Searching \ for '[OT] Police "LADAR"?' in subject line. ()
Help us get a faster server
Search entire site for: 'Police "LADAR"?'.

Exact match. Not showing close matches.
2005\01\21@121841 by

Does anyone know the details on police "LADAR" (laser based speed
detection). I'm wondering about optical wavelength, pulse width, and pulse
repetition rate.

Thanks!

Harold

--
FCC Rules Updated Daily at http://www.hallikainen.com

>-----Original Message-----
>From: piclist-bouncesmit.edu [piclist-bouncesmit.edu]
>Sent: 21 January 2005 17:19
>To: piclistmit.edu
>
>
>Does anyone know the details on police "LADAR" (laser based
>speed detection). I'm wondering about optical wavelength,
>pulse width, and pulse repetition rate.
>
>Thanks!
>
>Harold

This was posted some time ago on http://www.pistonsheads.co.uk, a UK car
forum.  The device in question is a Marksman LTI 2020, one of the most
common speed guns in the UK.

"There is a 905nm Infra red solid state laser module with deam
divergence of approx 3mrad. It flashes 44 pulses of IR over a period of
0.3 seconds. This light is aimed at something very reflective, ideally
the numberplate of a car which who's backing material has the same
reflective properties of a 'corner cube' mirror, known as a reflex
reflector (it reflects light in the direction in which it came to a
tolerence of +/- 3 degrees) The reflected light pulses are picked up by
an IR dependent resistor network behind refracting optics in the LTI
2020 and the time intervals are recorded into memory. The time intervals
plotted against time create a gradient which directly correlates to the
distance travelled by the point of reflection, and therefore the
velocity. The LTI must recieve at least 30 similar reflected pulses to
achieve a legitimate reading. It does this by applying the mathematical
'least squares' algorithm."

One of the members owns one of these guns, and it seems that it is not
very diffcult at all to confuse it or vastly reduce it's range.  Metalic
silver cars have the greatest detection range apparently.

Regards

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

Michael Rigby-Jones wrote:

{Quote hidden}

Standard microwave guns have problems too. Switching LED arrays held
close to the
antenna cause a false  high-speed reading on one of the most popular
units here in
the colonies. Its that tiny RF burst that is released when LED's are
switched on/off
that cause the problem. F-15 cockpit displays had to have a shield
within the display
glass to stop this, too.

{Quote hidden}

--
Note: To protect our network,
attachments must be sent to
attachengineer.cotse.net .
http://beam.to/azengineer

>-----Original Message-----
>From: piclist-bouncesmit.edu [piclist-bouncesmit.edu]
>Sent: 24 January 2005 11:28
>To: Microcontroller discussion list - Public.

>Standard microwave guns have problems too. Switching LED arrays held
>close to the
>antenna cause a false  high-speed reading on one of the most popular
>units here in
>the colonies. Its that tiny RF burst that is released when LED's are
>switched on/off
>that cause the problem. F-15 cockpit displays had to have a shield
>within the display
>glass to stop this, too.

Hand held Radar speed guns are no longer used in the UK.  The only Radar
based speed detection we have is the fixed GATSO camera, which has been
in the press several times for vastly over-reading the speed of
vehicles.

Regards

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

2005\01\24@071030 by
>Standard microwave guns have problems too. Switching LED arrays held
>close to the
>antenna cause a false  high-speed reading on one of the most popular
>units here in
>the colonies. Its that tiny RF burst that is released when LED's are
>switched on/off
>that cause the problem. F-15 cockpit displays had to have a shield
>within the display glass to stop this, too.

My understanding was that almost any radio transmitter could upset most of
the microwave units. A ham colleague used to take great delight in keying
his 2m unit and watching cop with 10GHz radar go looking around for whoever
waveguide filtering to stop this sort of interference.

Michael,

On Mon, 24 Jan 2005 12:04:36 -0000, Michael Rigby-Jones wrote:

> Hand held Radar speed guns are no longer used in the UK.

Really?  When did this happen?  I admit I've only seen the lasers recently, but I didn't realise that the
"hairdryers" had been decomissoned!  I wonder why, and what they did with the old ones?

Cheers,

Howard Winter
St.Albans, England

Bob,

On Mon, 24 Jan 2005 04:28:26 -0700, Bob Axtell wrote:

> Standard microwave guns have problems too. Switching LED arrays held close to the
> antenna cause a false  high-speed reading on one of the most popular
> units here in the colonies. Its that tiny RF burst that is released when LED's are
> switched on/off that cause the problem. F-15 cockpit displays had to have a shield
> within the display glass to stop this, too.

To stop them interfering with radar speed guns?  :-)

Reminds me of the story (Urban Legend, probably) about the Harrier that was doing a low-level training sortie
over the Yorkshire Moors, and it's anti-radar missile system (HARM, or something similar) locked onto a police
speed-trap!  Good thing that humans are still part of the "decision to fire" loop!  :-)

Cheers,

Howard Winter
St.Albans, England

>-----Original Message-----
>From: piclist-bouncesmit.edu [piclist-bouncesmit.edu]
>Sent: 24 January 2005 13:38
>To: Microcontroller discussion list - Public.
>
>
>Michael,
>
>On Mon, 24 Jan 2005 12:04:36 -0000, Michael Rigby-Jones wrote:
>
>> Hand held Radar speed guns are no longer used in the UK.
>
>Really?  When did this happen?  I admit I've only seen the
>lasers recently, but I didn't realise that the
>"hairdryers" had been decomissoned!  I wonder why, and what
>they did with the old ones?

AFAIK they haven't been used for quite some time, though I don't know
the exact year they were phased out (I'll ask on Pistonheads, there are
quite a few Trafic Police that regularly post there).

They were replaced by Laser based guns as they were more robust and more
immune to false readings.  They also aquire a "lock" much more quickly,
typicaly in well under a second.  The radar devices could take several
seconds, and a radar detector could give you enough warning to slow down
if you were over the limit, but laser detectors are a complete waste of
money.  If it alerts you then you can be expecting an NIP in the post
shortly.

Regards

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

Howard Winter writes:

> > Hand held Radar speed guns are no longer used in the UK.
>
> Really?  When did this happen?  I admit I've only seen the lasers recently, but I didn't realise that the
> "hairdryers" had been decomissoned!  I wonder why, and what they did with the old ones?

I can't speak for the UK, but here in the US there were concerns about
radiation exposure by the operators.  Whether this is a serious issue
or not, the media had a field day and many LEOs dumped their
radio-based devices with or without any regulation from the various US
governments.

-p.

> Reminds me of the story (Urban Legend, probably) about the Harrier
> that was doing a low-level training sortie
> over the Yorkshire Moors, and it's anti-radar missile system (HARM,
> or something similar) locked onto a police
> speed-trap!  Good thing that humans are still part of the "decision
> to fire" loop!  :-)

I would have thought it was urban legend too BUT I heard it told abut
a location in the US, and the man who told me worked at China Lake and
wrote anti-aircraft missile tracking software for them. AFAIR he said
it was true. In anyone I know knows he would. But then, maybe I'm just
adding to urban legend. I'll BCC this to him. (He'll probably have to

Dave?

Russell McMahon

On Mon, 24 Jan 2005, Michael Rigby-Jones wrote:

> They were replaced by Laser based guns as they were more robust and more
> immune to false readings.  They also aquire a "lock" much more quickly,
> typicaly in well under a second.  The radar devices could take several
> seconds, and a radar detector could give you enough warning to slow down
> if you were over the limit, but laser detectors are a complete waste of
> money.  If it alerts you then you can be expecting an NIP in the post
> shortly.

Is there a ban on ir leds mounted on the number plates ? ;-) If so I
haven't heard of it.

Peter
On Mon, 2005-01-24 at 21:23 +0200, Peter L. Peres wrote:
> On Mon, 24 Jan 2005, Michael Rigby-Jones wrote:
>
> > They were replaced by Laser based guns as they were more robust and more
> > immune to false readings.  They also aquire a "lock" much more quickly,
> > typicaly in well under a second.  The radar devices could take several
> > seconds, and a radar detector could give you enough warning to slow down
> > if you were over the limit, but laser detectors are a complete waste of
> > money.  If it alerts you then you can be expecting an NIP in the post
> > shortly.
>
> Is there a ban on ir leds mounted on the number plates ? ;-) If so I
> haven't heard of it.

