We make and sell echo sounders ourselves. Self-made mini-echo sounder on the Atmel ATMega8L microcontroller and LCD from a nokia3310 mobile phone. Cheap wireless fish finder with Aliexpress for fishing

An electronic echo sounder can be useful for a variety of underwater activities - not just for fishing.
The echo sounder can be made in two versions: with depth measurement limits up to 9.9 m (its display has two luminescent indicators) and 59.9 m (three indicators).
Their other characteristics are the same:
instrumental error - no more than ±0.1 m,
operating frequency - 170 ... 240 kHz (depending on the resonant frequency of the radiator),
pulse power - 2.5 W.
The ultrasonic emitter is also the echo signal receiver - a barium titanate plate with a diameter of 40 and a thickness of 10 mm.
The power source of the echo sounders is a "Korund" type battery.
Current consumption - no more than 19 and 25 mA (respectively, in echo sounders for shallow and great depths).
Echo sounder dimensions - 175x75x45 mm, weight - 0.4 kg.

Schematic diagram of the sonar

The clock generator G1 controls the interaction of the device nodes and ensures its operation in automatic mode. The short (0.1 s) rectangular pulses it generates are repeated every 10 s. With their front, these pulses set the digital counter PC1 to zero and close the receiver A2, making it insensitive to signals for the duration of the transmitter.

The falling clock pulse triggers the transmitter A1 and the transmitter BQ1 emits a short (40 μs) ultrasonic probing pulse towards the bottom. At the same time, the electronic key S1 opens and the oscillations of the reference frequency from the generator G2 are fed to the counter PC1.

At the end of the transmitter, the receiver A2 opens and acquires normal sensitivity. The echo signal reflected from the bottom is received by the same BQ1 and closes the key S1. The measurement is completed, the measured depth is displayed on the indicators of the PC1 counter.
Depth calculation is easy : at a speed of sound propagation in water of 1500 m/s, in 1/7500 s the front of the signal making the double path will move 0.2 m; and, accordingly, the lowest unit on the counter display will correspond to a depth of 0.1 m.

The next clock pulse will again transfer the PC1 counter to the zero state and the process will repeat.

circuit diagram echo sounder with a depth measurement limit of 59.9 m is shown in Fig. 2.

Its transmitter, self-excited at the frequency of the ultrasonic emitter BQ1, is made on transistors VT8, VT9. Switching the transmitter on and off is controlled by a modulator - a waiting single vibrator (VT11, VT12, etc.), which supplies power to the transmitter through its key (VT10) for 40 μs.

Transistors VT1, VT2 in the receiver amplify the echo signal received by the piezoelectric element BQ1, transistor VT3 detects them, and transistor VT4 amplifies the detected signal. A single vibrator is assembled on transistors VT5, VT6, which ensures the constancy of the parameters of the output pulses and the sensitivity threshold of the receiver. From the direct impact of the transmitter pulses, the receiver is protected by a diode limiter (R1, VD1, VD2).

The digital part of the echo sounder is assembled on DD1-DD4 microcircuits. It includes a key (DD1.1) controlled by an RS flip-flop (DD1.3, DD1.4). The counting start pulse is supplied to the trigger from the transmitter modulator through the VT16 transistor, the end pulse is from the receiver output through the VT15 transistor.

The exemplary frequency pulse generator (7500 Hz) is assembled on the DD1.2 element. By the circuit R33, L1, it is put into the linear amplifier mode, which creates the conditions for its excitation at a frequency that depends on the parameters of the circuit L1 C 18. The generator is output exactly at a frequency of 7500 Hz by tuning L1.

The reference frequency signal is fed through the key to a three-digit counter DD2-DD4. It is set to the zero state by the front of the clock pulse that comes through the VD4 diode to the R-inputs of these microcircuits.

The clock generator is assembled on transistors VT13, VT14. The pulse repetition rate depends on the time constant R28-C15.

The filaments of the fluorescent indicators HG1-HG3 are powered by a voltage converter made on transistors VT17, VT18 and transformer T2.

Button SB1 ("Control") is used to check the performance of the device. When it is pressed, a closing pulse arrives on the VT15 key and some random number will appear on the echo sounder display. After some time, the clock pulse will restart the echo sounder, and if it is working, the number 88.8 will appear on the scoreboard.

All resistors in the echo sounder are MLT type, capacitors are KLS, KTK and K53-1. Transistors KT312V and GT402I can be replaced by any other of these series, MP42B - by MP25; KT315G - by KT315V. Chips of the K176 series can be replaced with equivalent ones from the K561 series. If the echo sounder is supposed to be used at depths up to 10 m, the DD4 chip and the HG3 indicator can be omitted.

Transformer T2 is made on a ferrite (3000NM) ring of size K16x 10x4.5 Winding I contains 2x180 turns of wire PEV-2 0.12, winding II - 16 turns of wire PEV-2 0.39.

Coil L1 (1500 turns of wire PEV-2 0.07) is wound between the cheeks on a frame with a diameter of 6 mm. The diameter of the cheeks is 15, the distance between them is 9 mm. The trimmer is made of carbonyl iron (from the armored magnetic circuit SB-1a).

