proximity sensor up to 200metres for outdoor application

Thread Starter

jpf88

Joined Oct 4, 2021
3
Hi,
I have a project that i would like to complete.
i need to activate an LED light outdoors, whenever a designated vehicle comes within 200-300metres of the LED light.

i was thinking of using a simple 12v FM radio transmitter on the vehicle.
the LED would have an FM radio reciever tuned to the correct wavelength, which would then activate the LED light.

all systems need to be 12V so it can be integrated into the vehicle, and also have a solar/ 12v battery system to power the LED light.

i am hoping to get some feedback on:
- will this work?
- are there any off-the-shelf items that i can put together to make this easily?
- i am not able to code, or do complex circuit work :)

Any info is greatly appreciated
 

BobTPH

Joined Jun 5, 2013
4,046
Why don’t you tell us what you are really trying to do. A literal reading of your post says you want the light on when the vehicle is between 200 and 300m of the LED, whether it is east. west, north, south, above, or below. And that it is off when the vehicle is closer or further away.

I doubt that that is what you mean, and doing it be very hard.

So, give us the actual scenario. Something more like: I have a cabin in the woods, I would like to turn on an LED light when my car gets close to it. It should turn in somewhere in n the range if 200 to 300m. I can only approach it from a single access road.

Information like that would lead to an optimal solution. What you have given us will lead to lots of speculation about what you really want.

Bob
 

Thread Starter

jpf88

Joined Oct 4, 2021
3
Why don’t you tell us what you are really trying to do. A literal reading of your post says you want the light on when the vehicle is between 200 and 300m of the LED, whether it is east. west, north, south, above, or below. And that it is off when the vehicle is closer or further away.

I doubt that that is what you mean, and doing it be very hard.

So, give us the actual scenario. Something more like: I have a cabin in the woods, I would like to turn on an LED light when my car gets close to it. It should turn in somewhere in n the range if 200 to 300m. I can only approach it from a single access road.

Information like that would lead to an optimal solution. What you have given us will lead to lots of speculation about what you really want.

Bob
yeah fair call bob,

so I work in an orchard.

I would like to install an FM transmitter in each tractor/ machine working in the orchard.

as visibility is very poor throughout the orchard, I hope to install a series of flashing lights at 200m intervals throughout the orchard, that activate (FM RECIEVER) when a machine is within range.
The flashing light would indicate that a larger machine is working in that area so workers on lighter machines, on foot, or even other large machines can be aware of danger when not immediately visible.

we do have 2way radios, but not all workers are reliable for this, and we often have 'visitors' on the farm who do not have access to the 2way system.

it seemed like a simple solution to a large problem that could be multiplied on a large scale if required across many acres, and many vehicles.

-RF sensors don't have enough range?
-UHF or VHF has too much range
-IR sensors are too specific to 'passing through' the beam.

I am looking for a 200-300m radius in all directions. This will be best for a work safety point of view.
As soon as the reciever looses signal (beyond 200m of vehicle) the signal light can turn off as the area would be deemed 'clear/ safe'.

thanks again for taking the time
 

BobTPH

Joined Jun 5, 2013
4,046
Thank you. That really clarifies what you are trying to do.

Unfortunately, I don’t have a really good solution for you. The distance at which a radio signal is detected depends on too many variables. Directionally of the transmitter and receiver, obstructions, interference and even the weather will affect this. And with multiple transmitters, it becomes quite difficult to predict or adjust how it performs.

With an infinite budget and expertise, a system using transponders would work. The tower would send out pulses which are received by each tractor which then replies. The tower unit would measure the time of arrival of the first response and calculate time of flight to determine how far away it was. I am sure a military contractor could do this!

I am not optimistic that a simple solution would be reliable enough. Maybe someone else will have a brilliant idea.

Bob
 

BobTPH

Joined Jun 5, 2013
4,046
Bump- Anyone else like to weigh in on this problem now that it is better defined?

I find it interesting, and would like to know if there is a simple solution that would be adequate.

Bob
 

Juhahoo

Joined Jun 3, 2019
250
GPS is the way to go. Your Tractors have GPS and will send their locations via radio link.

