The module operates over the doppler principle and has the capacity to detect a relocating item in it’s proximity that makes it optimum for purposes that require movement sensing including doors, gates and lights.
Doppler result occurs whenever a audio or radio frequency is transmitted and hits a relocating object, the echo of it alterations relative into the velocity and route the thing.
Doppler outcome case in point in everyday life
At any time puzzled why does the seem of the ambulance, firetruck or simply a honking car or truck improvements mainly because it comes closer and passes by?
A shifting object that may be transmitting or echoing a frequency will compress it while in the route it can be transferring and decompress it in the route it really is moving far from. The amount of alter while in the wavelength is relative to the object’s speed.
When a honking or sirened vehicle is shifting toward you, It'll be listened to as ‘escalating pitch’ and when it's relocating clear of you, will likely be read as ‘reducing pitch’.
In everyday life, law enforcement speed gun is a gadget that mainly features on doppler impact to stamp speeds of moving automobiles.
The device transmits a selected frequency inside a continous waveform, the wave then bounces off the car and is recieved back. The transform from the frequency is then calculated to find the velocity with the motor vehicle.
Human ears and Mind do the job in exactly the same way with soundwaves and we've been subconciously making use of each day to percieve relocating objects all-around us without the need to appear.
Animals and birds use it to perception danger whether it is shifting to them or away.
Doppler impact calculator
There may be formulae to work out doppler outcome whether it is audio or radio wave.
file = file₀(v + vr)/(v + vs)
f will be the noticed frequency. Illustration will be the audio you here from the transferring ambulance once the doppler effect.
fo is the first frequency. Instance is the particular seem frequency emitted from that ambulance prior to the doppler impact
v will be the velocity in the wave. Case in point the audio wave travels at 343 m/s and radio or light travels at 299,792,458 m/s.
vr would be the velocity of your reciever. Case in point, Should you be stationary Hearing the seem then it can be 0.
vs could be the velocity with the source. Case in point, the ambulance travelling at 70km/h.
If you already know the values then you can use this calculator to solve the doppler result.
HB100 circuit
The module has a simple layout with IF(Intermediate Frequency), Ability and Ground Pins
The oscillator provides the reference frequency ten.525 Ghz https://hackaday.io/project/182808-doppler-radar-hb100 that goes two means, first one on the transmitting antennas and the following goes In the mixer .
After the wave bounces off any object, it is actually recieved by the two receiver antennas and goes Within the mixer in which it gets subtracted with the reference frequency.
If the article it bounced off was stationary, then the worth soon after subraction is going to be 0, since the frequency sent is exact the frequency recieved.
Having said that, if the article was moving then the wave bouncing back again will likely have a doppler result and will be different from the initial transmission. The value In such cases might be aside from 0.
This price is Please read on the ‘IF’ pin.
Here is the entrance aspect of your module. The round white disc will be the Dielectric Resonator Oscillator (DRO) which makes the reference frequency at 10.525 Ghz.
The other main factors Allow me to share the mixer along with the reduced go filter.
This is actually the back aspect on the module and the foremost elements Here i will discuss the PCB antennas. Two for transmission and other two for recieving.
Amplifier for HB100
Given that HB100 IF output electrical power is reduced and must be amplified as a way to be read through by Arduino or just plugging right into a speaker to hear it.
Possibly you can build a circuit for from scratch or just order LM358 module which functions beautifully with it
The amplifiction achieve is 100 moments, if you utilize two of these you can find it to generally be ten,000 periods, and 3 will get you one million times gain.