Re: WiFi out to 800 feet

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Arlen Holder

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Oct 4, 2020, 8:48:25 PM10/4/20
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On Sat, 26 Sep 2020 03:25:16 -0400, Paul wrote:

> There are companies that make good products for jobs like this, but
> you need a secret-decoder-ring to figure out which one to use.

To Paul's point, I recommend two companies, both out of San Jose,
but both do mail order (one via distributors like Amazon).

More importantly, both give you specification sheets galore.
o And both, IMHO, are reliable dependable outfits.

o For equipment, I'd stick with Ubiquiti on both ends, if I could:
<https://www.ui.com/products/>

o For ordering "stuff" (poles, bolts, etc.) I'd compare with Streakwave:
<https://www.streakwave.com/product-ubiquiti.asp>

I'm sure other outfits are just as good, but you can't go wrong with them.
o Prices are ok, quality is good, service is good, sales is experienced

BTW, with LOS & radios at each end, 800 feet is child's play for WiFi.
o Curious how far your Wi-Fi access point is from your desktop computer
<https://groups.google.com/forum/#!topic/microsoft.public.windowsxp.general/PkD0jfa9GqM>
--
On Usenet adults can pool their knowledge & experience to help others.

Arlen Holder

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Oct 4, 2020, 8:59:25 PM10/4/20
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On Sat, 26 Sep 2020 13:59:43 -0400, gfre...@aol.com wrote:

> I have a good mount at the house, a DSS dish bracket that I am not
> using. In fact I was thinking the dish might work with a little
> hacking. I think the far end will end up on a 6" wood pole so that
> should be pretty stable. I guess I need to do more reading on this.
> Our plan B is to buy another WiFi connection from the cable company
> but the cost is prohibitive and it requires 120v that we don't have so
> that is even more money. I see plenty of solar WiFi cameras. They all
> seem to want to use the cloud and I would rather keep this whole thing
> in house if possible. I have enough residents protesting the camera
> in the first place and if we are shipping it out to the internet that
> would bother more of them. Some are pissed at how many Ring cameras
> are in the neighborhood. A black helicopter has them hiding under the
> bed. ;-)

You must live in my neighborhood! :)

You bring up two important issues:
a. Power at the remote site 800 feet away, and,
b. The Fresnel zone of a pole only six feet tall

You can look up the Fresnel zone stuff separately, which, in my experience,
is more theoretical than practical since you just shove more directional
beam power to overcome the losses due to lack of height.

Power is an issue.

I'll ping "alt.internet.wireless" & "sci.electronics.repair" with this
post, who may be able to assist you more so than I can in how to set up the
power (be advised to ignore the three infants on s.e.r if they respond).

What we do here in the Santa Cruz mountains, where the zoning is 40 acres
per household, is "bucket routers" which are simply routers plugged into
anything we can plug them into, between homes when we need to clear
obstructions to our Line of Sight (LOS) WiFi transceivers.

But your suggestion of solar seems far better than bucket routers.
--
A "bucket router" is just a router under a bucket for weather protection.

Fox's Mercantile

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Oct 4, 2020, 9:51:29 PM10/4/20
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On 10/4/20 7:59 PM, Arlen Holder wrote:
[ nothing of any importance, as usual ]

Piss the fuck off.



--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

Jeff Liebermann

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Oct 6, 2020, 7:35:52 PM10/6/20
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On Sun, 4 Oct 2020 20:51:21 -0500, Fox's Mercantile <jda...@att.net>
wrote:

>On 10/4/20 7:59 PM, Arlen Holder wrote:
>[ nothing of any importance, as usual ]

>Piss the fuck off.

Oh, be nice. 300ft is about the limit for omnidirectional antennas on
both ends of a 2.4GHz link. For 800ft, directional antennas with some
gain are going to be required. To get some decent speeds, 5GHz
instead of 2.4GHz.

Small antennas, long range, high speed... pick any two.

Drivel: For your amusement, a Model 15 TTY used as a terminal for a
Linux computah. Handling upper/lower case was a kludge and handling
arithmetic and programming symbols was impossible. No mention of
termcap or terminfo:

"Using a 1930 Teletype as a Linux Terminal"
<https://www.youtube.com/watch?v=2XLZ4Z8LpEE>

Try it with your Model 15. That should keep you out of trouble for at
least a little while.

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

Fox's Mercantile

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Oct 6, 2020, 8:09:21 PM10/6/20
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On 10/6/20 6:35 PM, Jeff Liebermann wrote:
> 300ft is about the limit for omnidirectional antennas on
> both ends of a 2.4GHz link.

I tried linking the shop to the house on 2.4 using 24" antennas
at both ends. Distance was 1400 feet.
Never could get it to work.

> For 800ft, directional antennas with some
> gain are going to be required. To get some decent speeds, 5GHz
> instead of 2.4GHz.

I bought a pair of Ubiquiti LiteBeam M5 with 23 dB antennas.
Absolutely solid link.

> "Using a 1930 Teletype as a Linux Terminal"
> <https://www.youtube.com/watch?v=2XLZ4Z8LpEE>

I've seen that before. I don't have a Model 15. I have a Lorenz
Lo-15c (made in Germany under license from the Teletype Corp.

