Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????

On Wednesday, August 10, 2016 at 4:11:00 AM UTC-4, wrote:
Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????

Obviously your town doesn't have a Idiot Ordinance. If they did, the cops would have
arrested you on the spot.

On Wed, 10 Aug 2016 03:09:05 -0400, wrote:



Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say".

That was probably a wrong answer too. At that speed you'd probably be
arrested and charged with a series of reckless endangerment type
charges. In CT if you are more than 20 over, off to the pokey.

On 8/10/2016 3:09 AM, wrote:
Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????


He's mixing the sign and physical presence of cop.
There are a couple of signs I frequently go through here and they blink
off when your car has passed. They do not keep a record of your car and
speed.

In Europe over 25 years ago we were told that trucks were required to
have a recorded record of their trip and when cops pulled them over
would check the record and could give them a speeding ticket even though
they exceeded the speed hours ago.

One day with gps's and computers recording they could do this to anybody.

On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

Interesting.

Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.

The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

On Wednesday, August 10, 2016 at 9:11:53 AM UTC-4, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

So I want to speed past one of those set-ups I should drive in reverse?

On Wednesday, August 10, 2016 at 4:11:00 AM UTC-4, wrote:
Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????


....or they show 3 digits.

http://fcdn.mtbr.com/attachments/cal...iler176mph.gif

On 8/10/2016 6:21 AM, DerbyDad03 wrote:
On Wednesday, August 10, 2016 at 9:11:53 AM UTC-4, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

So I want to speed past one of those set-ups I should drive in reverse?


no, that is how you turn back your odometer before you sell the car.

On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

It fires a rocket.

On Wed, 10 Aug 2016 08:19:03 -0400, Frank "frank wrote:


In Europe over 25 years ago we were told that trucks were required to
have a recorded record

That's the best kind.

of their trip and when cops pulled them over
would check the record and could give them a speeding ticket even though
they exceeded the speed hours ago.

One day with gps's and computers recording they could do this to anybody.

Unquestionably wrote:
On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.
Interesting.
Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.
The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

Those speed detectors always show my vehicle is going 3 mph slower than my speedometer.

DerbyDad03 wrote:
On Wednesday, August 10, 2016 at 4:11:00 AM UTC-4,
wrote:
Our town recently got one of those Traffic Speed Detecting Signs,
that tell you how fast you're going. I've always wondered how they
work, and why they dont detect cars going the opposite direction.(I
assume they work on radar). I also noticed that they only have TWO
digits. Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone
exceeds 99mph. His reply was "I'll give you a speeding ticket". I
laughed and said "that's what I thought you'd say". Then I said,
"besides the ticket, what would the sign do?" He said he never tried
it, so he dont know.

If a cop dont know, who does? I'm wondering if they go back to zero,
or just keep showing 99?????

Obviously your town doesn't have a Idiot Ordinance. If they did, the
cops would have arrested you on the spot.

+10 and bet the cop had a good laugh later telling his fellow cops about the
idiot at the store

On Wednesday, August 10, 2016 at 10:41:26 AM UTC-4, cowabunga dude wrote:
Unquestionably wrote:
On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.
Interesting.
Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.
The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

Those speed detectors always show my vehicle is going 3 mph slower than my speedometer.

Have you compared your speedometer with a GPS or GPS app on a smartphone?

When you use the words "Those speed detectors always", I have to suspect
the one thing that is consistent in every case: Your speedometer. I'd find
it hard to believe that every one of those detectors is off by 3 MPH.

Somehow you'd think that they'd have fixed that by now...

On Wed, 10 Aug 2016 15:34:43 +0100, Micky wrote:

On Wed, 10 Aug 2016 08:19:03 -0400, Frank "frank wrote:


In Europe over 25 years ago we were told that trucks were required to
have a recorded record

That's the best kind.

It's ****ing stupid, and drivers bypass that nonsense anyway.

of their trip and when cops pulled them over
would check the record and could give them a speeding ticket even though
they exceeded the speed hours ago.

One day with gps's and computers recording they could do this to anybody.



--
A group of cowboys were branding some cattle.
While they were out the cook saw a sheep tied to a post. Thinking it was for that nights dinner he cooked it.
That night after dinner the cowboys were all sulking and ignoring the cook. He pulled one aside and asked, "Did I screw up the cooking?"
"No", the cowboy replied, "You cooked up the screwing."

On Wed, 10 Aug 2016 15:41:16 +0100, cowabunga dude wrote:



Unquestionably wrote:
On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.
Interesting.
Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.
The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

Those speed detectors always show my vehicle is going 3 mph slower than my speedometer.

Because your speedometer (like in most cars) is ****. Compare it with your GPS it should be dead on.

