DPRG mailing list archives: [DPRG] Cool Christmas Presents

Wed Dec 27 20:48:56 CST 2006

Ed O.,

I just read the entire thread here:
http://www.austech.info/showthread.php?t=135840&page=1

They seem to be most concerned with using the measuring electronics
with other more powerful TX/RX pairs to make homebrew radar guns, but
the posts by "mitaux8030" and "Trash" are pretty informative.

I just finished tearing the beast apart, etc.  First off: its a real
beast to get apart.  You have to drill out the plastic plugs to get at
the screws.  A big hint is to get the two end caps off first.

I've got the waveguide/TX/RX/mixer unit on my bench.  The signal
coming out of it doesn't seem to get any better by powering the unit
continuously versus the 25% on, 8khz duty cycle the unit originally
uses.

I need to build an amp and fiddle with some filters to see if I can
get an obviously measurable signal out of it.  I'm also need to find a
book to figure out what sort of frequency range to expect out.
0-100Hz seems to appear, but I'm not sure if thats due to real doppler
affect, or my hand affecting the near-field of the TX/RX pair.

I've got pictures of the gun disassembled. They sort of fill the gaps
of the pictures on that forum.  I'll get them up on a site soon.

Ed P.

On 12/27/06, Ed Okerson <ed at okerson.com> wrote:
> Ed,
>
> What search terms did you use?  I have not been able to find any useful
> info so far.
>
> Ed
>
> > Ed,
> >
> > When I got back to Austin today, I stopped by the local Walmart and
> > picked up one of those hot wheels radar guns.  Pretty slick!  They
> > appear to be on clearance for $20.00 and I saw them at HEB later for
> > $12.50.
> >
> > I found some pictures online, and it seems that its using doppler
> > shift, not time of flight.  Makes sense, because thats cheap.   There
> > is some discussion on boosting the power, too.
> >
> > But it seems that the base signal is being measured and displayed by a
> > microcontroller of some sort.
> >
> > So the question to everyone is this:
> > Given a sensor that gives you the speed of a moving object, can you
> > produce 'interesting' data for navigation?
> >
> > Perhaps use it while driving to check your odometry by measuring your
> > own speed against the ground?
> >
> > Sweep it 360 degrees and create a sort of optical flow map?
> >
> > Use two at once and come up with the speed of two points in front of
> > you, then compute a line (gradient) that could give you speed and
> > direction of travel?
> >
> > I've not opened mine up yet, but from the pictures, the base-band
> > processor would easily be replaced.
> >
> > Ed P
> >
> >
> > On 12/26/06, Ed Okerson <ed at okerson.com> wrote:
> >> So what cool toys did everyone find under the tree?
> >>
> >> My kids got me the Hot Wheels Radar Gun.  How they manage to make a real
> >> Doppler radar gun for $20 is beyond me.  Now to figure out a good
> >> robotics
> >> use for it.  I wonder how hard it would be to make a sonar replacement?
> >>
> >> Anyone going to RBNO tonight?
> >>
> >> Ed
> >>
> >> _______________________________________________
> >> DPRGlist mailing list
> >> DPRGlist at dprg.org
> >> http://list.dprg.org/mailman/listinfo/dprglist
> >>
> >
>
>
>