> Try it with your Model 15. That should keep you out of trouble for at
> least a little while.

Actually, I use it on i-Telex.
<https://www.i-telex.net/>


--
"I am a river to my people."
Jeff-1.0
WA6FWI
http:foxsmercantile.com

Arlen Holder

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Oct 6, 2020, 9:34:23 PM10/6/20
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On Tue, 06 Oct 2020 16:35:44 -0700, Jeff Liebermann wrote:

> Small antennas, long range, high speed... pick any two.

Hi Jeff,

We go way back, decades, regarding Fox's/Snit's childish rants on Usenet...
o Nobody takes Snit/Fox seriously (just google for his name for reference).

Don't worry about Snit (Michael Glasser is who Fox's Mercantile really is).
o He admitted it himself, years ago, when we caught him with the same IP

What I want to say is that I THANK YOU for helping the OP out.
o I know there are adults on s.e.r who, like you, are knowledgeable.

The whole point of adding s.e.r and a.i.w was that the Windows group needed
your expert assistance, which I, as an adult, for one, greatly appreciate.

Let's hope the OP reads your advice and takes it to heart for his problem
o Adults like you can help him, and, in doing so, you help all of us.

It's what Usenet is supposed to be all about...
o To that end, I include the OP's original post, verbatim, below:

o WiFi out to 800 feet
<https://groups.google.com/forum/#!topic/microsoft.public.windowsxp.general/uEhm2dTCc2o>

From: gfre...@aol.com
Newsgroups: microsoft.public.windowsxp.general
Subject: WiFi out to 800 feet
Date: Fri, 25 Sep 2020 23:28:01 -0400
Message-ID: <vsctmflrf2puspliv...@4ax.com>

I didn't want to hijack the other thread but Arlen got my interest
with those antennas.

If I wanted to hit a LAN based camera 800' away, what would I need to
to do (clear LOS).

The objective would be to attach it to an existing security DVR that
has 2 unused WiFi portals.

I am trying to avoid the cloud/phone thing but that seems to be what
most of these ones I see are doing these days. I assume once they are
on the network I could coax my DVR to see them.

Do I need an enhanced antenna at both ends or would the dish at the
host end give me enough signal strength to talk?

Thanks
--
There are only two kinds of people on Usenet - one of whom adds value.

Fox's Mercantile

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Oct 6, 2020, 10:03:25 PM10/6/20
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On 10/6/20 8:34 PM, Arlen Holder wrote:
> We go way back, decades, regarding Fox's/Snit's childish rants on Usenet...
> o Nobody takes Snit/Fox seriously (just google for his name for reference).
>
> Don't worry about Snit (Michael Glasser is who Fox's Mercantile really is).
> o He admitted it himself, years ago, when we caught him with the same IP

You ignorant cunt, ask Jeff who I am.

Jeff Liebermann

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Oct 7, 2020, 1:42:55 PM10/7/20
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On Wed, 7 Oct 2020 01:34:21 -0000 (UTC), Arlen Holder
<arlen_...@newmachines.com> wrote:

>On Tue, 06 Oct 2020 16:35:44 -0700, Jeff Liebermann wrote:
>
>> Small antennas, long range, high speed... pick any two.
>
>Hi Jeff,
>
>We go way back, decades...

The other Jeff and I go back before that to when we both lived in the
Smog Angeles and Orange County areas and were involved commercial and
ham radio. Later, I moved to the SF/Monterey Bay area, and Jeff moved
to Texas. We reconnected when we were both involved with SCO
Unix/Xenix products.

>Don't worry about Snit (Michael Glasser is who Fox's Mercantile really is).

Wrong. I'm not sure if Jeff wants me to reveal his real name, so I'll
just keep quiet.
>
>The whole point of adding s.e.r and a.i.w was that the Windows group needed
>your expert assistance, which I, as an adult, for one, greatly appreciate.

12 KILOMETER (7.5 miles) Wi-Fi:
<https://www.youtube.com/watch?v=lYJFwXw1ZIc>
Notice that they're using 5GHz, no bore sight alignment, no bubble
level to set the mounting poles vertical, no binoculars, no map table,
etc. Fortunately, none of this will be needed at 800 feet on 2.4 GHz.

>It's what Usenet is supposed to be all about...

Based on quantity, I thought that Usenet was the for distributing
porno, copyright violations, pirated software, fake news, bad jokes,
character assassinations, ego inflation, reputation aggrandizement,
and spam. If there is any useful information involved in Usenet, it's
a very tiny amount.


Marginally related drivel (for my ego and your amusement):
<http://www.learnbydestroying.com/jeffl/ADS-B/FR24/NooElec-SDR-indoor-monopole.jpg>
ADS-B receiver using Raspberry Pi 3, Virtual Radar Server, and
problematic Flight Radar FR24 software. Antenna is a paper clip
plugged into a NooElec Nano 1 SDR sitting on my desk. The colorful
display is the coverage area from my receiver. Different colors are
different altitude ranges. Notice the big peak at 45deg towards Lake
Tahoe and the big "holes" either side of the peak. After fiddling
with the antenna for several hours, I look out the window and notice a
small grove of redwood trees in the "holes" and an open area at 45
deg. Lesson learned: 1GHz RF doesn't go through big tree trunks.

