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WiFi out to 800 feet



 
 
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  #1  
Old October 14th 20, 08:23 AM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Johann Beretta
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Posts: 32
Default WiFi out to 800 feet

On 10/4/20 5:59 PM, Arlen Holder wrote:

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.



What the hell? Clearly you don't do this for a living.



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  #2  
Old October 14th 20, 08:45 AM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Arlen Holder
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Posts: 186
Default WiFi out to 800 feet

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.
  #3  
Old October 15th 20, 02:06 AM posted to microsoft.public.windowsxp.general
No_Name
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Posts: 627
Default WiFi out to 800 feet

On Wed, 14 Oct 2020 07:45:18 -0000 (UTC), Arlen Holder
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.

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.


I am talking about a target I can hit, unobstructed with a laser. It
really looks like the HOA has cooled on the idea ... again. There are
some privacy folks who certainly do not want any cloud solution and
they are talking about the disposition of the video we collect.
OTOH the Ring fans say "let'r rip".

I am at the point of saying, let Comcast do this and pay the damned
bill.
  #4  
Old October 15th 20, 03:42 AM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Jeff Liebermann[_2_]
external usenet poster
 
Posts: 49
Default WiFi out to 800 feet

On Wed, 14 Oct 2020 07:45:18 -0000 (UTC), Arlen Holder
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 he
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.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #5  
Old October 15th 20, 03:47 AM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Fox's Mercantile
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Posts: 2
Default WiFi out to 800 feet

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.


--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com
  #6  
Old October 15th 20, 12:37 PM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
AnthonyL
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Posts: 6
Default WiFi out to 800 feet

On Wed, 14 Oct 2020 19:42:48 -0700, Jeff Liebermann
wrote:

On Wed, 14 Oct 2020 07:45:18 -0000 (UTC), Arlen Holder
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?
  #7  
Old October 18th 20, 08:12 PM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Johann Beretta
external usenet poster
 
Posts: 32
Default WiFi out to 800 feet

On 10/14/20 12:45 AM, Arlen Holder 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.

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.


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.

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

  #8  
Old October 18th 20, 09:45 PM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Jeff Liebermann[_2_]
external usenet poster
 
Posts: 49
Default WiFi out to 800 feet

On Sun, 18 Oct 2020 12:12:01 -0700, Johann Beretta
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
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #9  
Old October 19th 20, 03:26 AM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Johann Beretta
external usenet poster
 
Posts: 32
Default WiFi out to 800 feet

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.



  #10  
Old October 19th 20, 06:09 AM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Jeff Liebermann[_2_]
external usenet poster
 
Posts: 49
Default WiFi out to 800 feet

On Sun, 18 Oct 2020 19:26:40 -0700, Johann Beretta
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_zone s
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
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #11  
Old October 22nd 20, 06:12 AM posted to microsoft.public.windowsxp.general,sci.electronics.repair,alt.internet.wireless
Johann Beretta
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Posts: 32
Default WiFi out to 800 feet

 




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