Thin leads are soldered to the silver-plated planes of the emitter plate with Wood's alloy. The emitter is assembled in an aluminum cup with a diameter of 45...50 mm (bottom part of the oxide capacitor housing). Its height - 23 ... 25 mm - is specified during assembly. In the center of the bottom of the glass, a hole is drilled for a fitting, through which a coaxial cable 1 ... 1.25 m long will be brought out, connecting the ultrasonic head with the electronic part of the echo sounder. The emitter plate is glued with 88-N glue to a disc of soft microporous rubber 10 mm thick. During installation, the cable braid is soldered to the fitting, the central conductor - to the output of the lining glued to the rubber disk, the output of the other emitter lining - to the cable braid. The emitter assembled in this way is pushed into the glass. The surface of the emitter plate should be 2 mm below the edge of the glass. The glass is fixed strictly vertically and poured to the edge with epoxy. After it is wound, the end of the emitter is ground with fine-grained sandpaper until a smooth flat surface is obtained. Solder the counterpart of the X1 connector to the free end of the coaxial cable.

Establishing an echo sounder

To set up an echo sounder, you will need an oscilloscope and digital frequency counter. Turning on the power, check the operability of the counting device: if it is working, then the indicators should display the number 88.8.

The operation of the transmitter is checked with an oscilloscope operating in standby sweep mode. It is connected to the winding II of the transformer T1. With the arrival of each clock pulse, an RF pulse should appear on the oscilloscope screen. By adjusting the transformer T1 (roughly - by selecting the capacitance of the capacitor C 10), its maximum amplitude is achieved. The amplitude of the radio pulse on the piezo emitter must be at least 70 V.

To set up the reference frequency generator, you will need a frequency counter. It is connected through a resistor with a resistance of 5.1 kOhm to the output (pin 4) of the DD1.2 element and, by changing the position of the trimmer in the coil L1 (roughly - by changing the capacitance of the capacitor C18), set the required 7500 Hz.

The receiver and modulator are tuned according to the echo signals. To do this, the emitter is attached with a rubber band to the end wall of a plastic box measuring 300x100x100 mm (to eliminate the air gap, this place is lubricated with technical petroleum jelly). Then the box is filled with water, the VD3 diode is removed from the receiver and an oscilloscope is connected to the output of the receiver. The criterion for the correct setting of the receiver, modulator and the quality of the ultrasonic emitter is the number of echo signals observed on the screen, resulting from multiple reflections of the ultrasonic pulse from the end (300 mm apart) walls of the box. To increase the visible number of pulses, resistors R2 and R7 are selected in the receiver, capacitor C 13 in the modulator and transformer T1 is adjusted.

Having returned the VD3 diode to its place, they begin to adjust the receiver turn-on delay. It depends on the resistance of the resistor R18. This resistor is replaced by a variable of 10 kOhm and its value is found at which the first two echo signals disappear on the oscilloscope screen. This resistance should have a resistor R18. After tuning, the number of echo signals on the oscilloscope screen should be at least 20.

To measure the depth of a reservoir, the lower part of the ultrasonic head is immersed in water by 10...20 mm. It is better to have a special float for her.

Finding fish in a pond is not an easy task, especially for winter fishing. However, if you have this modern gadget in your hands, which can be connected to your phone or tablet in five minutes, then you will not only find fish, but also find out what the depth and topography of the bottom are under you, and even estimate the size of your future trophy .

Bluetooth fish finder for Android and iOS

Friends ahead. New Year It's time to think about gifts not only for your loved ones, but also for yourself. We present you a unique, modern and functional gadget that real fishermen have already appreciated - the Fishfinder wireless fish finder.

This is not just an echo sounder, but a real smart sonar, which can be easily connected via modern Bluetooth wireless technology to your phone or tablet with your own hands, without the help of specialists.

The application looks simple and clear, allowing you to enjoy the process of fishing without constantly focusing on the screen.

By the way, this gadget works with the two most popular operating systems for modern smartphones - Android and iOS, so you can use this fish finder regardless of your preferences in mobile OS.

The echo sounder is ideal for both fishing from the shore and from a boat - its light weight allows it to be cast far without breaking the cord or fishing line. For lovers of winter fishing, it will also become an indispensable assistant in the search for fish.

In addition, iBobber offers the functionality of expensive fish finders at a low price. With it, you will find out the depth and topography of the bottom of any reservoir to determine the location of the possible deployment of fish and the correct selection of gear. You will not only find a fishing spot, but you will also have an idea of the size of the future catch.

10 Benefits of the iBobber Wireless Fish Finder

The range of the sonar in the iBobber fish finder allows you to show depths up to 45 meters. The angle of coverage of the sonar sensor is 42 degrees. This will allow you to find even more fish.
The echo sounder is able to fully draw the bottom topography in the intended fishing area. In the summer, for this, the echo sounder is mounted on a spinning rod and thrown in the right direction, after which it is pulled towards itself. In winter, the echo sounder will successfully draw the bottom topography under the hole. Knowing the habits of the fish, you will most likely be able to determine the places of its accumulation.
If you decide to save data about trophy fishing: air temperature, water temperature, or even photos of the fish you caught, then the iBobber wireless fish finder will help you with this.
Have you decided to return to the hole that brought you trophy fish a week later? No problem! Function GPS tracker will help save the coordinates.
The bite has begun, but is it getting dark outside? The LED backlight of the echo sounder will allow you to fish not only at dusk, but also in total darkness.
To predict the activity of biting on a pond, depending on weather conditions, use the "Weather Forecast" function - the iBobber echo sounder will determine atmospheric pressure, the likelihood of precipitation and many other indicators.
Use the echo sounder as a float with a bite alarm. The Strike Alert system will notice even the most careful bite and will not let you miss your trophy.
The iBobber sonar app also includes a lunar calendar, so you'll always have data like sunrise and sunset times, moon phases, and even tide charts at your fingertips.
The built-in lithium battery will allow you to enjoy fishing for more than 8 hours without recharging.
And finally, the iBobber echo sounder is one of the best gifts that can be given to a true lover of both winter and summer fishing!