Fox's Mercantile

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Oct 7, 2020, 4:00:49 PM10/7/20
to
On 10/7/20 12:42 PM, Jeff Liebermann wrote:
>
> The other Jeff and I go back before that to when we both lived in the
> Smog Angeles and Orange County areas and were involved commercial and
> ham radio. Later, I moved to the SF/Monterey Bay area, and Jeff moved
> to Texas. We reconnected when we were both involved with SCO
> Unix/Xenix products.

That would have been in the early '90s.

>> Don't worry about Snit (Michael Glasser is who Fox's Mercantile really is).

> Wrong. I'm not sure if Jeff wants me to reveal his real name, so I'll
> just keep quiet.

That's actually pretty funny, since it's right out in plain sight in the
"From" field on all the postings I make.

But then this is the "due diligence" I've come to expect from Arlen.
Zero and none.

Fox's Mercantile

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Oct 10, 2020, 5:10:31 AM10/10/20
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On 10/4/20 7:59 PM, Arlen Holder wrote:
[ nothing of value as usual ]

Let me know when you get tired of proving how useless you are.

Arlen Holder

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Oct 14, 2020, 3:45:20 AM10/14/20
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On Wed, 14 Oct 2020 00:23:10 -0700, Johann Beretta wrote:

> Clearly you don't do this for a living.

That is an absolutely correct assessment.

You can advise the OP better than I on potential Fresnel Zone issues, as
he's apparently asking how best to paint a LOS location 800 feet away with
the transceiver on a pole I believe.

You can run the math to explain to him how high that pole may need to be.
(We do that stuff by trial and error - but you may know the math better.)

Please advise the OP on the math so he knows how high to mount the radio.

Jeff Liebermann

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Oct 14, 2020, 10:22:02 PM10/14/20
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On Wed, 14 Oct 2020 00:25:08 -0700, Johann Beretta
<ber...@nun-ya-bizness.com> wrote:

>On 10/6/20 4:35 PM, Jeff Liebermann wrote:
>
>> To get some decent speeds, 5GHz
>> instead of 2.4GHz.

>Generally speaking, yes. Practically speaking you can do several
>hundred mbps over a 2.4 link. You just need to widen the channel.

While there are 2.4GHz routers available that have a 40MHz channel
bandwidth setting, I prefer not to use it because it reduces the
available bandwidth to other users on 2.4GHz. If one is sufficiently
clueless to use a 40 MHz channel set to CH6, it will effectively
trash most of the 2.4GHz band. Since Wi-Fi pollution can be
symmetrical, it also makes the receiver susceptible to more
interference. Stay with 20MHz channel bandwidth on 2.4GHz.

On the other foot, the minimum channel bandwidth on 5GHz is 40MHz
(depending on channel selected) with an option to use 80MHz or 160MHz
for 802.11AC and AX (Wi-Fi 6).
<https://en.wikipedia.org/wiki/List_of_WLAN_channels#5_GHz_or_5.9_GHz_(802.11a/h/j/n/ac/ax)>
With 1024-QAM, 802.11AX can theoretically do 1.2Gbits/sec in a 160MHz
channel. Your mileage will certainly be less.

The test below was to demonstrate something else. However, it does
show what can be done with 5GHz.
<http://www.learnbydestroying.com/jeffl/FLUG-talk-2015-02-28/802.1a%20direct.jpg>
Unfortunately, the radios at both ends were only 802.11a, so the speed
never went above 75 Mbits/sec at a distance of about 5 meters. It
also uses Jperf 2.0.2, which doesn't work very well above 100
Mbit/sec. I should have used Iperf 3, which works well into the
gigabit range:
<https://iperf.fr/iperf-download.php>
My home network is now mostly gigabit, so I could easily run some 5GHz
performance tests with a later version of Iperf 3. However, no pretty
graphs as nobody has bothered to port the Java code to work with
Iperf3. I'm a horrible programmist, so I won't attempt it.

Anyway, the performance limiting factor is usually interference from
co-channel users and noise sources. You could have all the bandwidth
in the world, the most efficient modulation scheme, maximum legal RF
power, and still not be able to communicate very well or far if there
is an interference source nearby. In other words, one needs to do
more than just "widen the channel".

Jeff Liebermann

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Oct 14, 2020, 10:42:56 PM10/14/20
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On Wed, 14 Oct 2020 07:45:18 -0000 (UTC), Arlen Holder
<arlen_...@newmachines.com> wrote:

>On Wed, 14 Oct 2020 00:23:10 -0700, Johann Beretta wrote:
>
>> Clearly you don't do this for a living.
>That is an absolutely correct assessment.

By the way, I officially retired on Sept 30, 2020. The office is
closed, the bank accounts emptied, and much of the equipment donated
or sold.

>You can advise the OP better than I on potential Fresnel Zone issues, as
>he's apparently asking how best to paint a LOS location 800 feet away with
>the transceiver on a pole I believe.
>
>You can run the math to explain to him how high that pole may need to be.
>(We do that stuff by trial and error - but you may know the math better.)

