and
channel 10 have no common frequencies, so nothing to worry about.

You figured out a lot from that waterfall graph that I hadn't mentioned
(because I didn't realize it might be relevant). Yes, the WISP is on both
channel 2 and 10, and both antennas are on the same tower; but only one
(channel 10) is meant for me to connect to.

You have two neighbors on channel 3, so that would be a bad channel for
you, as would any channel that overlaps channel 3. Probably the WISP
installer already knew that from when the site survey was done.

The point is duly noted to stay away from channel 3.
h
I'm not really sure how they determine the noise floor. At any one time,
there is somebody on a wifi channel. It might be really low RF level, but
not zero. Probably the receiver makes a determination that if it can't
sniff a signal, it must be noise. Not a good assumption.

I think anything the antenna sees which is not a connection signal,
is considered noise.

At -50dBm over 3 miles, I'd call it a day and go looking for something
else to fix.

You have a point that the -50dBm isn't bad for a distance of 3 miles.
I was more worried about the -88dBm of noise, but, now, after looking
further, I think that the noise level is just about at the receiver
sensitivity of -90dBm ± 2dB.

The main figure that worries me is the instantaneous noise of -40dBm.
Do you know what effect this instantaneous noise might have on the radio?

On 12/18/2013 12:12 AM, Danny D'Amico wrote:
On Wed, 18 Dec 2013 00:21:46 -0700, Tony Hwang wrote:

When you talk about noise there are many different kinda noise.

In the case here, it's all 2.4GHz signals which are not coming
from the access point that I'm connecting to, yet, which the
rooftop antenna sees.

Would wrapping the feed in tinfoil give a measure of internally
generated noise?

On Wed, 18 Dec 2013 01:51:40 -0800, mike wrote:

Would wrapping the feed in tinfoil give a measure of internally
generated noise?

They do sell RF Armor for the Rocketdish, but, it's prohibitively expensive:
http://www.rfarmor.com/cart/index.ph...=index&cPath=1

I guess I could fabricate the RF Armor out of steel sheathing.
http://www.youtube.com/watch?feature...PMnc1rW_o#t=58

That would make it a neat home-repair project!
http://www.youtube.com/watch?feature...7ev2NnXr0#t=38

On Wed, 18 Dec 2013 08:28:49 +0000 (UTC), Danny D'Amico
wrote:

I think anything the antenna sees which is not a connection signal,
is considered noise.

One receiver's signal is another receiver's noise.

Char Jackson wrote:
On Wed, 18 Dec 2013 08:28:49 +0000 (UTC), Danny D'Amico
wrote:

I think anything the antenna sees which is not a connection signal,
is considered noise.

One receiver's signal is another receiver's noise.

Hi,
First of all two kinda noises. One is internal, the other is external.
Under this two there are many different kind of noises.

On Wed, 18 Dec 2013 01:48:13 +0000 (UTC), Danny D'Amico
wrote:

Can you help me interpret this 2.4GHz WiFi spectrum analysis noise plot
that I just ran from my Ubiquiti Rocket M2 rooftop antenna?

I'm trying to debug why I have -88dBm of noise at my rooftop radio.

Right. That's the symptom. Now, what problem are you trying to
solve? Lack of speed? Variations in speed? VoIP jitter?
Disconnects?

My Rocket M2 rooftop radio is on channel 10.

Why is your WISP using Ch 10. Is there a problem with Ch 11 or does
he have his AP setup for the dreaded "auto"?

My home broadband router inside the house is on channel 1.

Here is the "waterfall" plot:
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

If you look at the lower graph, in the area of Ch 10, you'll see that
the baseline "noise" level for Ch 10 is about -110dBm.

Any observations with respect to the source of the -88dB noise?
(I don't really know how to interpret this stuff.)

