How to choose a laser or ultrasonic rangefinder? Arduino: ultrasonic rangefinder HC-SR04 Ultrasonic rangefinder manual
Laser rangefinders have been on the market for quite some time and every year manufacturers introduce new models with new functions. To help you understand the question: “Which laser rangefinder is better?” — we have made a brief overview of popular models and will tell you what criteria you should pay attention to when choosing.
Without which it is impossible to even imagine any construction or repair work, regardless of the scale and level of complexity - this is without taking measurements and without making markings. The accuracy and precision of such operations always become the key to the quality and durability of the resulting result. Therefore, the measuring instrument is always unconditional an important component of any owner’s tool arsenal houses or apartments.
One of the basic measurements is always the determination of distances and linear dimensions of objects. These values, in turn, become the starting points for calculations, for example, areas and volumes. For a long time, for these purposes, in addition to ordinary rulers, a cord with marks applied to it, corresponding to units of length, was used. A regular tape measure is the same tool, but instead of a cord, a metal, fabric or plastic tape with a printed scale is used. It is quite convenient and accurate, but if the distances being measured are small, or if there is an assistant when taking measurements. But alone, and at considerable lengths, you have to “split” the measured area into smaller ones, which, of course, affects both the time it takes to complete the work and its accuracy.
It’s a different matter if you have a compact and accurate device at your disposal - a laser rangefinder (or, as it is often called, a laser tape measure). Performing measurements takes a matter of seconds, and the accuracy of the results obtained is beyond praise. In addition, modern tools of this type often have additional functionality - they allow you to quickly carry out the necessary calculations, so to speak, in “field conditions”. The variety of models on sale is very wide, so before purchasing it would be useful to get information about which laser rangefinder is better.
What is the laser rangefinder based on?
There is no doubt that all high-tech developments are primarily “tested” in the military sphere. When the author of these lines entered the Odessa Higher Artillery School back in 1981, the first reconnaissance skills were mastered on the stereoscopic rangefinders DS-1 and DS-2. But, by the way, very few could work for them with a sufficient degree of accuracy. Therefore, the study of the DAK-1 laser rangefinder, which in those years was considered a secret weapon, was a great “revelation” for us.
Our joy was only overshadowed by the fact that delivering the rangefinder to the observation post turned into a considerable ordeal. The set consisted of two heavy metal boxes and a tripod. Therefore, having sweated a lot in class, we built bold dreams that someday such equipment would become much more compact, and would almost be an item of individual equipment for an artillery reconnaissance officer.
And so it happened, but much later.
Over time, military developments migrated to the public sphere, in particular to construction. And the development of technology has led to the fact that a device of this operating principle can now be easily bought in a store.
Of course, laser rangefinders that are offered to consumers today are still inferior in capabilities to modern military equipment. But they are not required to take measurements amounting to many hundreds of meters and kilometers. But the operating principle of both is very similar.
Distance measurement is based on the ability of an optically opaque surface to reflect light directed at it. That is, if you direct a powerful light pulse generated by a built-in emitter (laser) at the “target”, and then detect reflected signal, then, knowing the speed of light, you can determine the distance to the object.
But in reality, the measurement is performed somewhat differently. The fact is that the speed of light is enormous, and at small measured distances one has to operate with extremely short time intervals, measured in nanoseconds. Making a compact timer that could very accurately measure such small intervals is a very difficult and expensive task. Therefore, construction rangefinders use the principle combsphase shiftreflectedinfrared light pulse.
When you press the start button, the laser rangefinder emitter generates a light beam of a strictly defined wavelength and frequency. The beam directed at the desired point is reflected from it and received by the photodetector of the device. The built-in microprocessor compares the phases of the beam at the exit from the device and the reflected one. Since the frequency and wavelength of the radiation are known, the distance traveled by the beam can be estimated with high accuracy. The error is usually no more than half the wavelength, which gives an error within 1÷1.5 mm per meter of measured distance, which is considered an excellent indicator for construction conditions.
There are other types of rangefinders. Thus, powerful devices capable of accurately assessing distances of hundreds or more meters are equipped with a powerful pulsed laser that does not scatter the light beam, and a high-precision timer capable of measuring time intervals with the highest accuracy. But the cost of such devices is very high, and they are not used in everyday life.
The principle of reflection of sound waves is also used to measure range. Such ultrasonic “roulettes” are commercially available, they are designed to work for short distances. Judging by the reviews, they are not particularly praised by experienced builders, although this is not a categorical judgment.
But in this article, we will further focus only on phase-type laser rangefinders.
The device of a compact laser construction rangefinder
The shape of most modern laser construction rangefinders is largely reminiscent of Cell phones early 2000s. That is, they are quite compact, easily fit in a work clothes pocket, and are not at all difficult to use in construction or home renovation conditions.
As a rule, the device body is made of impact-resistant plastic and has a shape that is comfortable to hold in the palms of your hands. Since the rangefinder is designed to operate under construction or repair conditions, that is, in possible heavy dust and in any weather, the housing is provided with very serious protection - usually not lower than IP-44. Special shock-absorbing elastic linings on the body protect the device from damage if accidentally dropped.
Inside the case there is a light pulse generator (laser), an optical circuit for transmitting and receiving a signal, a microprocessor unit programmed to measure distances and perform a number of other useful functions.
Few people would probably think of the idea of disassembling this device, so we will limit ourselves to its external structure.
At the front end of the device, “windows” of the pulse emitter and photodetector are always visible. In some models, a compact optical view camera may also be located there.
