[sci.electronics] the laser speed measuring device

BHB3@PSUVM.BITNET (11/22/89)

I finally got the long awaited information I requested on the laser speed
measuring device(laser radar) that is/will be being tested soon by many police
agencies throughout the country.  The following is the entire un-edited text
of the information bulletin send out by Internation Measurement to police
departments.

                     LASER SPEED GUN

International Measurement and Control Company has developed five laser-based
measuring and positioning systems over the last three years.  Most recently
the company developed a laser that is being used by the U.S. Navy in a
sophisticated missle test system.  THE IMC laser is mounted in one aircraft
and used to track another aircraft.  The laser provides a continuous update as
to the distance detween the two aircraft.  Through the design of this and other
laser systems IMC has developed the capability to produce a laser that can be
used to measure car velocity.  The laser you are seeing today is almost
identical to the laser used by the Navy.  We have modified it to measure
velocity, but it is by no means a final product.  The final product will be
smaller, lighter, and quciker.  Extensive work is being dome that will provide
safeguards to guarantee accurate readings.

It is our understanding that the law enforcement community has been seeking a
method for positive identification of vehicles as they are being clocked.  The
laser instrument provides this capability as you will witness today.  The
instrument must be aimed through a scope similar to a rifle, therefore the
officer using the instrument knows exactly which car is being targeted.  Laser
cannot be detected by radar detectors and is not vulnerable to radio interfer-
ence.  In addition it would be very difficult to develop a laser detector
because of the laser's inherent narrow beam.  The instrument will distinguish
between an approachin and departing target which would enable clocking of
a car moving the same direction while in transit.

Below please find the projected specifications of the IMC laser which will
be released within the next 6 - 9 months:


                 SPECIFICATIONS

(1) RANGE    1000-2000 feet
(2) TARGET SPEED +/- 200 mph
    ACCURACY +/- 1 mph
    AQUISITION TIME 0.5 seconds
    BEAM WIDTH 4 ft. at 1000 ft. range
    WEIGHT 5 lbs.
    SIZE 4" X 6" X 7"
    EYE SAFETY  FDA Class 1/CFR 21

(1) The range will vary depending upon the reflective qualities of the target
surface.
(2) The system will give a positive speed reading for an approaching target
and a negative reading for a departing target.  It will also give an accurate
zero reading.

International Measurement . 200 E. Mineral #5 . Littleton, Colorado 80122
(303) 797-7722

End of Text

This demo bulleting is about 3 months old so the 6 - 9 month time frame is
about 3 - 6 months now.  The rumor mill is that the Michigan State Police and
a
the Kansas State Police have test units already.  The unit initially will
probably only be used from a stationary police vehicle, since a way of
determining the police vehicles speed would be necessary.  They would have to
use their radar unit for that, which would defeat the purpose of the device
anyway.  The company rep I talked to said the device would cost $3000.  The
moral of the post is don't throw away your radar detectors for a long time,
just don't try to think they will be foolproof.


                                               Brent H. Besler

tomcat@cbnewsl.ATT.COM (fred.j.shubert) (11/23/89)

In article <89325.164006BHB3@PSUVM.BITNET>, BHB3@PSUVM.BITNET writes:
>
>                      LASER SPEED GUN
> 
>                  SPECIFICATIONS
> 
> (1) RANGE    1000-2000 feet
> (2) TARGET SPEED +/- 200 mph
>     ACCURACY +/- 1 mph
>     AQUISITION TIME 0.5 seconds
>     BEAM WIDTH 4 ft. at 1000 ft. range
>     WEIGHT 5 lbs.
>     SIZE 4" X 6" X 7"
>     EYE SAFETY  FDA Class 1/CFR 21
> 
> (1) The range will vary depending upon the reflective qualities of the target
> surface.
> (2) The system will give a positive speed reading for an approaching target
> and a negative reading for a departing target.  It will also give an accurate
> zero reading.
> 
> International Measurement . 200 E. Mineral #5 . Littleton, Colorado 80122
> (303) 797-7722

Are they willing (or have they indicated) the power output of the laser?
(Seems a bit weak; beam width). Can we find out what type of laser and 
wavelength?

