LTI 20-20 UltraLyte 100 Calibration checks
Discussion
Of course the measurement recorded is the differential speed between the two 'devices' - the gun and the car. Thus if the officer is moving the hand-held gun to or from the horizontal this speed must be either added or subtracted if you want an accurate speed of an approaching item.
If the officer was holding the gun above the line of sight and lowered the gun quickly into position to 'catch' a target approaching him he could easily increase the measured speed of the vehicle by 5 mph.
Handheld differential speed measuring units' accuracy are therefore partially subject to the operator being slow and deliberate in their aiming - the contrary is also true. A speed reading could be deliberately 'adjusted' so be very wary in areas where Police Forces issue guns to citizens who moan as these groups are not objective participants!
If the officer was holding the gun above the line of sight and lowered the gun quickly into position to 'catch' a target approaching him he could easily increase the measured speed of the vehicle by 5 mph.
Handheld differential speed measuring units' accuracy are therefore partially subject to the operator being slow and deliberate in their aiming - the contrary is also true. A speed reading could be deliberately 'adjusted' so be very wary in areas where Police Forces issue guns to citizens who moan as these groups are not objective participants!
Toltec said:
In the sense that the definition of a metre is the distance light travels in 1/299792458th of a second by measuring the time of the pulse reflection you are are also fundamentally measuring distance.
I'm bored of this back and forth now. You guys can think you're measuring distance if you want.What great point were you trying to prove with this meaningless argument?
Edited by Devil2575 on Friday 27th November 08:17
drdel said:
Of course the measurement recorded is the differential speed between the two 'devices' - the gun and the car. Thus if the officer is moving the hand-held gun to or from the horizontal this speed must be either added or subtracted if you want an accurate speed of an approaching item.
If the officer was holding the gun above the line of sight and lowered the gun quickly into position to 'catch' a target approaching him he could easily increase the measured speed of the vehicle by 5 mph.
Handheld differential speed measuring units' accuracy are therefore partially subject to the operator being slow and deliberate in their aiming - the contrary is also true. A speed reading could be deliberately 'adjusted' so be very wary in areas where Police Forces issue guns to citizens who moan as these groups are not objective participants!
This is even more wrong than the absolute distance being significant to the speed measurement.If the officer was holding the gun above the line of sight and lowered the gun quickly into position to 'catch' a target approaching him he could easily increase the measured speed of the vehicle by 5 mph.
Handheld differential speed measuring units' accuracy are therefore partially subject to the operator being slow and deliberate in their aiming - the contrary is also true. A speed reading could be deliberately 'adjusted' so be very wary in areas where Police Forces issue guns to citizens who moan as these groups are not objective participants!
The objects reflecting the light back along the beam axis being attached to the target massivly reduce any affect on the reading caused by incident beam motion. Retro-reflective objects on the target even more so. Then you have the acceptance criteria in the speedmeter. These combine to make any effect from what you say improbable and only possible from deliberate action. To make movement of an incident beam significant to a speed measurement the action to do so must be deliberate and specific. Speedmeter operators don't operate in the way that would make the effect significant but I have seen some circus tricks performed to make them read incorrectly. To date, I am yet to see any operators dressed as clowns and driving cars to site with exploding doors but I have seen demonstrations performed by operators outside of police operations that were worthy of being included in an act by Charlie Carroli.
Breadvan72 said:
MASSIVE Star Wars FAIL.
I believe the correct response to be "Watch your mouth, kid, or you'll find yourself floating home". Do you live near a suitable river?Breadvan72 said:
See me after class.
Very sweet of you, but I've been mostly straight since leaving public school.Rovinghawk said:
Breadvan72 said:
MASSIVE Star Wars FAIL.
I believe the correct response to be "Watch your mouth, kid, or you'll find yourself floating home". Do you live near a suitable river?Breadvan72 said:
See me after class.
Very sweet of you, but I've been mostly straight since leaving public school.Devil2575 said:
Surely Star Wars is far too "Popular culture" for you 
Not so: I am a huuuuuuuuuuuge Sci Fi and comics and Dungeons and Dragons geek, and am in fact an utter spod. I bunked off school only twice, tiresome swot that I was, once circa 1979 to get tickets for an Ian Dury and the Blockheads concert, and once in 1977 to see the original Star Wars.Mill Wheel said:
Rovinghawk said:
Very sweet of you, but I've been mostly straight since leaving public school.
Then there is still a chance... depending whether BV would risk wasting his time! 
By the way, is this "sledge the shouty technodullards off the thread" strategy working?
tapereel said:
drdel said:
Of course the measurement recorded is the differential speed between the two 'devices' - the gun and the car. Thus if the officer is moving the hand-held gun to or from the horizontal this speed must be either added or subtracted if you want an accurate speed of an approaching item.
If the officer was holding the gun above the line of sight and lowered the gun quickly into position to 'catch' a target approaching him he could easily increase the measured speed of the vehicle by 5 mph.
Handheld differential speed measuring units' accuracy are therefore partially subject to the operator being slow and deliberate in their aiming - the contrary is also true. A speed reading could be deliberately 'adjusted' so be very wary in areas where Police Forces issue guns to citizens who moan as these groups are not objective participants!
This is even more wrong than the absolute distance being significant to the speed measurement.If the officer was holding the gun above the line of sight and lowered the gun quickly into position to 'catch' a target approaching him he could easily increase the measured speed of the vehicle by 5 mph.
Handheld differential speed measuring units' accuracy are therefore partially subject to the operator being slow and deliberate in their aiming - the contrary is also true. A speed reading could be deliberately 'adjusted' so be very wary in areas where Police Forces issue guns to citizens who moan as these groups are not objective participants!
The objects reflecting the light back along the beam axis being attached to the target massivly reduce any affect on the reading caused by incident beam motion. Retro-reflective objects on the target even more so. Then you have the acceptance criteria in the speedmeter. These combine to make any effect from what you say improbable and only possible from deliberate action. To make movement of an incident beam significant to a speed measurement the action to do so must be deliberate and specific. Speedmeter operators don't operate in the way that would make the effect significant but I have seen some circus tricks performed to make them read incorrectly. To date, I am yet to see any operators dressed as clowns and driving cars to site with exploding doors but I have seen demonstrations performed by operators outside of police operations that were worthy of being included in an act by Charlie Carroli.
Breadvan72 said:
Mill Wheel said:
Rovinghawk said:
Very sweet of you, but I've been mostly straight since leaving public school.
Then there is still a chance... depending whether BV would risk wasting his time! Gassing Station | Speed, Plod & the Law | Top of Page | What's New | My Stuff