On the front panel of the rangefinder there is a display on which the current settings of the device and the results of the measurements are displayed. Usually a monochrome liquid crystal display is used, although you can also find devices with color displays, although this, frankly speaking, seems like overkill.
Near the display there are rangefinder control buttons. Among them, of course, the start button, that is, the measurement button, always stands out. But most modern laser roulettes are equipped with a number of interesting useful functions - access to them or programming the device for a specific operating mode is also done using buttons, and the procedure is described in detail in the attached instructions.
There are also devices with touch “buttons” displayed on the display. True, how convenient it will be to work with them with dirty hands, which often happens during repair or construction, is not entirely clear.
For precise aiming of the device, if measurements are carried out at long distances, or due to the illumination characteristics of the object, the laser point may become invisible, additional capabilities can be provided to direct the beam precisely to the target. So, some rangefinders have an optical sight, similar to what we are used to seeing on cameras. The visor can be built-in or removable. The degree of optical approximation of the object in the viewfinder may also vary. If in professional-class devices designed to measure long distances, the magnification can reach up to 12 times, then in simpler models the sights are simpler, with 6-8 times magnification.
Some modern models are even cooler. The display of such devices through the built-in video camera can display image of the object to which the range is determined, with an aiming crosshair that allows you to accurately indicate the desired point.
On the back of the body of many models there is a folding or retractable stop (bracket or pin). This is a very convenient option that allows you to measure length from hard-to-reach points. For example, you can rest the rangefinder in the corner between the walls to measure the diagonal, etc.
Many rangefinders are equipped with a threaded bushing or other mechanism that allows the device to be fixed, for example, on a tripod, in order to accurately check distances in different directions from one point.
Bubble levels are often provided on instrument cases to allow the rangefinder to be positioned correctly vertically or horizontally.
The device may be equipped with a port for cable connection to a computer and have a slot for a memory card.
At the bottom of the case there is usually a battery compartment or a connector socket for connecting charger(if power is supplied from built-in batteries).
The device may include a case and straps for safer use of the device. Good application The set may include special targets that allow you to set the length measurement point as accurately as possible, for example, if it has not yet been set by any object capable of reflecting a light beam (often happens when laying out on the ground).
Criteria for evaluating a laser rangefinder when choosing
The variety of laser rangefinders presented in stores is quite wide. And in order not to overpay or encounter insufficient built-in functionality of the device, it is necessary to have a clear understanding of the scope of its application in advance.
- To carry out large-scale construction work on a site related to breaking out and marking the territory, linking objects, etc., apparently, it makes sense to purchase a device with an emphasis on the maximum measurement range. Thus, many professional or semi-professional class rangefinders (the division is fairly arbitrary) can operate at distances over 40÷50 meters. If the potential owner is going to use the device for internal repairs, then there is no point in chasing range. Indicators less than 40 m will be sufficient.
- But the accuracy of the measurements taken is always important. Especially if the laser tape measure will be used, for example, for precise fitting of furniture parts or installation of plumbing junctions, where every millimeter is always taken into account.
The smaller the error, the better. Devices whose deviations do not exceed 1÷1.5 mm are highly accurate. Most of the most affordable laser tape measures have an error of up to 3 mm. But if this range is larger, then the device can no longer be called particularly accurate, and you should think about whether you need such measurements with such significant errors. .
- Most rangefinders in an affordable price range are equipped with second-class lasers with a red glow. Color does not in any way affect the accuracy of measurements, but in bright light the point becomes barely noticeable. In addition, direct contact with the eye close at a distance such a beam can cause a burn to the cornea.
The green beam from a first class laser does not pose such a danger, and is more noticeable even in bright sunshine. True, rangefinders with such a laser are still rare, and are much more expensive.
- It is definitely worth assessing the body of the device. It has already been said that the security class must be at least IP44, and the higher this indicator, the better. This will allow you to work in conditions of heavy dust and in the rain. Elastic lining will help protect the rangefinder if it is suddenly dropped from your hand. Devices in a shock-resistant case do not lose their functionality when dropped onto a hard base from a height of one to two meters.
But, of course, it’s better not to drop it. For this purpose, many models are equipped with special straps, clips for carrying in a pocket, and belt pouches.
An important quality of any device used in construction is its operating temperature range. That is, it should function equally well both at the peak of summer heat and in frosty winter weather. This parameter must be indicated in the technical data sheet of the product.
Ideally, the rangefinder should be convenient to work in cold weather without removing seals or gloves, that is, the control buttons should be quite large. There is one more nuance - rubber buttons can become stiff in the cold and lose elasticity. So it makes more sense to purchase a rangefinder with silicone buttons for such purposes.
When working in the cold season, fogging of the optics becomes a “scourge”. Therefore, you should choose a rangefinder that uses lenses that eliminate this drawback.
- The rangefinder should be convenient for the owner. You should evaluate how it “fits in your hand” and how convenient it will be to press the start button in difficult positions.
It is difficult to say whether the excessive compactness and low weight of the device is an advantage. Sometimes it happens that it's too miniaturized and a lightweight laser rangefinder, on the contrary, complicates measurements, since it reacts sensitively to even very slight trembling of the hand. Of course, there must be a reasonable measure in everything - a device that is too large and heavy will also be extremely inconvenient.
If you plan to carry out a large number of measurements from one “base” point, then you should choose a device that has the ability to be fixedly mounted on a rotating tripod.
- It would be useful to immediately clarify which batteries and in what quantity ensure the operation of the device. Sometimes the duration of operation on a set of batteries is also indicated. If the laser rangefinder is powered by a built-in battery, then the kit must include a corresponding adapter for charging from the mains.
