Author Topic: Atlas/Access in a metal building  (Read 1047 times)

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Offline Beech33

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Atlas/Access in a metal building
« on: January 10, 2019, 06:58:08 PM »
Any tips or experience getting the wireless signals into a metal building? The distance will be 20 feet. The Atlas sensor will be on a pole about 5 feet above the roof and the Access will be almost directly below by 20 feet.
What do you think?

Offline John Z

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Re: Atlas/Access in a metal building
« Reply #1 on: January 11, 2019, 07:56:07 AM »
One certainty: The signal will not pass through metal.

If it gets inside your structure it's because it has found paths that avoid the metal. A vent or window for example. All you can do is to try, but I wouldn't be hopeful. If you can receive FM radio or broadcast TV inside your structure, those waves are getting in somehow.

I keep a tower sensor in a freezer, a big metal box. That works only because the seal around the door lets some signal through.
« Last Edit: January 11, 2019, 09:01:46 AM by John Z »

Offline miraculon

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Re: Atlas/Access in a metal building
« Reply #2 on: January 11, 2019, 08:45:35 AM »
One thing that led me to buy a Davis was when some guys at work got a VP2. I helped them set it up.

Our building was steel frame construction with concrete filled metal floor pans (standard stuff).

I was very skeptical since the plan was to place the ISS on the roof and have the console on the first floor of the two-story building.

I was wrong, it worked fine. Now, this is for Davis and I don't know how the Atlas RF performance compares.

I assume that this metal building of yours has windows? There might be enough signal refracting around the roof and/or reflecting off of nearby objects.

Greg H.


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Offline Beech33

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Re: Atlas/Access in a metal building
« Reply #3 on: January 11, 2019, 09:09:14 AM »
Thanks for the real examples. The building is an airplane hangar that has 4 4X8 fiberglass panels on its southern side to let some light in. Otherwise it is all galvanized steel. One option would be to cut a hole and mount a plastic enclosure so the Access could sit in the enclosure outside of the steel walls.

Offline John Z

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Re: Atlas/Access in a metal building
« Reply #4 on: January 11, 2019, 09:36:45 AM »
The fiberglas panels give you a good shot at success, I think.

Offline Beech33

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Re: Atlas/Access in a metal building
« Reply #5 on: January 11, 2019, 10:14:19 AM »
John Z - I will give it a try and find out. The fiberglass panels are not at all in line with the proposed mounting for the Atlas. Will that mater?
Thanks

Offline John Z

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Re: Atlas/Access in a metal building
« Reply #6 on: January 11, 2019, 10:25:50 AM »
Beech33,

A line of sight path from Atlas to Access would be ideal, but not essential. The signal waves reflect off of things, and bend around the edges of objects ( diffraction). What's most important is that there is a path into the building. If that exists, it's likely that at least some signal will find a way in, even if it means bouncing back off of adjacent buildings, or trees, or diffracting around a corner. Good luck and post back on this!
« Last Edit: January 11, 2019, 10:38:22 AM by John Z »

Offline Beech33

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Re: Atlas/Access in a metal building
« Reply #7 on: January 11, 2019, 09:31:28 PM »
Installed the new Atlas and Access (paid $150) unit this afternoon in the metal Hangar. So far no dropped signals.
After the help from John Z, I placed the Atlas close to the fiberglass panels with hopes of a good signal - no problems so far.
The Atlas is a beast compared to my 5-in-one! The Access was a breeze to set up. 

Have a look!
https://www.wunderground.com/personal-weather-station/dashboard?ID=KNCKNIGH19

Offline DoctorKnow

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Re: Atlas/Access in a metal building
« Reply #8 on: January 12, 2019, 08:55:55 AM »
The Atlas is a good wx station. You made a good choice. Very accurate.

Offline John Z

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Re: Atlas/Access in a metal building
« Reply #9 on: January 12, 2019, 02:53:15 PM »
Reinforcing DoctorKnow,
I also think highly of Atlas.
Glad to hear your hangar installation went well!

Offline Beech33

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Re: Atlas/Access in a metal building
« Reply #10 on: January 12, 2019, 03:08:05 PM »
Thanks again. I bought 2 of the Atlas/Access units- next install is to replace my old 5-in-1/Hub at a beach house. That will be a good test with the windy and salty conditions.

Offline DoctorKnow

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Re: Atlas/Access in a metal building
« Reply #11 on: January 13, 2019, 11:03:40 AM »
Beech,
I looked at your station today. It seems you forgot to open the rain bucket and pull out the stabilizer, so as a result, you are not getting any action on the rain tipper.

Offline Beech33

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Re: Atlas/Access in a metal building
« Reply #12 on: January 13, 2019, 12:30:19 PM »
DoctorKnow
I did not remove the shipping pad  :sad:
It will be next Saturday before I can get back on the hangar roof.