Sigh. I've lost count how many times I've done that in this
newsgroup. Start here:
<https://www.proxim.com/en/products/knowledge-center/calculations/calculations-fresnel-clearance-zone>
800 ft is not far enough apart to worry about the curvature of the
earth.
800ft / 5280ft/mile = 0.152 miles
At 2.4Ghz, the Fresnel Zone is 9 ft radius at the midpoint of the
link. Therefore, the antenna at both ends of the link need to be at
least 9 ft off the ground, or 9 ft above any major obstructions
(fences, trees, buildings, cars, etc). Actually, it's somewhat more
complicated if I throw in fade margin, frequency selective fading, and
system availability, but we won't need to go there for this example.

At 5 GHz, the Fresnel Zone radius is only 6.3 ft. Therefore, the
antenna pole can be 2.7 feet shorter.

>Please advise the OP on the math so he knows how high to mount the radio.

Methinks we've lost the OP long ago.

Fox's Mercantile

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Oct 14, 2020, 10:47:56 PM10/14/20
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On 10/14/20 9:42 PM, Jeff Liebermann wrote:
> By the way, I officially retired on Sept 30, 2020. The office is
> closed, the bank accounts emptied, and much of the equipment donated
> or sold.

Well done sir.

AnthonyL

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Oct 15, 2020, 7:37:50 AM10/15/20
to
On Wed, 14 Oct 2020 19:42:48 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

>On Wed, 14 Oct 2020 07:45:18 -0000 (UTC), Arlen Holder
><arlen_...@newmachines.com> wrote:
>
>>On Wed, 14 Oct 2020 00:23:10 -0700, Johann Beretta wrote:
>>
>>> Clearly you don't do this for a living.
>>That is an absolutely correct assessment.
>
>By the way, I officially retired on Sept 30, 2020. The office is
>closed, the bank accounts emptied, and much of the equipment donated
>or sold.
>

Congratulations. You'll now enjoyably find everything you knew
disappainting or being replaced by new kids on the block. I don't see
any of those filling your shoes here and I usually only bother to lurk
to see what you are posting.

>>You can advise the OP better than I on potential Fresnel Zone issues, as
>>he's apparently asking how best to paint a LOS location 800 feet away with
>>the transceiver on a pole I believe.
>>
>>You can run the math to explain to him how high that pole may need to be.
>>(We do that stuff by trial and error - but you may know the math better.)
>


I've run cantenna line-of-site over 400m reliably for years. I didn't
measure the fresnel zone but a farmer's apple tree in his front must
have encroached the signal line every few years and he would kindly
lop a few branches, restoring normal service. I have a note of the
speeds somewhere but the system gave me office access from home, home
broadband via the office and all I remember is that the Wi-Fi speed
was better than the rather poor broadband speed available at the end
of a long exchange line.

After moving several years ago from the little hamlet (60 properties)
the pathetic broadband (I think I had one of the best connections at
2mbps) was replaced by FTTP. I don't think I could have got mi Wi-Fi
signal to keep up with the resulting 80Mbps broadband. Those we now
Zoom with in that hamlet are always very clear and no blurring motion
issues - I'm somewhat jealous.

(UK in case any folk are struggling to understand any terminology or
words).
--
AnthonyL

Why ever wait to finish a job before starting the next?

Jeff Liebermann

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Oct 16, 2020, 9:40:50 AM10/16/20
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On Fri, 16 Oct 2020 01:52:13 -0700 (PDT), Michael Terrell
<terrell....@gmail.com> wrote:

>On Wednesday, October 14, 2020 at 10:42:58 PM UTC-4, Jeff Liebermann wrote:
>>
>> By the way, I officially retired on Sept 30, 2020. The office is
>> closed, the bank accounts emptied, and much of the equipment donated
>> or sold.

>Enjoy your retirement, my friend! :)

Thanks. However, it's not easy to find enjoyment while trying to
adjust to Covid-19, dysfunctional government at all levels, impending
economic collapse, limits on travel, increasing weather related
problems, an increasing homeless problem, and probably increased taxes
to keep the economy afloat. Health problems and advancing age
increasingly limit my activities. I can survive on Social Security
payments and the 80% that Medicare provides, but suspect those
benefits to will eventually be reduced by inflation as the government
resorts to printing money to finance its activities. I expect my
"retirement" to more closely resemble living on unemployment with the
added bonus of having no debt and a modest bank account. Since I have
no children or immediate family, I could easily have obtained a
reverse mortgage on my house, and lived off the cash. However, the
recent fires in California might make that impossible due to
increasing difficulties obtaining replacement value fire insurance, a
basic requirement for a reverse mortgage. In other words, the long
term prospects for an enjoyable retirement look rather grim.

However, before I blunder on into this dismal future, I have an
immediate problem to deal with. I brought about 75% of the contents
of my formerly palatial office to my house when I moved out. There
was no time to do sorting, only time to box everything and move. I
moved it in small increments because I have no garage or storage space
at the house and because I had to carry the boxes up about 50 stairs.
The boxes are now piled up both inside and outside the house. Much of
it is covered with ash that is still falling from the trees due to the
recent nearby fires. Rain will likely arrive in a few weeks and
nothing outside is protected. I need to deal with that immediately,
but can't during the current heat waves. At least I won't be bored
looking for something to do.

