A secondary -but planned!- use for the speed-detecting radar signal?

We all know the primary use of a speed-detecting radar signal used by
law enforcement. The signal is bounced off vehicles in order to
measure their speed. I believe, however, that here are, a few other
(intended?, unintended? bug? feature?) by-products of such signals.

- When I drive near any mall, the signal to detect customers and open
the store doors automatically triggers a false positive in my radar
detector.

- When an ambulance is running, there is also a detectable signal
going on.

- In some toll booths the signal is also present, even though there
are no cops or anything related nearby (there is no need for the speed-
measuring aspect).

Therefore, I speculate that perhaps there is an intended use by the
radar designers. When the ambulances are running in emergency mode,
the signal is a way to tell drivers to move away, to slow down, etc.
BUT (and this is the key issue) the ambulance has no way to detect the
speed of anybody. Some friends of mine claim -with no evidence
whatsoever- that ambulances have a signal to turn on green lights
along their route and this signal "happens" (just by sheer
coincidence) to be in the same band as the speed-detecting radar
signals.

Frankly, I find that very hard to believe. The mall door are perhaps a
coincidence (are they, really?), but the design of a remote street
light changer (with all the dangers that an unexpected asynchronous
light change implies) which by error just happens to be the same
frequency!? Come on!

I claim that the whole thing is planned: I remember reading in the
Boston news that a guy fell asleep and crashed into a toll booth,
killing the attendant. Don't know the details, but such sad accidents
could be prevented by having a radar detector triggering (NOT
measuring I insist) to turn on the beeper in the sleeping guys' car.

Any comments, informed guesses?

-Ramon

ps: which ones would be some pertinent NGs to post this?

"Ramon F Herrera" > wrote in
oups.com:

>
> We all know the primary use of a speed-detecting radar signal used by
> law enforcement. The signal is bounced off vehicles in order to
> measure their speed. I believe, however, that here are, a few other
> (intended?, unintended? bug? feature?) by-products of such signals.
>
> - When I drive near any mall, the signal to detect customers and open
> the store doors automatically triggers a false positive in my radar
> detector.

Those door openers are radar tranceivers just like in a radar gun,same
operating band,too. Gunn oscillators.


>
> - When an ambulance is running, there is also a detectable signal
> going on.
>

Ambulances have a low power xmtr installed so that cars with RDs would be
alerted to their approach.IIRC,the Road Rangers(emergency breakdown
service) also have them.They don't measure speed,just send a signal.

> - In some toll booths the signal is also present, even though there
> are no cops or anything related nearby (there is no need for the speed-
> measuring aspect).

such toll booths often have speed measuring cameras to give you a ticket
for exceeding the toll plaza SL.
>
> Therefore, I speculate that perhaps there is an intended use by the
> radar designers. When the ambulances are running in emergency mode,
> the signal is a way to tell drivers to move away, to slow down, etc.
> BUT (and this is the key issue) the ambulance has no way to detect the
> speed of anybody.

No. all the RD responds to is a radar signal in the appropriate band,it
could be a door opener,a "code practice oscillator"(an item sold for sloths
to set off speeders RDs,now illegal.The signal need not be "measuring
speed.)

> Some friends of mine claim -with no evidence
> whatsoever- that ambulances have a signal to turn on green lights
> along their route and this signal "happens" (just by sheer
> coincidence) to be in the same band as the speed-detecting radar
> signals.

No,that light changing is done by IR flashing of the emergency lights on
the ambulance or police cruiser. Gated apt. complexes have them too,so fire
and EMT vehicles can enter without knowing the gate code or needing a key.
Mine does,so does the complex next door.
(Google "MIRT")
>
> Frankly, I find that very hard to believe. The mall door are perhaps a
> coincidence (are they, really?), but the design of a remote street
> light changer (with all the dangers that an unexpected asynchronous
> light change implies) which by error just happens to be the same
> frequency!? Come on!