Unplug your antenna and see what manner of "noise" level you get.
The -88dBm "noise" level is what the Rocket M2 hears between bursts of
RF, when there's presumably nothing to hear. With an all digital
receiver, the Rocket M2 is going to hear about 25 MHz or more of RF
spectrum. I put "noise" in quotes because it's not really noise in
the sense of measuring receiver NF (-174dBm/Hz). My guess(tm) is that
it's mostly other users on Ch 10. That could be other client radios,
such as your neighbors talking to the same WISP on Ch 10 or the 2-3
adjacent channels. It could also be additional WISP access points on
Ch 10. I know you have a rather directional antenna, which is a big
help at removing such "noise", but if you have the bad luck of having
another client radio in the direction of the main lobe, or nearby to
the side, you'll hear their "noise".



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

On Wed, 18 Dec 2013 08:59:51 -0800, Jeff Liebermann
wrote:

Here is the "waterfall" plot:
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

Duh. I didn't look at the pictures very carefully. Sorry.

Looks like you have interference from someone nearby using Ch 9. I
marked the area on a copy of your screendump in red. I also took the
liberty of tweaking the contrast so that the Ch 9 junk can be more
easily seen:
http://www.learnbydestroying.com/jeffl/crud/Rocket-M2-interference.jpg
There's a 20dB signal level difference between your WISP and the
interference, but that's probably enough to cause problems. It also
explains the -88dBm "noise" level.

If you post any more images, please do NOT stretch the image. Just
leave the aspect ratio the same as the original.

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

On Wed, 18 Dec 2013 01:48:13 +0000, Danny D'Amico wrote:

Here is the "waterfall" plot:
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

Here is the "channel" plot:
http://farm8.staticflickr.com/7310/1...e93b109b_o.jpg

Here's a site survey:
http://farm6.staticflickr.com/5484/1...32590c4f_o.png

And, here's a view of the rooftop radio signal to noise strength:
http://farm8.staticflickr.com/7380/1...0692ea50_o.png

I found a good description of the three (actually four) plots he
http://wiki.ubnt.com/Best_channel_using_airview

The Waterfall chart is a time-based graph showing the aggregate
energy collected over time for each frequency, where colder colors
indicate lower energy levels & warmer colors mean higher energy
levels at that frequency bin.

My Waterfall chart shows relatively cool colors (low energy) over
all the bands except those surrounding 802.,11n channel 2 & 10,
which are the two channels of the WISP antennas facing me:
http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

The Channel Usage chart, each Wi-Fi channel is represented by a
bar displaying a percentage showing the relative "crowdedness"
of that specific channel. This percentage is calculated based
on both the popularity and the strength of RF energy in that
channel.

My Channel Usage chart shows that the channel usage is between
5% and 10% where I live. I don't know if that is a high or low
number, but, it *seems* low, simply based on percentages.

In my case, the channel usage is again highest in the channels
that the WISP has an antenna aimed at me, namely channel 2 and
10; but the chart also shows relatively high usage in channel
1 & 3, and in 8, 9, & 11. The lowest usage is in channels 4, 5,
6, and 7, so, I guess that's where I'd put my home broadband
http://farm8.staticflickr.com/7310/1...e93b109b_o.jpg

The middle chart in both those screenshots above is the
Waveform chart. Just like the Waterfall chart, this time-based
graph shows aggregate energy where the color of the energy
indicates amplitude.

It also shows the signal strength humping around WiFi channels
2 and 10, which are the two antennas from my WISP facing me.
Oddly, it also shows red areas in the middle bands, which makes
no sense to me unless they're instantaneous and short lived
bursts of energy (perhaps from cellphones or microwaves?).

The bottom chart in both those screenshots is the Real-time
chart which shows what a traditional Spectrum Analyzer would
display in energy (in dBm) as a function of frequency.

The blue trace is called "Max Hold" of maximum power levels
across the frequency. The green trace is the average energy
across frequency. And the yellow line is the real-time energy.

On Wed, 18 Dec 2013 10:07:41 -0600, Char Jackson wrote:

One receiver's signal is another receiver's noise.

That's aptly shown by the fact that my WISP has two
antennas facing me, one at channel 2 and the other
(which is my "signal") on channel 10.