When the "beacon" detects the tractor is close by, it will go on. Alternatively, each tractor could have each others real time positions and alarm for presence of other machines. You need a bit more than just an FM transmitter.. You need a radio network which can handle transmission collisions.
 

Thread Starter

jpf88

Joined Oct 4, 2021
3
GPS is the way to go. Your Tractors have GPS and will send their locations via radio link.

When the "beacon" detects the tractor is close by, it will go on. Alternatively, each tractor could have each others real time positions and alarm for presence of other machines. You need a bit more than just an FM transmitter.. You need a radio network which can handle transmission collisions.
This is a good idea, however, the GPS and cell phone reception in the large trees and low areas of the orchard are patchy at best. Heck, even in open paddocks on some of the farms we have no cell or GPS reception. And a standard GPS unit in the tractor costs us min. $15k to install..
So this will not work.
This is why I was hoping to go a bit more 'analogue' with the whole thing..
Anyway I'll bash something together with what I was thinking because I'm still pretty sure I'll get some sort of result.
Thanks
 

Sensacell

Joined Jun 19, 2012
2,917
GPS idea is cool, but not reliable enough for a true "Safety System"

If people become habituated to the lights warning them of proximity, they will stop using due caution, when the system fails- crash!
 

MrSalts

Joined Apr 2, 2020
723
You could try sensing the low frequency rumble of the tractors as the sensing target. I would start with four small microphone capsules, a quad op amp and a microcontroller - ideally an ESP32 that could be used to build a wifi mesh-network.
 

Juhahoo

Joined Jun 3, 2019
250
GPS system can be as reliable as you want it to be. If you have no reception, that's an issue. Modern GPS systems however, even in Mobile phones with crappy antennas, can have GPS reception surprisingly well..
Your best choice then is to use simple beacon transmitter and receivers on every machine, close proximity will trigger them, but you just have to accept the fact that the distance can alter in a scale of 50 meters up to 200meters depending on many external factors. This would lead to a problem that soon you start ignoring the warnings if they happen too often from the far distance.
 

MisterBill2

Joined Jan 23, 2018
9,824
A GPS system with a beacon to report it's position every second or so will allow others with the suitable smart receiver with it's own GPS receiver to know the positions adequately. BUT those packages are not at all cheap, and a person walking would probably not be carrying one. How fast do the vehicles go that they are a hazard? In a jungle with very limited vision range even GPS was not useful. This sounds like a very closely packed orchard
 

DickCappels

Joined Aug 21, 2008
7,981
Have you looked into existing solutions? You can't be the only one who has this concern, and it looks like a solution such as those we are thinking about will be involved and take a lot of design/test/revision cycles.
 

MisterBill2

Joined Jan 23, 2018
9,824
Have you looked into existing solutions? You can't be the only one who has this concern, and it looks like a solution such as those we are thinking about will be involved and take a lot of design/test/revision cycles.
If it is designed starting from zero, yes, but a lot of the functions are available. But neither simple nor cheap.
 

MisterBill2

Joined Jan 23, 2018
9,824
One more consideration not previously presented is that because this would be a safety system designed to protect human life and safety, the reliability requirements are a lot more demanding.. That affects the cost quite a bit.
 

MrSalts

Joined Apr 2, 2020
723
One more consideration not previously presented is that because this would be a safety system designed to protect human life and safety, the reliability requirements are a lot more demanding.. That affects the cost quite a bit.
Considering the fact that nothing is used now, and no regulations require safety mechanisms for tractors roaming on orchards, I don't think we have to call it a life-saving device. It is more of a convenience.
 

MisterBill2

Joined Jan 23, 2018
9,824
Considering the fact that nothing is used now, and no regulations require safety mechanisms for tractors roaming on orchards, I don't think we have to call it a life-saving device. It is more of a convenience.
My observation is that mostly the courts will not agree with that. Once a safety function is added people depend on it working, and so it is then mandatory that it keep working. That even included a light installed for a previously unlighted stairway. When it burned out my employer was liable.
 
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