It would seem to me that you could add a frequency counter, and calibrate
frequency to speed.

About the flourescent light deal, my guess is that the lamp is such a non
linear device that the 60 Hz being fed into it is being distorted to the
extent of creating many higher order harmonics, and the radar gun is
concentrating these high order harmonics and that's what you're detecting.

BTW, how much was the Gunnplexer?  I am a Ham and would like to get one for
some experiments I have in mind.

                                                                Regards,

                                                                    Jim


-Original Message-----
From: Sean H. Breheny <shb7@CORNELL.EDU>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Friday, February 22, 2002 11:54 PM
Subject: [EE]: 10GHz and fluorescent light


>Hi all,
>
>A while back I bought a 10GHz gunnplexer (combination 10GHz low-power
>transmitter and simple homodyne receiver) and attached a sensitive audio
>amplifier in an attempt to make a simple doppler radar. It was quite
>successful; I can point it at cars up to about 100 feet away and hear a
>tone which varies with their speed. I also can get some very interesting
>sounds by pointing it at my PC's power supply fan or the CD drive while it
>plays a CD or is ejecting a CD. I recorded a WAV file of this and I put it
>up on my web site:
>
>http://www.rocket-roar.com/BT
>(look under the section on "Small Doppler Radar Experiment" about 1/4 down
>the page)
>
>For the most part, I understand how this works. However, one thing puzzles
>me: when I point it at a fluorescent light, I hear a VERY loud 60Hz hum
>(might actually be 120Hz, it is hard to tell because most of what we
>usually attribute to 60Hz is really full wave rectified 60Hz which is
>actually 120Hz).
>
>If it were simply a case of the audio amp picking up 60Hz noise, I wouldn't
>think that the antenna direction would make a difference, only the
>proximity to the lamp. But it makes a profound difference whether I point
>the horn antenna at the lamp or not. So, my only guess is that the radar is
>seeing an echo from all the mercury (?) ions being jostled around inside
>the light at 60 or 120Hz. I'm not surprised that I would be able to detect
>such an echo, only surprised that it is SO strong, it is much stronger, for
>example, than the echo from my power supply fan.
>
>Any ideas?
>
>Sean
>
>----------------------------------------------------
>Sign Up for NetZero Platinum Today
>Only $9.95 per month!
>http://my.netzero.net/s/signup?r=platinum&refcd=PT97
>
>--
>http://www.piclist.com hint: The PICList is archived three different
>ways.  See http://www.piclist.com/#archives for details.
>
>

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.