In most areas it is illegal to purposely interfere with police speed
measuring devices. If you can come up with a completely legitimate and
believable reason that you needed IR LEDs on your plate you MAY get away
with it. OTOH you may not, and end up in BIG trouble.

I find this whole "issue" just silly. The best way to defeat radar/lidar
is VERY simple: DON'T SPEED. It's not that hard really.

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

Actually, this was covered last night on Mythbusters. The infrared
LEDs did nothing to disturb the LIDAR. Of course, I don't think they
checked the exact wavelength of either the LIDAR or the LEDs. I'd
imagine there is a pretty good filter on the LIDAR that rejects
anything not modulated just right.

And yes, tampering with bits of your car like that can be illegal
depending on where you live.

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.

On Mon, 24 Jan 2005 16:14:21 -0500, Herbert Graf
<mailinglist2farcite.net> wrote:
> > Is there a ban on ir leds mounted on the number plates ? ;-) If so I
> > haven't heard of it.
>
> In most areas it is illegal to purposely interfere with police speed
> measuring devices. If you can come up with a completely legitimate and
> believable reason that you needed IR LEDs on your plate you MAY get away
> with it. OTOH you may not, and end up in BIG trouble.

>
>In most areas it is illegal to purposely interfere with police speed
>measuring devices. If you can come up with a completely legitimate and
>believable reason that you needed IR LEDs on your plate you MAY get away
>with it. OTOH you may not, and end up in BIG trouble.

Optical garage door opener??

On Mon, 2005-01-24 at 17:32 -0500, Josh Koffman wrote:
> Actually, this was covered last night on Mythbusters. The infrared
> LEDs did nothing to disturb the LIDAR. Of course, I don't think they
> checked the exact wavelength of either the LIDAR or the LEDs. I'd
> imagine there is a pretty good filter on the LIDAR that rejects
> anything not modulated just right.
>
> And yes, tampering with bits of your car like that can be illegal
> depending on where you live.

Yes I saw that too, and while Mythbusters does do things the fun way,
they don't always test things the RIGHT way, and this is just another
case of where they are "wrong" (the other big one in my mind was the
frozen chicken through a plane or fast train window thing).

A British show I watch (I find I actually prefer British produced shows
these days, I think it's the accent) called "Fifth Gear" demonstrated a
product that absolutely interferes with Lidar to the point it's useless.
It was actually quite clever: it had a Lidar detector, once it detected
a Lidar beam it sounded a warning and shot it's IR laser to interfere
with the Lidar. The the second time it detects a Lidar beam it sounds an
alarm, but doesn't interfere. The theory is that you will slow down when
you hear the alarm the first time, and the second time the cop presses
the trigger the gun shows your true speed. The cop thinks the first time
was "just a glitch" and lets you go on your way.

Obviously such a device is quite illegal in most areas, but it's
definitely possible.

Again, all of this stuff is silly in my mind since the best way to
"defeat" these tools is to simply NOT speed. But I digress...

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

On Mon, 2005-01-24 at 17:39 -0500, Dave VanHorn wrote:
> >
> >In most areas it is illegal to purposely interfere with police speed
> >measuring devices. If you can come up with a completely legitimate and
> >believable reason that you needed IR LEDs on your plate you MAY get away
> >with it. OTOH you may not, and end up in BIG trouble.
>
> Optical garage door opener??

Yes, I've seen that "excuse" for it's purpose, fortunately I don't think
there is a judge out there that would fall for it. TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

At 05:44 PM 1/24/2005, Herbert Graf wrote:
>On Mon, 2005-01-24 at 17:39 -0500, Dave VanHorn wrote:
> > >
> > >In most areas it is illegal to purposely interfere with police speed
> > >measuring devices. If you can come up with a completely legitimate and
> > >believable reason that you needed IR LEDs on your plate you MAY get away
> > >with it. OTOH you may not, and end up in BIG trouble.
> >
> > Optical garage door opener??
>
>Yes, I've seen that "excuse" for it's purpose, fortunately I don't think
>there is a judge out there that would fall for it. TTYL

But if you really HAD such a unit.. :)

OTOH, I've never even been pulled over since disco was in.

----- Original Message -----
From: "Herbert Graf" <mailinglist2farcite.net>
To: "Microcontroller discussion list - Public." <piclistmit.edu>
Sent: Monday, January 24, 2005 9:14 PM

{Quote hidden}

> -----------------------------
> Herbert's PIC Stuff:
> http://repatch.dyndns.org:8383/pic_stuff/
>
> --
Richard Benfield <piclistmit.edu> quoted two dozen irrelevant lines
of text from three different authors without bothering to trim even
the email headers, then quoted these two lines from Herbert Graf and
wrote:

> > The best way to defeat radar/lidar is VERY simple: DON'T SPEED.
> > It's not that hard really.
>

... then quoted Herbert's signature, quoted the piclist footer,
quoted two of his own AVG "incoming" footers, then attached two AVG
"outgoing" footers.

Richard:

Perhaps you SHOULD take Herbert's advice.  I mean, if you drive as
poorly as you post...

-Andy

=== Andrew Warren - aiwcypress.com
===
=== Principal Design Engineer
=== Cypress Semiconductor Corporation

{Quote hidden}

Most definitely an urban legend!

Regards

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

>>> Reminds me of the story (Urban Legend, probably) about the Harrier
>>> that was doing a low-level training sortie over the Yorkshire
>>> Moors, and it's anti-radar missile system
>>> (HARM,

> Most definitely an urban legend!

I'd rate even the general story as most likely an urban legend, even
given my source.
But the Snopes debunking was far from perfect. They have drawn an
initial conclusion and then tried to heap as much half reasonable
technical argument on it as they can think of. I reasonably convinced,
but not by Snopes.

RM

Russell,

On Tue, 25 Jan 2005 22:24:15 +1300, Russell McMahon wrote:

> > Most definitely an urban legend!
>
> I'd rate even the general story as most likely an urban legend, even
> given my source.
> But the Snopes debunking was far from perfect. They have drawn an
> initial conclusion and then tried to heap as much half reasonable
> technical argument on it as they can think of. I reasonably convinced,
> but not by Snopes.

Indeed!  The version I heard (and repeated) was much more believable than theirs - I know it wouldn't have
been a Sidewinder, and the power/range of the radar gun would be too low to work out to sea, but would have
worked on the Moors where they do fly along the valleys below the level of roads along the ridges (I've seen
this - very impressive!).  And their "different types of RADAR" thing is just daft - most of the differences
they cite would not change the signal seen by an aircraft, but are differences in processing (Doppler takes
account of the change in reflected frequency, others just ignore it).  Who's to say whether the radiated
signal from a "hairdryer" looks like any type of ground-to-air system?  (I used to know someone who designed
airborne threat-detect systems so she *would* know, but I haven't seen her for years).  I'm not saying it's
true, just that Snopes debunking only works for their version of the story, and that other versions would get
past their reasoning.

Cheers,

Howard Winter
St.Albans, England

On Mon, 2005-01-24 at 21:31 +0000, Richard Benfield wrote:

> > I find this whole "issue" just silly. The best way to defeat radar/lidar
> > is VERY simple: DON'T SPEED. It's not that hard really.
> >
>

Pointlessness of your response aside, did you REALLY have to quote my
entire post, my sig, and four of those antivirus sigs just to spew TWO
words?

Consider this a warning. If you continue to waste others bandwidth like
this we will have to take action.

----- Original Message -----
To: "Microcontroller discussion list - Public." <piclistmit.edu>
Sent: Monday, January 24, 2005 5:50 PM

> > Reminds me of the story (Urban Legend, probably) about the Harrier
> > that was doing a low-level training sortie

> I would have thought it was urban legend too...

A friend of mine who is a radio amateur, was once using 10GHz and 24GHz
portable equipment in the scottish highlands and "had his collar felt" by
the RAF who were very interested in his DIY "enemy radar equipment", so I
think the story about the police radar and Harrier might well be true.

I don't know how much power the police radars use, but this guy would have
been using 10's of Watts.

Cheers...Mike.