So, his channel 2 is creating noise for me, based on
these spectrum analysis results yesterday.
http://farm8.staticflickr.com/7310/1...e93b109b_o.jpg

In the middle chart, you can see high signal surrounding
channels 2 & 10. So, if I select channel 10, channel 2 is
noise to me.

On Wed, 18 Dec 2013 09:21:54 -0700, Tony Hwang wrote:

First of all two kinda noises. One is internal, the other is external.
Under this two there are many different kind of noises.

I see what you mean.

I'm only looking at external noise (AFAIK) with these
spectrum analysis runs.

These plots are all taken in a direction looking *away*
from the city of San Jose. I'm pretty sure I'd get quite
different results had I pointed directly at the Fairmont
Plaza building!

On Wed, 18 Dec 2013 08:59:51 -0800, Jeff Liebermann wrote:

what problem are you trying to solve? Lack of speed?
Variations in speed? VoIP jitter? Disconnects?

Hi Jeff,
Thanks for chiming in, as I know you're a God in the wireless
forums, and, your information is especially useful since we're
both on each side of the Santa Cruz mountains.

My speeds are actually OK, as shown in this speedtest, which
shows 10ms, 19Mbps down, 18Mbps up, even though the antenna
system spans over 20 miles until it gets to a bona-fide wi
http://farm8.staticflickr.com/7310/1...e93b109b_o.jpg

I just want to make it faster. Whatever I do to decrease noise
makes the signal that much better. Notice, at 56% and 66%, my
signal quality figures aren't close to maxing out yet:
http://farm8.staticflickr.com/7419/1...26611246_o.jpg

Although, sometimes they get up into the 86% to 90% range:
http://farm4.staticflickr.com/3790/1...5699bec3_o.jpg

Why is your WISP using Ch 10. Is there a problem with Ch 11 or does
he have his AP setup for the dreaded "auto"?

Hmmm.... I don't have a clue as to the answer. All I know is
that he had texted me how to set up my radio, and I set it up
just like he had texted me to. I just looked at the settings
in the radio, and I see the channel width set to 20MHz and
channel shifting disabled, but I don't see where the channel
is actually set.

If you look at the lower graph, in the area of Ch 10, you'll see that
the baseline "noise" level for Ch 10 is about -110dBm.

Hmmm... I see the green "average" area to be around -90 at channel 10.
Now I don't know if that's a good average or not, but, I'm beginning
to think it's actually low signal strength, even though there's
a radio aimed right at me on channel 10.

Unplug your antenna and see what manner of "noise" level you get.

That's an interesting test to run. The radio & antenna are on
the roof, so, I will have to climb up there to unplug it, and then
climb back down, and then back up. So it will take a while.
(Luckily it's something like 70 degrees outside today!)

The -88dBm "noise" level is what the Rocket M2 hears between
bursts of RF, when there's presumably nothing to hear.

That's interesting. It makes sense.

My guess(tm) is that it's mostly other users on Ch 10.
That could be other client radios, such as your neighbors talking
to the same WISP on Ch 10 or the 2-3 adjacent channels.

I think all the neighbors are on the same channel as the WISP radio,
so, from that, I can see there will always be noise on that channel
(since we're all using it).

I know you have a rather directional antenna, which is a big
help at removing such "noise", but if you have the bad luck of having
another client radio in the direction of the main lobe, or nearby to
the side, you'll hear their "noise".

Thanks Jeff for that insight. There are a couple of houses right
under my signal, but a few hundred feet lower in elevation than
I am. Perhaps some of their signal is bouncing to me. There are
also a few to the side, and behind me, and above me, so, they're
going to be the most problematic, I would think.

Thanks for the insight. I think everyone should post what they
see from their radios so that we can all compare to each other.

