Measuring and Marking Tools : Find out which tools come in handy how does digital tape measure work visible calculating sizes and marking off placement in certain home improvement jobs on mesure page. Move your iPad Pro close to a line measurement to see the ruler view appear, then tap the shutter button to take a photo so you can use the increments for planning projects. Hot Network Questions. The dull serrated edge on the end of the tang can also be used as a marker. The DG is the opposite of the circuit you have in mind, i. This gives your device a frame of reference for the object you're measuring and the surface visiblr on.

It only depends on its two major features: lock and spring mechanism. The lock button behaves to stop the tape from retracting when you extend it. The spring mechanism plays as the automatic roller to retract the tape. The spring mechanism of a tape measure is actually a long flat coiled metallic material. Not all types of metallic material are able to generate spring property, however, steel commonly is. As you pull the tape out, the spring characteristic will be getting higher, and it is used to retract your tape automatically.

The tape is marked along the tape edge in inches and Unitool Digital Tape Measure 500 fractional inches, typically in quarter-, eight-, sixteenth-inch increments. Some tape measures are marked in millimeters, centimeters, and meters on one edge. The most common tape measures are 12 feet, 25 feet, or feet in length.

A foot tape measure is handiest for consumers. The foot length is called a builder's tape and is marked in feet and at inch increments to make measuring the standard distance between wall studs easier.

The foot tape, usually of reinforced cloth, is useful for determining property boundaries and other exterior measurements.

Tape measures are relatively safe and easy to use. Extend the tape from point to point placing the end-clip at the location you want to measure from. Most tape measures have a clip that can be attached to a fixed object to measure spans easily. Signal averaging would be your friend: sending a train of pulses and timing their average round trip time helps. This immediately suggests that continuous modulation would probably work better - it has an inherent filtering characteristic.

That leads to the second way to get an accurate measurement: by comparing the phase of the emitted and returned signal. This is quite trivial with a circuit that squares the transmitted and reflected wave, then takes the XOR of the two signals and averages the result.

Such a circuit will give minimum voltage when the two signals are exactly in phase, and maximum voltage when they are exactly out of phase; and the voltage will be very linear with phase shift. You then add a second circuit that detects whether signal 2 is high when signal 1 has a rising edge: that will distinguish whether signal 1 or signal 2 is leading. Putting the output of the logic gates into a low pass filter resistor and capacitor and feeding it into a low speed 12 bit ADC is sufficient to determine the phase with high accuracy.

There are ready made circuits that can do this for you - for example, the AD The only problem with the phase method is that you will find the distance modulo half the wavelength; to resolve this, you use multiple frequencies. There is only a single distance that has the right wavelength for all frequencies. A possible variation of this uses a sweeping frequency source, and detects the zero crossings of the phase - that is, every time the phase detector output is zero perfectly in phase you record the modulation frequency at which this occurred.

This can easily be done very accurately - and has the advantage that "detecting zero phase" doesn't even require an accurate ADC. A wise man taught me many years ago that "the only thing you can measure accurately is zero".

The distance would correspond to the round trip time of the lowest frequency which has a zero crossing - but you don't necessarily know what that frequency is you may not be able to go that low. Note that a technique like that requires very little compute power, and most of the processing is the result of very simple signal averaging in analog electronics.

You can Hilti Digital Tape Measure Warning read for example US patent application US for some details on how these things are implemented. A variation of the above is actually the basis of an incredibly sensitive instrument called the lock-in amplifier. The principle of a lock-in amplifier is that you know there is a weak signal at a known frequency, but with unknown phase which is the case for us when we look at the reflected signal of a modulated laser.

And then you average the output over many cycles. Something interesting happens when you do that: the circuit acts, in effect, as a phase sensitive bandpass filter, and the longer you wait the more cycles' output you average over , the narrower the filter becomes. Because you have both the I and the Q signals with their phase shift , you get both amplitude and phase information - with the ability to recover a tiny signal on top of a hug amount of noise, which is exactly the scenario you will often have with a laser range finder.

See for example the wiki article. The quadrature detection becomes quite trivial when you use a clock at twice the modulation frequency, and put two dividers on it: one that triggers on the positive edge, and one that triggers on the negative edge.

A couple of fast, electronic analog switches Etape Digital Tape Measure Uk 4g and a simple RC circuit complete the project. Which has turned a very hard measurement into a really easy one. The timing circuit doesn't have to run that fast. It just needs a time-to-digital converter which has a high enough resolution 0.

These are all fairly standard engineering techniques that sound complicated, but they are actually rather simple to implement. You could build something like that at home with an FPGA and cheap analog components.

If you want to see how it can be done, look at the schematics of an old DG Delay Generator from a company called Stanford Research Systems. That's an instrument that you can find in almost any physics lab and that can generate pulses with something like 5ps timing resolution.

Lumber Fencing Products Inc Amazon Woodcraft Cnc Piranha Xl For Sale