--
Outgoing mail certified virus free.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.7.3 - Release Date: 24/01/2005

>-----Original Message-----
>From: piclist-bouncesmit.edu [piclist-bouncesmit.edu]
>Sent: 24 January 2005 21:14
>To: Microcontroller discussion list - Public.
>
>
>I find this whole "issue" just silly. The best way to defeat
>radar/lidar is VERY simple: DON'T SPEED. It's not that hard really.

The BEST way to avoid drivers breaking the law is to put sensible speed
limits on roads, and then use intelligent enforcing i.e. judge a
situation on the danger, not on wether speed is above or below some
arbirary number.  The current system is plainly ridiculous and does not
promote safe driving.

Regards

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

>
>Indeed!  The version I heard (and repeated) was much more believable than
>theirs - I know it wouldn't have been a Sidewinder,

Sidewinders seek on infrared, not RF.

It's also very unlikely that a HARM would be interested in an X or K band
CW source, especially one at such low power, even assuming that the gun was
pointed directly at the missile.

If so, that would be a very cheap way to defeat the HARM, just tie a cheap
gunn source onto a balloon. :)

On Tue, 2005-01-25 at 14:03 +0000, Michael Rigby-Jones wrote:
> >I find this whole "issue" just silly. The best way to defeat
> >radar/lidar is VERY simple: DON'T SPEED. It's not that hard really.
>
> The BEST way to avoid drivers breaking the law is to put sensible speed
> limits on roads, and then use intelligent enforcing i.e. judge a
> situation on the danger, not on wether speed is above or below some
> arbirary number.  The current system is plainly ridiculous and does not
> promote safe driving.

There's no doubt about that. In my area the speed limit is 100, despite
the fact that most of the roads in question were designed for 130.

That said, just because it's "unfair" or "unreasonable" that doesn't
give ANYONE the right to skirt the law. The law is the law. Get it
changed if you will, but until it's changed that's what it is.

I agree better enforcement is necessary, but that is too NO excuse for
breaking the law. TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

Herbert Graf wrote:

> On Tue, 2005-01-25 at 14:03 +0000, Michael Rigby-Jones wrote:
>
>>>I find this whole "issue" just silly. The best way to defeat
>>>radar/lidar is VERY simple: DON'T SPEED. It's not that hard really.
>>
>>The BEST way to avoid drivers breaking the law is to put sensible speed
>>limits on roads, and then use intelligent enforcing i.e. judge a
>>situation on the danger, not on wether speed is above or below some
>>arbirary number.  The current system is plainly ridiculous and does not
>>promote safe driving.

nab a drunk driver blowing by at 2x the speed limit.
It's entirely about revenue since you most often see it at the
bottom of hills, or in hidden past a hill on a freeway,
and almost never on  a residential street near a school,
where it might actually have an impact on safety.

> There's no doubt about that. In my area the speed limit is 100, despite
> the fact that most of the roads in question were designed for 130.
>
> That said, just because it's "unfair" or "unreasonable" that doesn't
> give ANYONE the right to skirt the law. The law is the law. Get it
> changed if you will, but until it's changed that's what it is.

Hence the expression 'the law is an a--'.
And remember it's a 'legal' system. NOT a 'justice' system.

> I agree better enforcement is necessary, but that is too NO excuse for
> breaking the law. TTYL

But how do you PROVE that you WERE NOT speeding, given that
there are many examples of how police radar/lidar makes
inaccurate measurements. 60 Minutes (US news show) did a
story a decade ago showing how a radar pointed out through the
front window was reading a stationary vehicle as doing 66MPH.
The speed changed as the A/C fan speed changed. There have been
similar stories about lidar and ornamentation on vehicles causing

R

On Mon, 24 Jan 2005, Herbert Graf wrote:

> In most areas it is illegal to purposely interfere with police speed
> measuring devices. If you can come up with a completely legitimate and
> believable reason that you needed IR LEDs on your plate you MAY get away
> with it. OTOH you may not, and end up in BIG trouble.

I was just trying to point out that every poison has its antidote. If
the powers that be are so interested in knowing whether someone drives
fast they can use the buried-in-the-road kind of sensor and cameras or
chip tags to much better effect. The wire loops that do the sensing can
be embedded in 1 hour per wire without stopping traffic (there is a
machine that cuts a slot and lays the sense cable in one go - the slot
is only 5mm wide).

> I find this whole "issue" just silly. The best way to defeat radar/lidar
> is VERY simple: DON'T SPEED. It's not that hard really.

I agree. But road humps are more efficient than radars, work in any
weather and cannot be tampered with. You don't argue with something that
whacks your suspension hard enough that you hear metal rending. Building
high quality roads suitable for high speed traffic from tax money and
then using more tax money to make people travel *slowly* on them is one
of those things I have trouble understanding for some reason.

Peter
On Tue, 2005-01-25 at 09:04 -0700, Robert Rolf wrote:
> But how do you PROVE that you WERE NOT speeding, given that
> there are many examples of how police radar/lidar makes
> inaccurate measurements. 60 Minutes (US news show) did a
> story a decade ago showing how a radar pointed out through the
> front window was reading a stationary vehicle as doing 66MPH.
> The speed changed as the A/C fan speed changed. There have been
> similar stories about lidar and ornamentation on vehicles causing

There is no doubt the machines aren't perfect, and in my area at least,
most speeding tickets, if challenged by someone who knows what they are
doing in court, are either brought down a peg or two or completely
thrown out (for reasons you have mentioned).

That said, there is no doubt that the machines DO work most of the time
very well.

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

>
>That said, there is no doubt that the machines DO work most of the time
>very well.

My local department bought a few of those K band speed boards that display

I decided to do some testing.

The target is a 1998 ford expedition, it certainly shouldn't have any
trouble seeing that, especially on such a long straight road, with no other
plausible targets in sight.

I just waited till a nice quiet time of night, and made speed runs
calibrating against my GPS.  At 40 MPH nominal, my displayed speed was
about 10 miles off, in both directions sometimes, and most times was at
least 3-5 miles off.

GPS guarantees 1MPH accuracy.

get the people around me to slow down to something approximating the speed
limit by tripping their radar detectors.

Harold

{Quote hidden}

--
FCC Rules Updated Daily at http://www.hallikainen.com
Did you account for the 'cosine' factor?
At long range the cosine error will be small.
As you pass right by the sign, the error will be significant
since the doppler reading will not be along the vector of your
motion.

sign is crap since the cosine error will always make you
look slower.

As as aside, I have found that my GPS speed and vehicle
speedometer were in close agreement above 80 km/hour, but
as slower speed the speedometer read proportionally high (5-10kph).
I wonder if this is deliberate in the firmware since it's an electronic
speedo (Chrysler Voyager, '93) so should have no non linearity.

R

Dave VanHorn wrote:
{Quote hidden}

Harold Hallikainen <piclistmit.edu> wrote:

> to get the people around me to slow down to something approximating the
> speed limit by tripping their radar detectors.

Wow.  Do you REALLY want people suddenly slamming on their brakes
all around you?  After all, mommies in minivans drive fast, too.  If
one of them is driving without a radar detector but is closely
following a Corvette that has one, aren't you putting her and her
passengers at risk by, as it were, activating the Corvette's brakes
by remote control?

Unless you plan to blanket an entire city with your jammers so radar
detectors are continuously being tripped, it would seem that your
plan will make the roads MORE dangerous... But maybe I'm missing
something.

-Andy

=== Andrew Warren - aiwcypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
=== (but open to offers)
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

Or, you could make a wooden silhouette of a police car and place it in
your front yard. On of the carpenters I know keeps a newspaper
clipping in his shop about a guy that did this. He says he used to sit
on his porch and watch people slam on their brakes as they came around
the corner and saw the silhouette. It wasn't even a really great
representation of a cop car...but it worked!

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.

On Tue, 25 Jan 2005 12:23:56 -0800, Andrew Warren <aiwcypress.com> wrote:
>     Wow.  Do you REALLY want people suddenly slamming on their brakes
>     all around you?  After all, mommies in minivans drive fast, too.  If
>     one of them is driving without a radar detector but is closely
>     following a Corvette that has one, aren't you putting her and her
>     passengers at risk by, as it were, activating the Corvette's brakes
>     by remote control?
At 03:11 PM 1/25/2005, Harold Hallikainen wrote:

>get the people around me to slow down to something approximating the speed
>limit by tripping their radar detectors.