Download the app for your phone or tablet

Download free manual >>>
The instructions describe in detail how to install the software and start working with the echo sounder.

App for iOS >>>
Works with iOS from version 6.0.

Application for Android >>>
Works with Android operating system version 4.3 or higher, if the smartphone/tablet supports Bluetooth 4.0.

Specifications

The frequency of the sensor 118 KHz;
The depth of the sensor is 41-42 meters;
Continuous working time 8 hours;
Bluetooth range 30 meters;
Diameter 59 millimeters;
The weight of the echo sounder is 47 grams.

For those who still doubt whether to buy an iBobber echo sounder or not, we offer you to watch a video, after which it will become clear that this gadget can be used not only for fishing :)

Well, are you eager to buy this modern echo sounder? You can do this on the website of the online store "" using a secret promotional code -LH2018 which will give you 10% discount !

Dear fishing enthusiasts, you no longer need to think about what to give yourself or a friend for the New Year and any other holiday. A modern iBobber fish finder for a smartphone or tablet is a great gift that not only fans of winter fishing, but also summer fishing will be happy about!

The process of fishing is becoming more technologically advanced and efficient. This is facilitated by the emergence of new devices that expand the possibilities of fishermen. The echo sounder is one of the most common gadgets used in this field. Sensitive sensors scan the underwater space, providing the user with the necessary information through the screen. Today, an echo sounder for an Android smartphone is gaining more and more popularity, the workflow of which requires only the connection of a sensor. All recorded information is displayed on a mobile device without additional electronic devices.

What is a smartphone echo sounder?

This is a type of portable sonar sensors that can be attached to a fishing line or a special rope. The traditional design of the device is the shape of a ball into which the transducer is integrated. You can use the echo sounder with a smartphone only from the shore, because on the boat, especially while moving, it will be impossible to ensure its reliable fixation. There are models for iOS and Android operating systems. In this case, the second option is considered, but increasingly, manufacturers provide support for both systems.

It is important to emphasize the absence of wires in the communication system. If stationary transom models have a cable connection to the display, then the echo sounder that works with a smartphone transmits a signal via Bluetooth or Wi-Fi. There are also modifications with radio modules.

The principle of operation of the device

Despite the significant difference between portable wireless and stationary models, all echo sounders work on the basis of pulse radiation, which are processed and presented to the user in a convenient form. The same smartphone, using a special application, will graphically reflect the bottom relief, show the depth and activity of the fish - a specific set of information depends on the model. The main means of echolocation is the aforementioned transducer. This is a sensor-emitter that sends signals to the bottom surface and receives reflected waves. During operation, the echo sounder with a smartphone can change the interaction parameters depending on the conditions. In particular, the user can initially set the communication properties himself, but high-tech models are able to automatically adjust, for example, the frequency of sending impulses. After the information has appeared on the smartphone screen, the user makes certain decisions to change the tactics of fishing. Such devices allow you to search for the most favorable places for fishing.

Power supply system

The lack of wires causes one of the main disadvantages of such sonars. The thing is, fishing is Long procces, and autonomy for wireless electronics is always limited to a few hours. The sensors are equipped with batteries, the average capacity of which is 500-1000 mAh. Although the device can remain potentially operational for several days in standby mode, the active format of operation consumes energy in 8-10 hours. This applies to models with 700-800 mAh batteries. We are talking about average indicators, since the intensity of the reduction in battery volume will also be affected by weather conditions. For example, a winter echo sounder for a smartphone consumes 15-20% more energy, which should be taken into account. Some manufacturers also provide multiple batteries in one set. Moreover, depending on the format of the battery, the possibility of recharging it from a car cigarette lighter may also be allowed. In this case, it is possible to ensure an almost non-stop scanning process by charging and changing batteries.

Basic characteristics of the sensor

The efficiency of the device is primarily determined by its power. For portable sonars, it rarely exceeds 300 watts. Models with such a potential are optimally suited for ordinary fishing from the shore with a casting distance of about 30-40 m. Power affects the detection depth, which can reach from several tens to hundreds of meters - most models work in the ranges of 40-500 m. The frequency will also affect the range of radiation. The lower it is, the higher the range. For example, 50 kHz will provide the same 500 m. But it is important to consider that the function wireless sensor sonar for a smartphone will also affect the characteristics of the water. Thus, in conditions of increased mineralization, the depth of monitoring can be halved. In this case, you should not focus solely on power with frequency. The scanning angle is also important, which on average varies from 15° to 45°. This is the amount of coverage of the underwater space - respectively, from a narrow field to a wide one.

