Hi, I am wondering if it is possible to use a set of 433Mhz radio transmitter and receiver modules as a sort of distance sensor or crude radar. I understand given the weak radio signal they wouldn't have much range but at the same time they wouldn't function at short range because of the speed of radio waves, but I'm wondering if it could be possible to send out a radio signal through the transmitter and wait for a return signal bouncing off things using the receiver, similar to cheap sonar sensors or really any other TOF sensor.
Some special ones do but they are expensive. The cheap ones won't do it the way you describe. So what is your budget?
Another problem, is a highly directional antenna. Those can get quite huge at 433MHz, e.g. a meter or more long.
Yet another one, you have to disable or switch the transmit/receive faster than the return pulse delay, or else be able to transmit and receive simultaneously. But that is difficult, because the transmit signal is hard to isolate from the receive.
Early RADAR made use of VHF frequencies, slightly lower. But the antenna arrays were bigger than a billboard, and the distances very far, 10's of kilometers.
Do you remember that radio waves are traveling at 186,200 miles per second. Sonar is sound in a medium like air or water and travels VERY slowly.
Automotive radars that run at 70gHz will work for distances between moving automobiles. You might see if you can get one and see if you can get it to work for you.
TOF laser units work on the timing of a pulse of light, not the speed of the light.
i think you are better off with a HB100 motion detector.
A little while back I made this speed radar, that i can put in my garden near the road and then transmits the speed of passing cars via 433MHz to a receiver indoors.
The trick is to build the right amplifier, which is what you are looking at. the HB100 module itself is mounted on the bottom side of the amplifier. For best results the amplifier needs to be put in a metal box to shield it from EMF.
[Edit] After some searching I found the source where I originally started from. Credits to Markus Kantola.
Alright everyone thanks for the quick replies. This all helped a lot. I think I’m gonna drop the 433Mhz modules at least for this project and try and look into getting a cheap automotive radar. I might also look into the capabilities of those motion detectors to see if they might work for this. Thanks again!
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