Doppler radar unit (speed)

[PaulTech]

I was watching a Youtube vid of a stand at the 2010 CES trying to sell handheld doppler radar units, for speed , at around $275.
It was apperent the unit was using a patch type moudle, and I started to think ( I have built my own doppler speed guns in the past), if you take a microwave sensor from an old dual sensor movement dectector, these units are usually thrown out once the IR sensor degrades, feed the output into the mic input of an Android - you would have a cheap compact speed gun.
Ok, background over, what is needed...
frequency counter app, maybe FFT and the upper limit only has to be around 3KHz
front end for frequency counter.

One little bit of extra icing would be to double/triple the input frequency as an audio out, to have a battlefield man radar for paintballers, the frequencies involved with someone moving are quite small and this would amplify the doppler effect.

I also need to check the low frequency response of the mic input, I would like to try this with a bluetooth module as well to transfer the signal, but at the moment I only have a slave module, guess I'll have to get a master one as well.
I'll check to see if there any realtime spectograph, SDR (maybe) or FFT apps waiting to be used.

[PaulTech]

OK, I've had the scope out working on some other projects and had a quick look at some Microwave movement detectors, well there is a bit of a struggle ahead of me as the variation in the output signal is only 20mV. The sensors look like they go into JFET opamps, no suprise, but the real nasty problem is that at the moment ie still on alarm boards, they are pulsed 1KHz, <10% duty cycle. I'll see how many I have and may see if they work with DC or are simply fried.

[gaditano]

Hi Paul
I'm looking products to catch cars velocity.
Do you know some product?
Thanks
JAvier



I was watching a Youtube vid of a stand at the 2010 CES trying to sell handheld doppler radar units, for speed , at around $275.
It was apperent the unit was using a patch type moudle, and I started to think ( I have built my own doppler speed guns in the past), if you take a microwave sensor from an old dual sensor movement dectector, these units are usually thrown out once the IR sensor degrades, feed the output into the mic input of an Android - you would have a cheap compact speed gun.
Ok, background over, what is needed...
frequency counter app, maybe FFT and the upper limit only has to be around 3KHz
front end for frequency counter.

One little bit of extra icing would be to double/triple the input frequency as an audio out, to have a battlefield man radar for paintballers, the frequencies involved with someone moving are quite small and this would amplify the doppler effect.

I also need to check the low frequency response of the mic input, I would like to try this with a bluetooth module as well to transfer the signal, but at the moment I only have a slave module, guess I'll have to get a master one as well.
I'll check to see if there any realtime spectograph, SDR (maybe) or FFT apps waiting to be used.

[PaulTech]

anything from a Mattel radar gun up will indicate speed, how far away before it gets a good reading is the real question. The Mattel will pickup a car at at least 50 metres away, haven't tried real long range but I doubt it would be over 200m. The microwave modules I'm using now are designed to detect a person moving at up to 15m and people aren't good radar reflectors.