Laser tape measure
- Thread starter jmumby
- Start date
Probably is round-trip pulse timing.
From another forum, a clever trick for measuring very short pulses ( the period between pulse initiation and echo recieved ) easily and cheaply is to quickly charge up a cap during that time. You have then translated an incredibly short pulse into a very usable voltage. Assuming 1ns for 1 foot, a cap which charges to full over 1ns and a 10-bit ADC, you can measure that foot to near 0.001 foot accuracy, equivalent to 1000GHz.
I'm sure it's not as simple in practice, but the principle is simple enough.
From another forum, a clever trick for measuring very short pulses ( the period between pulse initiation and echo recieved ) easily and cheaply is to quickly charge up a cap during that time. You have then translated an incredibly short pulse into a very usable voltage. Assuming 1ns for 1 foot, a cap which charges to full over 1ns and a 10-bit ADC, you can measure that foot to near 0.001 foot accuracy, equivalent to 1000GHz.
I'm sure it's not as simple in practice, but the principle is simple enough.
Michael 2727
Senior Member
If the unit is a - Leica Disto A5 - 0.05mtrs to 200mtrs +/- 2mm, or similar.
Then yes it is a real LASER measuring device.
But at $600.00+ AUD I can live without one for the moment
( they also have a delux model at $1,400.00 )
Not Picaxeable unfortunately, they only just keep up with U/Sonic.
Then yes it is a real LASER measuring device.
But at $600.00+ AUD I can live without one for the moment
( they also have a delux model at $1,400.00 )
Not Picaxeable unfortunately, they only just keep up with U/Sonic.
The true laser-based units start at $120US. Sears has one for that price that lists +/- 3/16 inch accuracy at 150 feet (0.5 cm at 46 meters).
http://www.sears.com/shc/s/p_10153_12605_00948298000P
There's also a long distance ultrasonic unit ($15US) that lists 1 inch at 150 feet - but it's a two piece unit with separate transmitter and receiver.
http://www.sears.com/shc/s/p_10153_12605_00948254000P?mv=rr
John
http://www.sears.com/shc/s/p_10153_12605_00948298000P
There's also a long distance ultrasonic unit ($15US) that lists 1 inch at 150 feet - but it's a two piece unit with separate transmitter and receiver.
http://www.sears.com/shc/s/p_10153_12605_00948254000P?mv=rr
John
For $120 Amazon has this http://www.amazon.com/Bosch-DLR165K-Laser-Rangefinder-Kit/dp/B000T7LISM/ref=pd_bbs_sr_2?ie=UTF8&s=hi&qid=1223091145&sr=8-2 Bosch one that claims an accuracy of +/- 1/16" over its entire range.
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How does the two piece unit work? How can the receiver measure the pulse-travel-time without knowing when the pulse was sent?
Only way I can think of ATM is that the first unit works just the same as a normal ‘reflection’ range finder, and the second is some sort of amplifier/repeater.
Only way I can think of ATM is that the first unit works just the same as a normal ‘reflection’ range finder, and the second is some sort of amplifier/repeater.