To preserve the potential of power supplies for as long as possible, many laser rangefinders are equipped with an automatic shutdown feature when not in use. For example, if no measurements have been taken for a minute, the power will be turned off. The duration of the pause can be different, and often you can set it yourself in the preliminary settings.
It is convenient if the device screen has an indicator of the power supply charge level.
- The simplest rangefinders are designed only to measure distances from one reference point, which in most cases is the rear end of the body. That is, the device is applied to the surface from which it is necessary to take measurements, and then the start button is pressed.
More advanced rangefinders provide the ability to take measurements from several reference points of your choice. For example, four points: from the rear or front end sides, from the point of attachment of the device to the tripod, from the tilted or extended support. By the way, in some models, when this stop is opened, switching to the desired measurement mode occurs automatically.
- Modern laser rangefinders represent a whole “computational complex” that allows not only to determine distances, but based on these values also to carry out a number of necessary calculations:
— For such a device it will not be difficult to quickly and accurately display the area and volume of a room. Moreover, areas can often be calculated for figures located on a slope (for example, roof slopes).
— The built-in “Pythagoras” function makes it possible to determine the length of the side of a triangle, which is impossible or extremely difficult to measure in the usual way. For example, you can determine the height of an object by measuring the distance to its base and top point. Or, say, calculate the required distance to an object if direct visibility to it is limited by some temporary or permanent obstacle.
A built-in calculator with included calculation programs allows you to quickly determine those values that are in this moment it is impossible to measure or extremely inconvenient. For example, the Pythagoras function calculates the unknown side of a triangle from two measured ones.— A convenient function is to divide the distance into a given number of segments of equal or equal proportions to the length. For example, this will make it easier to accurately position fence or foundation posts, guide sheathing, etc.
— The discrete ranging (tracking) function will be a good help. This means that the rangefinder will take measurements at certain small intervals as the direction of the laser beam moves. It becomes possible, for example, to find the distance to an outer or inner corner, when it is not possible or very difficult to “aim” accurately. The display will optionally show the minimum or maximum value of all those obtained during such “probing” of the object.
— Measured readings and calculated values can be entered into cells internal memory rangefinder or recorded on an SD card. You can purchase a device that will automatic mode transfer data via Bluetooth to a mobile device. Often a cable connection to computers is provided for the exchange of received information.
— Some devices also allow you to carry out angular measurements - for this they are equipped with an inclinometer function. That is, after placing the rangefinder on a tripod and checking its horizontality, you can accurately calculate the angular values of the heights of nearby objects. This will further expand the capabilities of the device for “field” work and when marking for finishing.
- When choosing, you should evaluate the information content of the display and its clarity for quick perception. Don’t be too lazy to immediately check how clearly the operating instructions are written, so that you don’t have to look for answers on the Internet or master working with the device “empirically”, that is, by the “trial and error” method.
The disadvantage of some models is that the readings are very difficult to read or become completely invisible in clear sunny weather or at dusk. Therefore, it is preferable for such operating conditions to have a rangefinder with a backlit screen.
- The completeness has already been mentioned above. But we still need to add a couple more points.
— The accuracy of measurements often depends on the state of the surface of the object to which the range is determined. Thus, it may have too high an absorbing or scattering ability, making it difficult to reflect the beam. Or, conversely, a mirror-polished surface can make its own “adjustments.” So that you don’t have to come up with anything along the way, it’s better to have a standard target. It is usually double-sided, with thoughtful contrasting colors on the sides. When measuring at short distances (up to 40 meters), a light target is often used, and vice versa.
— And to make the trace of the laser beam more visible in unfavorable conditions, glasses with a special light filter are often included in the kit. If they are not included in the kit, you can purchase them separately - they are not that expensive.
- Finally, one of the important selection criteria is always the brand of the product. Preference, of course, should be given to proven brands that enjoy unquestioned authority in this area. These include devices from Leica, Bosch, DeWalt, Makita, and AEG. Excellent rangefinders at a fairly reasonable price are offered by Condtrol, ADA, Hammer, ADA, RGK, STABILA, and Skill. Interestingly, Chinese products from various companies also show very good results. But they, as a rule, have a common problem, which is the almost complete absence of warranty obligations and the possibility service. That is, they serve regularly for who knows how long (depending on your luck), and then it is better to replace them - fortunately, the price is low.
By the way, if you choose a “branded” product, then it makes sense to immediately check in the store both the terms of the warranty and the availability of branded service centers in the immediate vicinity.
Now let’s take a short “excursion” into the models of laser rangefinders that won the greatest appreciation from users in 2017.
Brief overview of the top models of laser rangefinders (2017)
To avoid confusion, we will divide the rating models into two subcategories. The first of them is rangefinders, mainly intended for indoor work, that is, with relatively small measured distances. In the second - devices that allow successful do work on the ground.
Laser rangefinders for work indoors or at short distances
"BOSCH DLE 40"
One of the undisputed leaders in popularity among devices of this class.
“Bosch DLE 40” - the model is in extremely high demand among a wide range of consumersBasic device characteristics:
— Laser class - 2;
— Wavelength - 635 nm;
40 m.
- Amount of pointscountdown- two.
— from -10 to +50 degrees.
.
— Measurement time- 0.5 s.
.
— Batteries - 4 batteriesAAA.
— Dimensions - 100×58×32 mm.
— Weight - 180 g.
volume, calculations triangles.
— Approximate cost - 6200 rubles.
