LTI 20-20 UltraLyte 100 Calibration checks
Discussion
tapereel said:
You chaps are all missing the point that is in contention.
The distance displayed on laser speedometers need not be and is not that used in the speed calculation. Because of the good design and quality of the instruments the displayed speed is usually, by not always, consistent to the distance around the mid point of the measurement data.
It's you who's missing the point.The distance displayed on laser speedometers need not be and is not that used in the speed calculation. Because of the good design and quality of the instruments the displayed speed is usually, by not always, consistent to the distance around the mid point of the measurement data.
Nobody has suggested that the distance displayed is used in the speed calculation, but rather that it's necessary to get some measurement of relative distance, not necessarily in fixed units of distance, in order to calculate the speed.
Granted, a lot of the problems normally associated with distance measurement are overcome by the pulse timing measurement and the pulse repetition rate operating from a common mode timebase, but some related problems persist.
And when you start going on about irrelevancies like the ratio of the speed of light, it leads me to strongly believe that you have little or no understanding of the way it works - either that or you're vainly trying to appear super-intelligent
Edited by Pete317 on Thursday 26th November 15:36
Pete317 said:
It's you who's missing the point.
Nobody has suggested that the distance displayed is used in the speed calculation, but rather that it's necessary to get some measurement of relative distance, not necessarily in fixed units of distance, in order to calculate the speed.
Granted, a lot of the problems normally associated with distance measurement are overcome by the pulse timing measurement and the pulse repetition rate operating from a common mode timebase, but some related problems persist.
And when you start going on about irrelevancies like the ratio of the speed of light, it leads me to strongly believe that you have little or no understanding of the way it works - either that or you're vainly trying to appear super-intelligent
you do seem to know a lot more about this after the last 2 days, good for you.Nobody has suggested that the distance displayed is used in the speed calculation, but rather that it's necessary to get some measurement of relative distance, not necessarily in fixed units of distance, in order to calculate the speed.
Granted, a lot of the problems normally associated with distance measurement are overcome by the pulse timing measurement and the pulse repetition rate operating from a common mode timebase, but some related problems persist.
And when you start going on about irrelevancies like the ratio of the speed of light, it leads me to strongly believe that you have little or no understanding of the way it works - either that or you're vainly trying to appear super-intelligent
Edited by Pete317 on Thursday 26th November 15:36
What related problems are bothering you?
tapereel said:
Pete317 said:
It's you who's missing the point.
Nobody has suggested that the distance displayed is used in the speed calculation, but rather that it's necessary to get some measurement of relative distance, not necessarily in fixed units of distance, in order to calculate the speed.
Granted, a lot of the problems normally associated with distance measurement are overcome by the pulse timing measurement and the pulse repetition rate operating from a common mode timebase, but some related problems persist.
And when you start going on about irrelevancies like the ratio of the speed of light, it leads me to strongly believe that you have little or no understanding of the way it works - either that or you're vainly trying to appear super-intelligent
you do seem to know a lot more about this after the last 2 days, good for you.Nobody has suggested that the distance displayed is used in the speed calculation, but rather that it's necessary to get some measurement of relative distance, not necessarily in fixed units of distance, in order to calculate the speed.
Granted, a lot of the problems normally associated with distance measurement are overcome by the pulse timing measurement and the pulse repetition rate operating from a common mode timebase, but some related problems persist.
And when you start going on about irrelevancies like the ratio of the speed of light, it leads me to strongly believe that you have little or no understanding of the way it works - either that or you're vainly trying to appear super-intelligent
Edited by Pete317 on Thursday 26th November 15:36
What related problems are bothering you?
One related problem is that of getting a measurement to a sloping surface, such as a car bonnet. Although there are measures in place to minimise such errors, they're not foolproof.
WinstonWolf said:
tapereel said:
Monty Python said:
So we're agreed then - the device measures the distance to the target numerous times then uses the time between the measurements to calculate the speed.
NoBased on the difference between two consecutive readings it is able to determine a speed.
Monty Python said:
So we're agreed then - the device measures the distance to the target numerous times then uses the time between the measurements to calculate the speed.
Tbf it calculates the distance based on time intervals between pulse & 'echo'. It then uses those distance figures to calculate speed.Distance is nevertheless involved.
Rovinghawk said:
Tbf it calculates the distance based on time intervals between pulse & 'echo'. It then uses those distance figures to calculate speed.
Distance is nevertheless involved.
I know that and you know that, but it seems others here exist in an alternate universe where speed can be determined without involving distance (using this particular device).Distance is nevertheless involved.
V8LM said:
Devil2575 said:
The device doesn't measure distance, it measures the length of time it takes the beam to travel too and from the vehicle.
Based on the difference between two consecutive readings it is able to determine a speed.
Which is a distance. Just as a light year is.Based on the difference between two consecutive readings it is able to determine a speed.
All that it is actually being measured is time.
Pete317 said:
Devil2575 said:
The device doesn't measure distance, it measures the length of time it takes the beam to travel too and from the vehicle.
What would you call that if not a measurement of distance?Just because you don't call it distance doesn't mean that the mechanism isn't the same.
I uses this to calculate the speed and the distance but what is being measured is time. Everything else is a constant.
Devil2575 said:
Pete317 said:
Devil2575 said:
The device doesn't measure distance, it measures the length of time it takes the beam to travel too and from the vehicle.
What would you call that if not a measurement of distance?Just because you don't call it distance doesn't mean that the mechanism isn't the same.
I uses this to calculate the speed and the distance but what is being measured is time. Everything else is a constant.
Devil2575 said:
Because what the device is actually measuring is the time between how long the beam of light takes to return.
I uses this to calculate the speed and the distance but what is being measured is time. Everything else is a constant.
It might measure time but it doesn't use it directly to calculate speed - it has to convert the travel time into a distance first. At no time does it directly measure the speed of the car it's pointed it.I uses this to calculate the speed and the distance but what is being measured is time. Everything else is a constant.
Devil2575 said:
Pete317 said:
Devil2575 said:
The device doesn't measure distance, it measures the length of time it takes the beam to travel too and from the vehicle.
What would you call that if not a measurement of distance?Just because you don't call it distance doesn't mean that the mechanism isn't the same.
I uses this to calculate the speed and the distance but what is being measured is time. Everything else is a constant.
Just because you don't call it a distance measurement doesn't mean that you don't use exactly the same method as for getting a measure of distance.
Devil2575 said:
WinstonWolf said:
tapereel said:
Monty Python said:
So we're agreed then - the device measures the distance to the target numerous times then uses the time between the measurements to calculate the speed.
NoBased on the difference between two consecutive readings it is able to determine a speed.
Pete317 said:
Yes, you measure distance by measuring how long the pulse takes to return, because the two are exactly proportional.
Just because you don't call it a distance measurement doesn't mean that you don't use exactly the same method as for getting a measure of distance.
If you can measure it using a clock it is time.Just because you don't call it a distance measurement doesn't mean that you don't use exactly the same method as for getting a measure of distance.
I'm not sure why any of this matters however...
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