Incidentally, it's now 6AM and 75F (24C) outside. NWS predicts the
temperature to rise to 101F (38C) today. I might be able to do 2-3
hrs of box shuffling today. It's likely that the local power company,
PG&E, will intentionally disconnect the power to prevent falling power
lines from starting more fires and to reduce the load on the power
grid from air conditioning.

Thanks again for the hopeful thoughts, but this is not the retirement
that I had planned and is unlikely to be enjoyable.

Sqwertz

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Oct 17, 2020, 11:19:25 PM10/17/20
to
I see alchemy as your next hobby: Turning all that computer stuff
into Gold! In which case you don't have to move any of. Rain won't
hurt it.

I know it's hard to let go, but .....

-sw

Sqwertz

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Oct 18, 2020, 12:12:09 AM10/18/20
to
On Sat, 17 Oct 2020 22:19:23 -0500, Sqwertz wrote:

> I see alchemy as your next hobby: Turning all that computer stuff
> into Gold! In which case you don't have to move any of. Rain won't
> hurt it.
>
> I know it's hard to let go, but .....

So I was curious and youtubed it....This guy got $1,900 worth (about
an ounce) of .99% gold from 6 pounds of clipped OLDER PCB
connectors.

https://www.youtube.com/watch?v=o3cqZ5kqEB4

I suspect getting chemistry glass and HCL delivered to the Santa
Cruz mountains may be difficult and raise some eyebrows. Or used
to. It's kinda pointless to manufacture domestic meth anymore since
it's so cheap from Mexico, so they may have deregulated that stuff.

Food for thought...

-sw

Arthur Conan Doyle

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Oct 18, 2020, 6:03:44 AM10/18/20
to
Sqwertz <sqwe...@gmail.invalid> wrote:

> It's kinda pointless to manufacture domestic meth anymore since
>it's so cheap from Mexico, so they may have deregulated that stuff.

Afraid not. The stupid federal regulation about restricting the amount of
pseudoephedrine (Sudafed) that can be sold to an individual and requiring it be
sold blister packs still exists.

Jeff Liebermann

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Oct 18, 2020, 3:25:15 PM10/18/20
to
On Sat, 17 Oct 2020 23:12:08 -0500, Sqwertz <sqwe...@gmail.invalid>
wrote:

>So I was curious and youtubed it....This guy got $1,900 worth (about
>an ounce) of .99% gold from 6 pounds of clipped OLDER PCB
>connectors.

That's a very good yield from older PCB edge connectors, which were
plated with 50 microns gold plating. These days, the commercial stuff
is more like 5 microns. (1 micron = 1痠 = 1 millionth of a meter).
Therefore, the yield is much less. I have a small forge that I use
mostly for aluminum and brass casting, but has been used to melt gold.
Also, part of my house once looked like a chemistry lab, but that's
long gone.

>https://www.youtube.com/watch?v=o3cqZ5kqEB4

Nice video. He points out and demonstrates some of the common
problems with gold recovery. In terms of gross profit and time burn,
I've found it best to just sell the scrap gold and let someone else
deal with the chemicals and gold brokers.

I just emptied my safe deposit box so here is a photo of some gold
extraction that I did about 40 years ago.
<http://www.11junk.com/jeffl/pics/drivel/index.html#Gold-01.jpg>
At about $1,900/oz (spot price), they should be worth $2,470. However,
it's not so simple. The two blobs are not pure 24K gold. I don't
recall exactly, but I think they're only about 90%. I need to refine
them to at least 99% before I can sell them as 24K. Then, I have to
have them assayed by a certified lab for about $135. I don't know how
much dealer will take, but I'm sure it's too much.
<https://santacruzgold.biz>

However, I may have done something dumb. I couldn't find anyone to
buy my collection of old PCB's (printed circuit boards). It was quite
a pile that filled the back of my Subaru. I failed to find anyone who
wanted to buy it all. 1.5 months of office rent was about equal to
what I might obtain from the sale or from gold extraction. So, I
donated the entire mess to a local charity run recycler:
<https://www.greybears.org/our-programs/recycle/electronics-recycling/>
I would have dragged everything home and stored it until I had time to
do another gold extraction, but there was no time and no storage
space.

>I suspect getting chemistry glass and HCL delivered to the Santa
>Cruz mountains may be difficult and raise some eyebrows.

Not a problem. I've had a chemistry lab of sorts in my house for
years without incident. Over the years, we've also had various meth
labs and recreational chemical factories operating nearby. The
glassware and chemicals are not much of a problem. Disposing of the
waste and cleaning up the mess after the chemists move out, are very
real problems.

>Or used
>to. It's kinda pointless to manufacture domestic meth anymore since
>it's so cheap from Mexico, so they may have deregulated that stuff.

I prefer not to explain, but if I can contrive a believable and
documented reason for purchasing chemicals, it's not a problem.

>Food for thought...

Thanks, but I don't think that eating the stuff is a good idea.