The door openers operate by monitoring the reflected signal level;once it
reaches some level,the door is opened.There are handheld LED devices sold
online that change traffic signals from a distance;it's now a Federal crime
to possess them in a motor vehicle,and most states also have their own laws
on that.
>
> I claim that the whole thing is planned:

You are wrong.

> I remember reading in the
> Boston news that a guy fell asleep and crashed into a toll booth,
> killing the attendant. Don't know the details, but such sad accidents
> could be prevented by having a radar detector triggering (NOT
> measuring I insist) to turn on the beeper in the sleeping guys' car.
>
> Any comments, informed guesses?
>
> -Ramon
>
> ps: which ones would be some pertinent NGs to post this?
>
>



--
Jim Yanik
jyanik
at
kua.net

On Mar 26, 6:27 pm, Jim Yanik > wrote:
> "Ramon F Herrera" > wrote groups.com:
>
>
>
> > We all know the primary use of a speed-detecting radar signal used by
> > law enforcement. The signal is bounced off vehicles in order to
> > measure their speed. I believe, however, that here are, a few other
> > (intended?, unintended? bug? feature?) by-products of such signals.
>
> > - When I drive near any mall, the signal to detect customers and open
> > the store doors automatically triggers a false positive in my radar
> > detector.
>
> Those door openers are radar tranceivers just like in a radar gun,same
> operating band,too. Gunn oscillators.
>
>
>
> > - When an ambulance is running, there is also a detectable signal
> > going on.
>
> Ambulances have a low power xmtr installed so that cars with RDs would be
> alerted to their approach.IIRC,the Road Rangers(emergency breakdown
> service) also have them.They don't measure speed,just send a signal.
>
> > - In some toll booths the signal is also present, even though there
> > are no cops or anything related nearby (there is no need for the speed-
> > measuring aspect).
>
> such toll booths often have speed measuring cameras to give you a ticket
> for exceeding the toll plaza SL.
>
>
>
> > Therefore, I speculate that perhaps there is an intended use by the
> > radar designers. When the ambulances are running in emergency mode,
> > the signal is a way to tell drivers to move away, to slow down, etc.
> > BUT (and this is the key issue) the ambulance has no way to detect the
> > speed of anybody.
>
> No. all the RD responds to is a radar signal in the appropriate band,it
> could be a door opener,a "code practice oscillator"(an item sold for sloths
> to set off speeders RDs,now illegal.The signal need not be "measuring
> speed.)
>
> > Some friends of mine claim -with no evidence
> > whatsoever- that ambulances have a signal to turn on green lights
> > along their route and this signal "happens" (just by sheer
> > coincidence) to be in the same band as the speed-detecting radar
> > signals.
>
> No,that light changing is done by IR flashing of the emergency lights on
> the ambulance or police cruiser. Gated apt. complexes have them too,so fire
> and EMT vehicles can enter without knowing the gate code or needing a key.
> Mine does,so does the complex next door.
> (Google "MIRT")
>
>
>
> > Frankly, I find that very hard to believe. The mall door are perhaps a
> > coincidence (are they, really?), but the design of a remote street
> > light changer (with all the dangers that an unexpected asynchronous
> > light change implies) which by error just happens to be the same
> > frequency!? Come on!
>
> The door openers operate by monitoring the reflected signal level;once it
> reaches some level,the door is opened.There are handheld LED devices sold
> online that change traffic signals from a distance;it's now a Federal crime
> to possess them in a motor vehicle,and most states also have their own laws
> on that.
>
>
>
> > I claim that the whole thing is planned:
>
> You are wrong.
>

No, you are the one who wrongly interpreted what I wrote, Jim.

I still claim that there is a plan. There are authorities -such as the
FCC- which assign frequencies and make thorough studies to make sure
that a signal does not affect some other application. That's what I am
talking about.

The fact that the emergency vehicles carry a device which triggers RDs
is a planned feature. The fabrication of those devices is planned. It
is not like my buddies claimed that it was just an accidental (i.e.
not planned) feature. The issues at hand are not like the Captain
Crunch whistle which happened to emit a 2600 Hz tone that allowed toll
free calls: that was NOT planned by AT&T or the whistle manufacturer.