Web search on "trolling for tail lights". :)

----- Original Message -----
From: "Dave VanHorn"
To: "Microcontroller discussion list - Public." <piclistmit.edu>
Sent: Tuesday, January 25, 2005 7:21 PM

> My local department bought a few of those K band speed boards that display
> your speed.... At 40 MPH nominal, my displayed speed was
> about 10 miles off, in both directions sometimes, and most times was at
> least 3-5 miles off.

I doubt that the boards that display your speed are very well calibrated
(certainly sounds not). The detectors which are used to get convictions are
calibrated, and to get a conviction, two independent methods of speed
measurement are neccesary, i.e. police man + radar gun, or detector + camera
taking two picures a certain time apart and lines on the road for distance
measurement. (This is in the UK anyway) I would imagine that if you
challenged this in court they would produce the certificates of calibration

Take care....Mike.

--
Outgoing mail certified virus free.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.7.4 - Release Date: 25/01/2005

At 03:22 PM 1/25/2005, Robert Rolf wrote:

>Did you account for the 'cosine' factor?
>At long range the cosine error will be small.
>As you pass right by the sign, the error will be significant
>since the doppler reading will not be along the vector of your
>motion.

edge, so you'd have to be right on top of it to become significant.

>sign is crap since the cosine error will always make you
>look slower.

It did, error seemed to be +/- about the same.

>As as aside, I have found that my GPS speed and vehicle
>speedometer were in close agreement above 80 km/hour, but
>as slower speed the speedometer read proportionally high (5-10kph).
>I wonder if this is deliberate in the firmware since it's an electronic
>speedo (Chrysler Voyager, '93) so should have no non linearity.

I've passed cops while sitting in cruise at 65.0 on the GPS, with the car
speedo reading almost 70.  My old explorer, in cold weather, would read
just about DOUBLE actual speed. Very non linear, at some threshold
temperature, the effect would just disappear.

>     Unless you plan to blanket an entire city with your jammers so radar
>     detectors are continuously being tripped, it would seem that your
>     plan will make the roads MORE dangerous... But maybe I'm missing
>     something.

This actually isn't too bad an idea- IR LEDs are cheap enough to make
constant false triggering of detectors render them almost useless.  Of
course, that might also make the actual speed sensing devices useless,
but hey, no plan is perfect!

The other problem is that it would be technically infeasible to do an
ENTIRE city, so most cities would settle for main roads, forcing the
speeders onto side streets through neighborhoods where their speeding
will likely kill kids rather than dent bumpers.  I like the idea of
passive sensors- be it magnetic sensors in the road or some kind of
photoelectric devices.  The first time someone gets home from a 200
mile road trip to discover 400 tickets in their mailbox, one from each
sensor embedded per mile in the road along the length of their trip,
would be the last time they exceeded the posted speed limit.

Mike H.
On Tue, 2005-01-25 at 14:21 -0500, Dave VanHorn wrote:
{Quote hidden}

Well, first off who's to say those devices are anywhere near as accurate
as the guns the police use as real evidence?

Second, I'd have to say you hit an anomaly, perhaps that unit was just
faulty. In the few times I've done something relatively similar (I have
a GPS installed in my car with a small display that tells me my speed
according to GPS, so testing those things is pretty easy for me to do!),
the speed board was off by at most 1 or 2 kph, sometimes hi, sometimes
low, but always very close. I also confirmed that my cars speedometer
was smack on.

I even tried getting out of the car and rollerblading, and even there it
was quite accurate (had a hand held GPS, a different unit then in the
car, with me at the time to confirm my speed). It's range certainly
wasn't as good as with a car, but I guess I was reflecting enough RF to

As I said before, the devices aren't perfect, but a cop isn't going to
believe his/her gun when he/she points it at you going a visual 20mph
and the gun reads 50mph. TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

> It's also very unlikely that a HARM would be interested in an X or K
> band CW source, especially one at such low power, even assuming that
> the gun was pointed directly at the missile.

> If so, that would be a very cheap way to defeat the HARM, just tie a
> cheap gunn source onto a balloon. :)

I understand that in Iraq people were indeed using low cost
antimissile measures which had to be programmed against once found.
Can't recall where I heard this alas.

RM

On Tue, 2005-01-25 at 12:11 -0800, Harold Hallikainen wrote:
> get the people around me to slow down to something approximating the speed
> limit by tripping their radar detectors.

Well, first off Radar and Lidar are two completely different things.

If you want their Lidar detectors to go off one device that tends to do
it well is those automatic door opener sensors at grocery store
entrances.

Other then that anything you send out that would trigger a Lidar
detector has the potential of interfering with a Lidar gun, so I'd
strongly suggest you find another safer way.

Beyond that, even if you DO figure out some way, I believe the sudden
braking most people do when their detectors go off will INCREASE the
number of incidents on your street...

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

At 03:23 PM 1/25/2005, Andrew Warren wrote:

>Harold Hallikainen <piclistmit.edu> wrote:
>
> > to get the people around me to slow down to something approximating the
> > speed limit by tripping their radar detectors.
>
>     Wow.  Do you REALLY want people suddenly slamming on their brakes
>     all around you?  After all, mommies in minivans drive fast, too.  If
>     one of them is driving without a radar detector but is closely
>     following a Corvette that has one, aren't you putting her and her
>     passengers at risk by, as it were, activating the Corvette's brakes
>     by remote control?

The folks that I've wanted to do this to, wouldn't have anyone tailgating
them, doing something like 50% over the limit or better, and weaving
traffic with many lane changes. Definitely a demonstration of the fact that
evolution is an imperfect process.

I have been known to light up my rear strobes for tailgaters. These are
professional strobes of the type that police and ambulances use, mounted in
the rear brake lights.
I have yellow tubes in the grille up front, but I don't use those unless
I'm "on duty" (in quotes, as I don't get PAID for it) or parked in a
hazardous place.

Normally I just slow down till they pass me, but some never seem to get the
hint.

>
>I doubt that the boards that display your speed are very well calibrated
>(certainly sounds not). The detectors which are used to get convictions are
>calibrated, and to get a conviction, two independent methods of speed
>measurement are neccesary, i.e. police man + radar gun, or detector + camera
>taking two picures a certain time apart and lines on the road for distance
>measurement. (This is in the UK anyway) I would imagine that if you
>challenged this in court they would produce the certificates of calibration

Well, if I had seen an offset, I'd agree, but what I saw was a large error
centered on my nominal speed.

This is why I'm so much in favour of the laser/lidar guns.
You know what target it's seeing, and it's not subject to nearly so much error.

>
>If you want their Lidar detectors to go off one device that tends to do
>it well is those automatic door opener sensors at grocery store
>entrances.

That's radar. A gunn diode doppler detector, operating in the K or X band.

>Other then that anything you send out that would trigger a Lidar
>detector has the potential of interfering with a Lidar gun, so I'd
>strongly suggest you find another safer way.

Doubtful, current designs use DSP and spread techniques to make sure they
are only seeing their own signal.  Try getting a false signal past a boxcar
integrator some time, without knowing exactly the commutation speed.

Since I'm looking at a mobile application, maybe I should just choose my
next car to look like a Highway Patrol car.

Harold

> Or, you could make a wooden silhouette of a police car and place it in
> your front yard. On of the carpenters I know keeps a newspaper
> clipping in his shop about a guy that did this. He says he used to sit
> on his porch and watch people slam on their brakes as they came around
> the corner and saw the silhouette. It wasn't even a really great
> representation of a cop car...but it worked!
>
> Josh

--
FCC Rules Updated Daily at http://www.hallikainen.com
At 04:08 PM 1/25/2005, Harold Hallikainen wrote:

>Since I'm looking at a mobile application, maybe I should just choose my
>next car to look like a Highway Patrol car.

That can be quit effective.
One of my friends bought a retired crown vic interceptor, and has various
VHF and UHF antennas on the trunk. Works well.

> ... but a cop isn't going to
> believe his/her gun when he/she points it at you going a visual
> 20mph
> and the gun reads 50mph.

