# Radar sensor to detect large animals in a forest

#### prenz69

Joined Aug 25, 2022
9
I thought of developing such a project due to Human-elephant conflict in my country. I did some research on possible radar devices. The best I found was https://www.infineon.com/cms/en/product/evaluation-boards/demo-sense2gol-pulse/

This is too expensive as well as it takes time to be here. I would love to know if there are any other less expensive methods I could use. Even using Raspberry Pi board is possible as I have few with me already. I would need to detect 20m (66 ft) or more for this to work

#### DickCappels

Joined Aug 21, 2008
9,510
From a quick look around the internet US $145 seems like a bargain. Detecting the presence of an elephant may only be part of the problem. You probably will want to differentiate elephants from deer and water buffalo. My thinking is that generally neither would pose a danger to people as water buffalo seem to respect fences and ignore people, so you probably would not want to sound the alarm for non-elephant visitors. I ran across this block diagram of an elephant detector. Apparently a tripwire signals the pyroelectric infrared sensor and a microwave sensor and a microcontroller watches the inputs from these detectors to determine whether there is an intruder. The NRF24L01 is a Bluetooth transceiver. My guess is that you simply use a tripwire arrangement by itself. Using two or more wires would allow you to sense the presence of large animals as well as estimate their size. A possible improvement over simple tripwires is to use a network of Microwave Impulse Radar modules (can be as cheap as U.S.$1.60), which have shorter range than you might need -hence a network of them. Communications with them might be the interesting part of the project. https://th.cytron.io/p-microwave-ra...-D84lqvBJqdH2IpdZwT88h7RroOMs78xoCsWEQAvD_BwE

The solution here in Thailand is to identify the elephants who are problems, tranquilize them, then truck them to a far away corner of the preserve or even further away.

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#### MrSalts

Joined Apr 2, 2020
2,599
Although I'm not a big fan of these radar modules because most users have a high expectation of focus, directionality and range but, in your case, they might be perfect to detect elephants moving in the Forrest.

They are triggered by movement of something with a large amount of high dielectric constant materials (water/human/elephant). The range is shorter than you want but these radar modules are so cheap, you can use an array of them. As a basic part, they only have a single-channel digital output (some thing detected or nothing detected). Range is 5 to 7 meters. Very easy and comparable with digital inputs of Raspberry pi. 8 units for $9 In the US. https://www.amazon.com/Microwave-RC...8BZDP63B/ref=pd_lpo_1?pd_rd_i=B08BZDP63B&th=1 Or. This one is a bit more expensive and the on-board antenna is more adaptable to a direction aluminum (sheet or foil) antenna. Some people claim large objects can be detected up to 100ft (30 meters). This one is also easier to access the analog pins to tap into and write filtering code to look for objects of a certain speed/size/dielectric constant. There is some good guidance on the datasheet and user shared info. About$12 each in USA. This will need an ADC if used directly with Raspberry Pi because the pi only has digital inputs. Otherwise, you can use an Arduino or other microcontroller with on-board ADC. The Arduino can be interfaced with your pi if needed.
https://www.amazon.com/SMAKN-Microwave-10-525GHz-Doppler-Detector/dp/B00FFW4AZ4

#### prenz69

Joined Aug 25, 2022
9
From a quick look around the internet US $145 seems like a bargain. Detecting the presence of an elephant may only be part of the problem. You probably will want to differentiate elephants from deer and water buffalo. My thinking is that generally neither would pose a danger to people as water buffalo seem to respect fences and ignore people, so you probably would not want to sound the alarm for non-elephant visitors. I ran across this block diagram of an elephant detector. Apparently a tripwire signals the pyroelectric infrared sensor and a microwave sensor and a microcontroller watches the inputs from these detectors to determine whether there is an intruder. The NRF24L01 is a Bluetooth transceiver. My guess is that you simply use a tripwire arrangement by itself. Using two or more wires would allow you to sense the presence of large animals as well as estimate their size. View attachment 277488 A possible improvement over simple tripwires is to use a network of Microwave Impulse Radar modules (can be as cheap as U.S.$1.60), which have shorter range than you might need -hence a network of them. Communications with them might be the interesting part of the project. https://th.cytron.io/p-microwave-ra...-D84lqvBJqdH2IpdZwT88h7RroOMs78xoCsWEQAvD_BwE

The solution here in Thailand is to identify the elephants who are problems, tranquilize them, then truck them to a far away corner of the preserve or even further away.

