Radar Question

[blake918]

I was cruising down the interstate the other day with my Passport 8500 X50 locked and loaded. I came up a hill only to see a State Policeman outside of his cruiser shooting radar at traffic going the oposite direction to me (thank goodness). My radar detector didn't make a single peep. In the past, it has been able to sniff out radar shooters on the side of the road. Other than this, I get excellent notification from the X50. Do they have undectable radar guns now?

[nc211]

They shouldn't, it would be a violation of FCC regulations, or was a few years ago anyway. Believe it or not, it was a regulation with the FCC that if they use a new device to check your speed, you had the right to "purchase" a device that would notify you of such a device being used against you. Now that doesn't mean that you have the legal right to "use" it, as some states have outlawed radar detectors. But that doesn't mean you don't "or didn't" have the right to purchase the device.

[steviej]

are you sure he was using a RADAR gun and not instant on LASAR?

steviej

[blake918]

They shouldn't, it would be a violation of FCC regulations, or was a few years ago anyway. Believe it or not, it was a regulation with the FCC that if they use a new device to check your speed, you had the right to "purchase" a device that would notify you of such a device being used against you. Now that doesn't mean that you have the legal right to "use" it, as some states have outlawed radar detectors. But that doesn't mean you don't "or didn't" have the right to purchase the device.

Cool, I never knew that!

are you sure he was using a RADAR gun and not instant on LASAR?

steviej

That's a good question, and I don't know the answer! The X50 can detect laser. I've gotten shot twice (with laser), and the sound this thing makes will send you through the sunroof when you aren't expecting it to happen!

Oh yeah, I forgot to add that on my way back the Trooper was still in the same spot shooting. I came up on him head on, and I still got nothing. <_<

[ArmyofOne]

They shouldn't, it would be a violation of FCC regulations, or was a few years ago anyway. Believe it or not, it was a regulation with the FCC that if they use a new device to check your speed, you had the right to "purchase" a device that would notify you of such a device being used against you. Now that doesn't mean that you have the legal right to "use" it, as some states have outlawed radar detectors. But that doesn't mean you don't "or didn't" have the right to purchase the device.

Cool, I never knew that!

are you sure he was using a RADAR gun and not instant on LASAR?

steviej

That's a good question, and I don't know the answer! The X50 can detect laser. I've gotten shot twice (with laser), and the sound this thing makes will send you through the sunroof when you aren't expecting it to happen!

Oh yeah, I forgot to add that on my way back the Trooper was still in the same spot shooting. I came up on him head on, and I still got nothing. <_<

Could it have been not rada, but VASCAR?

Im not sure what VASCAR is, but im not sure its radar.

[nc211]

Army, I believe Vascar is when they time you from one spot on the highway to another one. They've measured out the distance between the two, time you from one to the other, and that tells them how fast you're going. I got NAILED in Colorado when I was a teenager coming out of Eisenhower tunnel heading from Keystone to Denver by Vascar. The tropper told me "which one do you want, bad, or worse?" When I asked what he meant? he told me "90 or 105 mph". Luckily for me, I had just had the brakes worked on, that was not done correctly, and I used that to get out of it. Told the DA "with documented proof" that my brakes were not installed correctly, the pads were dragging, heating up the system, and making them fade badly. How in the h*ll that worked is beyond me...But I will say this, that was the most expensive parking ticket I've ever had!

Point is, I had a radar detector too, and it never went off. The tropper told me he tracked me via Vascar. Said he was actually behind me, but I never saw him. Apparently, the airplane above me sure did see me. A red VW 1987 GTI screaming through traffic kind of stands out.

[ArmyofOne]

Army, I believe Vascar is when they time you from one spot on the highway to another one. They've measured out the distance between the two, time you from one to the other, and that tells them how fast you're going. I got NAILED in Colorado when I was a teenager coming out of Eisenhower tunnel heading from Keystone to Denver by Vascar. The tropper told me "which one do you want, bad, or worse?" When I asked what he meant? he told me "90 or 105 mph". Luckily for me, I had just had the brakes worked on, that was not done correctly, and I used that to get out of it. Told the DA "with documented proof" that my brakes were not installed correctly, the pads were dragging, heating up the system, and making them fade badly. How in the h*ll that worked is beyond me...But I will say this, that was the most expensive parking ticket I've ever had!