— Highest reliability in any operating conditions.
— Economical consumption of food.
— Comfortable body with elastic linings that won’t slip even from wet hands.
Flaws:
— In bright sunlight, the display readings are not particularly visible. Additional lighting would be nice.
— This particular model does not have a bubble level.
"Makita LD030 P"
Compact laser rangefinder with a limited number of functions and low cost
Device characteristics:
— Laser class - 2;
— Wavelength - 635 nm;
— Maximum measurement range - up to30 m.
— Measurement accuracy - ± 1.5 mm.
- Amount of pointscountdown- two.
— Operating temperature range -from - 25 to +50 degrees.
— There is no threaded socket for a tripod.
— Batteries - 2 AAA batteries, which should be enough for 5000 measurements.
— Dimensions - 115×53×25 mm.
— Weight - 90 g.
— Set of functions: single range measurements, area calculations, tracking (discrete measurements)
— Included is a convenient belt pouch.
— Approximate cost - 4100 rubles.
Noted advantages:
— Convenient layout for operation.
— No “overload” with control buttons, simple operation algorithm.
— Large symbols on the display and good backlighting – readings are easy to take, including in sunny weather or in poor visibility conditions, and by people with low vision
- Affordable price.
Comments made:
Unfortunately, with such a “loud” brand, there is a very high percentage of complaints, apparently due to licensed assembly. Warranty obligations are strictly observed, but nevertheless...
Makita laser rangefinder prices
Makita laser rangefinder
"Control X2 Plus"
Multifunctional laser rangefinder in the mid-price range
Basic model characteristics:
— Laser class - 2;
— Wavelength - 650 nm;
— Maximum measurement range - up to60 m.
- Amount of pointscountdown- three, taking into account the folding bracket for measuring from corners.
— Measurement systems - metric and inch.
— Dimensions - 110×43×26 mm.
— Weight - 70 g.
— A set of functions for calculating area,volume, calculations triangles, segmentation, tracking.
— Included is a case.
— Approximate cost - 4400 rubles.
The indicated advantages:
— Good functionality;
- Quite affordable price.
— Original appearance and an easy-to-read display.
Claims made:
— The device is too “heat-loving” - even with a slight frost, malfunctions begin.
— The downward sloping body makes it difficult to maintain a stable vertical position of the rangefinder when measuring the distance from the top.
The buttons are located too close, and when working with mittens this creates considerable difficulties.
— The speed of measurements leaves much to be desired - you have to wait more than a second to get the result.
"ADA Cosmo MINI A00410"
Reliable and accurate laser rangefinder at short distances.
Laser rangefinder characteristics:
— Laser class - 2;
— Wavelength - 650 nm;
— Maximum measurement range - up to30 m.
— Measurement accuracy - ± 3 mm.
- Amount of pointscountdown- two;
— Temperature range of operation - from 0 to +40 degrees.
— Batteries - 2 AAA batteries.
— Dimensions - 107×428×24 mm.
— Weight - 110 g.
— A set of functions for calculating area,volume, calculationstriangles, tracking .
Advantages of the model:
— A good, but not redundant set of functions.
— Compact dimensions, impact-resistant housing with protection class IP54.
— A very simple and convenient operating algorithm. Just three buttons.
- Easy to read display.
— Well visible laser beam.
— Super attractive price for similar functionality
Flaws:
- Not the most outstanding accuracy indicators - an error of 3 mm sometimes becomes too much.
— Not designed for negative temperatures.
— No cover included.
— There are complaints about the clarity of the operating instructions supplied with the rangefinder.
"RGK D30"
An easy-to-use laser roulette with a minimum set of necessary functions and a high user rating.
Model characteristics:
— Laser class - 2;
— Wavelength - 6390 nm;
— Maximum measurement range - up to30 m.
— Measurement accuracy - ± 2 mm.
- Amount of pointscountdown- one.
— Operating temperature range is from 0 to +40 degrees.
— Measurement systems - metric and inch.
— Measurement time- from 0.5 to 4 s.
— Batteries - 2 AAA batteries.
— Dimensions - 110×43×24 mm.
— Weight - 69 g.
— A set of functions for calculating area,volume, calculationstriangles, tracking
— Includes a case and a wrist strap.
— Approximate cost - 2500 rubles.
Advantages mentioned by users:
— Excellent housing protection – IP54.
— Soft silicone buttons.
— 10 memory cells for storing measurement and calculation results.
— Automatic shutdown function when idle.
— Backlit display, easy to read in any conditions.
Flaws:
— The bubble level on the body is more of a decorative element, since it does not differ in accuracy.
— The error when measuring at the same point with a stationary device, although not much, still went beyond the stated ± 2 mm
- Not particularly good performance.
— You cannot work at subzero temperatures.
These disadvantages are largely compensated by the simplicity of the device and a very affordable price.
Laser rangefinders for field work
Such devices have fairly high measured ranges and are often equipped with optical sights or video cameras. They allow you to carry out a variety of operations on marking out a site, linking objects, and performing construction work.
"BOSCH GLM 250VF"
High-quality “all-weather” model with a wide range of functions
The model is far from new, but every year it consistently ranks among the most popular and reliable.
Basic device characteristics:
— Laser class - 2;
— Wavelength - 635 nm;
— Maximum measurement range - up to250 m.
- Amount of pointscountdown- four, including a folding pin for measuring from hard-to-reach places.
— Operating temperature range -from - 10 to +50 degrees.
— Measurement systems - metric and inch.
— Measurement time- 0.5 s.
