Hey guys,
I'm working on a new project in which I'm trying to get the shortest distance between 2 modules. I checked in other topics and couldn't get the answer. Here, I'm not trying to get the distance at all, just the shortest distance by sending a signal every second, and checking on the receiver what is the strongest signal. In this project, the distance between the 2 modules will be between about 0.5 and 4-5 meters. And there might have either woods, metals and any other materials between both modules.
Again, the value of the signal is not important as I will do a correction in the program. I'm just trying to find a sensor or a way to get a signal that could differentiate 0.5m to 0.7m, 1.0m, 2.0m...
With 2 ESP32, I tried to configurate one in Access Mode, and the other that was checking the RSSI. I also add a LoRa Module (868MHz, RF 7) with the same principle of checking the RSSI. In both cases, it worked OK, but I realized at a given distance, the intensity of the signal was dependent on the orientation of the transmitter (i.e. how the antenna was oriented), and I really don't want to depend on that.
Any ideas would be helpful
Thanks in advance
Laurent
You'll have that problem with all methods. You can find the direction to the other module.
That makes it impossible to determine the distance. Without such obstacles I'd suggest a sonic method (US, ping...) with the chance that the way around some obstacle is determined instead of the straight distance.
So you want a sensor method that will work through a 5 meter metal block ?
Yup. Take one step back and explain why you need to determine this distance. Then we can have a look together what other options there are to achieve the same without relying on something that's inherently impossible.
What kind of system is this and what does it need to do?
More information, such what modules, the mechanical configuration, the ambient conditions, etc.
Unusual concept.
Ok, I see I didn't give all the details and you wonder WTH am I doing 
No worries, there's a logic behind that.
In the company I'm working in, sometimes, I have to localize a particular point under a roof (made of woods, tiles, steel...) and I have to communicate the exact position to the person working on the top of the roof. To do so, I usually give the x and y positions based on another point we can both see. This is a bit tedious.
That's the reason why I don't need the distance. My idea is to leave a module (ESP32 +/- another sensor) that will be detected by the other one on the top of the roof. I will add a few leds for example that will give an idea how close it is... But this is another story that I will work later on.
The person on the roof shouldn't have to turn the antenna. It should give the same signal whatever the way he's holding it at a given position. That's my problem.
So do you guys have a better idea now? Sorry for being so mysterious. I hope you can help.
Thanks in advance to all of you
Point the antenna up?
How exact? If you need a rough position, maybe you could use one of those strong fishing magnets inside the building and the guy on the roof could hold a simple hiking compass. There may be enough of a magnetic field for the compass to find. Of course I'm no expert in magnetic fields so it may be a non-starter!
One could assume, that if such a positioning sensor, that could work through metal,wood etc of significant thickness were possible, someone would have invented it many many years ago.
The position of the transmitter could be 1 or 2m from the bottom of the roof, so probably hard to get from the top of the roof.
It doesn't have to be a sensor. That's why I used the LoRa. It could be a indirect method too.
I was actually going to try it. Seems to be my best option right now.
Could you mark the roof with a grid or measure angles between corners or landmarks as you would map orienteering using hill peaks and landmarks to find you position? I've done that in scouting and military (arty onserver).
Please answer this question.
Sorry, I forgot. Well, the position can be +/- 10-20cm.
A UWB positioning system may achieve your goals. Check this out from frequent forum contributor @jremington
Radio waves dont travel too well through metal.
Agree. But that's an excellent tools for other projects I had in mind.