"Jeff Liebermann" wrote in message
...
On Wed, 18 Dec 2013 02:21:53 +0000 (UTC), hh wrote:

only guy who can do this is gone, Jeff Liebermann

Rumors of my demise might be a bit premature. I'm buried in projects,
work, Christmas Chrisis', ladyfriend, and trying to untrash my house,
office, and vehicle. Incidentally, this is what I've been doing for
"fun".
http://www.learnbydestroying.com/jeffl/antennas/dish-move-project/

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


Lady friend means untrash house. You should have thought about this
:-).
--
Bill

Brought to you from Anchorage, Alaska.

On Wed, 18 Dec 2013 09:19:56 -0800, Jeff Liebermann wrote:

Looks like you have interference from someone nearby using Ch 9.

Hi Jeff,
Thanks for taking a closer look. I would *never* have been able
to see that channel 9 interference in that chart unless you had
outlined it as you did in your screenshot below:
http://www.learnbydestroying.com/jef...terference.jpg

A site survey from that same radio doesn't show anyone on channel
9, but, of course, it can be coming from portable devices & microwaves:
http://farm6.staticflickr.com/5484/1...32590c4f_o.png

To see if that channel 9 pollution was coming from the house,
I downloaded InsSSIDer freeware for Windows & Android:
http://www.metageek.net/products/inssider/

Roaming the house, I could easily see my channel 1 home broadband
router polluting channels 1 & 3; and I could see that 4 through
8 had "something" on them at much lower levels; but 9 seemed clear:
http://farm4.staticflickr.com/3774/1...22483f08_o.gif

The caveat here is that the radio measures things from miles away
while the Inssider program only measures what the absolutely puny
antenna and crippled radio on the laptop (or Android phone) can
see - which is miniscule.

So, all I can tell from that is that the channel 9 interference
isn't coming from *my* house!


PS:
I didn't stretch any of the screenshots, so, if they're stretched,
Flickr did it, not me.

On Wed, 18 Dec 2013 10:20:04 -0900, "Bill Bradshaw"
wrote:

"Jeff Liebermann" wrote in message
.. .
On Wed, 18 Dec 2013 02:21:53 +0000 (UTC), hh wrote:

only guy who can do this is gone, Jeff Liebermann

Rumors of my demise might be a bit premature. I'm buried in projects,
work, Christmas Chrisis', ladyfriend, and trying to untrash my house,
office, and vehicle. Incidentally, this is what I've been doing for
"fun".
http://www.learnbydestroying.com/jeffl/antennas/dish-move-project/

Lady friend means untrash house. You should have thought about this
:-).

Nope. It was my idea. I spent my first 50 years or so accumulating
all this junk. I'll probably spend another 50 years or so getting rid
of it. Do I really need 5 bicycles? I'm making weekly runs to the
recyclers, thrift shop, or municipal dump to get rid of the stuff. (I
really miss my pickup truck). At my present rate, I should have the
house and office cleaned up in about 50 years.

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

my friend just retired and moved from a huge custom house in the cold,
snowy, Chicago area
down to the middle of FL - sitting out on the lanai....

He coined the term --- de-crapification

Just prior to his leaving, we had our little college ski group lunch
gathering (4 guys)
with him presenting us each with a token from our past as part of his
de-crapification.
Some were FORTRAN puch cards, from our CS days,
some were check/receipts from our skiiing in Austria,
some were photos from frat parties - with fuzzy hair and long sideburns.

On Wed, 18 Dec 2013 19:18:38 +0000 (UTC), "Danny D."
wrote:

On Wed, 18 Dec 2013 08:59:51 -0800, Jeff Liebermann wrote:

Why is your WISP using Ch 10. Is there a problem with Ch 11 or does
he have his AP setup for the dreaded "auto"?

Hmmm.... I don't have a clue as to the answer. All I know is
that he had texted me how to set up my radio, and I set it up
just like he had texted me to. I just looked at the settings
in the radio, and I see the channel width set to 20MHz and
channel shifting disabled, but I don't see where the channel
is actually set.

Your equipment is the client, so you don't get to set the channel. The WISP
sets the channel and all you can do is follow their lead.