— Threaded socket for tripod ¼ inch.
— Built-in optical sight
— Dimensions - 120×66×37 mm.
— Weight - 240 g.
— A full set of functions for auxiliary calculations.
— Includes a carrying strap.
- Approximate cost - 22000 rub.
Advantages mentioned by users:
— Excellent performance in any measurement conditions.
— 20 memory cells for storing measurement and calculation results.
— Automatic shutdown when idle.
— Availability of a convenient optical “sight” for measuring distances to distant objects.
— Highest quality assemblies.
Flaws:
— There is no battery charge indicator.
— In dusty conditions and on a bright sunny day, the measurement range drops to about 100 meters.
— Despite the emergence of new models, apparently due to the remaining high demand, the price is quite high and does not yet have a downward trend.
Prices for BOSCH laser rangefinder
BOSCH laser rangefinder
"LEICA DISTO D510"
Professional model with high measurement accuracy.
Basic device characteristics:
— Laser class - 2;
— Wavelength - 635 nm;
— Maximum measurement range - up to200 m.
— Measurement accuracy - ± 1.0 mm.
- Amount of pointscountdown- five.
— Built-in video viewer with 4 multiple zoom;
— A tilt sensor with a range of 360 degrees allows for angular measurements. Units of measurement – degrees, percent, mm/m, inches by feet.
— Operating temperature range -from - 10 to +50 degrees.
— Measurement time - 0.5 s.
— Threaded socket for tripod ¼ inch.
— Batteries - 2 AAA batteries.
— Dimensions - 143×58×29 mm.
— Weight - 198 g.
- Full set.
— Communication system with mobile devices via Bluetooth protocol.
— Built-in memory for 30 cells. Possibility of installing an additional memory card.
— The set includes a convenient belt pouch-holster and a wrist belt.
— Approximate cost - 38,500 rubles.
Advantages mentioned by users:
— Highest reliability and accuracy in any operating conditions.
— A very wide range of functions, a very convenient interface for working with them.
— Impeccable production quality.
— The device is included in the State Register of Measurement Systems.
Flaws:
— High price, making the device inaccessible.
— Batteries run out quickly, even when the device is turned off. When left for a long time, it is better to remove the batteries from the compartment.
"CST/Berger RF25"
Professional grade laser rangefinder. Natural glass coated optics and an original ceramic lens fixation system determine the highest measurement accuracy.
Device characteristics:
— Laser class - 2;
— Wavelength - 635 nm;
— Maximum measurement range - up to250 m.
— Measurement accuracy - ± 1.0 mm.
- Amount of pointscountdown- four .
— Three-position stop pin on the rear of the housing.
— Built-in sight and additional connection of a full-fledged optical “sight” for working at extreme distances.
— Length measurement systems - metric and inch.
— Operating temperature range -from - 10 to +50 degrees.
— Measurement time - 0.5 s.
— Threaded socket for tripod ¼ inch.
— Precise bubble level on the body.
— Batteries - 4 AAA batteries.
— Dimensions - 120×66×37 mm.
— Weight - 240 g.
- Full setnecessary functions for “field” calculations.
— Built-in memory for 30 cells.
— Includes a convenient protective case and a wrist strap.
— Approximate cost - depending on the configuration and the region of sales - from 19 to 25 thousand rubles.
Advantages of the model:
— unquestionable measurement accuracy at any distance thanks to high-quality optics.
— Wide range of functions.
— Multi-line informative display with easy to read readings.
— Excellent build quality.
— Impact-resistant housing with protection degree IP54. The device can easily withstand falls onto a concrete floor from a height of 1 meter.
— There is no data recorded on model returns due to lack of quality.
Flaws:
Users have not expressed any significant shortcomings, with the exception of the inflated price (taking into account the lack of a slope sensor).
So, the criteria for choosing a laser rangefinder were considered, and an overview of popular models was given. In conclusion, it is worth saying, perhaps a banality, but it is still necessary.
Tools of this class should be purchased exclusively in reliable specialized stores, where you can get competent advice, study the terms of the guarantee, and be sure to make a note in your passport about the place and date of purchase. Trusting dubious retail outlets or paying a lot of money for a “pig in a poke” when buying online from random sellers is hardly wise.
Prices for popular laser rangefinders
In conclusion, an interesting video showing the capabilities of the Bosch GLM 50 C laser rangefinder
Video: Demonstration of the functionality of the Bosch GLM 50 C laser rangefinder
Non-contact methods of measuring distances using waves in the ultrasonic range are widely used in our Everyday life. We encounter them when doing ultrasound in the clinic, using an echo sounder while fishing. Parking sensors in a car help us avoid a collision by reversing. And of course, ultrasonic sensors are widely used in robotics, helping our robot to better “feel” the world. In wildlife, the principle of ultrasonic location is used, for example, by bats and dolphins. Today I will tell you how it all works.
What is ultrasound
A person is capable of perceiving sound waves that oscillate in the range from 20 to 20,000 Hz (let me remind you, 1 Hertz is the number of oscillations per second). With age, the range of frequencies we perceive decreases, but on average, a child is able to perceive sound in this range. If the vibrations of sound waves exceed this range, then a person ceases to perceive them, but bats, dogs, dolphins, and moths may well hear them. Such vibrations are examples of ultrasound. Ultrasound is elastic oscillations and waves in the range from 20 kHz to 1 GHz. Term elastic emphasizes non-electromagnetic the nature of these vibrations and waves.