Seems possible to build a "jammer" for this by flooding the area in front of
and behind of your car as you book to work/play.  (Assuming it can be done
safely)



Fred J. Shubert         | "You haven't lived until you've seen a 'cat fly!!!"
AT&T Bell Labs          |-----------------------------------------------------
Whippany, N.J.          | DISCLAIMER:  All views are that of my own. PERIOD.
Ma-Bell 201-386-3094    |              Who else could be so 'cat crazy!!

                  |    _    |  
                  |  /^ ^\  |                          F-14D 
      ____________|_(  .  )_|____________          SUPERTOMCATS
           --*/--|_| (___) |_|--\*--                   RULE
              *       O O       *                  (I Love 'Em)

             Let's turn and burn!!

dave@umbc5.umbc.edu (David A Freeman) (11/23/89)

In article <89325.164006BHB3@PSUVM.BITNET> BHB3@PSUVM.BITNET writes:
>I finally got the long awaited information I requested on the laser speed
>
>                     LASER SPEED GUN


  Now this is a prime candidate for a jammer.  I assume all that is needed is
an IR laser diode with a lens to disperse the beam about 25 degrees.  A power
supply would generate pulses at a frequence that would screw up the guns 
timing ability.  This could be coupled with an IR photo transistor that 
reacts to IR pulses of the proper wavelength.  
  Any idea what wavelength the beam is?  How about the guns pulse frequence 
and interval?





						dave


David Freeman
Systems Programmer			dave@umbc3.umbc.edu
Univ Md Baltimore County		dave@umbc             !bitnet

jwabik@uc.msc.umn.edu (Jeff Wabik) (11/23/89)

In article <89325.164006BHB3@PSUVM.BITNET>, BHB3@PSUVM.BITNET writes:

> I finally got the long awaited information I requested on the laser speed
> measuring device(laser radar) that is/will be being tested soon by many police
> agencies throughout the country.  The following is the entire un-edited text
> of the information bulletin send out by Internation Measurement to police
> departments.
> [ ... ]

The question is:  How easy/difficult will this be to jam?  I know
virtually nothing about this technology (other than the obvious), but,
wouldn't creating "light noise" (i.e.  Have your own wide-beam laser
strapped to the front of your car sending all sorts of bizarre patterns
and such), much the same as RF noise for Radar applications,
effectively jam the "laser radar"?   Seems easy, and also seems as though
the FCC couldn't control it.

Then again, I spoze if this were possible the Navy wouldn't be using it?

	-Jeff

welty@lewis.crd.ge.com (richard welty) (11/23/89)

[i'm not sure i understand what this is doing crossposted to
misc.consumers, as there are no consumer issues i know of
associated with the topic.  therefore, i'm deleting it from
the followup-to line -- rpw]

In article <807@uc.msc.umn.edu>, Jeff Wabik writes: 
*In article <89325.164006BHB3@PSUVM.BITNET>, BHB3@PSUVM.BITNET writes:

*>... about infrared speed measuring devices ...

*The question is:  How easy/difficult will this be to jam?

how legal will it be to jam?  this may fall pretty easily
under `obstructing justice' and `interfering with police officer'
type laws.

* (i.e.  Have your own wide-beam laser

what's a wide-beam laser?

richard
-- 
richard welty    518-387-6346, GE R&D, K1-5C39, Niskayuna, New York
..!crdgw1!lewis.crd.ge.com!welty            welty@lewis.crd.ge.com
     ``i've got a girlfriend with bows in her hair,
         and nothing is better than that'' -- David Byrne

koziarz@halibut.nosc.mil (Walter A. Koziarz) (11/23/89)

Get set  to buy those 'Edmunds Scientific' LASERs!  The transmission of light
is not regulated by the FCC so we can JAM the LASER toys!!

henry@utzoo.uucp (Henry Spencer) (11/24/89)

In article <1517@nosc.NOSC.MIL> koziarz@halibut.nosc.mil.UUCP (Walter A. Koziarz) writes:
>Get set  to buy those 'Edmunds Scientific' LASERs!  The transmission of light
>is not regulated by the FCC so we can JAM the LASER toys!!

Interfering with a police officer in the performance of his duties is illegal
almost everywhere.

Also, the FCC's jurisdiction, as I understand it, technically includes the
entire man-made electromagnetic spectrum.  The FCC *specifically decided*,
for fairly obvious reasons, that optical frequencies weren't worth worrying
about and exempted them from regulation.  They could un-exempt them easily
enough.  I don't think anybody is going to take very kindly to you spraying
laser light around at random.  (The FCC specifically prevented the police
from setting up radar-detector spoofers along the highways, on the grounds
that spraying the law-abiding populace with microwaves unnecessarily was
antisocial.)
-- 
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

grabhorn@marlin.NOSC.MIL (Steven W. Grabhorn) (11/24/89)

Does anyone have any idea what type of damage this instrument might 
inflict on the eyes of drivers approaching such a "speed trap"??