Having said that, I claim ignorance on the mall doors. But an
ambulance or toll booth triggering my RD is not a random act of
natu i.e.: it was planned.

-Ramon

On Mar 26, 8:17 pm, "Ramon F Herrera" > wrote:
> On Mar 26, 6:27 pm, Jim Yanik > wrote:
>
>
>
>
>
> > "Ramon F Herrera" > wrote groups.com:
>
> > > We all know the primary use of a speed-detecting radar signal used by
> > > law enforcement. The signal is bounced off vehicles in order to
> > > measure their speed. I believe, however, that here are, a few other
> > > (intended?, unintended? bug? feature?) by-products of such signals.
>
> > > - When I drive near any mall, the signal to detect customers and open
> > > the store doors automatically triggers a false positive in my radar
> > > detector.
>
> > Those door openers are radar tranceivers just like in a radar gun,same
> > operating band,too. Gunn oscillators.
>
> > > - When an ambulance is running, there is also a detectable signal
> > > going on.
>
> > Ambulances have a low power xmtr installed so that cars with RDs would be
> > alerted to their approach.IIRC,the Road Rangers(emergency breakdown
> > service) also have them.They don't measure speed,just send a signal.
>
> > > - In some toll booths the signal is also present, even though there
> > > are no cops or anything related nearby (there is no need for the speed-
> > > measuring aspect).
>
> > such toll booths often have speed measuring cameras to give you a ticket
> > for exceeding the toll plaza SL.
>
> > > Therefore, I speculate that perhaps there is an intended use by the
> > > radar designers. When the ambulances are running in emergency mode,
> > > the signal is a way to tell drivers to move away, to slow down, etc.
> > > BUT (and this is the key issue) the ambulance has no way to detect the
> > > speed of anybody.
>
> > No. all the RD responds to is a radar signal in the appropriate band,it
> > could be a door opener,a "code practice oscillator"(an item sold for sloths
> > to set off speeders RDs,now illegal.The signal need not be "measuring
> > speed.)
>
> > > Some friends of mine claim -with no evidence
> > > whatsoever- that ambulances have a signal to turn on green lights
> > > along their route and this signal "happens" (just by sheer
> > > coincidence) to be in the same band as the speed-detecting radar
> > > signals.
>
> > No,that light changing is done by IR flashing of the emergency lights on
> > the ambulance or police cruiser. Gated apt. complexes have them too,so fire
> > and EMT vehicles can enter without knowing the gate code or needing a key.
> > Mine does,so does the complex next door.
> > (Google "MIRT")
>
> > > Frankly, I find that very hard to believe. The mall door are perhaps a
> > > coincidence (are they, really?), but the design of a remote street
> > > light changer (with all the dangers that an unexpected asynchronous
> > > light change implies) which by error just happens to be the same
> > > frequency!? Come on!
>
> > The door openers operate by monitoring the reflected signal level;once it
> > reaches some level,the door is opened.There are handheld LED devices sold
> > online that change traffic signals from a distance;it's now a Federal crime
> > to possess them in a motor vehicle,and most states also have their own laws
> > on that.
>
> > > I claim that the whole thing is planned:
>
> > You are wrong.
>
> No, you are the one who wrongly interpreted what I wrote, Jim.
>
> I still claim that there is a plan. There are authorities -such as the
> FCC- which assign frequencies and make thorough studies to make sure
> that a signal does not affect some other application. That's what I am
> talking about.
>
> The fact that the emergency vehicles carry a device which triggers RDs
> is a planned feature. The fabrication of those devices is planned. It
> is not like my buddies claimed that it was just an accidental (i.e.
> not planned) feature. The issues at hand are not like the Captain
> Crunch whistle which happened to emit a 2600 Hz tone that allowed toll
> free calls: that was NOT planned by AT&T or the whistle manufacturer.
>
> Having said that, I claim ignorance on the mall doors. But an
> ambulance or toll booth triggering my RD is not a random act of
> natu i.e.: it was planned.
>

There's only so much RF spectrum to go around, that's all.