Where can we get cops like that ? :-)

RM

> This was posted some time ago on http://www.pistonsheads.co.uk, a UK car
> forum.  The device in question is a Marksman LTI 2020, one of the most
> common speed guns in the UK.
>
> "There is a 905nm Infra red solid state laser module with deam
> divergence of approx 3mrad. It flashes 44 pulses of IR over a period of
> 0.3 seconds.

Any idea what the pulse width is?

THANKS!

Harold

--
FCC Rules Updated Daily at http://www.hallikainen.com
On Tue, 2005-01-25 at 19:03 +0200, Peter L. Peres wrote:
> I agree. But road humps are more efficient than radars, work in any
> weather and cannot be tampered with. You don't argue with something that
> whacks your suspension hard enough that you hear metal rending.

Which is exactly why I despise them. They can damage a car, even if that
car is going below the speed limit. Some of the designs can get
equipment, which ends up getting damaged. Trust me, the odd car going
5kph over the speed limit is far less dangerous then an unplowed road.

Beyond that there was a study recently in my area that showed speed
humps can add up to a minute or two to an emergency vehicles response
time. A minute or two might not sound like much, unless you're the one
suffering a heart attack.

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

On Tue, 2005-01-25 at 15:54 -0500, Dave VanHorn wrote:
> >
> >If you want their Lidar detectors to go off one device that tends to do
> >it well is those automatic door opener sensors at grocery store
> >entrances.
>
> That's radar. A gunn diode doppler detector, operating in the K or X band.

Nope. I recently saw an episode of Fifth Gear where they were testing
radar and lidar detectors, and one of the major gripes was the lidar
detector going off in front of certain grocery stores.

Most of the grocery stores in my area us IR (I've seen them opened).

> >Other then that anything you send out that would trigger a Lidar
> >detector has the potential of interfering with a Lidar gun, so I'd
> >strongly suggest you find another safer way.
>
> Doubtful, current designs use DSP and spread techniques to make sure they
> are only seeing their own signal.  Try getting a false signal past a boxcar
> integrator some time, without knowing exactly the commutation speed.

But that's the point: the signal LOOKS like it comes from a Lidar, which
is why Lidar detectors are triggered. Anything that sets off a Lidar
detector has the good potential, if strong enough, at interfering with a
Lidar gun.

Remember, it doesn't have to interfere 100% for you to be charged.
Intent is what counts, not reliability. TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

On Tue, 2005-01-25 at 15:31 -0500, Josh Koffman wrote:
> Or, you could make a wooden silhouette of a police car and place it in
> your front yard. On of the carpenters I know keeps a newspaper
> clipping in his shop about a guy that did this. He says he used to sit
> on his porch and watch people slam on their brakes as they came around
> the corner and saw the silhouette. It wasn't even a really great
> representation of a cop car...but it worked!

I saw one of those recently in Austria. It was a cut out of a cop. VERY
realistic, even when you get pretty close to it! But again, it tends to
cause people to slam on their brakes, so I don't believe it's a wise
solution. TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

>
>Nope. I recently saw an episode of Fifth Gear where they were testing
>radar and lidar detectors, and one of the major gripes was the lidar
>detector going off in front of certain grocery stores.
>
>Most of the grocery stores in my area us IR (I've seen them opened).

Passive IR won't set off a lidar detector.

>But that's the point: the signal LOOKS like it comes from a Lidar, which
>is why Lidar detectors are triggered. Anything that sets off a Lidar
>detector has the good potential, if strong enough, at interfering with a
>Lidar gun.

Primitive ones maybe. How likely is it for your video sender to interfere
with my cordless phone? They are both in the 2.4 GHz band.  Not at all,
since my cordless is direct sequence spread spectrum. I just don't "see"

On Tue, 2005-01-25 at 22:54 -0500, Dave VanHorn wrote:
> >
> >Nope. I recently saw an episode of Fifth Gear where they were testing
> >radar and lidar detectors, and one of the major gripes was the lidar
> >detector going off in front of certain grocery stores.
> >
> >Most of the grocery stores in my area us IR (I've seen them opened).
>
> Passive IR won't set off a lidar detector.

They are NOT passive IR, the ones I've seen have a set of transmitters
and a receiver. Why don't you just believe me on this? Do I have to take
one apart and take pictures??

{Quote hidden}

uses a laser diode. Laser diodes transmit a VERY narrow band of
frequencies. All you need is a transmitter on the same "frequency"
keying a certain pattern strongly enough to jam a Lidar gun. It's not
that hard to do actually, which is why the door sensors have been known
to set off the detectors.

Again, a Lidar detector is pretty much just the receiver half of a Lidar
gun, they are both "looking" for the same signal, so ANYTHING that sets
off a Lidar detector has a fair chance of interfering with a Lidar gun.
I don't know why this point is so hard to get across.

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

{Quote hidden}

Virtualy all the cheap detectors have radar and laser detection, and
virtualy all of them are useless.  Most are designed for the US market
and have X band radar detection which is set off by supermarket door
openers etc (X band is not used for speed guns in the UK).  The only
"laser only" detectors I know of are the ones combined with the GPS
speed camera locator such as the Road Angel and Origin B2.  Laser
detectors by themselves are virtualy 100% useless however, the only
chance a driver would have of detecting a speed gun before being clocked
is if the unit could pick up scatter from another vehicle being targeted
which is a remote chance at best.

Regards

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

>Well, if I had seen an offset, I'd agree, but what I saw was a large error
>centered on my nominal speed.

This would suggest to me that the processing of the information is being
done in a simplified way to allow more time to get the "smiley face" or
"frowning face" up on the board.

>detector + camera taking two picures a certain time apart and
>lines on the road for distance measurement. (This is in the UK anyway)

The UK is odd ball in this - in quite extensive travelling around the world
the UK is the only place I have come across this. Everywhere else one
picture on a calibrated camera is enough.

>Since I'm looking at a mobile application, maybe I should just choose my
>next car to look like a Highway Patrol car.

I remember getting a reasonable queue behind me one evening travelling on an
otherwise deserted motorway. I was wearing a windbreaker jacket that had
coloured stripes down the sleeve, which had the potential to look vaguely
like a hi-vis law enforcement officers jacket. This despite my driving a
little 1300cc Corolla station wagon.

I guy I knew was in the St Johns ambulance, and he drove a 1950's Austin
A30, and he always had a similar thing happen when he was wearing his
uniform while driving. This was just after NZ had introduced unmarked
traffic cars, and no-one knew what was being used by them.

> I agree. But road humps are more efficient than radars, work in any
> weather and cannot be tampered with.

Try telling that to the Oxford Council who had one dug up by a JCB after the
guy got fed up with having his house shaken to bits. He got prosecuted and
fined, but the national attention also got the council looking at
alternatives.

On Tue, 25 Jan 2005 22:20:41 -0500, Herbert Graf wrote:

> On Tue, 2005-01-25 at 19:03 +0200, Peter L. Peres wrote:
> > I agree. But road humps are more efficient than radars, work in any
> > weather and cannot be tampered with. You don't argue with something that
> > whacks your suspension hard enough that you hear metal rending.
>
> Which is exactly why I despise them. They can damage a car, even if that
> car is going below the speed limit.

Hear hear!  I have no problem with schemes that enforce the speed limit as it exists, but those such as speed
bumps ("sleeping policemen" as they are known here) introduce a lower limit, because I have yet to see one
that has no effect at 30mph but is undriveable at 31mph!  I have recently had to spend hundreds of pounds
replacing my car's exhaust because it scraped on some of them at *any* speed.  In fact it seemed to be better
to go faster over them because it seemed to "jump" the exhaust over them somewhat.

>...<

> Beyond that there was a study recently in my area that showed speed
> humps can add up to a minute or two to an emergency vehicles response
> time. A minute or two might not sound like much, unless you're the one
> suffering a heart attack.

Indeed - or if you're at an upper-floor window of a burning building, waiting to be rescued.  The emergency
services here say that a hump slows down a fire engine by 30 seconds, an ambulance by a minute, and some roads
here may have half-a-dozen humps, one after another.  People *have* died because the services arrived a minute
or two late.

Howard Winter
St.Albans, England

Herbert,

Just a small point...

On Wed, 26 Jan 2005 00:18:30 -0500, Herbert Graf wrote:

> Laser diodes transmit a VERY narrow band of
frequencies.