Offline WXman

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Re: Atlas/Access in a metal building
« Reply #13 on: January 15, 2019, 01:40:22 PM »
For Christmas, I bought my parents a box store Acu-Rite station (Cabela's).  It has the 5-n-1 sensor and LCD display console.  I was concerned that it wouldn't work, because their house is a "pole barn" that has a 100% metal exterior.  Metal sheeting for the walls, roof, trim, etc.  They do have a few windows, however.

Currently I have the 5-n-1 mounted to a post 182 feet away from their house and to my surprise the console display still receives a good signal and the best I can tell it's updating every 30 seconds or less.

I'm very surprised that it works, but somehow it does.  I suppose the few windows they have are just enough to let the signal through.   =D>

That's one thing I appreciate about the 433mHz band.  It seems to do better at distance compared to the higher frequencies that Ambient uses.
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Offline Beech33

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Re: Atlas/Access in a metal building
« Reply #14 on: January 15, 2019, 10:08:48 PM »
It seems amazing!

Offline miraculon

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Re: Atlas/Access in a metal building
« Reply #15 on: January 16, 2019, 08:57:46 AM »
I just got a new freezer this past week. I was looking into various thermometer options to monitor the freezer temperature.

On Amazon, I saw some Acu-Rite thermometers for freezers that appeared to be the usual stuff, just labeled for refrigerator/freezer application.

I got to wondering if an old Acu-Rite that I have would work. I put new Lithium batteries in the sender, and new alkaline ones in the indicator. Much to my surprise, it works fine.

When I was working, we had to test our automotive amplifiers to the OEM EMC specs. We did this in a special shielded room. When I was inside the screen room, the cell phone reception went to "no bars" and didn't work. (we left the room when testing...) All we had to do is crack the door open and we could get cell phone reception again. This was in a double shielded room with ferrite plates on the inside of the steel walls and RF absorbent foam cones.

I suspect that any opening that is a good fraction of the wavelength will let signal through.

I guess that the freezer has enough of a path to let the signal out. The thermometer is a 00380. It works on 433 MHz. I do have it fairly close to the freezer, about 1 meter (3 ft) away.

I think that the pole barns and hangar have large enough gaps to let signals pass with no problem.

Greg H.


Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline Beech33

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Re: Atlas/Access in a metal building
« Reply #16 on: February 01, 2019, 10:52:49 AM »
Well the Atlas/Access stopped reporting from the hangar yesterday.
I got two separate email notifications back to back:
1) My AcuRite has lost communication with RaleighEastHub. No signal has been received for more than 2 hours. This could be due to power outage or disruption of Internet service at this location
2) My AcuRite has not received a signal from W17 AcuRite Atlas for more than 2 hours. Check sensor batteries and verify range and placement

Is there a easy remote way to determine if it is the Access or the Atlas? I'll be making the drive out to see this afternoon.

Offline Victoria

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Re: Atlas/Access in a metal building
« Reply #17 on: February 01, 2019, 11:34:23 AM »
Hello Beech.

From these symptoms alone, it's not possible to differentiate which one it is. There is a known issue with Access where sometimes, in the event of a power interruption, sometimes it does not come back online the way it should. (Btw, we're in final testing for a fix for this now)

When you visit, you can log into the IP of the Access through a web browser and check the signal strength of the Atlas is good. If it is, it's probably Access, which you should just reboot. If you've got no signal, it's the Atlas.

Hope that helps.

Offline daman

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Re: Atlas/Access in a metal building
« Reply #18 on: February 01, 2019, 12:01:06 PM »
Hello Beech.

From these symptoms alone, it's not possible to differentiate which one it is. There is a known issue with Access where sometimes, in the event of a power interruption, sometimes it does not come back online the way it should. (Btw, we're in final testing for a fix for this now)

When you visit, you can log into the IP of the Access through a web browser and check the signal strength of the Atlas is good. If it is, it's probably Access, which you should just reboot. If you've got no signal, it's the Atlas.

Hope that helps.
Victoria very nice to hear, will this be rolled out in a firmware update once final?

Thank you for your continuing support you show here on the forums we all appreciate it very much!
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Offline Victoria

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Re: Atlas/Access in a metal building
« Reply #19 on: February 01, 2019, 12:48:30 PM »
Hello Beech.

From these symptoms alone, it's not possible to differentiate which one it is. There is a known issue with Access where sometimes, in the event of a power interruption, sometimes it does not come back online the way it should. (Btw, we're in final testing for a fix for this now)

When you visit, you can log into the IP of the Access through a web browser and check the signal strength of the Atlas is good. If it is, it's probably Access, which you should just reboot. If you've got no signal, it's the Atlas.

Hope that helps.
Victoria very nice to hear, will this be rolled out in a firmware update once final?

Thank you for your continuing support you show here on the forums we all appreciate it very much!

Hi Daman, yes; we're at the stage of testing the actual upcoming firmware update, which will be announced formally with release notes and rolled out once validation has been passed.