Point is, I had a radar detector too, and it never went off. The tropper told me he tracked me via Vascar. Said he was actually behind me, but I never saw him. Apparently, the airplane above me sure did see me. A red VW 1987 GTI screaming through traffic kind of stands out.

Ah see the state troopers in texas use that technique alot.

Maybe the trooper just hadnt turned his radar on blake? He saw the black LS400 and said...

"Its an old man, he aint speedin' "

He dont know you very well...do he? :P

[blake918]

Maybe the trooper just hadnt turned his radar on blake? He saw the black LS400 and said...

I think you are probably right, Josh. ;) I got to try it again today-the trooper was parked in the same spot, and this time my X50 went off big time and wrote LASER across the screen. I guess the other day he didn't have it on. Either way, anyone who's drving I20 (east or west) in LA don't speed from mile markers 120 through about 50 since they are all over the place. It's pretty hilly, and radar detectors don't like that. Not to mention, you're pretty much screwed any way Laser is concerned! lol

"Its an old man, he aint speedin' "

He dont know you very well...do he? :P

LOL

What's VASCAR?

[RFeldes]

Probably more than you wanted to know!!!

VASCAR (Visual Average Speed Computer and Recorder) is really a stopwatch coupled with a calculator. Once a distance is entered, the operator pushes a button to start then stop the stopwatch. VASCAR displays the speed calculated from the distance entered and the time measured.

Thus, a VASCAR measurement depends on human input. Therefore, in order to make a VASCAR measurement as accurate as possible, the observer's/operator's reaction time must be as short as possible. (Reaction time is defined as "the time interval between an input signal (physiological) or a stimulus (psychophysiological) and the response elicited by the signal.)

What is considered "normal" human reaction time? First, let's take a look at the best: Drag racers. Average reaction time of (Top Fuel) drag racers at the 1997 U.S. Nationals was 0.124 ± 0.082 second. Imagine that our cop running VASCAR is a super cop, with drag racer like reaction times: What kind of error is introduced into the VASCAR speed measurement by a reaction time of 0.124 second? With the numbers testified to by our cop:

Distance

_________________ = Measured Speed

Real time ± Error

100

____________ = 60.096 feet/second (40.97 mph)

1.54 + 0.124

or

100

____________ = 70.621 feet/second (48.15 mph)

1.54 - 0.124

depending on whether the cop was 0.124 second too quick or too late.

The calculation above takes into consideration only one opportunity for error. However, the cop must not only start the VASCAR's stopwatch, but he also must stop it. Thus, he can introduce the error twice:

100

____________ = 55.928 feet/second (38.13 mph)

1.54 + 0.248

or

100

____________ = 77.399 feet/second (52.77 mph)

1.54 - 0.248

Looks like we are getting some error margin here: it is almost 15 mph. But wait a minute: the cop alleged that he clocked our man 66 mph (96.8 feet/second). If true, the elapsed time over 100 feet distance was 1.033 second. The error in speed reading introduced by human reaction time becomes even more severe:

100

_____________ = 78.064 feet/second (53.225 mph)

1.033 + 0.248

or

100

_____________ = 127.388 feet/second (86.855 mph)

1.033 - 0.248

WOW! An error margin of more than 33 mph! And remember, we assumed that the super cop in this example has reaction times similar to a drag racer!

Imagine if the cop is only human: Average adults show reaction times around 0.3 second -- it's not even worthwile to do the calculation. Obviously, we can no longer talk about accuracy and VASCAR in the same sentence. One can conclude that using VASCAR over a 100-foot distance cannot yield any accurate speed reading for the speeds alleged in our man's case. We come to this conclusion even before considering other sources of error, such as visual distortion introduced by the parallax effect.

And what about the law? This is what you find in § 3368 of Title 75 of the Pennsylvania Code:

(4) No person may be convicted upon evidence obtained through

the use of devices authorized by paragraphs (2) and (3) unless the

speed recorded is six or more miles per hour in excess of the legal

speed limit. Furthermore, no person may be convicted upon

evidence obtained through the use of devices authorized by paragraph (3)

in an area where the legal speed limit is less than 55

miles per hour if the speed recorded is less than ten miles per hour

in excess of the legal speed limit. This paragraph shall not apply

to evidence obtained through the use of devices authorized by

paragraph (3) within a school zone.