Your radar detector just picks up a signal, ANY signal, on a specific
frequency. But it doesn't analyze that signal to see if it's a radar
signal, or toll booth, or mall doors.

It's like IR. IR is a specific frequency, but you can operate your
TV, VCR, cable box, etc without interfering w/ each other. But if you
put an IR detector among any of those devices, it would go off.

> - When I drive near any mall, the signal to detect customers and open
> the store doors automatically triggers a false positive in my radar
> detector.
>
> - When an ambulance is running, there is also a detectable signal
> going on.
>
> - In some toll booths the signal is also present, even though there
> are no cops or anything related nearby (there is no need for the speed-
> measuring aspect).

> I claim that the whole thing is planned

Wouldn't a simpler explaination be that its an unlicensed spectrum which
is well suited to use for radar?

Door sensors use radar to detect people, I don't know about ambulances but
I can think of a couple of reasons they might want to be able to detect
obsticals, at the airport near here we have little cameras setup to record
number plates as cars are leaving, your toll booths could have a similar
system in place connected to a motion sensor.

I can't see the benefit of installing hundreds of thousands of dollars
worth of radar gear just for the benefit of the minority who have radar
detectors. Especially when the people with the radar detectors obviously
haven't been told about it so their first instinct is to look for cameras
drawing attention away from ambulances, toll booths, etc.

-- Michael Heydon

On Mon, 26 Mar 2007 15:21:17 -0700, Ramon F Herrera wrote:
....
> Therefore, I speculate that perhaps there is an intended use by the
> radar designers. When the ambulances are running in emergency mode,
> the signal is a way to tell drivers to move away, to slow down, etc.
....

That's done with a strobe light, that flashes at a certain rate. Radar
has nothing to do with it.

Cheers!
Rich

On Mar 26, 8:53 pm, Rich Grise > wrote:
> On Mon, 26 Mar 2007 15:21:17 -0700, Ramon F Herrera wrote:
>
> ...> Therefore, I speculate that perhaps there is an intended use by the
> > radar designers. When the ambulances are running in emergency mode,
> > the signal is a way to tell drivers to move away, to slow down, etc.
>
> ...
>
> That's done with a strobe light, that flashes at a certain rate. Radar
> has nothing to do with it.
>
> Cheers!
> Rich


I should have explained (I thought it was obvious) that when a nearby
ambulance is in emergency mode, my radar detector goes crazy. As the
ambulance goes away, the beeping of my RD slows down.

I find rather doubtful that my RD has an optical strobe light
detector. When it boots up, it clearly displays: X-Band, K-Band and
Laser. All 3 are electromagnetic radiations, but they are very far
from the strobe used by ambulances and the infrared used by street
light preempting devices.

A reader in another newsgroup confirmed my suspicion: the emergency
vehicles indeed carry a low level radar transmitter *only* whose
specific purpose is to turn on your RD, and cannot measure (or care)
about your speed. It is the high tech way of saying "out of my way!".
That device is cheap enough, specially when balanced against human
lives and property they save, Michael Heydon.

-Ramon

On Mar 26, 8:53 pm, Rich Grise > wrote:
> On Mon, 26 Mar 2007 15:21:17 -0700, Ramon F Herrera wrote:
>
> ...> Therefore, I speculate that perhaps there is an intended use by the
> > radar designers. When the ambulances are running in emergency mode,
> > the signal is a way to tell drivers to move away, to slow down, etc.
>
> ...
>
> That's done with a strobe light, that flashes at a certain rate. Radar
> has nothing to do with it.
>
> Cheers!
> Rich


Now I understand your point. Are you saying that what is detected is
the low frequency (as it can be counted by a human being) rate, as
opposed to a certain modulated frequency, like the ones used to
distinguish a VCR remote control from a TV remote control?

What about day vs. night, obstacles, fog, etc?