The length of a wave is inversely related to its frequency, therefore ultrasonic waves have a shorter wavelength compared to ordinary sound. As a result, ultrasonic waves reflect from various obstacles much better than ordinary sound waves, which makes them very useful in practice.
Piezoelectric effect and magnetostriction
How to obtain vibrations in the ultrasonic range?
The crystals of some materials (such as quartz) are capable of very rapid vibrations when electricity passes through them. This is the so-called back piezoelectric effect. As they vibrate, they push and pull the air around them, thereby producing ultrasonic waves. Devices that produce ultrasonic waves using piezoelectricity are known as piezoelectric transducers. Piezoelectric crystals also work in the reverse order: if ultrasonic waves, propagating through the air, collide with a piezoelectric crystal, slightly deform its surface, resulting in an electric field in the crystal. So, if we connect a piezoelectric crystal to an electrical voltage meter, we get an ultrasound detector.
Ultrasonic waves can be produced using magnetism instead of electricity. Just as piezoelectric crystals produce ultrasonic waves in response to electricity, there are other crystals that emit ultrasound in response to magnetism. This is the effect magnetism. Such crystals are called magnetostrictive crystals. Sensors using them are called magnetostrictive transducers.
In English-language literature, ultrasonic sensors are called ultrasound sensor.
Ultrasonic range finder
Using piezoelectric or magnetostrictive transducers, we can create a device that measures the distance to objects - an ultrasonic rangefinder, which works as follows.
At the moment of measurement, we create an electrical vibration using a generator, which, transformed (for example, using a piezocrystal) into an ultrasonic wave, is emitted into the surrounding space. This wave is reflected from the obstacle and returns as an echo to the receiver (a piezo crystal can also be used). By measuring the time between sending and receiving our reflected signal and knowing the speed sound wave distributed in a given environment (for air this value is about 340 m/s), we can calculate the distance to the obstacle.
- Measuring objects made of sound-absorbing, insulating materials or having a fabric (wool) surface may lead to incorrect measurements due to signal absorption (attenuation). A domestic shepherd can become a kind of “stealth” for an ultrasonic rangefinder.
- The smaller the object, the less reflective surface it has. This results in a weaker reflected signal.
Knowing the limitations associated with the physical nature of ultrasound, you can decide whether this type of rangefinder is suitable for your task or not.
Vasilyeva Maria 108
A thankless task such as measuring the distance between objects or walls in a room with a regular tape measure has long since become a thing of the past. Today, a modern device for accurate and fast non-contact measurement distances – rangefinder . This device is used in construction and repair, geodesy, hunting, fishing, photography and comes in the following types: ultrasonic rangefinder and laser rangefinder.
Ultrasonic rangefinder like an echo sounder, it sends and picks up the reflection of directed beams of sound waves in the ultrasonic range (approximately 40 kHz), analyzes the time it takes for the sound to return, and from this data calculates the distance between distant objects. The disadvantages of these types of devices are: a short measurement distance of up to 35 meters, the object to reflect the sound signal must be quite large in size, ultrasound can be extinguished when passing obstacles in the form of fabric materials. However, ultrasonic rangefinders are more common because they are less expensive than laser rangefinders.
Laser rangefinder does not analyze the reflection time of the sound signal, but compares the phases of the sent and reflected light signals. The distance measurement accuracy of a laser rangefinder is higher than that of an ultrasonic rangefinder. The measurement error is very small - only 1–5 mm when the laser signal passes through curtains and carpets. The maximum measured distance can be up to 250 meters, but bright sunlight or rainy weather somewhat dims the brightness and clarity of the laser beam. And most importantly, the high cost of laser rangefinders compared to ultrasonic ones tips the balance when purchasing a measuring device in favor of the latter.
 |
viva-telecom.org | RUB 20,100 | |
| OptTools | RUB 14,669.70 | ||
 |
Bigham | RUB 11,645 | |
 |
viva-telecom.org | RUB 11,205 |
Considering the short measurement range and relative measurement accuracy, ultrasonic devices belong to the household class of rangefinders, while most laser models belong to professional rangefinders.
In addition to directly measuring the distance between objects, many rangefinders have a number of useful and necessary options, such as:
Calculation of the area and volume of the room;
Addition, subtraction, calculation of the area of a triangle, calculation using the Pythagorean formula and memorizing the results;
Display backlight, sound signal, automatic shutdown, measuring point marker, compass, thermometer, timer, built-in level, inclinometer, magnetic declination;
Installing the device on a tripod, on a folding bracket, on a wrist strap, or on a belt case;
Possibility of providing data to Personal Computer, Bluetooth support and so on.
 |
viva-telecom.org | RUB 12,500 | |
 |
Rangefinder is a device for measuring the distance to an object. The rangefinder helps robots in different situations. A simple wheeled robot can use this device to detect obstacles. The flying drone uses a rangefinder to hover above the ground at a predetermined altitude. Using a rangefinder, you can even build a map of the room using a special SLAM algorithm.
1. Operating principle
This time we will analyze the operation of one of the most popular sensors - an ultrasonic (US) rangefinder. There are many different modifications of such devices, but they all work on the principle of measuring the travel time of reflected sound. That is, the sensor sends a sound signal in a given direction, then catches the reflected echo and calculates the flight time of the sound from the sensor to the obstacle and back.