Jeff Liebermann

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Oct 18, 2020, 4:25:33 PM10/18/20
to
On Sun, 18 Oct 2020 12:05:43 -0700, Johann Beretta
<ber...@nun-ya-bizness.com> wrote:

>On 10/14/20 7:21 PM, Jeff Liebermann wrote:
>> On Wed, 14 Oct 2020 00:25:08 -0700, Johann Beretta
>> <ber...@nun-ya-bizness.com> wrote:
>>
>>> On 10/6/20 4:35 PM, Jeff Liebermann wrote:
>>>
>>>> To get some decent speeds, 5GHz
>>>> instead of 2.4GHz.
>>
>>> Generally speaking, yes. Practically speaking you can do several
>>> hundred mbps over a 2.4 link. You just need to widen the channel.
>>
>> While there are 2.4GHz routers available that have a 40MHz channel
>> bandwidth setting, I prefer not to use it because it reduces the
>> available bandwidth to other users on 2.4GHz. If one is sufficiently
>> clueless to use a 40 MHz channel set to CH6, it will effectively
>> trash most of the 2.4GHz band. Since Wi-Fi pollution can be
>> symmetrical, it also makes the receiver susceptible to more
>> interference. Stay with 20MHz channel bandwidth on 2.4GHz.
>
>In dense environments, I agree. In rural areas, interference may not be
>a factor. In extremely rural areas, interference PROBABLY won't be a
>factor.

Those are fair assumptions. However, I've been surprised a few times.
For example, I couldn't figure out why I was getting miserable 2.4GHz
performance in an isolated farm house that was 2 miles from the
nearest neighbor or potential source of RF interference. I finally
got around to doing a site survey with a spectrum analyzer and
directional dish antenna. I wound that there was a point to point
2.4GHz wireless link between an office building about 5 miles away,
and an isolated pump house about 3 miles away. The farm house was
directly in the line of sight. At first, I simply changed channels
(1, 6, or 11), but the pump house link changed channel every time the
link faded or was obstructed. So much for adaptive channel selection.
So, I switched to 5GHz, and avoided the problem. Yes, interference
can be a problem in the middle of nowhere.

>> On the other foot, the minimum channel bandwidth on 5GHz is 40MHz
>> (depending on channel selected) with an option to use 80MHz or 160MHz
>> for 802.11AC and AX (Wi-Fi 6).
>> <https://en.wikipedia.org/wiki/List_of_WLAN_channels#5_GHz_or_5.9_GHz_(802.11a/h/j/n/ac/ax)>
>> With 1024-QAM, 802.11AX can theoretically do 1.2Gbits/sec in a 160MHz
>> channel. Your mileage will certainly be less.

>No.. The minimum 5GHz channel bandwidth is 5MHz.

Correct. However, 5MHz is not the occupied bandwidth of the signal.
It varies by modulation mode and type. For example, conventional
2.4GHz 802.11b/g is typically about 22MHz wide and occupies four 5MHz
channels. The 2.4GHz band is 83.5MHz wide. Therefore, if it is only
possible to fit 3 non-overlapping 22MHz wide signals in the band
before running out of bandwidth. This is where the recommended CH1,
6, and 11 comes from. Incidentally, picking a channel that lands in
between CH1, 6, or 11 will end up overlapping the two adjacent
channels and interfere with both.

On 5 GHz, it's the same story. You divide the available bandwidth by
the occupied bandwidth of the signal to get the number of available
non-overlapping channels. Diagrams such as these show how it works:
<https://www.google.com/search?q=802.11+channel+bandwidth&tbm=isch>

>Not sure where you are
>coming up with 40MHz as a minimum. Out of several dozen transmitters, I
>only have two set to 40MHz (backhauls). The rest are set to 20MHz with a
>couple at 10Mhz.

You can use 20, 40, 80, or 160 on *PARTS* of the 5GHz band. 10 MHz is
available but I don't know any situation where it might be useful. The
bandwidth situation is a mess on 5GHz. I don't have the time to
explain where all the various protocols, power levels, bandwidth
restrictions, and standards, DFS radar protection, etc, fit together.
Also, things get really strange with 802.11ax. See Fig 9:
<https://www.ni.com/en-us/innovations/white-papers/16/introduction-to-802-11ax-high-efficiency-wireless.html>

>My gear (Ubiquiti) supports 5, 8, 10, 20, 30, 40, 50, 80 Mhz wide channels.

In what country? See:
<https://en.wikipedia.org/wiki/List_of_WLAN_channels#5_GHz_or_5.9_GHz_(802.11a/h/j/n/ac/ax)>
Go to the column marked United States. Notice that 20 MHz is the
minimum allocated occupied bandwidth. 10 MHz is on the chart, but it
look like no country is using it. 5, 8, 30, and 50 MHz are not on the
chart.

>> Anyway, the performance limiting factor is usually interference from
>> co-channel users and noise sources. You could have all the bandwidth
>> in the world, the most efficient modulation scheme, maximum legal RF
>> power, and still not be able to communicate very well or far if there
>> is an interference source nearby. In other words, one needs to do
>> more than just "widen the channel".

>Once again, sometimes. Sometimes ALL you need to do is widen the channel.

Yep. However, if a wide bandwidth is such a great solution, why
doesn't everyone just setup their routers to use as much occupied
bandwidth as possible, or perhaps just use the entire band? Sure,
there are benefits, but compromises must be made to use a larger part
of the band? Hint: Think about how long a radio needs to be
transmitting in order to deliver (for example) 1 MByte of payload
data. If it can deliver the data twice as fast and therefore uses
half the air time, that's that much more air time for other users of
the bandwidth used.