If I can afford a *precise* infrared remote control made by Sony
($9.95 at Radio Shack) the police and fire departments in a life
critical jobs, certainly can.

-Ramon

On Mar 26, 10:32 pm, "Ramon F Herrera" > wrote:
> On Mar 26, 8:53 pm, Rich Grise > wrote:
>
> > On Mon, 26 Mar 2007 15:21:17 -0700, Ramon F Herrera wrote:
>
> > ...> Therefore, I speculate that perhaps there is an intended use by the
> > > radar designers. When the ambulances are running in emergency mode,
> > > the signal is a way to tell drivers to move away, to slow down, etc.
>
> > ...
>
> > That's done with a strobe light, that flashes at a certain rate. Radar
> > has nothing to do with it.
>
> > Cheers!
> > Rich
>
> Now I understand your point. Are you saying that what is detected is
> the low frequency (as it can be counted by a human being) rate, as
> opposed to a certain modulated frequency, like the ones used to
> distinguish a VCR remote control from a TV remote control?
>
> What about day vs. night, obstacles, fog, etc?
>
> If I can afford a *precise* infrared remote control made by Sony
> ($9.95 at Radio Shack) the police and fire departments in a life
> critical jobs, certainly can.
>
> -Ramon


Aha! My suspicions were correct. The strobe-light detector seemed too
crude, susceptible to errors, easy to counterfeit. Plus, you want the
street-light preempting functionality to be independent of the strobe,
visible light.

I got this from another NG (sometimes it pays to cross post):

-Ramon

----------------

On Mon, 26 Mar 2007 22:44:51 GMT, Arif Khokar >
wrote:

> Ramon F Herrera wrote:

> > ps: which ones would be some pertinent NGs to post this?

> Not the one you chose. A better choice would be rec.autos.driving.

Well, traffic engineers know quite a bit about radar, its attendant
transportation and non-transportation uses, and emergency vehicle
pre-emption (EVP).

Modern EVP systems use an encrypted signal sent via a modulated 14.035
Hz wave. If it seems low frequency, it is. Most systems send the
signal out whenever the front strobe lights of the vehicle are
flashing (and it is obviously invisible, with visible light being
several orders of magnitude higher in frequency).

You'll occasionally see peace officers detaining a motorist, the whole
time leaving their forward strobes activated and tying up traffic in
all directions but their own (which is usually already tied up behind
them). I had a conversation with the Cook County Sheriff's Department
one morning a few years ago after they repeatedly destroyed the
operation of a busy suburban intersection over several days. They
would pull over speeding motorists and direct them onto a side street
for an entertainment venue that had zero traffic in the AM peak. The
motorist and the sheriffs patrol vehicle would end up facing back out.
Because of the EVP call, the traffic signal was held in green for the
EVP max-out (about two minutes), then recalled immediately after
returning to serve the other movements. This left the main arterials
(the cross road and the oncoming arterial) with about six seconds of
green per cycle - and no arrows for the left turns, either, since the
detector loops "tuned out" after a few of those incidents and were not
vacated to "reset" until after the AM peak had diminished.

Obviously, the only real "fix" for a problem like this, from a traffic
signal control standpoint, is to not serve an incoming EVP call until
the previous call is terminated, if the call is from the same unit.

This requires that the EVP module recognize the difference between a
fire truck and an ambulance, so that vehicles in a procession but
separated are not denied calls on the basis of the passage of a
previous vehicle. There are pitfalls to this practice (all units must
have unique ID's), but it's probably easier than asking the cops to
turn off their forward strobes (although some agencies are very good
about strobe light and traffic advisor management, most are ignorant
of good practices).

--
Scott O. Kuznicki, P.E.
Civil (Traffic) Engineer
Dedicated Highway Enthusiast
Driving Enthusiast:
'03 525i 5-speed
'90 Ninja 250R (cheap fun!)

On Mar 27, 10:21 am, "Ramon F Herrera" > wrote:
The mall door are perhaps a
> coincidence (are they, really?),
RF used to detect tags on goods.