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RF sensor to detect cat

Discussion in 'Sensors and Actuators' started by Josephine, Oct 29, 2017.

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  1. Josephine


    Oct 29, 2017
    I am a beginner and have been darting all over the place looking up odds and ends. I will soon have a Raspberry Pi server loaded with HomeBridge on it so that it will work with Apple's HomeKit, and I want to expand it's use around the house.

    Recently a cat has been quite attached to our house and pays a visit daily, my window is on the ground floor so it likes to sit there, but I don't know when it's there and would like to use a sensor to alert me.

    I found out that normal PIR sensors are no good when trying to go through glass (never mind double glazing) in rooms with backlights, so I found a RF sensor called "RCWL-0516" that focuses on body heat, perfect for me. I was advised to use a ESP8266 module in place of another Pi to cut down on costs and then connect it to a battery which would last a lot longer, but I don't know how to put all this together.

    The following guide is what I was working from, but it's with a PIR:

    I was hoping somebody might come to my rescue..
  2. davenn

    davenn Moderator

    Sep 5, 2009
    welcome to EP :)

    No It Doesn't

    IT's a typical microwave Doppler radar motion detector and probably wont work reliably through a window

    whichever sensor you use RF or PIR, it's likely to have to be mounted outside and aimed at the window in question

  3. ChosunOne


    Jun 20, 2010
    Josephine, it's pretty easy to rig a sensor to let you know when your neighborly cat is visiting. Unfortunately, the hard part of motion detection is finding a sensor that alerts you only when your neighborly cat is visiting. Whatever you use will likely alert you when your window is visited by cats, bats, rats, and brats; also by birds, butterflies, moths, grasshoppers and the praying mantises chasing them; windblown debris (leaves and paper), and you may be surprised by the amount of wildlife that passes your window, even if you live in town.

    Don't underestimate the tendency of motion sensors (Microwave, ultrasonic, or PIR) to be triggered by moths and other insects: A moth 6 inches away from the sensor can have the motion signature of a horse at ten meters. Basically, if you set a sensor to detect motion outside your house, expect a lot of unexplained notifications. Most of the time the transient condition that caused the trigger will be gone by the time you get there to look.
  4. Arouse1973

    Arouse1973 Adam

    Dec 18, 2013
    What about a waterproof IR break beam that with detect the cat if it jumps up onto the window sill. A more advanced option would be to use a camera and some software to do pixel recognition.
    FuZZ1L0G1C likes this.
  5. duke37


    Jan 9, 2011
    Try a fluffy ball tied to a microswitch.
    bushtech and Arouse1973 like this.
  6. kellys_eye


    Jun 25, 2010
    Put a dog on the inside of the window.
    Terry01 likes this.
  7. Terry01


    Jul 5, 2017
    I have one of those.

    It farts quite a lot though and I do have to feed and walk it twice a day. It's called Buster. It doesnt need batteries and i havent charged it since i got it a year ago! It does have a hole in the back I may try and plug it into the wall socket later and see what happens when I give it 240v AC...... :cool::cool:
    FuZZ1L0G1C and Arouse1973 like this.
  8. Josephine


    Oct 29, 2017
    You make a valid point, but I just want to get it working first of all. Interfacing it with Homebridge is my main goal, later on I can use different sensors, perhaps a combination.

    So far I think I need the following parts:

    • sensor:

    • breadboard:

    • battery holder:

    • wifichip:

    davenn: 7mins in the person managed to get the sensor to work through glass (outside looking in):
  9. FuZZ1L0G1C


    Mar 25, 2014
    ... with a sound-activated relay trigger, as long as the dog's farts aren't too noisy!!
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