If it is a genuine laser, it's transmitting a *single*
frequency, I believe!  :-)

Cheers,

Howard Winter
St.Albans, England

On Wed, 26 Jan 2005 09:43:01 -0000, Alan B. Pearce wrote:

> >detector + camera taking two picures a certain time apart and
> >lines on the road for distance measurement. (This is in the UK anyway)
>
> The UK is odd ball in this - in quite extensive travelling around the world
> the UK is the only place I have come across this. Everywhere else one
> picture on a calibrated camera is enough.

Corroboration of evidence is a basic tenet of English law, and a policeman and his radar/lidar gun counts as
such, as does an unattended radar camera and the two photos of the vehicle crossing a measured set of lines on
the road.  It is different in Scotland, by the way, where a policeman on his own can estimate the speed and it
can be accepted without corroboration.

The thing is that calibrating the camera doesn't account for such things as a large flat-backed lorry, where
the signal can reflect from it onto traffic in the other direction, and then back again to the camera, giving
an apparent speed which is the sum of that of the lorry (in the photo) and the other traffic (not visible).
There was a case here recently where the driver challenged the accusation, and the pair of photos showed he
was doing 18mph, but the camera's radar said something like 55mph.  He was acquitted, of course.  The camera
wasn't out of calibration, but the reflected signal it detected wasn't "correct".

Cheers,

Howard Winter
St.Albans, England

> I guy I knew was in the St Johns ambulance, and he drove a 1950's
> Austin
> A30, and he always had a similar thing happen when he was wearing
> his
> uniform while driving. This was just after NZ had introduced
> unmarked
> traffic cars, and no-one knew what was being used by them.

Long ago a cop in Te Atatu DID drive an A30 as an unmarked car. Very
effective apparently.
Can't imagine how it got sanctioned ;-).

RM

>> Laser diodes transmit a VERY narrow band of
> frequencies.

> If it is a genuine laser, it's transmitting a *single*
> frequency, I believe!  :-)

What makes a LASER a LASER is not directly related to how many
frequencies it works on at once. LASERs can emit at a range of
frequencies and some do. Any given frequency band will usually be
narrow and stable. It is generally desirable that operation be
at a single frequency and even when more than one is present one
wavelength will usually predominate.

RM

>The thing is that calibrating the camera doesn't account for

>such things as a large flat-backed lorry, where the signal can

>reflect from it onto traffic in the other direction, and then

>back again to the camera, giving an apparent speed which is the

>sum of that of the lorry (in the photo) and the other traffic

>(not visible).  There was a case here recently where the driver

>challenged the accusation, and the pair of photos showed he was

>doing 18mph, but the camera's radar said something like 55mph.

>He was acquitted, of course.  The camera wasn't out of calibration,

>but the reflected signal it detected wasn't "correct".

This is the sort of thing that should never get to court in the first place.
In NZ any photo with more than one mobile vehicle in the picture is
disregarded, unless it is a camera system that has wire sensors in the road,
where the vehicle triggering the sensor can be specifically identified.

I always wondered how long it would take someone to notice that those
measurement markings had been painted over, and a new set with wider
spacings put down overnight. I was also intrigued with a picture I saw which
had a squirrel sitting in the middle of the road, and no vehicle in sight,
and the photo showed 40mph. It seems the squirrel moved its tail fast enough
to trigger the camera.

there are speed humps that are made of rubber
they are hollow with holes in them
if you hit them at or below the rated speed they deflate as your car drives
over them
hit them too fast and you get a bump.

alternatly you take the route my uni took and make speedhumps way to high
and narrow
then widen them (twice) so people can drive over them faster than a crawl.
(and presumablly reduce the wear on first gear, the clutch and brakes of the
uni busses) but wind up with the busses almost getting stuck on them

there was one speedhump i used to like, my cars suspension was harmonicly
tuned to it (thats my story and i'm sticking to it) hit it at exacly 50kph
and it was as smooth as a dirt road

> {Original Message removed}
> Indeed - or if you're at an upper-floor window of a burning
> building, waiting to be rescued.  The emergency
> services here say that a hump slows down a fire engine by 30
> seconds, an ambulance by a minute, and some roads
> here may have half-a-dozen humps, one after another.  People
> *have* died because the services arrived a minute
> or two late.

This is a known catch-22 for the road designers (my wife is sideways
involved in this kind of work). Include the bumps - loose lives because
the emergency vehicles have to slow down. Remove them - loose lives to
fatal traffic accidents. The only way out seems to be electronically
enforced speed limiting.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu

Alan,

On Wed, 26 Jan 2005 11:02:37 -0000, Alan B. Pearce wrote:

> This is the sort of thing that should never get to court in the first place.

I'm not sure it did - I think the Police sent him a copy of the photo when he challenged it, and he did the
calculations and told them that they'd got it wrong, at which point they dropped it.  But you're right in that
they police should have checked the photos' distance evidence, not just gone from the radar readout, but they
followed the line of loeast resistance!

> In NZ any photo with more than one mobile vehicle in the picture is
> disregarded, unless it is a camera system that has wire sensors in the road,
> where the vehicle triggering the sensor can be specifically identified.

But that's because in New Zealand it's rare to see two vehicles at once!  :-)))  (I couldn't believe how empty
the roads are on the South Island when I was there).  In the case I mentioned the opposing traffic wasn't
visible in the picture anyway because it had passed out of camera-shot, but in the UK seeing just a single
vehicle in one direction in a picture would be the exception rather than the rule.  And some cameras cover
three lanes of a road, each with its own measured stripes, staggered across the road.  (If you could change
lanes between the two photos (within a second?) you might defeat a camera's evidence but I wouldn't try it!)

Cheers,

Howard Winter
St.Albans, England

>there was one speedhump i used to like, my cars suspension was harmonicly
>tuned to it (thats my story and i'm sticking to it) hit it at exacly 50kph
>and it was as smooth as a dirt road

I find many speed humps are like that. People slow down to a speed where the
car gets tossed around, but at a suitable speed many of the narrow ones will
work at the suspension rate. Some authorities realise this this and make
them about a meter wide so that this does not happen.

> But that's because in New Zealand it's rare to see two vehicles at
> once!  :-)))

This is clearly a man who has never driven in Auckland 2 hours either
side of morning and evening rush hour. (It's approximately impossible
to do this)

>(I couldn't believe how empty
> the roads are on the South Island when I was there).

That's because of how fast the cars that are there drive ! :-)
Especially across the Canterbury Plaiiiiiiiiiiiiiiiiiiiins.

RM

>>(I couldn't believe how empty
>> the roads are on the South Island when I was there).

>That's because of how fast the cars that are there drive ! :-)
>Especially across the Canterbury Plaiiiiiiiiiiiiiiiiiiiins.

At one stage I worked for a while with a guy who was the son of the Czech
Ambassador to NZ. he enjoyed driving "Dads Car" at 100mph across the
Canterbury Plains. Couldn't find anywhere near home to get anything like
that fast, I guess he didn't drive in Germany much.

And I can vouch for driving in Auckland during the rush hour, having worked
there for about 15 years. You got very adept at keeping a gap in front of
you which was just small enough that the guy in the next lane decided it was
too small for him to do a lane change, but gave you enough room to not leave
black marks on the road if things stopped.

However it also gave me another amusing side issue. Driving across the
causeway from West Auckland to Point Chevalier, these was a guy who always
had at least half that straight in front of his car empty, as he drove so
slow. However on the occasions when the fog came in he had to drive closer
to the car in front, and hence faster, as he otherwise lost the tail lights
from visibility in the fog.

On Wed, 2005-01-26 at 10:21 +0000, Howard Winter wrote:
> Herbert,
>
> Just a small point...
>
> On Wed, 26 Jan 2005 00:18:30 -0500, Herbert Graf wrote:
>
> > Laser diodes transmit a VERY narrow band of
> frequencies.
>
> If it is a genuine laser, it's transmitting a *single*
> frequency, I believe!  :-)

True, but I wasn't certain whether practical semiconductor lasers where
that "good". :) TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

At 12:18 AM 1/26/2005, Herbert Graf wrote:

>On Tue, 2005-01-25 at 22:54 -0500, Dave VanHorn wrote:
> > >
> > >Nope. I recently saw an episode of Fifth Gear where they were testing
> > >radar and lidar detectors, and one of the major gripes was the lidar
> > >detector going off in front of certain grocery stores.
> > >
> > >Most of the grocery stores in my area us IR (I've seen them opened).
> >
> > Passive IR won't set off a lidar detector.
>
>They are NOT passive IR, the ones I've seen have a set of transmitters
>and a receiver. Why don't you just believe me on this? Do I have to take
>one apart and take pictures??