From a school physics course we know that the speed of sound in a certain medium is constant, but depends on the density of the medium. Knowing the speed of sound in air and the flight time of sound to the target, we can calculate the distance traveled by sound using the formula: s = v*t where v is the speed of sound in m/s, and t is time in seconds. The speed of sound in air, by the way, is 340.29 m/s. To cope with its task, the rangefinder has two important design features. Firstly, in order for sound to be reflected well from obstacles, the sensor emits ultrasound with a frequency of 40 kHz. To do this, the sensor has a piezoceramic emitter that is capable of generating such high frequency sound. Secondly, the emitter is designed in such a way that the sound does not spread in all directions (as is the case with conventional speakers), but in a narrow direction. The figure shows the radiation pattern of a typical ultrasonic rangefinder. 
As can be seen in the diagram, the viewing angle of the simplest ultrasonic rangefinder is approximately 50-60 degrees. For a typical use case, where the sensor detects obstacles in front of it, this viewing angle is quite suitable. Ultrasound can even detect a chair leg, while a laser rangefinder, for example, may not notice it. If we decide to scan the surrounding space, rotating the rangefinder in a circle like a radar, the ultrasonic rangefinder will give us a very inaccurate and noisy picture. For such purposes, it is better to use a laser rangefinder. It is also worth noting two serious disadvantages of the ultrasonic rangefinder. The first is that surfaces with a porous structure absorb ultrasound well, and the sensor cannot measure the distance to them. For example, if we decide to measure the distance from a multicopter to the surface of a field with tall grass, we will most likely get very fuzzy data. The same problems await us when measuring the distance to a wall covered with foam rubber. The second disadvantage is related to the speed of the sound wave. This speed is not fast enough to make the measurement process more frequent. Let's say there is an obstacle in front of the robot at a distance of 4 meters. It takes as much as 24ms for the sound to travel back and forth. You should measure 7 times before installing an ultrasonic rangefinder on flying robots. 2. Ultrasonic rangefinder HC-SR04
In this tutorial we will work with the HC-SR04 sensor and the Arduino Uno controller. This popular rangefinder can measure distances from 1-2 cm to 4-6 meters. At the same time, the measurement accuracy is 0.5 - 1 cm. There are different versions of the same HC-SR04. Some work better, others worse. You can distinguish them by the pattern of the board on back side. The version that works well looks like this:
Here's a version that may fail: 
3. Connection HC-SR04
The HC-SR04 sensor has four outputs. In addition to ground (Gnd) and power (Vcc), there is also Trig and Echo. Both of these pins are digital, so we connect them to any pins of the Arduino Uno:| HC-SR04 | GND | VCC | Trig | Echo |
| Arduino Uno | GND | +5V | 3 | 2 |
Layout appearance
4. Program
So, let's try to order the sensor to send a probing ultrasonic pulse, and then record its return. Let's see what the timing diagram of the HC-SR04 looks like.
The diagram shows that to start measuring we need to generate at the output Trig positive pulse 10 µs long. Following this, the sensor will release a series of 8 pulses and raise the level at the output Echo, switching to the mode of waiting for the reflected signal. Once the rangefinder senses that the sound has returned, it will complete a positive pulse on Echo. It turns out that we need to do only two things: create a pulse on Trig to start measuring, and measure the length of the pulse on Echo, so that we can then calculate the distance using a simple formula. Let's do it. int echoPin = 2; int trigPin = 3; void setup() ( Serial.begin (9600); pinMode(trigPin, OUTPUT); pinMode(echoPin, INPUT); ) void loop() ( int duration, cm; digitalWrite(trigPin, LOW); delayMicroseconds(2); digitalWrite (trigPin, HIGH); delayMicroseconds(10); digitalWrite(trigPin, LOW); duration = pulseIn(echoPin, HIGH); cm = duration / 58; Serial.print(cm); Serial.println(" cm"); delay (100); ) Function pulseIn measures the length of the positive pulse on the echoPin leg in microseconds. In the program, we record the flight time of the sound in the duration variable. As we found out earlier, we will need to multiply the time by the speed of sound: s = duration * v = duration * 340 m/s Convert the speed of sound from m/s to cm/μs: s = duration * 0.034 m/µs For convenience, we convert the decimal fraction to an ordinary fraction: s = duration * 1/29 = duration / 29 Now let’s remember that the sound traveled two required distances: to the target and back. Let's divide everything by 2: s = duration / 58 Now we know where the number 58 in the program came from! Load the program onto the Arduino Uno and open the serial port monitor. Let's now try to point the sensor at different objects and look at the calculated distance in the monitor. Tasks
Now that we can calculate distance using a rangefinder, we will make several useful devices.- Construction rangefinder. The program measures the distance every 100ms using a rangefinder and displays the result on a symbolic LCD display. For convenience, the resulting device can be placed in a small case and powered by batteries.
- Ultrasonic cane. Let's write a program that will “beep” a buzzer at different frequencies, depending on the measured distance. For example, if the distance to an obstacle is more than three meters, the buzzer makes a sound once every half a second. At a distance of 1 meter - once every 100ms. Less than 10cm - beeps constantly.
Conclusion
The ultrasonic rangefinder is an easy-to-use, low-cost, and accurate sensor that has performed its function well on thousands of robots. As we learned in the lesson, the sensor has disadvantages that should be taken into account when building a robot. Good decision may be the joint use of an ultrasonic rangefinder paired with a laser one. In this case, they will level out each other’s shortcomings.I ordered this device because of my craving for multifunctional gadgets. Rangefinder, and even a tape measure for measurements short distances in one bottle - it's cool! Of course, I was aware that measuring distances with ultrasound has many disadvantages and cannot be compared with measuring with a laser rangefinder, but the opportunity to test a new, and not yet described, device prevailed, and I ordered it.
So if you're wondering what happened...