Model Deeper Smart Sonar

One of best models portable echo sounders in the segment from the well-known Estonian manufacturer Deeper. The features of the device include the presence of two radiation points - transducers with frequencies of 90 and 290 kHz cover angles of 55° to 15°. This means that the fish finder sensor for a smartphone will reflect the fish on the screen in high detail. The functionality of the model also deserves attention. The device has a GPS module, so the scan data can be superimposed on a real cartographic scheme in a special application. This feature allows you to record information about visited objects.

The high power of the sensor had a negative impact on autonomy. If you need a winter fish finder for your smartphone, you will have to count on no more than 5 hours of work on a single charge. Moreover, the volume of the battery is replenished for at least 2 hours. The disadvantages of this proposal include the high cost, which is about 20 thousand rubles.

Model Deeper Smart Fishfinder

Modification from the same manufacturer, but with more modest capabilities. Signal propagation reaches 40 m, and high scanning accuracy is maintained at depths of about 50 m. At the same time, the device also has two beams, but with smaller ranges. This version also inherited the lack of autonomy - the battery is able to function for 4 hours. As for strengths, then they are reflected in high-quality monitoring with a high degree of detail and the presence lunar calendar. On average, the price of an echo sounder for an Android smartphone of this modification is 10-11 thousand. That is, this a budget option the previous device with understandable limitations in technical and operational qualities.

FishHunter Directional 3D Model

A high-tech model of a portable fish finder that has five transducers. The frequency range extends from 381 to 675 kHz, which makes it possible to accurately reflect the position of the fish. However, the depth of research still limits this echo sounder for an Android smartphone to 55 m. But the device also has a GPS module with which you can create an underwater map of an object.

The additional functionality of the model should include tips for the angler. So, during the scanning process, the device signals where it is best to throw the hook. As for the prefix 3D, it indicates the possibility of three-dimensional modeling of the map with the selection of the relief texture. Previously, only stationary expensive models were provided with such an option, but the price of an echo sounder for an Android smartphone from FishHunter is quite acceptable for its class - an average of 21 thousand rubles.

How to choose the right model?

The main operational qualities should be taken into account - radiation frequency, scanning depth and battery capacity.
Here you can move on to additional functions. If 3D mapping is more of an ergonomic option, then, for example, a GPS receiver can be considered a useful practical tool. With its help, the fisherman will be able to draw up full-fledged maps, indicating the places visited and the corresponding comments to them. In terms of quality selection, it is better to focus on large manufacturers. It is undesirable to buy an echo sounder for a smartphone from China at prices of 5-7 thousand, since even with wide functionality they are unlikely to provide high accuracy of bottom research. Only in rare cases, such products confirm the high initially declared parameters in practice. You should also take into account the availability of external protection - the sensitive element must have at least a waterproof shell and a coating that protects against mechanical stress.

The nuances of operating echo sounders for a smartphone on Android

At the first stage of application, synchronization should be established between the mobile device and the sensor. Special applications from the sonar manufacturers themselves help to automatically perform this procedure. Next, at the place of operation, you should fix the smartphone. Since it will interfere with the fishing process, it will not be superfluous to provide a special holder and fix the case on it. Some sensor kits include such attachments. After that, the echo sounder itself for a smartphone on the Android must be securely fixed on a fishing line or a separately thrown rope. But it is important not to confuse its direction - the beam is on working surface The sensor must point downwards.

Conclusion

Using portable bottom monitors is certainly a convenient way for anglers to get the information they need. But their working qualities are significantly inferior to stationary counterparts with their own displays. This difference is especially visible in the examples of echo sounders for smartphones from China with price tags no higher than 8-10 thousand. As a rule, these are low-power models with low efficiency. But what, in this case, justifies the use of such sensors other than ergonomics? Still, such gadgets can be useful if you plan to use them at shallow depths when casting from the shore. But to go out into the open waters on a boat, for example, there will simply be no point in such equipment.

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Acquaintance with the echo sounder, or the specifics of sonar

With the advent of inexpensive echo sounders, navigating the water has become much easier. Previously, the main instrument of the "small-sized" was the sailing boat, which often did not see the corrector's hand for years, and therefore does not take into account changes in the structure of the bottom. Today, the picture of the bottom in real time no longer surprises anyone.

For anglers and divers, there are expensive structural scanners that show a color picture of the bottom with amazing accuracy.
Travelers have access to chartplotters that combine the functions of a navigator, an echo sounder, and an engine control instrument panel.
Forward-looking echo sounders help owners of slow-speed yachts. For high-speed vessels in conditions of shallow depths, these devices are not relevant, since they differ little in functionality from conventional sonar. After all, the sensor is able to "look" forward only 2-3 depths.
The most popular segment is inexpensive one- and two-beam echo sounders. They are used by fishermen, tourists, and even ice fishers.

Even the simplest device is able to measure the temperature of the outboard water, report a drop in the voltage of the on-board network, and also inform sound signal about a sharp decrease in depth. We will not consider the “fish” indication, because today we are talking about the benefits of sonar for navigation in conditions of insufficient depth.

Focusing on sound

The principle of operation of the echo sounder has not changed over the past hundred years. The dimensions of the devices have been reduced, the signal processing algorithms have been optimized. But as before, the transceiver sends a high-frequency signal deep into the water and waits for it to return, reflected from the bottom topography.

Depending on the density of the ground, the reflected signal weakens. To obtain depth data, the instrument analyzes the return time of the signal. The structure of the bottom is characterized by signal attenuation. Thus, on the echo sounder screen, we see the bottom topography different shade- from black (stone) to light gray (silt).