I can't say that I have NOT seen an active beam-break system used, but they
are rare.
Most common, is doppler microwave, followed by passive IR.

>uses a laser diode. Laser diodes transmit a VERY narrow band of
>frequencies. All you need is a transmitter on the same "frequency"
>keying a certain pattern strongly enough to jam a Lidar gun. It's not
>that hard to do actually, which is why the door sensors have been known
>to set off the detectors.

The keying pattern is where the spread spectrum is applied.
The detector is only open to saturation interference, which would take a
LOT of energy.

>Again, a Lidar detector is pretty much just the receiver half of a Lidar
>gun, they are both "looking" for the same signal, so ANYTHING that sets
>off a Lidar detector has a fair chance of interfering with a Lidar gun.
>I don't know why this point is so hard to get across.

This was true of the first designs, but not anymore.

At 04:40 AM 1/26/2005, Alan B. Pearce wrote:

> >Well, if I had seen an offset, I'd agree, but what I saw was a large error
> >centered on my nominal speed.
>
>This would suggest to me that the processing of the information is being
>done in a simplified way to allow more time to get the "smiley face" or
>"frowning face" up on the board.

>
>True, but I wasn't certain whether practical semiconductor lasers where
>that "good". :) TTYL

They are pretty narrow, but that doesn't really matter.
It's the modulation that's spread. The carrier osc in my cordless is also
"single frequency", but after the DS modulation is applied, it's a couple
MHz wide, and single frequency carriers, or my Wi-Fi or Video transmitters
in the same band don't bother it at all.

>>This would suggest to me that the processing of the information is being
>>done in a simplified way to allow more time to get the "smiley face" or
>>"frowning face" up on the board.

<VBG> I wondered if I might get a response like this. Ones that get used in
the UK come in two styles. Fixed ones at the entrance to a village or other
speed sensitive area, with a speed restriction sign that lights up if you
are exceeding the speed limit. Not sure what the sense mechanism is, but I
think it is a road loop rather than radar. There is no camera associated
with these.

The second stlye are portable ones which show a smiley face if you are below
the speed limit, but I cannot remember if they show a frowning face or
actual speed if you are above the limit. These are designed for local
councils to move around to remind people what the speed limit is, without
doing any actual enforcement by issuing tickets.

On Wed, 2005-01-26 at 14:03 +0000, Alan B. Pearce wrote:
> The second stlye are portable ones which show a smiley face if you are below
> the speed limit, but I cannot remember if they show a frowning face or
> actual speed if you are above the limit. These are designed for local
> councils to move around to remind people what the speed limit is, without
> doing any actual enforcement by issuing tickets.

Have never myself seen the "smiley" face one, but ours read your speed
continuously, and if your over the limit they start flashing the number.
I've seen similar ones in Austria. TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

Russell,

On Thu, 27 Jan 2005 00:50:43 +1300, Russell McMahon wrote:

> > But that's because in New Zealand it's rare to see two vehicles at
> > once!  :-)))
>
> This is clearly a man who has never driven in Auckland 2 hours either
> side of morning and evening rush hour. (It's approximately impossible
> to do this)

Indeed - my experince of Auckland amounts to an afternoon wandering around the waterfront, killing 4 hours until a connecting flight.

> >(I couldn't believe how empty
> > the roads are on the South Island when I was there).
>
> That's because of how fast the cars that are there drive ! :-)
> Especially across the Canterbury Plaiiiiiiiiiiiiiiiiiiiins.

Well they can't drive *that* fast because the police have always-running radar sets mounted in the car, firing through the windscreen.  How do I know this?  :-(  I got my second-ever speeding ticket there!  It was on the West Coast on a dead straight, empty road, but which had up-and-down humps.  I was the only car I could see, and was batting along at what felt like a reasonable speed, when a mounting holding a set of lights rose above the hump ahead.  I lifted off, but it was too late - those pretty coloured lights came on and the car below them and I stopped for a chat.  129km/h in the (country-wide) 100k limit = NZ\$240 fine (about UK£80, US\$120 at the time).  I was impressed by the fact that the fine is prescribed - he looked it up on a speed/fine table and I would have had another \$60 to pay if I'd been another 1km faster (probably lifting off did that much :-)  I was also impressed that the speeding ticket has a paying-in slip attached to the bottom - just stroll into any bank and hand it over with the cash and the fine's paid - neat!  And of course being a grockle I didn't get my licence endorsed...  After that I set the GPS's speed warning to 100k and it's amazing how often it triggered when I didn't realise I was letting the speed creep up.  I'm just not used to empty, fast-capable roads and it's really easy to go faster than you realise in that situation.

Cheers,

Howard Winter
St.Albans, England

Similar system here in Ireland.

Joe

-----Original Message-----
From: piclist-bouncesmit.edu [piclist-bouncesmit.edu] On Behalf Of
Alan B. Pearce
Sent: 26 January 2005 09:43
To: Microcontroller discussion list - Public.

>detector + camera taking two picures a certain time apart and lines on
>the road for distance measurement. (This is in the UK anyway)

The UK is odd ball in this - in quite extensive travelling around the world
the UK is the only place I have come across this. Everywhere else one
picture on a calibrated camera is enough.

Alan,

On Wed, 26 Jan 2005 14:03:25 -0000, Alan B. Pearce wrote:

> Ones that get used in
> the UK come in two styles. Fixed ones at the entrance to a village or other
> speed sensitive area, with a speed restriction sign that lights up if you
> are exceeding the speed limit. Not sure what the sense mechanism is, but I
> think it is a road loop rather than radar. There is no camera associated
> with these.

Most of the "village" ones I've seen have a little radar unit on top - it's painted black so it's not easy to
see.  They light up a "sign" image (red triangular frame) showing the speed limit with orange flashers to get
attention.  The exception I know of is near Hatfield, just past the start of a 50mph limit that leads to a
dogs-bone shaped roundabout.  That one has road-loops and says "Slow Down" with no "sign" image.  I take it as
a matter of pride not to trigger these!

> The second stlye are portable ones which show a smiley face if you are below
> the speed limit, but I cannot remember if they show a frowning face or
> actual speed if you are above the limit. These are designed for local
> councils to move around to remind people what the speed limit is, without
> doing any actual enforcement by issuing tickets.

Never seen these at all, although I have seen a GATSO speed camera mounted on a trailer for portable
speed-nabbing.  They still have to paint the lines on the road though...  (I've seen these with a sign saying
"Traffic Control Monitor" on them - who are they kidding? :-)

Cheers,

Howard Winter
St.Albans, England

Dave,

On Wed, 26 Jan 2005 08:33:41 -0500, Dave VanHorn wrote:

> At 04:40 AM 1/26/2005, Alan B. Pearce wrote:
>
>...<
> >This would suggest to me that the processing of the information is being
> >done in a simplified way to allow more time to get the "smiley face" or
> >"frowning face" up on the board.
>

None of the UK devices like this tell you your speed - I believe it's thought that people will try to use it
to calibrate their speedo's, or worse still lead to youths driving up and down trying to get Fastest Time of
the Day!

Cheers,

Howard Winter
St.Albans, England

Here in a suburb of Buffalo, New York, USA ours do indeed show your speed
when you are over the limit. The change to flashing orange too.

Bob Ammerman
RAm Systems

{Original Message removed}

{Quote hidden}

Actually there are devices like this in the UK that flash up the speed,
there was one quite close to my house for a few weeks.  However, you are
of course correct, it's simply seen as a challenge for the testosterone
fueled teenagers in their bodykitted Novas/Corsas/Saxos etc.

Regards

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

On Tue, 25 Jan 2005, Dave VanHorn wrote:

>> Nope. I recently saw an episode of Fifth Gear where they were testing
>> radar and lidar detectors, and one of the major gripes was the lidar
>> detector going off in front of certain grocery stores.
>>
>> Most of the grocery stores in my area us IR (I've seen them opened).
>
> Passive IR won't set off a lidar detector.