Jeff Liebermann

unread,
Oct 18, 2020, 4:45:42 PM10/18/20
to
On Sun, 18 Oct 2020 12:12:01 -0700, Johann Beretta
<ber...@nun-ya-bizness.com> wrote:

>All he has to do is search google for "fresnel zone calculator"
>
>At 1,056 feet (0.2 miles) the Fresnel for 5.1 GHz is 7.1 feet.
>(for 5.8 Ghz it would be 6.7 feet). The higher the freq, the smaller the
>zone.

The question was for an 800ft link.
800ft / 5280ft/mile = 0.152 miles
Please adjust your computation accordingly.

>You can intrude the fresnel by 40% (max), but I try to avoid even that.

That depends on whether the intruding material is absorptive or
reflective. You can get a way with much less clearance if the signal
is absorbed. Yes, the signal level goes down, but it also stays down
and does not vary. However, if it's reflective, then it will refract
(bend) part of the signal, creating the opportunity for fades, nulls,
cancellation, etc. It can also create reinforcement and stronger
signal levels, but those tend to change radically if anything moves.

40% intrusion is a usable number for real links, but only works if you
have a sufficiently large fade margin, also known as SOM (system
operating margin). 20 dB would be a good minimum. I carry 20dB and
30dB attenuators in my toolbox. If the system still works reasonably
well with 20dB loss inserted at one antenna, it will probably be
reliable. If it dies completely, you need a bigger antenna or more
transmit power.

While I'm ranting on the topic, fade margin (or SOM) is related to
reliability (or downtime):

SOM dB Reliability % Downtime per year
8 90 876 hrs
18 99 88 hrs
28 99.9 8.8 hrs
38 99.99 53 minutes
48 99.999 5.3 minutes
58 99.9999 32 seconds

99% reliability might sound great, but that means your link will be
useless for 1% of the year, or 3.6 days per year. Don't go below 20 dB
fade margin, which is 70 hours of downtime per year.

Jeff Liebermann

unread,
Oct 19, 2020, 12:32:30 AM10/19/20
to
On Sun, 18 Oct 2020 19:32:40 -0700, Johann Beretta
<ber...@nun-ya-bizness.com> wrote:

>On 10/18/20 1:25 PM, Jeff Liebermann wrote:
>
>
>>
>>> My gear (Ubiquiti) supports 5, 8, 10, 20, 30, 40, 50, 80 Mhz wide channels.
>>
>> In what country? See:
>
>The United States. I'm using official firmware on a US radio. I had
>heard that newer radios were limited to 10MHz as the smallest slice, but
>older gear is grandfathered in.

I'll assume a Ubiquiti M5 radio. I have some really old M5-Bullet
radios, with firmware that can't be upgraded to the latest greatest.
However, my house is a mess resulting from my office move, and I'm not
inclined to dig one out and check what it can do. I did some Googling
and found that the Rocket-M5 does support 5 and 10 MHz channel
bandwidth, so I'll assume that your unspecified M5 version also does
the same.
<https://community.ui.com/questions/Channel-width-max-bandwidth-and-max-clients-per-AP/cdf020af-0d11-4982-8c0d-785e3e1c2030>

The article conveniently explains part of the logic behind using wider
channels and mostly answers my question from my previous rant, which
you deleted and/or ignored. Basically, the approximate math is
simple. If your WISP configures their access point for a 40 MHz
bandwidth channel and the ISP has 10 full time connected users, the
system can deliver no more than 4 Mbits/sec to each user. If the WISP
reduces the occupied bandwidth to 5 MHz, and still has 10 full time
users, each one will only get 0.5 MBits/sec, which is inadequate. If
your WISP doesn't have much of a user load, or doesn't overload the
channel with too many wireless users, 5 MHz occupied bandwidth will
work just fine. Note that this simplistic channel loading estimate
ignores various factors that will either increase or decrease the
channel loading. For example, I'm assuming that the channel usage is
sustained at the maximum available rate, which is sometimes a bad
assumption. This becomes really messy if the streaming media provider
adjusts their deliver rate based upon error rate levels returns from
the viewers computer or media player.

Also, there is a problem. This assumes that the WISP has exclusive
use of the channel and that there are no other users on the same
channel. Any co-channel users will appear as interference causing the
WISP access point to lower the data rate to a level where the BER (bit
error rate) is high enough to produce usable throughput. In many
cases, this throughput reduction can be drastic, but for this
discussion, I'll assume it reduces throughput to half. That means
that delivering a given amount of data will double the air time (how
long the transmitter occupies the channel) and delivery will therefore
take twice as long. Actually, it's longer because the packet size is
also reduced, but to keep things simple, I'll ignore that. The result
of slowing down due to interference is that every users connection
slows down, and data takes twice as long to deliver. Instead of ten
happy Netflix viewers, the ISP support phone will have 10 irate
customers complaining of buffering.

So, what can an WISP do? Well, it could not load the channel to the
maximum capacity for a given occupied bandwidth. It could add another
radio on a different channel and move some of the customers there. Or,
it could just size the occupied bandwidth setting to match the actual
channel loading with some overhead left for interference and high
usage peaks.