--
What do you call kinky sex with chocolate?
S&M&M

On Wed, 10 Aug 2016 14:20:58 +0100, Unquestionably Confused wrote:

On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

Interesting.

Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.

The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

Those detectors are ****, I got too many false positives from other things that use the same frequencies (apparently tractor and taxi radios?!). The best thing to use is a GPS which has all the spots they put cameras (including mobile ones) in its database.

--
What do you call kinky sex with chocolate?
S&M&M

On Wed, 10 Aug 2016 14:11:43 +0100, Pat wrote:

On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

If it's aimed along this side of the road, it shouldn't see cars on the other side. Otherwise what happens if there's cars going both ways at once?

--
The 2 most common elements in the universe are hydrogen and stupidity.

ChairMan wrote :
DerbyDad03 wrote:
On Wednesday, August 10, 2016 at 4:11:00 AM UTC-4,
wrote:
Our town recently got one of those Traffic Speed Detecting Signs,
that tell you how fast you're going. I've always wondered how they
work, and why they dont detect cars going the opposite direction.(I
assume they work on radar). I also noticed that they only have TWO
digits. Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone
exceeds 99mph. His reply was "I'll give you a speeding ticket". I
laughed and said "that's what I thought you'd say". Then I said,
"besides the ticket, what would the sign do?" He said he never tried
it, so he dont know.

If a cop dont know, who does? I'm wondering if they go back to zero,
or just keep showing 99?????

Obviously your town doesn't have a Idiot Ordinance. If they did, the
cops would have arrested you on the spot.

+10 and bet the cop had a good laugh later telling his fellow cops about the
idiot at the store

He was probably at the 99 cent store trying to hand the clerk a dollar
just to see what would happen.

On Wednesday, August 10, 2016 at 11:06:51 AM UTC-4, James Wilkinson wrote:
On Wed, 10 Aug 2016 15:41:16 +0100, cowabunga dude wrote:



Unquestionably wrote:
On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.
Interesting.
Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.
The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

Those speed detectors always show my vehicle is going 3 mph slower than my speedometer.

Because your speedometer (like in most cars) is ****. Compare it with your GPS it should be dead on.

Mr. MaCaw,

It could be tires if he is running something other than the OEM size.

On Wed, 10 Aug 2016 16:08:08 +0100, "James Wilkinson"
wrote:

On Wed, 10 Aug 2016 14:11:43 +0100, Pat wrote:

On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

If it's aimed along this side of the road, it shouldn't see cars on the other side.
Otherwise what happens if there's cars going both ways at once?

If there are a line of cars approaching the sign, the numbers tend to
jump around quite a bit. So which car is it sensing? (Of course a line
of cars are all doing roughly the same speed).

On Wed, 10 Aug 2016 09:11:43 -0400, Pat wrote:

On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

That makes sense....

I have also noted that those signs are always showing about 2mph slower
than my speedometer on my pickup truck. But vehicle speedos are never
100% accurate because of factors in the vehicle, gear ratios and so on,
but tire size is a huge factor. I have heard of guys changing the speedo
gear, just because they put on larger or smaller tires. As long as I
know that my speedo is showing "30" when I'm actually doing 28, I know I
can legally go a little faster. I actually like those signs, because
they do "test my speedometer.

I dont know what size tires came with my truck, but I tend to run
heavier tires than most people, because I haul farm equipment, hay
bales, etc. I'm sure that makes up the difference. My tires are all
10ply, and the quarter or half inch of extra thickness does matter in
the long run.

On Wed, 10 Aug 2016 08:19:03 -0400, Frank "frank wrote:

On 8/10/2016 3:09 AM, wrote:
Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????


He's mixing the sign and physical presence of cop.
There are a couple of signs I frequently go through here and they blink
off when your car has passed. They do not keep a record of your car and
speed.

In Europe over 25 years ago we were told that trucks were required to
have a recorded record of their trip and when cops pulled them over
would check the record and could give them a speeding ticket even though
they exceeded the speed hours ago.

One day with gps's and computers recording they could do this to anybody.

I rarely see a cop near those signs. I know they signal is not being
sent to the cops, recorded, or anything. The sign is programmed to flash
if I'm exceeding the speed by more than 3mph or something like that. In
town the speed limit is 20, and it wont flash at 21 or 22, but I think
it starts to flash at 23 or 24 (and up).

Ive seen those same signs used at tractor and truck pulls to record the
speed of the puller....

On Wed, 10 Aug 2016 19:47:03 +0100, "James Wilkinson"
wrote:



How much does it jump about? I could believe a line of cars varying by something like 28mph to 34mph.

That's about right.... plus/minus 5mph is about right

DerbyDad03 posted for all of us...



On Wednesday, August 10, 2016 at 4:11:00 AM UTC-4, wrote:
Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????