The indication of "fish" is based on the determination of air inclusions in the water column - the swim bladders of the alleged fish. If for anglers this option may be of some interest, then for navigation it is absolutely useless and distracts attention.

In the process of driving a high-speed motor boat on navigable rivers middle lane For Russia, the absolute values of depth are not so much important as the dynamics of its change. If there are 5-6 meters under the keel, and the bottom picture has crept up sharply - this is a reason for course correction - most likely, we have lost our way and are moving to a stall. In Karelia, it is quite possible to break the motor gearbox even at a depth of more than 5 meters. Pitfalls often stand alone and do not come to the surface. Together with fluctuations in the water level in such reservoirs with a rocky bottom, you need to be especially careful.

Another thing is when the depth is 30, 50, or even more than 100 meters. In this case, the echo sounder readings do not have priority. However, one should not underestimate the importance of this device - after all, sooner or later you will have to go to the coastal strip, where there may be flooded piles, hulls of large ships and stone spits.

In order to avoid chaotic changes in readings at the speed of the planing vessel, it is enough to manually limit the depth range. Almost all devices allow you to do this. Thus, harmonics that are multiples of the real depth are excluded.

We install the echo sounder with our own hands

It's fun to spend time improving the boat. Installing an echo sounder is a useful exercise. Therefore, we arm ourselves with knowledge and proceed with the installation.

As for the display, there are not many options. We install it from above on the horizontal part of the panel or on the inclined one facing the navigator. It is important that the screen does not block the view when driving under an awning and does not glare in sunny weather.

The situation with a remote sensor is much more complicated. Since it houses not only the receiver and transmitter, but also a temperature sensor, it is important to ensure reliable contact with water. By design, the sensors differ in external (outboard) and embedded in the bottom. Each of these options has its own disadvantages.

Since we still belong to the endangered subspecies of Homo sovieticus, since childhood we have had a craving for experiments, creativity and various research. So we will place the echo sounder sensor from the inside on the bottom next to the transom.

The options are discussed in the next chapter.

Glue the echo sounder sensor into the case

Indeed, it looks very tempting to be able to use the echo sounder at any speed, while not interfering with the design of the bottom, without fear of damage to the sensor, and without having a fountain of spray behind the transom. Why doesn't everyone do this? Let's consider cases when such a method is impossible or requires too much R&D ☺

Body with transverse redans. The aerated bottom favorably affects the speed performance of the vessel, but is completely unsuitable for installation inside the echo sounder sensor due to air bubbles in the boundary environment. The echo sounder in this case will work only during parking and when moving in displacement.
Wooden case. Not plywood covered with fiberglass, but real wood. Due to the porous structure of the board, the screen of the device is treacherously silent.
Displacement hulls with a whaleboat stern, which is in the air on the waves. At this point, the instrument readings are lost.
Some plastic cases are double-walled. In such “sandwiches”, the space between the fiberglass is filled with two-component polyurethane foam, and to install the sensor, you need to cut the inner “shell”, which is a pity, especially on a new boat.
Space in the area of the keel and longitudinal redans on keeled hulls. Swirls and air bubbles will not allow the device to work smoothly, therefore, before the final installation, we will check the operation of the device in several places and choose the best one.

To ensure the constancy of the environment, antifreeze, epoxy resin, auto plasticine, silicone sealant, hot melt adhesive, lubricant for a medical device (ultrasound). It is clear that all these materials introduce an error into the readings of the device and degrade the sensitivity, but practice has shown the efficiency of such a scheme.

Glued sensors work great on fiberglass and aluminum boats. However, no one can guarantee the performance of the proposed schemes on your case. Therefore, it remains to proceed by trial and error.

Looking for an echo

So, the cable is laid out in accordance with all the rules, the monitor is fixed and carefully covered with a lid, and in the stern, next to the bilge pump, there is an echo sounder sensor. Our task is to find the optimal place so that the sensor does not interfere with communications (for example, draining the bottom water), and the readings are not too affected by air bubbles falling under the bottom on the go. There are three ways to achieve the desired result.

Method one

Screw the sensor to the transom from the inside, directing the beam down perpendicular to the water surface. In this case, a constant presence of a certain level of subsoil water is mandatory so that there is no air wedge between the sensor and the bottom. The author of this article had a boat for a long time, in which for the correct operation of the echo sounder it was enough to pour only 2 liters of outboard water under the sleigh.

Moreover, this was found experimentally, when 5 or 6 positions of the sensor were tried. The sounder didn't want to work. It was decided to stop the races and raise the boat. As usual, after being put on the trailer, the drain scupper was opened to dry, but there was no water under the sleighs. Having decided to fix the boat on the trailer, he drove it back into the water without tightening the plug. What a surprise it was when the echo sounder suddenly worked properly. Reception even at speeds over 60 km/h. As a result, each trip began with pouring a two-liter bottle on the floor, which surprised the guests very much.

Second way

It consists in gluing the sensor on silicone on a flat area of the bottom between the redans. We try to fix the plane of the sensor not parallel to the bottom, but parallel to the water. However, a slight deviation (up to 10-15 degrees) is acceptable.

As a fixing mass, we use silicone sealant or autoplasticine. If during the tests they show the correct location, you can re-glue the sensor with epoxy glue. However, it is worth making sure that there are no air bubbles between the sensor and the bottom.