VASCAR is a device authorized by paragraph (3). Looks like even Pennsylvania lawmakers acknowledge that VASCAR is not a precise method for measuring speed.

Our man was pleased to find the section in red of the above paragraph: All he had to do to convince the judge that 100 feet in 1.54 second is not 66 mph but about 44 mph, with no error. The judge should dismiss the case. But will the judge listen? Although the math "problem" here is rather trivial, perhaps the judge will be more likely to believe someone with a degree in math. Thus, our man enlisted the help of his friend, who is a CMU graduate with a degree in mathematics.

Dismissed!!

[indiasfinest]

Probably more than you wanted to know!!!

VASCAR (Visual Average Speed Computer and Recorder) is really a stopwatch coupled with a calculator. Once a distance is entered, the operator pushes a button to start then stop the stopwatch. VASCAR displays the speed calculated from the distance entered and the time measured.

Thus, a VASCAR measurement depends on human input. Therefore, in order to make a VASCAR measurement as accurate as possible, the observer's/operator's reaction time must be as short as possible. (Reaction time is defined as "the time interval between an input signal (physiological) or a stimulus (psychophysiological) and the response elicited by the signal.)

What is considered "normal" human reaction time? First, let's take a look at the best: Drag racers. Average reaction time of (Top Fuel) drag racers at the 1997 U.S. Nationals was 0.124 ± 0.082 second. Imagine that our cop running VASCAR is a super cop, with drag racer like reaction times: What kind of error is introduced into the VASCAR speed measurement by a reaction time of 0.124 second? With the numbers testified to by our cop:

Distance

_________________ = Measured Speed

Real time ± Error

100

____________ = 60.096 feet/second (40.97 mph)

1.54 + 0.124

or

100

____________ = 70.621 feet/second (48.15 mph)

1.54 - 0.124

depending on whether the cop was 0.124 second too quick or too late.

The calculation above takes into consideration only one opportunity for error. However, the cop must not only start the VASCAR's stopwatch, but he also must stop it. Thus, he can introduce the error twice:

100

____________ = 55.928 feet/second (38.13 mph)

1.54 + 0.248

or

100

____________ = 77.399 feet/second (52.77 mph)

1.54 - 0.248

Looks like we are getting some error margin here: it is almost 15 mph. But wait a minute: the cop alleged that he clocked our man 66 mph (96.8 feet/second). If true, the elapsed time over 100 feet distance was 1.033 second. The error in speed reading introduced by human reaction time becomes even more severe:

100

_____________ = 78.064 feet/second (53.225 mph)

1.033 + 0.248

or

100

_____________ = 127.388 feet/second (86.855 mph)

1.033 - 0.248

WOW! An error margin of more than 33 mph! And remember, we assumed that the super cop in this example has reaction times similar to a drag racer!

Imagine if the cop is only human: Average adults show reaction times around 0.3 second -- it's not even worthwile to do the calculation. Obviously, we can no longer talk about accuracy and VASCAR in the same sentence. One can conclude that using VASCAR over a 100-foot distance cannot yield any accurate speed reading for the speeds alleged in our man's case. We come to this conclusion even before considering other sources of error, such as visual distortion introduced by the parallax effect.

And what about the law? This is what you find in § 3368 of Title 75 of the Pennsylvania Code:

(4) No person may be convicted upon evidence obtained through

the use of devices authorized by paragraphs (2) and (3) unless the

speed recorded is six or more miles per hour in excess of the legal

speed limit. Furthermore, no person may be convicted upon

evidence obtained through the use of devices authorized by paragraph (3)

in an area where the legal speed limit is less than 55

miles per hour if the speed recorded is less than ten miles per hour

in excess of the legal speed limit. This paragraph shall not apply

to evidence obtained through the use of devices authorized by

paragraph (3) within a school zone.

VASCAR is a device authorized by paragraph (3). Looks like even Pennsylvania lawmakers acknowledge that VASCAR is not a precise method for measuring speed.