#### prenz69

Joined Aug 25, 2022
9
Although I'm not a big fan of these radar modules because most users have a high expectation of focus, directionality and range but, in your case, they might be perfect to detect elephants moving in the Forrest.

They are triggered by movement of something with a large amount of high dielectric constant materials (water/human/elephant). The range is shorter than you want but these radar modules are so cheap, you can use an array of them. As a basic part, they only have a single-channel digital output (some thing detected or nothing detected). Range is 5 to 7 meters. Very easy and comparable with digital inputs of Raspberry pi. 8 units for $9 In the US. https://www.amazon.com/Microwave-RC...8BZDP63B/ref=pd_lpo_1?pd_rd_i=B08BZDP63B&th=1 Or. This one is a bit more expensive and the on-board antenna is more adaptable to a direction aluminum (sheet or foil) antenna. Some people claim large objects can be detected up to 100ft (30 meters). This one is also easier to access the analog pins to tap into and write filtering code to look for objects of a certain speed/size/dielectric constant. There is some good guidance on the datasheet and user shared info. About$12 each in USA. This will need an ADC if used directly with Raspberry Pi because the pi only has digital inputs. Otherwise, you can use an Arduino or other microcontroller with on-board ADC. The Arduino can be interfaced with your pi if needed.
https://www.amazon.com/SMAKN-Microwave-10-525GHz-Doppler-Detector/dp/B00FFW4AZ4

#### MrSalts

Joined Apr 2, 2020
2,599
Can anyone tell me if SP25 millimeter wave radar http://en.nanoradar.cn/File/view/id/432.html would work for this? Can it detect elephants hidden behind the trees?

Does a doppler radar need to be static when taking observations?
It depends on what is moving the Doppler radar. If a person is carrying it, then no, you cannot use it that way unless you somehow manage to shield the antenna from detecting the parson carrying the radar or decrease the detection threshold to some volume of a watery "body" bigger than a person and smaller than an elephant.

Joined Jan 15, 2015
7,079
While not RADAR a popular item is trail or game cameras. Typically a 120 degree field of view and distance varies depending on quality / cost. Some have WiFi or Bluetooth. Just something else which may or may not work for your application.

Ron

#### drjohsmith

Joined Dec 13, 2021
545
A radar , is itself unable to detect what a elephant or a tree is. To a radar , the world is just echos ,
The echos can be processed .

If the radar is made directional , and scanned , into say square box's ,then processing and scanning can provide a grid of distance from the radar for each box.

A doplar radar , the frequency of the returned signal is measured to check the change in frequency from that transmitted .
I've if the radar and the object are moving towards each other ,the returned frequency will be higher
Note the radar and or the object could he moving , and if they are moving parallel to each other , the returned frequency difference is zero .
So , you want to detect an elephant in trees
Are the trees moving , may be by wind , is the elephant moving , is it towatds or away from the radar ?
The question is discrimination.
If you were showed a picture of the elephant in the trees , how would detect the elephant ?
Given a picture with the details described above , how would you detect the elephant ?

Are the trees big , is the elephant small , how often do you want to trigger on wind , other animals .

In general. Given enough processing, it's going to be possible to point a radar at an elephant in trees and have the system detect.
But in the general case it's not going to be easy.

#### Janis59

Joined Aug 21, 2017
1,525
I remember as one wintery day I took our FLIC camera with me. I set the 20 micron wavelength and it was easy at night to see literally under each bush the two small eyes thinking they are completely hidden several hundred meters afar. So, am sure, at 20-40 micron wavelength Your through the wood stems visibility for so bright masses as elephants ought to mbe one to three kilometers afar. 40 microns are free going through wood. By the way, the best keyword to find any suitable FIR sensors is "microbolometer".

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