Third way

To some extent, it combines the advantages of the first and second methods. Its meaning is that there should be a conductor liquid between the sensor and the bottom, but this liquid was not in the boat itself. A little tricky, right? Let's try to understand and install the sensor.

For installation, we need a container with a narrow neck and a flat base. To do this, cut off the top of a two-liter plastic bottle or plastic canister. We will fix the sensor under the dome closer to the bottom. The sensor wire will exit through the neck of the bottle.

The main task is to securely fix the edge of the container to the bottom. The connection must be tight and secure. Silicone sealant or epoxy can be used. For better joint strength, the edge of the plastic adjacent to the bottom is roughened with a sandpaper. We leave the glued dome to dry. After polymerization, we proceed to the most important thing.

We fill the container through the neck with antifreeze. This will allow you to leave the boat with the sensor to spend the winter in the cold and forget that the echo sounder is installed abnormally. If you manage to securely fix the dome to the bottom, and the sensor to the dome, you will get best option sensor installation. It is worth noting that if you stop at the third method, you should not lay the sensor cable in advance. The first action will be threading the connector into the neck of the bottle, then pasting, filling, testing, and only on final stage- cabling.

It is worth noting that installation from inside the hull affects the accuracy of measuring the sea water temperature, damping the readings. Therefore, if temperature is a priority indicator for you, either take the sensor overboard, or wait 5-10 minutes until changes in water temperature reach the sensor, heating (or cooling) the bottom. In cases made of aluminum alloy, this effect is minimal, in fiberglass cases it is more pronounced.

A properly installed echo sounder sensor does not betray its presence and pleases the navigator with stable readings on the device display.

Summing up

An echo sounder is not only a device that shows depth. It is an indispensable tool in the management of small boats. Based on his testimony and comparing them with the pilot, you can confidently walk in difficult places, greatly reducing the risk of running aground or damaging the mover.

Expensive chartplotter models occupy a central position on the panel, displacing the rest of the devices. In fact, the chartplotter screen is the central control of the on-board system. It is able to replace all other telemetry - positioning on the map, navigation, navigation system, speedometer, compass, engine control devices and clocks. And only the principle of redundancy makes us have a separate analog compass and a spare navigator.

proboating.ru

Fisherman's echo sounder.

(Voitsekhovich V., Fedorova V.. Radio. 1988, No. 10, p. 32 ... 36)

Not only the angler, of course. An electronic echo sounder can be useful for a variety of underwater activities.

The echo sounder can be made in two versions: with depth measurement limits up to 9.9 m (its display has two fluorescent indicators) and 59.9 m (three indicators). Their other characteristics are the same: instrumental error - no more than ±0.1 m, operating frequency - 170 ... 240 kHz (depending on the resonant frequency of the emitter), pulse power - 2.5 W. The ultrasonic emitter is also the echo signal receiver - a barium titanate plate with a diameter of 40 and a thickness of 10 mm. The power source of the echo sounders is a Corundum type battery. Current consumption - no more than 19 and 25 mA (respectively, in echo sounders for shallow and great depths). Echo sounder dimensions - 175x75x45 mm, weight - 0.4 kg.

The block diagram explaining the operation of the echo sounder is shown in fig. 131. The clock generator G1 controls the interaction of the nodes of the device and ensures its operation in automatic mode. The short (0.1 s) rectangular pulses it generates are repeated every 10 s. With their front, these pulses set the digital counter PC1 to zero and close the receiver A2, making it insensitive to signals for the duration of the transmitter.

Rice. 131. Structural diagram of the echo sounder

A schematic diagram of an echo sounder with a depth measurement limit of 59.9 m is shown in fig. 132. Its transmitter, self-excited at the frequency of the ultrasonic emitter BQ1, is made on transistors VT8, VT9. Turning the transmitter on and off is controlled by a modulator - a waiting one-vibrator (VT11, VT12, etc.), which supplies power to the transmitter through its key (VT10) for 40 μs.

Rice. 132. Schematic diagram of the echo sounder

*) Its calculation is simple: at a speed of sound propagation in water of 1500 m/s, in 1/7500 s the front of the signal making the double path will move 0.2 m; and, accordingly, the lowest unit on the counter display will correspond to a depth of 0.1 m.

apox.ru

Radio circuits for everyday life

An electronic echo sounder can be useful for a variety of underwater activities - not just for fishing.
The echo sounder can be made in two versions: with depth measurement limits up to 9.9 m (its display has two fluorescent indicators) and 59.9 m (three indicators).
Their other characteristics are the same:
instrumental error - no more than ±0.1 m,
operating frequency - 170 ... 240 kHz (depending on the resonant frequency of the radiator),
pulse power - 2.5 W.
The ultrasonic emitter is also the echo signal receiver - a barium titanate plate with a diameter of 40 and a thickness of 10 mm.
The power source of the echo sounders is a Corundum type battery.
Current consumption - no more than 19 and 25 mA (respectively, in echo sounders for shallow and great depths).
Echo sounder dimensions - 175x75x45 mm, weight - 0.4 kg.

