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

[Ramon F Herrera]

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?

 

[Michael Heydon]

- 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

 

[Rich Grise]

.

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

 

[Scott en Aztlán]

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.

Sorry, but the gizmos that turn the lights green for emergency
vehicles are OPTICAL, not RADIO. The firetrucks have what amounts to a
strobe light mounted on their roofs; it pulses light in a specific
pattern, and a photodetector mounted on the light pole overrides the
signal and turns it green in the direction of the strobe light.

None of it has anything whtsoever to do with RADAR.

 

[Ramon F Herrera]

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

...

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

 

[Ramon F Herrera]

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

...

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

 

[Ramon F Herrera]

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

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

Ramon F Herrera wrote:

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!)

 

[GPG]

coincidence (are they, really?),

RF used to detect tags on goods.

 

[[email protected]]

X band radar is on a "license free" allocation near 10.5 ghz. Door
openers, microwave car detectors, are in a "license free" allocation
at 10.5 ghz. A while back it was decided to add a signaling protocol
to some radar detectors for emergencies and certain roadway warning
signs at you guessed it, 10.5 ghz.

Does that answer your observation questions?

Steve Roberts

 

[Scott en Aztlán]

RF used to detect tags on goods.

Um, no.

Automatic door openers triggering radar detectors predate RFID by many
decades.

 

[Jim Thompson]

Um, no.

Automatic door openers triggering radar detectors predate RFID by many
decades.

RFID tags are typically in the 1-2GHz range... but there are some as
low as 130KHz ;-)

...Jim Thompson

 

[Rich Grise]

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.

That could be, as an attention-getting device - after all, when your
radar detector sounds, you wake up and get back to the task of driving
the car responsibly, right?

So I can see that it's marginally feasible, but whatever radar jammer
they're running doesn't have anything to do with changing the signals.

Thanks,
Rich

 

[Rich Grise]

On Mon, 26 Mar 2007 22:44:51 GMT, Arif Khokar <[email protected]> ....

Modern EVP systems use an encrypted signal sent via a modulated 14.035
Hz wave. If it seems low frequency, it is.

It's a strobe with a flash rate of 14.035 flashes per second.

And if they catch you using one, they'll throw you in the clink.

Good Luck!
Rich

 

[Ramon F Herrera]

X band radar is on a "license free" allocation near 10.5 ghz. Door
openers, microwave car detectors, are in a "license free" allocation
at 10.5 ghz. A while back it was decided to add a signaling protocol
to some radar detectors for emergencies and certain roadway warning
signs at you guessed it, 10.5 ghz.

Does that answer your observation questions?

Steve Roberts

Thanks for your answers, Steve. Let me see if I understood you
correctly. You say that a signaling protocol was added with the
specific use of sending a "this is an emergency, get out of the way"
signal to properly equipped RDs. If that's the case, shouldn't the
display show something like "emergency vehicle coming"? I really have
bumped into many ambulances in emergency mode, but IIRC the display
and beeping sound is the same than for a regular police patrol car.

-Ramon

 

[[email protected]]

"SWS" aka safety warning system, 64 canned messages transmittted on a
x band or Ku band carrier,

see:

http://americancityandcounty.com/mag/government_radar_detectors_warn/

I doubt it will catch on outside of california or other real dense
traffic areas, too limited in the scope of messages, and number of
cars that can receive it.

Steve

 

[RG]

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.

Google a little, Google a lot. Type "radar detector" and read the result.

Results 1 - 20 of about 1,050,000 English and Spanish pages for radar
detector. (0.13 seconds)


Ever heard of:

Safety Alert®????

You have a radar detector, read the instructions..

From the Cobra XRS-9300 model:

The XRS-9300 features 2 safety alert systems The Strobe Alert, a Cobra
exclusive, works with tens of thousands of emergency vehicles currently
equipped with traffic light controlling strobe emitters and the Safety Alert
warns driver of emergency vehicles and road hazards from systems equipped
with Safety Alert transmitters.

Ahhh, the power of Google.

Sorry to be a "smart ass"...



Raul G

 

[RG]

Following my previous post a little bit more:
Since many motor vehicles are so soundproof that drivers often do not hear a
train or siren approaching or see warning lights immediately, Cobra offers
the Safety Alert(R) Traffic Warning system to help prevent possible
accidents. When the XT-1000 Transmitter is installed on a train or such
emergency vehicle as a police car or ambulance, it transmits special warning
signals that can be detected up to one mile away by Traffic Warning
Detectors. Detectors, installed in motor vehicles, warn drivers of upcoming
hazards with one of three alerts: train (at an unguarded crossing),
emergency vehicle, and road hazard.

And I don't work for Cobra.. Ha.

Raul G

 

[joseph2k]

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.

Sounds like you have a crappy detector, responding to "out-of-band" signals
like that. Field disturbance detector.

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

Same problem, telemetry this time.

- 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).

More out of band response, DSRC toll interrogators.

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.

Yes they have, and it is optical, not microwave. Would you like a link to
the specifications?

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?

See responses above.

-Ramon

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

alt.religion maybe?

 

[joseph2k]

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

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




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!)

Offhand i would say that there are some possibly seriously wrong assertions
here.

1. In most jurisdictions law enforcement is not allowed to use preemption
just to pull over someone for a traffic violation. Certainly not in
California.

2. The red and blue strobes are not at the right frequency.

3. What encrypted signal? Peruse the device specifications. Want a link?
http://www.dot.ca.gov/hq/esc/oe/specifications/SSPs/99_04-SSPs/Sec_10/86/86-425_A11-01-04.doc
It is an MSWord file

Joseph Barrett, P.E.
California Department of Transportation
Transportation Electrical Engineer

 

[joseph2k]

"SWS" aka safety warning system, 64 canned messages transmittted on a
x band or Ku band carrier,

see:

http://americancityandcounty.com/mag/government_radar_detectors_warn/

I doubt it will catch on outside of california or other real dense
traffic areas, too limited in the scope of messages, and number of
cars that can receive it.

Steve

It is not in use in California that i know of, and I am in a position likely
to know. Perhaps they are working with the local big city, Atlanta.