They are not passive. The radar type openers have a poor record in
certain areas and the ir type is less expensive to make so ...

f.ex. most single-sensor radar door openers refuse to open the door if
you approach it from the side and close enough, if they are adjusted to
open it right if someone approaches straight from front. I tend to walk
fast and I have to wave my hand in front of me (or above me) to get the
doors opening in time even head on. The active ir type is not so
affected by these problems (it does not rely on object motion and it has
a lens that fixes the can't-see-near-the-door problem). Also many
passive (PIR) ir sensors for door openers have reduced range for people
coming in from the cold wearing suitable clothing.

>> But that's the point: the signal LOOKS like it comes from a Lidar, which
>> is why Lidar detectors are triggered. Anything that sets off a Lidar
>> detector has the good potential, if strong enough, at interfering with a
>> Lidar gun.
>
> Primitive ones maybe. How likely is it for your video sender to interfere
> with my cordless phone? They are both in the 2.4 GHz band.  Not at all, since
> my cordless is direct sequence spread spectrum. I just don't "see" your
> signal.

You don't want to know. Phones, microwaves and 802.11 gear all share the
same band. You have white bands on your video link ? Just wait until the
802.11 retrains and leaves you alone (since you are jamming it too

Peter

On Wed, 26 Jan 2005, Howard Winter wrote:

> The thing is that calibrating the camera doesn't account for such
> things as a large flat-backed lorry, where the signal can reflect from
> it onto traffic in the other direction, and then back again to the
> camera, giving an apparent speed which is the sum of that of the lorry
> (in the photo) and the other traffic (not visible). There was a case
> here recently where the driver challenged the accusation, and the pair
> of photos showed he was doing 18mph, but the camera's radar said
> something like 55mph.  He was acquitted, of course.  The camera wasn't
> out of calibration, but the reflected signal it detected wasn't
> "correct".

And now you know how the basic delay line jammer works ...

Peter
>
>>The second stlye are portable ones which show a smiley face if you are below
>>the speed limit, but I cannot remember if they show a frowning face or
>>actual speed if you are above the limit. These are designed for local
>>councils to move around to remind people what the speed limit is, without
>>doing any actual enforcement by issuing tickets.
>
>
> Never seen these at all, although I have seen a GATSO speed camera mounted on a trailer for portable
> speed-nabbing.  They still have to paint the lines on the road though...  (I've seen these with a sign saying
> "Traffic Control Monitor" on them - who are they kidding? :-)

Well, they ARE monitoring traffic, and issuing speeding tickets
if you're driving too fast.

Around here they have taken to putting them into portable
boxes that look exactly like roadside pedestals that
are used to distribute power/cable/telco to homes.
Because they are so portable they have to have a cop
in an unmarked car sitting nearby to prevent their
being carted off by passers by.

I also find it amusing that the police service was
average overspeed to drop by 20km/hr (the camera keeps
stats on all vehicles). They seem to think we're
stupid. The real reason average overspeed dropped is that
drivers slow right down when they spot the not so
innocuous roadside vehicle with the camera, and then
speed right up once safely past it.

The way I see it, if I'm paying enough attention to
the road to spot their cameras in time to slow down,
I'm driving at a speed 'consistent with road conditions'.
Around here you can even get a ticket for driving below the
posted limit if the roads are slippery enough.
Good thing, considering the number of SUVs we
see on TV news wrapped around light poles after a
night of freezing rain.

R

On Wed, 26 Jan 2005, Wouter van Ooijen wrote:

{Quote hidden}

You *could* mandate emergency vehicles to have the suspension tuned in
a certain way. It could be done by any competent garage imho.

Peter

{Quote hidden}

No you could not.  To get the kind of suspenion travel required to drive
over these useless things at speed would require the vehicle to be
raised significantly.  That is really going to hurt handling and general
stability.  Also most garages are happy with fitting standard
replacement parts.  Ask them to do something significantly out of the
ordinary and they'll either refuse or make a pigs breakfast of the job.

The simple answer is the remove the stupid things, they have many more
negative attributes than positive ones.

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

On Wed, 26 Jan 2005, Dave VanHorn wrote:

> I can't say that I have NOT seen an active beam-break system used, but
> they are rare. Most common, is doppler microwave, followed by passive
> IR.

It's not beam-break, it's reflective. Send modulated IR, receive same
(using sensor in the same box usually). If the reflectivity of the
target changes significantly (either way!) for a certain amount of time
open the door.

Peter
At 12:18 PM 1/26/2005, Peter L. Peres wrote:

{Quote hidden}

The few places that have them here, seem to have no problems year round.
One easy way to tell, the PIRs usually have a white plastic "face" and
active IR is usually "black", which is IR transparent.
But both of those are in the small minority compared to 10/24 GHz doppler
units around here, which often have a white face, and look a lot like a PIR
unt.

>You don't want to know. Phones, microwaves and 802.11 gear all share the
>same band.

And hams, at up to 1500W, ask me how I know :)

>  You have white bands on your video link ? Just wait until the 802.11
> retrains and leaves you alone (since you are jamming it too with the

802 interferes with the video link, but neither those, or my ham gear,
bother the phone, since it's DS Spread.
That's why I bought that model.

How on earth did he manage to catch up with anything to pull it over?
(Speaking as an ex owner of an A30)

RP

Long ago a cop in Te Atatu DID drive an A30 as an unmarked car. Very
effective apparently.
Can't imagine how it got sanctioned ;-).

RM

It's amazing where you can fit a V-8 these days.  ;-)

Richard.Prosserpowerware.com wrote:

{Quote hidden}

>Around here they have taken to putting them into portable
>boxes that look exactly like roadside pedestals that
>are used to distribute power/cable/telco to homes.
>Because they are so portable they have to have a cop
>in an unmarked car sitting nearby to prevent their
>being carted off by passers by.

So they have not yet cottoned on the NZ trick of having it in the back of an
estate car. They used to have the back open when operating, but now they
just shoot through the rear window, and during daylight don't even use the
flash anymore.

Alan,

On Thu, 27 Jan 2005 09:00:50 -0000, Alan B. Pearce wrote:

>...<
> So they have not yet cottoned on the NZ trick of having it in the back of an
> estate car. They used to have the back open when operating, but now they
> just shoot through the rear window, and during daylight don't even use the
> flash anymore.

I was driving in the wilds of the South Island about three years ago (almost deserted roads, of course) and a
car coming the other way flashed his headlights.  I watched my speed carefully for a while, and then about
four and a half miles later, at the bottom of a hill, was the camera in the back of an estate car (rear door
open).  Now that's *really* sneaky, placing it where you've (perhaps unwittingly) accelerated down the hill!

Cheers,

Howard Winter
St.Albans, England

Or at the bottom of a valley between 2 hills - so that you can't maximise
your momentum to get up the next slope!

RP
(Who drives the "deserted" South Island roads on a daily basis).

Alan,

I was driving in the wilds of the South Island about three years ago
(almost deserted roads, of course) and a
car coming the other way flashed his headlights.  I watched my speed
carefully for a while, and then about
four and a half miles later, at the bottom of a hill, was the camera in the
back of an estate car (rear door
open).  Now that's *really* sneaky, placing it where you've (perhaps
unwittingly) accelerated down the hill!

Cheers,

Howard Winter
St.Albans, England

> I was driving in the wilds of the South Island about three years ago
> (almost deserted roads, of course) and a car coming the other way
> flashed his headlights.  I watched my speed carefully for a while, and
> then about four and a half miles later, at the bottom of a hill, was the
> camera in the back of an estate car (rear door open).  Now that's
> *really* sneaky, placing it where you've (perhaps unwittingly)
> accelerated down the hill!

A complaint to the NZ police was rejected last year about a
cop hiding in the median strip shubbery with a camera. No, no,
he's not hiding, they said, he's "covert". They are determined to
keep milking that cash cow (even though Bossy hardly affects
the accident rate)

But don't get me started about hiding in the shrubbery with a
camera - "I dinna say anything because in this country it makes
ya look like a pervert, but every single Scottish person does it" ;-)

More... (looser matching)
- Last day of these posts
- In 2005 , 2006 only
- Today
- New search...