Schematic diagram of the sonar

At the end of the transmitter, the receiver A2 opens and acquires normal sensitivity. The echo signal reflected from the bottom is received by the same BQ1 and closes the key S1. The measurement is completed, the measured depth is displayed on the indicators of the PC1 counter.
Depth calculation is easy: at a speed of sound propagation in water of 1500 m/s, in 1/7500 s the front of the signal making the double path will move 0.2 m; and, accordingly, the lowest unit on the counter display will correspond to a depth of 0.1 m.

The next clock pulse will again transfer the PC1 counter to the zero state and the process will repeat.

A schematic diagram of an echo sounder with a depth measurement limit of 59.9 m is shown in Figure 2.

Its transmitter, self-excited at the frequency of the ultrasonic emitter BQ1, is made on transistors VT8, VT9. Turning the transmitter on and off is controlled by a modulator - a waiting one-vibrator (VT11, VT12, etc.), which supplies power to the transmitter through its key (VT10) for 40 μs.

The clock generator is assembled on transistors VT13, VT14. The pulse repetition rate depends on the time constant R28-C15.

The filaments of the fluorescent indicators HG1-HG3 are powered by a voltage converter made on transistors VT17, VT18 and transformer T2.

All resistors in the echo sounder are of the MLT type, capacitors are KLS, KTK and K53-1. Transistors KT312V and GT402I can be replaced by any other of these series, MP42B - by MP25; KT315G - by KT315V. Chips of the K176 series can be replaced with equivalent ones from the K561 series. If the echo sounder is supposed to be used at depths up to 10 m, the DD4 chip and the HG3 indicator can be omitted.

Transformer T2 is made on a ferrite (3000NM) ring of size K16x 10x4.5 Winding I contains 2x180 turns of wire PEV-2 0.12, winding II - 16 turns of wire PEV-2 0.39.

Thin leads are soldered to the silver-plated planes of the emitter plate with Wood's alloy. The emitter is assembled in an aluminum cup with a diameter of 45 ... 50 mm (bottom part of the oxide capacitor housing). Its height - 23 ... 25 mm - is specified during assembly. In the center of the bottom of the glass, a hole is drilled for a fitting, through which a coaxial cable 1 ... 1.25 m long will be brought out, connecting the ultrasonic head with the electronic part of the echo sounder. The emitter plate is glued with 88-N glue to a disc of soft microporous rubber 10 mm thick. During installation, the cable braid is soldered to the fitting, the central conductor - to the output of the lining glued to the rubber disk, the output of the other radiator lining - to the cable braid. The emitter assembled in this way is pushed into the glass. The surface of the emitter plate should be 2 mm below the edge of the glass. The glass is fixed strictly vertically and poured to the edge with epoxy. After it is wound, the end of the emitter is ground with fine-grained sandpaper until a smooth flat surface is obtained. Solder the counterpart of the X1 connector to the free end of the coaxial cable.

Establishing an echo sounder

To establish an echo sounder, you will need an oscilloscope and a digital frequency counter. Turning on the power, check the operability of the counting device: if it is working, then the indicators should display the number 88.8.

To set up the reference frequency generator, you will need a frequency counter. It is connected through a resistor with a resistance of 5.1 kOhm to the output (pin 4) of the DD1.2 element and, by changing the position of the trimmer in the L1 coil (roughly by changing the capacitance of the capacitor C18), set the desired 7500 Hz.

To measure the depth of a reservoir, the lower part of the ultrasonic head is immersed in water by 10…20 mm. It is better to have a special float for her.

(Voitsekhovich V., Fedorova V.. Radio. 1988, No. 10, p. 32 ... 36)

radio-uchebnik.ru

Homemade mini-echo sounder on the Atmel ATMega8L microcontroller

and

LCD from nokia3310 mobile phone

I present to your attention the author's development - a home-made mini-echo sounder on the Atmel ATMega8L microcontroller and LCD from the nokia3310 mobile phone. The device is designed to be repeated by a radio amateur of average qualification, but, I think, anyone can repeat the design. I tried to present the material in such a way that readers in an accessible form give more useful information on this topic. I hope that the repetition of the design will bring you a lot of pleasure and benefit.

I will be glad to answer your questions / wishes / comments and help in repeating the design.

Sincerely, Alex

Echo sounder, sonar (sonar) - short for SOund NAvigation and Ranging. The echo sounder has been around since the 1940s, and the technology was developed during World War II to track enemy submarines. In 1957, Lowrance introduced the world's first transistorized sportfishing sonar.

The echo sounder consists of the following main functional blocks: a microcontroller, a transmitter, a transducer-emitter, a receiver and a display. The process of detecting the bottom (or fish) in a simplified form is as follows: the transmitter emits an electrical impulse, the sensor-emitter converts it into an ultrasonic wave and sends it into the water (the frequency of this ultrasonic wave is such that it is not felt by either a person or a fish). The sound wave is reflected from the object (bottom, fish, other objects) and returns to the sensor, which converts it into an electrical signal (see figure below).

The receiver amplifies this returned signal and sends it to the microprocessor. The microprocessor processes the signal received from the sensor and sends it to the display, where we already see the image of objects and the bottom topography in a form convenient for us.

What you should pay attention to: the echo sounder draws the bottom relief only in motion. This statement follows from the principle of operation of the echo sounder. That is, if the boat is stationary, then the information about the bottom topography is unchanged, and the sequence of values will consist of the same, absolutely identical values. This will draw a straight line on the screen.