Obviously your town doesn't have a Idiot Ordinance. If they did, the cops would have
arrested you on the spot.

Good one

--
Tekkie

Pat posted for all of us...



On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

A negative speed? Huh? NO It's doesn't care what direction you are going.
The beam pattern is narrowed so it's only measuring the oncoming traffic.
The ones we have recorders are installed so traffic studies can be
performed. When citizens complain about speeding in their neighborhood then
a study is done. If warranted then enforcement is started. Usually the
studies are done in nearby areas too. Catches the complainers speeding in
someone else's neighborhood. Enforcement catches the stop sign violators.

--
Tekkie

On 8/10/2016 10:41 AM, cowabunga dude wrote:



Those speed detectors always show my vehicle is going 3 mph slower than
my speedometer.



Your speedo is off. Manufacturers would rather it be that way the the
opposite so you don't get tickets.


§ 393.82 Speedometer.
Each bus, truck, and truck-tractor must be equipped with a speedometer
indicating vehicle speed in miles per hour and/or kilometers per hour.
The speedometer must be accurate to within plus or minus 8 km/hr (5 mph)
at a speed of 80 km/hr (50 mph).

Tire size and pressure will affect the readings too.

On Wed, 10 Aug 2016 18:28:15 +0100, wrote:

On Wed, 10 Aug 2016 16:08:08 +0100, "James Wilkinson"
wrote:

On Wed, 10 Aug 2016 14:11:43 +0100, Pat wrote:

On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

If it's aimed along this side of the road, it shouldn't see cars on the other side.
Otherwise what happens if there's cars going both ways at once?

If there are a line of cars approaching the sign, the numbers tend to
jump around quite a bit. So which car is it sensing? (Of course a line
of cars are all doing roughly the same speed).

How much does it jump about? I could believe a line of cars varying by something like 28mph to 34mph.

--
Avoid messes.. Remember to cover cat before microwaving.

On Wed, 10 Aug 2016 18:53:48 +0100, wrote:

On Wed, 10 Aug 2016 19:47:03 +0100, "James Wilkinson"
wrote:



How much does it jump about? I could believe a line of cars varying by something like 28mph to 34mph.

That's about right.... plus/minus 5mph is about right

A lot of drivers don't stay at the same speed, they're impatient and/or stupid and speed up, then brake as they approach the car in front. That's why you get those ridiculous rolling slow bits on motorways sometimes. I always delete them by just driving at the average speed of the cars in front.

--
Mary had a little lamb, it walked into a pylon. 10,000 volts went up its arse, and turned its wool to nylon.

On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????

Try it and find out. Make sure the same cop is there to catch you -
trhen you can say you were just trying to find the answer to the
question he could not answer - that way you both learn something - - -

On Wed, 10 Aug 2016 08:19:03 -0400, Frank "frank wrote:

On 8/10/2016 3:09 AM, wrote:
Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????


He's mixing the sign and physical presence of cop.
There are a couple of signs I frequently go through here and they blink
off when your car has passed. They do not keep a record of your car and
speed.

In Europe over 25 years ago we were told that trucks were required to
have a recorded record of their trip and when cops pulled them over
would check the record and could give them a speeding ticket even though
they exceeded the speed hours ago.

One day with gps's and computers recording they could do this to anybody.
The infamous "tachograph"

OBD2 computers on today's cars can apparently be queried to determine
speed and whether the brakes were applied in accident investigation.
Only the last few seconds are apparently available.

On Wed, 10 Aug 2016 08:20:58 -0500, Unquestionably Confused
wrote:

On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

Interesting.

Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.

The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.



Possibly LIDAR instead of Radar

On Wed, 10 Aug 2016 06:22:50 -0700 (PDT), DerbyDad03
wrote:

On Wednesday, August 10, 2016 at 4:11:00 AM UTC-4, wrote:
Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

Last night I was in a convenvience store, when one of the local cops
walked in. That was my chance to ask him what happens if someone exceeds
99mph. His reply was "I'll give you a speeding ticket". I laughed and
said "that's what I thought you'd say". Then I said, "besides the
ticket, what would the sign do?" He said he never tried it, so he dont
know.

If a cop dont know, who does? I'm wondering if they go back to zero, or
just keep showing 99?????


...or they show 3 digits.

http://fcdn.mtbr.com/attachments/cal...iler176mph.gif
Most metric units have 3 digit readout. Imperial units for urban use
generally have only 2 digits - 100mph in urban areas is not "expected"
but 100kph is far from unheard of.

