microwave doppler radar

Hi, I have a Doppler radar which I want to get going on my Arduino mega.

I have attached a datasheet that I think is it. WB-010 ( bought off ebay for $4, seller couldn’t provide any info ).

First off, it says its max current is 60ma. Is this fine to run off the Arduino 5v line?

I also have an LCD, its backlight, and two 74hc595’s running off 2 different 5v connections. Are these going to affect the amount of max current my third 5v pin can provide to the radar?

And finally, the data sheet says the output signal is 100uv min to 250uv max. Would a 2n3904 be usable as an amplifier or even two in a darlington configuration. ( I also have 2n3906 if they are of any use ).

If anyone else has had fun with a radar like this, let me know what you did with it.

cheers in advance.

wb-010.pdf (56.1 KB)

First off, it says its max current is 60ma. Is this fine to run off the Arduino 5v line?

Yes. The Arduino power supply should get you 300 mA without problem. More if you are using the power jack (or Vin) instead of USB.

I also have an LCD, its backlight, and two 74hc595's running off 2 different 5v connections. Are these going to affect the amount of max current my third 5v pin can provide to the radar?

Yes, they are all part of the 300 mA total.

And finally, the data sheet says the output signal is 100uv min to 250uv max. Would a 2n3904 be usable as an amplifier or even two in a darlington configuration. ( I also have 2n3906 if they are of any use ).

I'm nearly useless when comes to transistor circuits. I'd use a high gain op-amp. I think a gain of 100,000 would get you a usable signal. You can use that signal with frequency counting software to determine speed. Each pulse is half a wavelength change in distance (full wavelength change in round-trip distance). Wavelength = speed of light / 10.525 billion. SoL = 299792458000 mm/s. Wavelength = 28.5mm. Each pulse would be 14.25 mm.

It's a Doppler unit, it doesn't give range. It mixes a very attenuated part of the continuously transmitted signal with an amplified return signal to give an AF Doppler signal.

Thanks people. the wave length info is handy as i’ll most probably need it for any useful analysis.

AWOL, what do you mean by ‘It mixes a very attenuated part’.

My basic understanding is it sends a signal that gets increased in frequency by an object moving closer or decreased for an object moving away.

The return signal is a tiny fraction of the strength of the transmitted signal. If you were to mix the two directly, you would never see the heterodyne (beat) frequency, because the mix would be dominated by the strength of the transmitted signal. So, you attenuate the transmit signal before mixing.

You don't want to display the data visually. You want to listen to it. I know this from experience, it was my job in the army. Hearing things move, all the details at once can be fantastic. And with the low power you won't get enough range to need a gate (where you only hear a certain time interval of returns).

I'd be -really- interested in what it takes to make that work affordably.

Yes, listening was my first test option before plugging it into the arduino. I bought a little pizeo buzzer and a OPA2134PA op-amp. Jaycar reckons it is a hi-performance audio op-amp, so I might have some luck with that. It would be interesting if I can hear leaves rustling on a tree 200m away or a bird flapping its wings.

I have had some luck with the radar.
It is not currently attached to the arduino, it has a pezio speaker for debug purposes.

I got it audibly detecting up to 30cm.

With a slight change to the resistors I was able to filter its high frequency squeak, but the signal is only audible for 10cm of detection.

The op-amp I bought is a dual chip so is there a way I can safely operate the two sides in series for an extra gain?

I also power the op amp with 5v, it can handle up to 18v and my supply is 12v.
If I power the op-amp at 12v will it increase the gain more than 5v, and if so, is it safe for the sensitive 5v radar?

With a bit more amplification I think it would be usable as a great long range sensor. Apparently it will go through walls too.

EDIT: pretend the IR sensor in diagram is a radar

Radar.fz (212 KB)

Move or turn different shaped things in front of it. Get things that vibrate or hum and have different casings or even attach other things to them and try those. We could tell a light vehicle from heavy, wheels from tracks, a person in trousers from one wearing a skirt. What hearing can tell it would take an immense amount of circuitry to begin to distinguish.