Our man was pleased to find the section in red of the above paragraph: All he had to do to convince the judge that 100 feet in 1.54 second is not 66 mph but about 44 mph, with no error. The judge should dismiss the case. But will the judge listen? Although the math "problem" here is rather trivial, perhaps the judge will be more likely to believe someone with a degree in math. Thus, our man enlisted the help of his friend, who is a CMU graduate with a degree in mathematics.

Dismissed!!

i got a headache

[RFeldes]

Me too!!!!!

[93lexuses]

Probably more than you wanted to know!!!

VASCAR (Visual Average Speed Computer and Recorder) is really a stopwatch coupled with a calculator. Once a distance is entered, the operator pushes a button to start then stop the stopwatch. VASCAR displays the speed calculated from the distance entered and the time measured.

Thus, a VASCAR measurement depends on human input. Therefore, in order to make a VASCAR measurement as accurate as possible, the observer's/operator's reaction time must be as short as possible. (Reaction time is defined as "the time interval between an input signal (physiological) or a stimulus (psychophysiological) and the response elicited by the signal.)

What is considered "normal" human reaction time? First, let's take a look at the best: Drag racers. Average reaction time of (Top Fuel) drag racers at the 1997 U.S. Nationals was 0.124 ± 0.082 second. Imagine that our cop running VASCAR is a super cop, with drag racer like reaction times: What kind of error is introduced into the VASCAR speed measurement by a reaction time of 0.124 second? With the numbers testified to by our cop:

Distance

_________________ = Measured Speed

Real time ± Error

100

____________ = 60.096 feet/second (40.97 mph)

1.54 + 0.124

or

100

____________ = 70.621 feet/second (48.15 mph)

1.54 - 0.124

depending on whether the cop was 0.124 second too quick or too late.

The calculation above takes into consideration only one opportunity for error. However, the cop must not only start the VASCAR's stopwatch, but he also must stop it. Thus, he can introduce the error twice:

100

____________ = 55.928 feet/second (38.13 mph)

1.54 + 0.248

or

100

____________ = 77.399 feet/second (52.77 mph)

1.54 - 0.248

Looks like we are getting some error margin here: it is almost 15 mph. But wait a minute: the cop alleged that he clocked our man 66 mph (96.8 feet/second). If true, the elapsed time over 100 feet distance was 1.033 second. The error in speed reading introduced by human reaction time becomes even more severe:

100

_____________ = 78.064 feet/second (53.225 mph)

1.033 + 0.248

or

100

_____________ = 127.388 feet/second (86.855 mph)

1.033 - 0.248

WOW! An error margin of more than 33 mph! And remember, we assumed that the super cop in this example has reaction times similar to a drag racer!

Imagine if the cop is only human: Average adults show reaction times around 0.3 second -- it's not even worthwile to do the calculation. Obviously, we can no longer talk about accuracy and VASCAR in the same sentence. One can conclude that using VASCAR over a 100-foot distance cannot yield any accurate speed reading for the speeds alleged in our man's case. We come to this conclusion even before considering other sources of error, such as visual distortion introduced by the parallax effect.

And what about the law? This is what you find in § 3368 of Title 75 of the Pennsylvania Code:

(4) No person may be convicted upon evidence obtained through

the use of devices authorized by paragraphs (2) and (3) unless the

speed recorded is six or more miles per hour in excess of the legal

speed limit. Furthermore, no person may be convicted upon

evidence obtained through the use of devices authorized by paragraph (3)

in an area where the legal speed limit is less than 55

miles per hour if the speed recorded is less than ten miles per hour

in excess of the legal speed limit. This paragraph shall not apply

to evidence obtained through the use of devices authorized by

paragraph (3) within a school zone.

VASCAR is a device authorized by paragraph (3). Looks like even Pennsylvania lawmakers acknowledge that VASCAR is not a precise method for measuring speed.

Our man was pleased to find the section in red of the above paragraph: All he had to do to convince the judge that 100 feet in 1.54 second is not 66 mph but about 44 mph, with no error. The judge should dismiss the case. But will the judge listen? Although the math "problem" here is rather trivial, perhaps the judge will be more likely to believe someone with a degree in math. Thus, our man enlisted the help of his friend, who is a CMU graduate with a degree in mathematics.

Dismissed!!

And yet Pennsylvania uses it all the time. We have white lines painted all over our roads.