Offline DaleReid

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Re: Atlas/Access in a metal building
« Reply #20 on: February 01, 2019, 02:59:53 PM »
Greg,
In the early days of cellular phones, a friend had a series of metal sheds, fixed up pretty nice inside, in which he ran a business of taking muscle cars from the 60s and 70s and taking them completely apart, down the nuts and washers, and putting them back together all fixed up better than new.

Quite the operation, and quite the price, but a fun place to stop by and see what he was working on.  Anyway, he would lament that with the metal buildings and built as tight as they were, cell phones worked poorly inside.  Another common friend who was into electronics from the ground up, did some sort of passive antenna with one outside, connected to another inside which apparently re-radiated the signal and it worked pretty well.

Now I understand that sort of amplified cell antennas exist, with an out of doors antenna and then a smaller one in the house or office to re-radiate.  I'd think they'd get RF feedback, like a mic in an auditorium, but they seem to work.

I am fascinated by antennas hand have zero idea how the darned things work, which I probably won't be able to solve before I die.

Nonetheless, I think your comment about any electrically transparent hole big enough to let radiation in or out would do.

I'm wondering what the limit is for size.  1/2 wavelength?  2 wavelengths?  Just curious.
Dale
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Offline Beech33

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Re: Atlas/Access in a metal building
« Reply #21 on: February 01, 2019, 03:01:37 PM »
Thank You Victoria!
I drove out to the hangar and found the Access had an orange led. I removed power, batteries and reapplied.
It came back up in about 10 minutes.
The signal strength from the Atlas shows “excellent”

Must have been a power glitch.
All is good!

Offline John Z

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Re: Atlas/Access in a metal building
« Reply #22 on: February 01, 2019, 03:25:17 PM »
DaleReid,

"Amplified" cell antennas don't transmit and receive at the same time, so no feedback! Digital packets are captured  stored and rebroadcast. When the transmitter is working, the receiver is shut down. It all happens so fast a user never notices.

Electromagnetic signals can escape via gaps much smaller than a wavelength, although with much attenuation and drop off with distance. See references to evanescence.

Offline miraculon

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Re: Atlas/Access in a metal building
« Reply #23 on: February 01, 2019, 03:26:08 PM »
Greg,
In the early days of cellular phones, a friend had a series of metal sheds, fixed up pretty nice inside, in which he ran a business of taking muscle cars from the 60s and 70s and taking them completely apart, down the nuts and washers, and putting them back together all fixed up better than new.

Quite the operation, and quite the price, but a fun place to stop by and see what he was working on.  Anyway, he would lament that with the metal buildings and built as tight as they were, cell phones worked poorly inside.  Another common friend who was into electronics from the ground up, did some sort of passive antenna with one outside, connected to another inside which apparently re-radiated the signal and it worked pretty well.

Now I understand that sort of amplified cell antennas exist, with an out of doors antenna and then a smaller one in the house or office to re-radiate.  I'd think they'd get RF feedback, like a mic in an auditorium, but they seem to work.

I am fascinated by antennas hand have zero idea how the darned things work, which I probably won't be able to solve before I die.

Nonetheless, I think your comment about any electrically transparent hole big enough to let radiation in or out would do.

I'm wondering what the limit is for size.  1/2 wavelength?  2 wavelengths?  Just curious.
Dale

Since I have been retired for almost five years now, I find that I need to "dust off the brain cells" again.

I found something that brought some memories back about "shielding effectiveness". For the signal to "get out" we need something with poor shielding effectiveness.

Aperture lengths (for a slot) that are a small fraction of the wavelength increase shielding effectiveness and consequently don't let signal in or out. Where I used to work, we literally had "screen rooms" that had copper screen that resembled window screen. The openings in the screen are so small that they have a very high cutoff frequency and are the same as if they are solid. When the screen room door is open, the gap is a large fraction of a lot of signals bouncing around. Several wavelengths of cell phone frequencies and maybe fairly large at something like FM radio frequencies.

Here is a paper covering shielding effectiveness. You can plug wavelengths and slot dimensions into the formula for slots.

http://cdn.lairdtech.com/home/brandworld/files/EMI%20Rule-of-Thumb%20for%20Calculating%20Aperture%20Size%20Technical%20Note%20Download.pdf

Here is another reference: https://leadertechinc.com/blog/how-apertures-affect-emi-shielding/

I hope that this info helps.

Greg H.


Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline DaleReid

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Re: Atlas/Access in a metal building
« Reply #24 on: February 01, 2019, 03:39:01 PM »
Greg,
Thanks for the links, this is always fun stuff to read, even though I can't claim deep understanding, these tend to smooth out the rough edges and shove the simplifications to the side.

Dale
PS, now if I could just figure out how slot antennas for UHF digital TV broadcasts work.....  Or planar type antennas for cellular applications.
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