Author Topic: Feasibility of using moteino for an outside wheaterstation and mailbox notifier.  (Read 1808 times)

Duck

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Hey there. I've been wanting to make an outside wheater station for a while now, that'd also serve as a mailbox notifier. For this reason, I'd want to place the unit in my mailbox, and have it wirelessly transmit to a receiver in my appartment. That presents the first problem:
I live in an apartment, in the center of town. This means there's a lot of 2.4GHz radio noise from mostly wifi, hence the pull to moteinos and the lower frequency radios. The problem however is, that I'm not allowed to modify my mailbox in any way, so the entire unit would have to live inside the mailbox, which is made of metal, housed in concrete: http://i.imgur.com/5z0j9O9.jpg

Second problem is, that while my mailbox is thankfully the last in line, and therefore there's only one metal wall between it and my appartment, I live on the other side of the building, so the signal has to go through the building, except for the last outer wall ofc. The outer walls are brick.

Here's a shot of the distance it has to travel: http://i.imgur.com/zl3bg0i.png

Now, my question is, can moteino radios manage this task, and if so, which model?

Thanks for the help :)

syrinxtech

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Well, you first consideration is that Moteino radios don't work at 2.4GHz.  They can live in the 433/869/915 MHz.

I don't think the raw distance will be a problem....especially if you look around at the wide variety of projects involving long distance.  Obviously being inside a metal box inside of concrete is a concern.

You really only have two models to consider, a standard Moteino (FTDI or USB), and the Mega.  You do have several options for the radio, mainly around the frequency band and whether or not you need the "high power" RF model.  You can also select "Lo-Ra" which operates at a different frequency and is designed to work over longer distances.  I would encourage you to read as much as you can from the many contributors to this site.  I have learned a lot from reading other folks posts about their various projects.  There rarely is a "best" solution.....it usually depends on a lot of unique factors to your situation.

Duck

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Yeah the whole 2.4GHz thing was what brought me to moteino from RF24L01+ modules.

So the Lo-Ra modules are special in their frequency, not power. Interesting. I'd think to get through metal, I'd just have to power through as much as possible? So a high power module.

kobuki

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Your box is not completely radio sealed, since there's a plastic front section, judging from the image. So you have a slight chance. I guess if it works at all, you'd be good with the standard RFM69, I don't think LoRa would help you here. The 45m in itself is not a problem. Well, you don't know until you try!

captcha

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What a great challenge to make this work. It's obvious how you can benefit from not having to walk to the mailbox each time to check for new mail if it can be checked wirelessly.

One thing you can try is to look for a place that is near the mailbox and can house another moteino that acts as a repeater. The idea being that if the mailbox moteino would not produce a signal strong enough to reach the house you could pick it up from a nearby moteino that's in a much better place to send and receive to both. The code for a relay/repeater isn't all that difficult. I have hacked something up in the past and I'm more than happy to share the code if need be.

I'm not sure if the front of the mailbox is made of metal/aluminium or plastic. If plastic you may have a fighting chance but if it's all metal then you may also need to find a way to mechanically open the flap once per hour or so to send out a signal. I'm sure that would raise eyebrows if someone else was checking their mail at that time.. ;-)

If it's all metal you could try something with ultrasound. Have a transducer attached to the mailbox on the inside (the mailbox may even be a signal booster) and have a nearby moteino listen for incoming sounds.

If you can fit another moteino right across from it you may even try something with light signals.

Looks like you biggest hurdle will be to get out of the box somehow.

perky

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I agree with captcha, a repeater seems like a good solution. In fact 2.4GHz is possibly even better at escaping over short range due to the shorter wavelengths that are going to find the 'slots' and holes easier to get through. The longer wavelenths of sub GHz will be better after that for range and general penetration through walls and buildings. Having said that a repeater that's releatively close to the box is likely to pick a sub GHz signal up as the box is going to be leaky.
Mark.


kobuki

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Guys, it's not that bad. Please look at the first posted image. It doesn't look like a completely sealed box. In my previous post I also noted the door seems to have a clear plexiglass section (or maybe the whole door is made of it). Radio signals can easily escape. From the 2nd image I think the plane of the door is perpendicular to the direction the radio would have to transmit to on the left, so I'd put the transmitter close to the right side wall of the box, right behind the front door. With transmission optimised for high distances or multi-storey buildings, I think it's doable without any hocus-pocus.

EDIT: hmm, the 1st image is not that good, maybe what I think is a plexiglass is just the reflection on the inside of the front cover? Hopefully we get a clarification from OP. Well then, what if the small wire of the antenna sticks out a bit?
« Last Edit: September 04, 2016, 06:56:11 AM by kobuki »

Duck

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Sadly, it's entirely metal, the entire thing is metal with a thick coat of paint (probably why it could be mistaken for plastic) Even the flap is alu.

I've also been considering the repeater method, but sadly, short of parking my bike in the outdoor bike area across from the mailboxes, and leaving a repeater on the back of my bike, I have nowhere to put a repeater, and I prefer to keep my bike in the cellar.

Another sad thing. I started putting together a BOM, and now my biggest problem isn't getting the signal out of the metal box, but to afford the whole thing :/ I'd need 2 moteinos minimum, preferably a third for OTA programming, an indoor display, which would double as my watch (I've been looking at 64x32 RGB LED displays, as the are the cheapest large scale matrix displays I can find) and when I add all this up, it gets to around 150$ which I can't afford :/

So, until I get myself a better source of income, I guess this project will have to stay in my "todo" folder :/

That said, when the time does come, I really liked the idea of popping open the lid now and then to transmit! :P Kinda like a little creature popping out to shout it's most recent findings :P

kobuki

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The Moteino is probably one of the most suitable boards for the task but there are alternatives. You can use a simple pro micro clone with an OOK transmitter, an ESP8266 variant, etc. Not that I want to steer you away from the Moteino, but the possibilities are vast.

syrinxtech

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Duck, you might consider a 2x16 or 4x20 LCD screen for your indoor weather unit.

I use a 2x16 and actually scroll 3 different screens.  Each screen has an adjustable timer (in sec) that allows me to determine how long each screen is displayed.