On Wed, 18 Dec 2013 21:50:34 -0600, Char Jackson wrote:

Your equipment is the client, so you don't get to set the channel.
The WISP sets the channel and all you can do is follow their lead.

Thanks for clarifying that.
I had poured over every page of the router setup, and I
didn't see WHERE the channel was set.

I did see the channel width, and modulation, but, not
the channel itself.

You explained why that is.

Thanks!

What I love about this WiFi gear is that we can connect to
an access point five miles away, and it works as well as if
the access point was in the next bedroom over!

On 12/18/2013 5:14 PM, ps56k wrote:
my friend just retired and moved from a huge custom house in the cold,
snowy, Chicago area
down to the middle of FL - sitting out on the lanai....

He coined the term --- de-crapification

Just prior to his leaving, we had our little college ski group lunch
gathering (4 guys)
with him presenting us each with a token from our past as part of his
de-crapification.
Some were FORTRAN puch cards, from our CS days,
some were check/receipts from our skiiing in Austria,
some were photos from frat parties - with fuzzy hair and long sideburns.


When I was in college you could spot a nerd because he had a pocket
protector and a rectangular box of punch cards under one arm. Pocket
calculators came out later, cost around $400.00 and had nerds drooling
over them. I was out of college when I saw my first HP calculator but I
still had boxes of punch cards. ^_^

TDD

On Wed, 18 Dec 2013 22:59:04 -0600, The Daring Dufas
wrote:

When I was in college you could spot a nerd because he had a pocket
protector and a rectangular box of punch cards under one arm. Pocket
calculators came out later, cost around $400.00 and had nerds drooling
over them. I was out of college when I saw my first HP calculator but I
still had boxes of punch cards. ^_^

Yeah, that was the theory but it didn't quite work at Cal Poly Pomona
in the late 1960's. Among other divisions, Cal Poly had an
engineering skool and an ABM (agricultural business management) skool.
One would assume that the engineering students carried slide rules and
punched cards, and the ABM students looked like TV cowboys. Nope. The
engineering students wanted to look like cowboys and wore boots,
jeans, flannel, but not the hat. The ABM students wore suits, ties,
hats, and carried briefcases. There was also a skool of environmental
design, which true to the stereotype, everyone looked like hippies. I
tried to make sense of it at the time, and gave up.

Incidentally, it took me about 10 years to work my way through all the
punched card decks I had accumulated and used mostly as scratch paper.
I didn't make the same mistake with paper tape, which I converted to
floppy and burned the tapes.

My first calculator was an analog computer that I built into a brief
case. There were several 10 turn pots to input the numbers, and a big
mirrored meter to read the output. Basically, an electronic
implementation of a slide rule.
https://groups.google.com/forum/#!original/scruz.general/Egv8cT2-JGY/SNVk9zi1ULQJ

When I graduated from college, I could throw everything I owned into
my pickup truck and drive off into the sunset (and actually did that a
few times). If I tried that today, it would take at least two large
moving vans and a project manager.

He who dies with the most toys, wins.

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

On Wed, 18 Dec 2013 22:59:04 -0600, The Daring Dufas
wrote:

On 12/18/2013 5:14 PM, ps56k wrote:
my friend just retired and moved from a huge custom house in the cold,
snowy, Chicago area
down to the middle of FL - sitting out on the lanai....

He coined the term --- de-crapification

Just prior to his leaving, we had our little college ski group lunch
gathering (4 guys)
with him presenting us each with a token from our past as part of his
de-crapification.
Some were FORTRAN puch cards, from our CS days,
some were check/receipts from our skiiing in Austria,
some were photos from frat parties - with fuzzy hair and long sideburns.


When I was in college you could spot a nerd because he had a pocket
protector and a rectangular box of punch cards under one arm. Pocket
calculators came out later, cost around $400.00 and had nerds drooling
over them. I was out of college when I saw my first HP calculator but I
still had boxes of punch cards. ^_^

Punch cards were for the CS weenies. ;-) The real nerds had
slip-stick scabbards hanging from their belts (I carried mine with my
books). Over my senior year, the slip-sticks were being replaced by
calculators (and holsters for scabbards ;-). I bought an HP, and yes,
it was $400 (about 10-weeks gross pay).