On Wed, 10 Aug 2016 06:28:06 -0700, Taxed and Spent
wrote:

On 8/10/2016 6:21 AM, DerbyDad03 wrote:
On Wednesday, August 10, 2016 at 9:11:53 AM UTC-4, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

So I want to speed past one of those set-ups I should drive in reverse?


no, that is how you turn back your odometer before you sell the car.
Only if it is a rather old car. Most cars today with electronic
speedos will register mileage in both directions. Some even register
reverse speeds.

On Wed, 10 Aug 2016 09:41:16 -0500, "cowabunga dude"
wrote:



Unquestionably wrote:
On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.
Interesting.
Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.
The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

Those speed detectors always show my vehicle is going 3 mph slower than my speedometer.

because your speedo, like most, is inaccurate.. Perhaps your tires are
undersized??

On Wed, 10 Aug 2016 14:44:04 -0400, Tekkie®
wrote:

Pat posted for all of us...
Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

A negative speed? Huh? NO It's doesn't care what direction you are going.
The physics cares. A car appraoching at 35 is very different from a
car going the other way. The software might be programmed to display
the absolute value of the speed, but internally, the device knows
toward (positive) from away (negative).

The beam pattern is narrowed so it's only measuring the oncoming traffic.
That may be the intent, but real world roads have curves and cars on
the other side are sometimes detected.

On Wed, 10 Aug 2016 16:13:25 -0400, wrote:

On Wed, 10 Aug 2016 09:41:16 -0500, "cowabunga dude"
wrote:



Unquestionably wrote:
On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.
Interesting.
Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.
The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

Those speed detectors always show my vehicle is going 3 mph slower than my speedometer.

because your speedo, like most, is inaccurate.. Perhaps your tires are
undersized??
That could be it, or it might be working as designed. I believe that
cars in the US must have speedometers that are accurate to within
minus 0% and plus 5%. I don't recall the exact number, but the idea
is they can allowed read fast but never slow. If that is true, I
would think the average speedometer would read a liitle fast. At 60
mph, a designer working with a + or - 2 mph device would set it to be
2 mph fast thus turning -2 to +2 into -0 to +4 with an average of 2.

Pat posted for all of us...



On Wed, 10 Aug 2016 14:44:04 -0400, Tekkie®
wrote:

Pat posted for all of us...
Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

A negative speed? Huh? NO It's doesn't care what direction you are going..
The physics cares. A car appraoching at 35 is very different from a
car going the other way. The software might be programmed to display
the absolute value of the speed, but internally, the device knows
toward (positive) from away (negative).

So what is your point?

The beam pattern is narrowed so it's only measuring the oncoming traffic..
That may be the intent, but real world roads have curves and cars on
the other side are sometimes detected.

So. They are not being used for enforcement. To be used properly they just
aren't hung on a fence nail in the pole. Are you looking in the mirror when
you pass one going the "negative" direction; if so what is the reading?

--
Tekkie

On 8/10/2016 10:04 AM, DerbyDad03 wrote:
On Wednesday, August 10, 2016 at 10:41:26 AM UTC-4, cowabunga dude wrote:
Unquestionably wrote:
On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.
Interesting.
Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.
The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.

Those speed detectors always show my vehicle is going 3 mph slower than my speedometer.

Have you compared your speedometer with a GPS or GPS app on a smartphone?

When you use the words "Those speed detectors always", I have to suspect
the one thing that is consistent in every case: Your speedometer. I'd find
it hard to believe that every one of those detectors is off by 3 MPH.

Somehow you'd think that they'd have fixed that by now...

+1

Not mention that if it was done intentionally, they might want it
reading your speed as 3 mph higher to slow you down.

With my portable GPS I will occasionally check my car's speedo. Set the
cruise control at 60mph on a flat stretch and see what the GPS tells me.
Rarely is there a difference between the two.

On 8/10/2016 3:06 PM, wrote:
On Wed, 10 Aug 2016 08:20:58 -0500, Unquestionably Confused
wrote:

On 8/10/2016 8:11 AM, Pat wrote:
On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). ???

Yes, they work on radar. Cars going the opposite direction DO get
detected, but they show up as going a negative speed. The built-in
software just ignores those signals and displays only positive speeds.

Interesting.

Seems obvious that they must employ a unique radar frequency as
oftentimes my Valentine One (a great radar detector) doesn't utter a
sound even though it's set to report ALL threats.

The silent treatment occurs with a fair number of the portable "Speed
Alert" trailers the police move around to provide a courtesy warning to
motorists as well.



Possibly LIDAR instead of Radar

Doubtful as the Valentine One picks up LIDAR/Laser as well. Trips
everytime I run through a toll plaza where the cameras are equipped with
IR Illuminators to light up the plates at night.

One explanation I read was frequencies of the mobile units, since they
aren't used for enforcement, per se, are not calibrated/recalibrated and
the detectors won't pick them up.

No attribution was provided with that explanation so I rather doubt it
for that and several other reasons.