Instead of Lora, what?

[panoss]

I 've made a Lora (RA-01) temperature meter.
I want to put the transmitter on the top of a 7 floor building.
The receiver on the ground.
This means the signal will have to be able to pass through 7 floors.
I haven't tested it yet if it can do this, but I was thinking of alternatives in case it fails.

For example, I have a wireless door bell which works in a long distance and through many walls.
I guess it has a quite strong transmitter.
So how could I use a transmitter and a receiver from a door bell with an arduino?

[JVR]

Dont plan to fail. LoRa should do it easy enough if the RF design was done properly. If not, there are always PA's available.

[panoss]

if the RF design was done properly.

What RF design? I just connected the Lora module with the Arduino, what RF design are you talking about?

there are always PA's available.

What are PA's?

[JimRemington]

PA = power amplifier.

Be sure to use antennas on the RF modules.

[ogden]

I 've made a Lora (RA-01) temperature meter.
I want to put the transmitter on the top of a 7 floor building.
The receiver on the ground.
This means the signal will have to be able to pass through 7 floors.
I haven't tested it yet if it can do this, but I was thinking of alternatives in case it fails.

Sigfox then. Yet, it is not much better than LoRa, IMHO. Anyway 7-floor building does not mean that radio waves have to pass through 7 floors in straight line. They have ability to reflect/bounce. Most likely LoRa will be fine in any building having any number of floors unless that building stands alone in the middle of the nowhere. If you need hi-reliability system - make space-division MIMO (at least two base stations located in different locations).

[panoss]

PA = power amplifier.

Be sure to use antennas on the RF modules.

Yes I'm using the ones that came with the modules:


So, in case I need it (I suppose I won't, but just in case), where can I find a PA for Lora?
(you mean something like this?)

[ebastler]

Can't you go "around" the building instead of through all seven floors? I.e. place the transmitter on the side of the building, or on the roof but as close as possible to the edge. Place the transmitter outside a window on the ground, or maybe just inside behind the glass. I would expect a significantly stronger signal that way than if you have to go through seven iron/concrete floors.

[panoss]

I thought of this, but it would not be a very...'elegant' solution (for the client).

[ogden]

I thought of this, but it would not be a very...'elegant' solution (for the client).

Instead of asking public forum where anybody can tell you virtually anything, do site survey instead.

[ElectronicCat]

LoRa has one of the highest link budgets of any readily available consumer kit, it that doesn't work I'd be very surprised and you're pretty much out of luck. As I think others have already mentioned, the signal doesn't need to travel line-of-sight through the building, assuming there are other buildings and objects around there will be plenty of room for multipath propagation.

If for some reason it doesn't work, the first thing I would try is replacing the fully loaded coil antenna with a full or half wavelength whip antenna or dipole rather than immediately putting in a power amplifier. If you add a PA you will almost certainly breach your local regulations on RF power emissions and the module you have probably already outputs more than enough power (100mW or so should be plenty).

[hagster]

There are very few radio modules around with better link margin than LoRa. To get the best out of it you need to select the slowest data rate though.

The spring antenna that come with your module is pretty crappy. You could choose a better one, or experiment with directional antennas. Remember the best RF link may actually be a reflected signal coming in through a window or something similar.

An alternative is to use a different frequency. 433MHz for instance will be better at getting through the building structure.

[Marco]

Main alternatives are CC1120 and SI4463, with the latter available on the dirt cheap RFM26W.

169MHz looks like an interesting band, 500 mW ERP allowed. Used for Wireless M-bus, with slightly more expensive modules. Probably easier to use though.

[panoss]

An alternative is to use a different frequency. 433MHz for instance will be better at getting through the building structure.

The module I'm using works at 433MHz!
From what you guys are saying, I expect it should work.
I wil try it on Sunday and will let you know.

[Doctorandus_P]

I'm not a RF guy, but if both locations are fixed, then directional antenna's (cantenna) might help.
Maybe it is even a good idea to purposefully bounce your signals of a nearby building instead of trying to penetrate 7 floors.

[ogden]

I'm not a RF guy, but if both locations are fixed, then directional antenna's (cantenna) might help.

In right circumstances directional antennas could help, for instance both antennas are aimed at window and uses nearby building as reflector. Yagi kind of antennas shall be considered. Cantenna at 433MHz would be more like 20" diameter 50" deep bucket, way too directional as well. Narrow beam antennas are good for long, direct line of sight links where both antennas "optically see" each other.

[panoss]

Guys, you were right. It works! 
But what if I want a better antenna (in order to have a better signal, just in case) than the one that came with the modules?
Do you have any suggestion?

[ElectronicCat]

But what if I want a better antenna (in order to have a better signal, just in case) than the one that came with the modules?
Do you have any suggestion?

Yes...

I would try is replacing the fully loaded coil antenna with a full or half wavelength whip antenna or dipole

You can either buy one pre-made for the wavelength you are using or make one yourself from an old clothes hanger (or any source of semi-rigid copper wire) cut to the correct length.

[panoss]

Ok, a whip antenna is the simplest one as it's only a straight wire with a length of 34cm (half wavelength,according to what I read on the internet), I guess this is what I 'm going to make.
Only thing that bothers me is it will have to get out of the box as it's dimensions are 13cm x 13cm.
And find a metallic - elastic wire. (I suppose it 'd better be elastic)