I'm still wondering what problem you are trying to solve. Is your WiFi not working properly or are you just concerned about reading -88 dBm noise level on the analyzer? I wouldn't be surprised to read -88 dBm from a high gain antenna.
Do you think that is abnormal or is there some other problem?


Mark

On 12/19/2013 10:30 AM, Jeff Liebermann wrote:
On Wed, 18 Dec 2013 22:59:04 -0600, The Daring Dufas
wrote:

When I was in college you could spot a nerd because he had a
pocket protector and a rectangular box of punch cards under one
arm. Pocket calculators came out later, cost around $400.00 and had
nerds drooling over them. I was out of college when I saw my first
HP calculator but I still had boxes of punch cards. ^_^

Yeah, that was the theory but it didn't quite work at Cal Poly
Pomona in the late 1960's. Among other divisions, Cal Poly had an
engineering skool and an ABM (agricultural business management)
skool. One would assume that the engineering students carried slide
rules and punched cards, and the ABM students looked like TV cowboys.
Nope. The engineering students wanted to look like cowboys and wore
boots, jeans, flannel, but not the hat. The ABM students wore suits,
ties, hats, and carried briefcases. There was also a skool of
environmental design, which true to the stereotype, everyone looked
like hippies. I tried to make sense of it at the time, and gave up.

Incidentally, it took me about 10 years to work my way through all
the punched card decks I had accumulated and used mostly as scratch
paper. I didn't make the same mistake with paper tape, which I
converted to floppy and burned the tapes.

My first calculator was an analog computer that I built into a brief
case. There were several 10 turn pots to input the numbers, and a
big mirrored meter to read the output. Basically, an electronic
implementation of a slide rule.
https://groups.google.com/forum/#!original/scruz.general/Egv8cT2-JGY/SNVk9zi1ULQJ

When I graduated from college, I could throw everything I owned
into my pickup truck and drive off into the sunset (and actually did
that a few times). If I tried that today, it would take at least two
large moving vans and a project manager.

He who dies with the most toys, wins.


Here in Alabamastan we actually have a state college, The University of
Auburn, which is both the premier agricultural and engineering school. I
traveled to Auburn one year to visit some friends and drove past "The
Swine Research Unit". The smell could gag a maggot but the pigs were
happy. In the mid 1960's at The University of Alabama, I started playing
with and learning a tiny bit of Basic and Fortran in order to play with
the Univac which was on its way out and the new IBM 360/50 RAX system
which was replacing it. Kids these days have no idea how user friendly
computers are now compared to what I started playing with like the
analog computer at my school but I really believe computers were more
fun all those years ago. Now they're tools, not so exclusive anymore and
any kids gaming computer has much more computing power than what was
considered a super computer at one time. ^_^

TDD

On Wed, 18 Dec 2013 18:51:01 -0800, miso wrote:

You can by RF shield spray at Frys. Not cheap, well at least compared to
a can of spray paint.

Huh? Wow. I had never heard of that, for antennas & reflectors.
Hmmm... I've seen it on the inside of monitors I've disassembled, especially
the white ones (where the inside is a scratchy gray painted color).

Hmmmmm..... so what would I paint?

I guess I'd paint the backside of the Rocketdish reflector.
Would I also paint the outside of the Rocket M2 radio unit?
I guess I could also paint the CAT5 cable coming into the rocket.

Oooops. I just realized, I did NOT use shielded cable for my cat5.
I used indoor plenum stuff. I wonder if shielded cable would have
made a difference?

On 12/19/2013 11:13 AM, wrote:
On Wed, 18 Dec 2013 22:59:04 -0600, The Daring Dufas
wrote:

On 12/18/2013 5:14 PM, ps56k wrote:
my friend just retired and moved from a huge custom house in the cold,
snowy, Chicago area
down to the middle of FL - sitting out on the lanai....