Steve
-- 
-- 
Steve Grabhorn, Code 645, Naval Ocean Systems Center, San Diego, CA, 92152
Phone:619-553-3454 Internet:grabhorn@nosc.mil UUCP:..!sdcsvax!nosc!grabhorn

henry@utzoo.uucp (Henry Spencer) (11/25/89)

In article <1254@marlin.NOSC.MIL> grabhorn@marlin.nosc.mil.UUCP (Steven W. Grabhorn) writes:
>Does anyone have any idea what type of damage this instrument might 
>inflict on the eyes of drivers approaching such a "speed trap"??

Probably none, either through using low enough power or through using an
"eye-safe" wavelength.  The idea that all lasers are dangerous to your
eyesight is a good rule of thumb for safety when working with them but
is not literally true.
-- 
That's not a joke, that's      |     Henry Spencer at U of Toronto Zoology
NASA.  -Nick Szabo             | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

frankb@hpsad.HP.COM (Frank Ball) (11/25/89)

The article doesn't say what wavelength the laser is.
I would think that if it was visable light or infared (most likely)
that normal car headlights would jam it quite well.  They can't use
very much power, or it would be a hazard if it got aimed in a driver's
eye.  Halogen lamps put out about 90% of their light in the infared
range, coventional lights even more.  Maybe they weren't planning
on using these lasers at night?  Maybe car lamps aren't focused 
enough to jam at long distance, but they should when you get closer.

Frank Ball          frankb@hpsad.HP.COM

henry@utzoo.uucp (Henry Spencer) (11/26/89)

In article <1840014@hpsad.HP.COM> frankb@hpsad.HP.COM (Frank Ball) writes:
>I would think that if it was visable light or infared (most likely)
>that normal car headlights would jam it quite well.  They can't use
>very much power...

The laser gadget is almost certainly using a pulsed beam rather than a
continuous one, and picking pulses out of a continuous background is not
generally a difficult problem.  Car headlights don't even show the 120Hz
modulation of normal AC lighting, much less pulses short enough to confuse
something with nanosecond-range resolution.
-- 
That's not a joke, that's      |     Henry Spencer at U of Toronto Zoology
NASA.  -Nick Szabo             | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

dave@umbc5.umbc.edu (David A Freeman) (11/26/89)

>Interfering with a police officer in the performance of his duties is illegal
>almost everywhere.
>
>Also, the FCC's jurisdiction, as I understand it, technically includes the
>entire man-made electromagnetic spectrum.  The FCC *specifically decided*,



Well,  my "jammer" could have a real function.  It will measure the distance
to the car in front of me and a small light will come on if I'm following 
too closely...        ;-)    

And of course, its doesn't have to work well....





						dave
David Freeman
Systems Programmer			dave@umbc3.umbc.edu
Univ Md Baltimore County		dave@umbc             !bitnet

henry@utzoo.uucp (Henry Spencer) (11/26/89)

In article <2552@umbc3.UMBC.EDU> dave@umbc5.umbc.edu.UUCP (David A Freeman) writes:
>>Interfering with a police officer in the performance of his duties is illegal
>>almost everywhere.
>Well,  my "jammer" could have a real function.  It will measure the distance
>to the car in front of me...

Um, this doesn't affect the situation in the slightest.  You are still
interfering with the police; your motives are irrelevant.  A *convincing*
claim that you were doing it for an innocent purpose and weren't aware
of the side effects might get you a lighter sentence, but it wouldn't get
you acquitted.  This isn't like FCC regs, where you have a right to do
certain things and if this causes interference to others that's their
problem.
-- 
That's not a joke, that's      |     Henry Spencer at U of Toronto Zoology
NASA.  -Nick Szabo             | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

kean@tank.uchicago.edu (Keane Arase) (11/27/89)

In article <2552@umbc3.UMBC.EDU> dave@umbc5.umbc.edu.UUCP (David A Freeman) writes:
[Stuff about legalities of jammers deleted...]
>
>Well,  my "jammer" could have a real function.  It will measure the distance
>to the car in front of me and a small light will come on if I'm following 
>too closely...        ;-)    
>
>And of course, its doesn't have to work well....

Good point.  What will a Rashid anti-collision device do to a radar reading?
And what would happend if someone slightly detuned (or tuned :-)
the device?

All in the interest of safety, of course...
---
Keane Arase                   | All 312 area codes outside of the Chicago
kean@tank.uchicago.edu        | city limits will be changed to 708 after
syskean@uchimvs1.uchicago.edu | November 11th... You have been warned...