So, why did your WISP use 5 MHz. None of the advanced 5GHz mode
beyond 802.11a are going to work well crammed into a 5 MHz occupied
bandwidth channel. I'm not sure if 802.11a will work in a 5 MHz
channel. 802.11ac requires an 80 MHz channel. It would be
interesting to sniff the traffic between your Ubiquiti M5-something
radio and the WISP access point with a Wi-Fi Analyzer (Android) or
something similar. My guess(tm) is you're running 802.11a.

So, what kind of performance can one expect in a 5 MHz wide channel
compared to a 20 MHz channel? That would 1/4th the speed *OR* double
the range due to increase in power density (dBm/Hz). That's why it
was attractive to your WISP. Cut the data rate in half yields a range
increase of sqrt(2) or 1.414.

That's also why the FCC and other regulators seem to have purged 5 and
10 MHz occupied bandwidth from the rules-n-regs. It's much too close
to narrow band modulation and carries some of the detrimental effects
of narrow band modulation. It was fine when the typical 5 Ghz signal
used 20 MHz modulation. However, with 40, 80, and 160 MHz now
available, the narrower occupied bandwidths had to go.

>> 10 MHz is
>> available but I don't know any situation where it might be useful.
>
>
>As for the usefulness of 10Mhz, well... Seriously?
>
>I can think of all sorts of things.. Namely anything where you need
>70mbps or less.
>
>Or, in a really crowded area, you might be able to find 10Mhz of clean
>spectrum..
>
>My own link to my WISP is 10Mhz (I have my own dedicated AP). Delivers
>me everything I need without having another 10Mhz just polluting the area.
>
>I could probably get away with 5Mhz, but I've upgraded to the AC line
>and that is no longer an option. It is, however, still an option in the
>M series.

Sqwertz

unread,
Oct 19, 2020, 12:59:01 AM10/19/20
to
Yeah, that does. But I was referring to the glassware and the HCl.

-sw

Jeff Liebermann

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Oct 19, 2020, 1:09:44 AM10/19/20
to
On Sun, 18 Oct 2020 19:26:40 -0700, Johann Beretta
<ber...@nun-ya-bizness.com> wrote:

>On 10/18/20 1:45 PM, Jeff Liebermann wrote:
>> The question was for an 800ft link.
>> 800ft / 5280ft/mile = 0.152 miles
>> Please adjust your computation accordingly.

>Yep. And the calculator I used could handle tenths.
>That's why I calculated for .2 miles. I couldn't do 0.152 miles.

That's an input error of (0.2 - 0.152) / 0.2 = 24%
Perhaps using the online calculator which I provided might have been a
better idea? Or maybe a different Fresnel Zone calculator?
<https://www.google.com/search?q=rf+fresnel+zone+calculator>

This is interesting and might explain a few things:
<http://radiomobile.pe1mew.nl/?Calculations:Propagation_calculation:Fresnel_zones>
Since the F2 zone is detrimental to receive signal level,
antenna heights are often selected so that F1 is an
unobstructed path and F2 is obstructed by a hill or the
earth bulge along the path.
In other words, the area around the F1 line is where you get your
usable signal, while the area around the F2 line is where you get your
problems. The reason you can get away with 40% incursion into the F1
zone is that reflecting objects on or near the F1 line will add, not
cancel. I guess it really should be something like:
0.0 to 0.6 F1 = OK. Direct path.
0.6 F1 to 1.4 F1 = problems due to destructive cancellation.
1.4 F1 to 0.6 F2 = OK
1.4 F2 to 0.6 F3 = problems due to destructive cancellation.
I'm not too sure the exact coefficients are correct. I'll check
(later). In other words, there is a "band" straddling the various odd
numbered Fresnel Zone lines which define areas that should not contain
reflective objects.

Jeff Liebermann

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Oct 19, 2020, 1:31:28 AM10/19/20
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On Sun, 18 Oct 2020 23:58:58 -0500, Sqwertz <sqwe...@gmail.invalid>
wrote:
To the best of my knowledge, access to chemistry glassware is not
restricted in California.
<https://en.wikipedia.org/wiki/Amateur_chemistry>
In the United States, some regions have stringent
regulations concerning the ownership of chemicals
and equipment. For example, Texas once required
the registration of even the most basic laboratory
glassware.[20] However, this requirement was
repealed on June 6, 2019.[21]

Just buy what you need online:
<https://www.ebay.com/sch/i.html?_nkw=chemistry+glassware>
<https://www.amazon.com/Glassware-Labware/b?node=318049011>
Or, you can make your own:
<https://www.google.com/search?q=make+your+own+laboratory+glassware>
I have some glass tubing which I use to make the small stuff. However,
I haven't had much luck with glass blowing.

For HCL, if you can't get the real stuff, buy some muriatic acid and
distill it:
<https://www.google.com/search?q=how+to+purify+muriatic+acid>
I've never had to do this but it doesn't seem difficult. (famous last
assumption).

Mike S

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Oct 21, 2020, 12:10:34 AM10/21/20
to
Interesting video, thanks, I live near downtown SC I wonder the same.
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