He coined the term --- de-crapification

Just prior to his leaving, we had our little college ski group lunch
gathering (4 guys)
with him presenting us each with a token from our past as part of his
de-crapification.
Some were FORTRAN puch cards, from our CS days,
some were check/receipts from our skiiing in Austria,
some were photos from frat parties - with fuzzy hair and long sideburns.


When I was in college you could spot a nerd because he had a pocket
protector and a rectangular box of punch cards under one arm. Pocket
calculators came out later, cost around $400.00 and had nerds drooling
over them. I was out of college when I saw my first HP calculator but I
still had boxes of punch cards. ^_^

Punch cards were for the CS weenies. ;-) The real nerds had
slip-stick scabbards hanging from their belts (I carried mine with my
books). Over my senior year, the slip-sticks were being replaced by
calculators (and holsters for scabbards ;-). I bought an HP, and yes,
it was $400 (about 10-weeks gross pay).

Oh I had a slide rule too. It was a K&E as I remember and I wish I still
had it. ^_^

TDD

On Wed, 18 Dec 2013 09:19:56 -0800, Jeff Liebermann wrote:

http://farm8.staticflickr.com/7299/1...48f3922e_o.jpg

Looks like you have interference from someone nearby using Ch 9.

I'm still amazed that you saw that, lurking inside the graphs!

You must have eyes like an eagle, because I had not seen it
(until you pointed it out).

Although, for the life of me, I can't determine the *source*
of that channel 9 interference since nothing inside the house
or nearby seems to have a strong enough signal to register as
channel 9 WiFi...

For example, here is a scan on my laptop for access points:
http://farm8.staticflickr.com/7364/1...a0cdf3b1_o.gif

Nothing is on channel 9.

Here is a scan of the access points from my radio:
http://farm6.staticflickr.com/5484/1...32590c4f_o.png

So, I do agree with you that there is a good amount of channel
9 interference; but I must conclude the source of that noise
is distant (but clearly in the path of the radio).

On Thu, 19 Dec 2013 11:45:23 -0600, The Daring Dufas wrote:

Oh I had a slide rule too. It was a K&E as I remember and
I wish I still had it. ^_^

My Dad, bless his heart, taught me how to use a slide rule
when I was in high school trig class. His was bamboo and white,
as I remember it. He bought me a smaller one, and I cherished
it. I hope I still have it, but, I've moved a half dozen times
since so it's somewhere.

On Wed, 18 Dec 2013 19:44:34 -0800, Jeff Liebermann wrote:

Unplug your antenna and see what manner of "noise" level you get.
You should replace the antenna with a 50 ohm terminator.
That's easy if there's an antenna connector available.

Hmmm... this always confuses me, as to what is the radio, what
is the antenna, and what is "just" a reflector.

I have three radios, one of which is on the (tile) roof, so, that's
the hard one to get to.
a. Rocket M2 + Rocketdish (rooftop antenna connected to my WISP).
b. Nanobridge M2 + dish reflector (I have this in my hand right now).
c. Bullet M2 + planar antenna (this is mounted on a pole outside).

In the case of the Bullet M2, it's clear the 27dBm (600mW) radio
is a wholly separate unit than whatever antenna you attach to it:
http://store.netgate.com/Ubiquiti-Bu...r-CPE-P71.aspx

It's less clear in the case of the Nanobridge M2, where the "feedhorn"
is actually a 23dBm (200mW) radio + integral 3dBi antenna, but, where
the radio+antenna comes already attached to the 15dBi reflector.
http://www.solidsignal.com/pview.asp...i-%28nb2g18%29

It's unclear to me which is the antenna and which is the reflector
in the case of the Rocket M2 + Rocketdish:
ROCKET M2: http://store.netgate.com/Ubiquiti-Ro...-P287C128.aspx
ROCKETDISH: http://store.netgate.com/RocketDish-...nna-P1727.aspx

Is that "thing" at the end of the feedhorn on the Rocketdish the
antenna? Or is the antenna elsewhere?