              *  Please file the usual disclaimers here  *

BHB3@PSUVM.BITNET (11/28/89)

I am working on getting the frequency and output power of the device.  Putting
out anything but the same frequency it uses will do no good.  Also frankly a
police scanner is the most effective countermeasure.  They won't be able to use
the laser device while moving for a while yet.


                                              Brent H. Besler

BHB3@PSUVM.BITNET (11/28/89)

The bean spread on the laser device is 0.23 degrees.  That is awfully small
compared to Ka band radar or any other radar based speed measuring device.

                                               Brent H. Besler

BHB3@PSUVM.BITNET (11/28/89)

The critical facts needed are the output power and the frequency of the
device.  The reflectance off of a car surface is going to be pretty week, so
the thing has to have a quite sensitive detector for that frequency.  It is
probably possible to overwhelm the detector with light of the same frequency.
IR light is of couse invisible to the human eye, so even if you had a bright
IR strobe, it would be too obvious.  It is going to be extremely obvious
to the cop that you are jamming it with high intensity light, since the
device is scope aimed(i.e. He knows who you are right away).  An effective
jammer is going to have to cause it to register the correct speed.  Since the
device works on succesive distance measurements, you would have to know the
pulse rate it puts out.  I would say a police scanner would be the best real
countermeasure.

                                              Brent H. Besler

BHB3@PSUVM.BITNET (11/28/89)

I have two good guesses on the wavelength of the laser device:  0.9 microns
being the most common cheap GaAs laser diodes or 1.54 micron being in the
"eye-safe" zone for which diode laser also exist.  I am checking the eyesafety
standards ANSI publication Z 136.1 - 1980 to see if that will give me a clue
to the frequency and/or output power

myers@hpfcdj.HP.COM (Bob Myers) (11/28/89)

>The laser gadget is almost certainly using a pulsed beam rather than a
>continuous one, and picking pulses out of a continuous background is not
>generally a difficult problem.  Car headlights don't even show the 120Hz
>modulation of normal AC lighting, much less pulses short enough to confuse
>something with nanosecond-range resolution.

Ah, but they *COULD*.......:-)


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
myers%hpfcla@hplabs.hp.com               |  sentient life-form on this planet.

batman@watsci.uwaterloo.ca (Marcell Stoer) (11/29/89)

The laser beam will probably be modulated ( ie chopped). This will make
jamming difficult, since you don't know the chopping frequency.  This in
turn increases the sensitivity of the measurement (phase sensitive detection)
.   0.9 microns is near IR and can be seen by the human eye if the beam is
scattered by a medium (ie glass does it all the time).  You'd be
able to see the beam with an IR viewer  ( they cost about $2K pre-built) if
you're interested in watching those kind of things.  Currently, radar is not
a perfect  speed detection technique either,  and can be fooled by a moving cop car or when multiple cars are being scanned.  The question is, is there less
noise at 0.91 microns +/- a bit than at radar wavelengths.  And is that
sufficient to make this technique a superior one ?

Marcell Stoer
Centre for Molecular Beams And Laser Chemistry
.

jeffg@shamu.WV.TEK.COM (Jeff C. Glover) (11/30/89)

In article <89331.143759BHB3@PSUVM.BITNET> in misc.consumers,
Brent H. Besler writes:
> [discussion of infrared speed-measuring device ommitted]
>                          I would say a police scanner would be the best real
> countermeasure.

Most of the time the speed measuring is done by a single officer.  This
means the only communications will be a license plate check that you'll
have no idea of where it's coming from unless the officer deems it
important to the dispatcher.

Even if they're running a speed trap with multiple cars, the
communications is often of the form 'Red Camaro, Idaho Plates, 75',
again with no indication of location.  Here in the Portland area they
use the same frequency that they use for dispatch, which means that the
transmission could have come from anywhere within about 500 square
miles.

Besides, it's illegal in some states to carry a mobile police-band
receiver.  Not that such a law stops anyone.  We were talking about
evading the police anyway, right? :-)

Jeff

Disclaimer: All opinions expressed within this article are mine.

besler@egrunix.UUCP (Brent Besler) (11/30/89)

The atmoshpere is pretty transparent at 0.91 microns.  The laser speed 
measuring device is "better" than radar I think, because the beam is 
much more narrow 0.22 degrees vs. 15 or so for K band radar.  It is rifle
sight aimed, so the cop will know which car he is clocking.