The rangefinder came in standard OEM packaging for the store - a white cardboard box. The kit included the rangefinder itself, a power source (a rare 23A 12V battery in our region) and instructions. 
The rangefinder is similar in design and size to a regular tape measure. Only, unlike a roulette, there is a liquid crystal display and functional buttons on the side. 
On the opposite side there is a battery compartment and a button for folding the tape measure. Yes, here, unlike a regular tape measure, the tape is fixed when removed. 
On the front side there is an ultrasound emitter/receiver, a laser pointer and a measurement activation button. 
At the top there is a power switch and a tape measure output. The total length of the tape measure is 1 m. Material is plastic. On one side the scale is in millimeters, on the other - in inches. Compared to my 3-meter tape measure made of metal tape, it looks quite modest. 
The weight of the rangefinder with battery is almost 90 g. 
The body of the device is fastened with only two bolts (the other two cover the compartment with the tape measure). This made it possible to open it without any problems in order to get acquainted with the internal structure. 
Measurements
Declared device parameters:Measuring distance: 0.5 – 18 m.
Accuracy: 0.5%
Operating frequency: 40 kHz
Working temperature: 0 – +43 degrees Celsius
Unlike measurements with a tape measure, to carry out correct measurements with ultrasound, certain conditions must be met:
1) Since the measurement is carried out according to the principle of echolocation (the time during which the ultrasonic wave reaches an obstacle, is reflected from it and returns back is measured), it is necessary that the space between the device and the object, the distance to which is measured, be free. It is also undesirable to measure objects that can absorb sound waves (for example, curtains) and have an uneven surface.
2) The speed of propagation of ultrasound in air depends on temperature. To assess the temperature, a temperature sensor is built into the rangefinder. Since it is located inside the device, when transferring it from one temperature environment to another, before measuring, you should wait until the temperature of the device is equal to the ambient temperature.
3) The front of the sound wave expands as it propagates, so if the object to which the measurement is being made is located at a greater distance, it must also be large enough (that is, measuring the length of a narrow and long corridor may be incorrect).
4) Atmospheric fluctuations also affect the measurement, so it is not recommended to use the device outdoors.
The limitations imposed on the measurements, as you can see, are so significant that they exclude the professional use of this instrument.
In everyday life, measurements are needed quite rarely; they usually take place in more comfortable conditions and do not require millimeter precision. Personally, I did them with a regular tape measure. The applicability of an ultrasonic rangefinder for household measurements, in my opinion, depended on how convenient and accurate it would be compared to a tape measure.
First of all, let's check the accuracy of temperature determination. I think it's acceptable. 
The measurement process consists of pointing the device at the surface to which the distance is being measured and pressing the “MEAS” button. The surface at the place where the sound wave is applied is illuminated with a laser (this is so that we can see where exactly we are measuring the distance), a soft click is heard and the result is displayed on the screen. Everything takes a couple of seconds.
As for the accuracy of measurements. The rangefinder has the option of measuring distance from the trailing (default) or leading edge. Regardless of the choice of edge, for some reason the device adds 2 cm to the measurement result. Judging by a similar problem described in, this is obviously some kind of electronic nuance. The accuracy, as you can see, in both cases is comparable to the accuracy of a tape measure (naturally, taking into account the 2 cm indentation). The distance between the edges is 7cm.
From trailing edge 
From leading edge 
The measurements were carried out in a narrow and long corridor, precisely in conditions where the use of an ultrasonic rangefinder is not recommended. For this reason, the starting point of measurements was located approximately in the middle of the corridor, distances were measured on both sides of it, and the summation function was used to determine the total length (button " +/= ").
In one direction it turned out to be 5.29 m. 
To the other - 9.29 m. 
Total – 14.58 m. Total measurement time – 30 seconds. 
In principle, any number of distances can be summed up in this way; the main thing here is not to get lost in the measurement process.
The length of the corridor, as measured with a tape measure, was 15 m, and the process of measuring with a 3-meter tape took about 5 minutes (including pencil marks). This result is more accurate, but labor costs are significantly higher.
In addition to summation, the device can multiply values (button " x/="), which allows you to calculate the area 
And volume 
conclusions
Regarding the use of an ultrasonic rangefinder as such:
Pros:Comfortable. No need to wander around the room with a tape measure. The measurement process takes just seconds.
Minuses:
Low measurement accuracy. The process of sound transmission is influenced by quite a few external factors, so the measurement error in different conditions will also be different. In addition, if with a tape measure we can simply measure on the floor, regardless of its slope, then the rangefinder will have to be fixed at the level so that the wave does not go to the side.
Limited scope. Distances can only be measured to relatively large and flat objects and only indoors.
Regarding the very idea of combining a tape measure and a rangefinder.
As usual, the Chinese have a great idea and lame implementation. The ultrasonic rangefinder itself is in little demand due to low accuracy and limited scope. If you equip it with a tape measure, you can take quick measurements with a rangefinder, and more accurate or inaccessible to the rangefinder measurements with a tape measure.In reality, the scope of application of tape measurements is much higher, therefore, it would be necessary to quality roulette attach a range finder. That is, a rangefinder should be an additional option, rather than a mediocre tape measure turning a mediocre rangefinder into a multifunctional device.
In general, as an idea, such a “combine” has a right to life. As for this specific implementation, it's up to you. Personally, I satisfied my curiosity by receiving this tool for free for review from the online store Chinabuye.com. Would I buy it? I think no. There are too few situations in which I would find a use for it.
I'm planning to buy +9 Add to favorites I liked the review +9 +30