The first question I'm sure readers will have is "Why such a small display?" Therefore, I will immediately answer it: this “mini-sonar” was developed at the request of a friend from what was at hand. And these improvised means turned out to be ATMega8L, a display from nokia3310 and some kind of emitter with the designation f=200kHz. You may also ask if it is possible to remake the program / circuit for a different, larger display? Yes. Theoretically, this is possible.

My design differs from the echo sounders described in the use of a graphic LCD display, which gives the device advantages in displaying useful information.

The whole structure is assembled in the "Z14" case. Power is provided by a 9V GP17R9H battery. The maximum current consumption is not more than 30 mA (in the author's version 23 mA).

Now about the possibilities of the echo sounder. The operating frequency is 200 kHz and is configured for a specific existing emitter. Software implemented the ability to measure depth up to 99.9 meters. But I will say right away: the maximum depth that the echo sounder can “see” will largely depend on the parameters of the emitter used. My design has so far been tested only on a reservoir with a maximum depth of about 4 m. The device showed excellent results. As far as possible, I will try to test the operation of the echo sounder at greater depths, which will be reported to readers.

So, let's move on to the scheme. Mini echo sounder scheme shown in the figure below:

The main functional blocks of the echo sounder: control circuit (ie ATMega8L microcontroller), transmitter, emitter, receiver, display, keyboard, battery charging circuit.

The echo sounder works as follows: the microcontroller at the output PB7 generates a control signal (rectangular pulses log. "0") with a duration of approximately 40 μs. This signal triggers the 400 kHz master oscillator on IC4 for the specified time. Next, the signal is fed to the IC5 chip, where the signal frequency is divided by 2. The signal from IC5 is fed to the buffer stage on the IC6 chip and then to the Q3 and Q4 switches. Further, the signal from the secondary winding of the transformer T1 is fed to the piezoelectric sensor-emitter LS2, which sends ultrasonic messages to the external environment.

The signal reflected from the bottom/obstacle is received by the transmitter-emitter and fed to the input of the receiver, which is assembled on the SA614AD chip in a typical inclusion (see Datasheet on SA614AD). The diode assembly BAV99 at the input of the receiver limits the input voltage of the receiver at the time of transmitter operation.

The signal from the receiver is fed to the comparator on the LM2903 chip, the sensitivity of which is controlled by the microcontroller.

The transmitter transformer T1 is wound on a K16 * 8 * 6 core made of M1000NM ferrite. The primary winding is wound in 2 wires and contains 2x14 turns, the secondary - 150 turns of PEV-2 wire 0.21 mm. The secondary winding is wound first. The halves of the primary winding must be "stretched" along the entire length of the core. The windings must be isolated from each other with a layer of varnished cloth or transformer paper.

Now the most interesting and problematic part: the emitter sensor. This problem was solved for me initially: I already had a ready emitter. How about you?
Option 1: purchase a ready-made sensor.
Option 2: make it yourself from piezoceramics TsTS-19.

When flashing the ATMega8L microcontroller, set the fuse bits according to the picture below:

Complete information on the manufacture, configuration, firmware and manual for using the mini-echo sounder

look in the attached archive!

Questions and wishes _ self-made echo sounder _ mini echo sounder_files\
Instructions _ homemade echo sounder _ mini echo sounder_files\
setup _ homemade echo sounder _ mini echo sounder_files\
firmware _ homemade echo sounder _ mini echo sounder_files\
links _ homemade fish finder _ mini fish finder_files\
diagram and description _ self-made echo sounder _ mini echo sounder_files\
Theory _ homemade echo sounder _ mini echo sounder_files\
Files _ homemade fish finder _ mini fish finder_files\
device photo _ self-made echo sounder _ mini echo sounder_files\
echolot_v1.43.dch
echolot_v1.53.dch
pcb_v1.53_A4.doc
pcb_v1.53_components.doc
plata_v2.doc
0012.gif
firmware_demo_v1.0.hex
firmware_demo_v1.1.hex
firmware_demo_v1.2.hex
firmware_demo_v1.5.hex
Questions and wishes _ self-made echo sounder _ mini echo sounder.html
Instructions _ homemade echo sounder _ mini echo sounder.html
setup _ homemade echo sounder _ mini echo sounder.html
firmware _ self-made echo sounder _ mini echo sounder.html
links _ homemade echo sounder _ mini echo sounder.html
diagram and description _ homemade echo sounder _ mini echo sounder.html
Theory _ homemade echo sounder _ mini echo sounder.html
Files _ homemade echo sounder _ mini echo sounder.html
device photo _ self-made echo sounder _ mini echo sounder.html
fuse_bits.jpg
gen400kHz.jpg
mini-sonar_circuit_v1.53.jpg
mini-sonar_review_01.jpg
MH2009V.pdf
SA614AD.pdf
mini-sonar_circuit_v1.43.PNG
mini-sonar_circuit_v1.43_800x600.png
echolot_user_manual.zip

Currently, fish finders are very popular among fishermen and sportsmen.
What gives echo sounder fisherman?
The answer to this question seems to be quite simple - echo sounder seeks and finds fish, and this is its main purpose. However, the unambiguity of this answer may seem absolutely fair only to a novice angler. Every more or less literate fisherman knows that fish are not distributed evenly over the space of reservoirs, but are collected in certain places, determined by the bottom topography, sharp changes in depths, and even temperature differences between water layers. Of interest may be snags, stones, pits, vegetation. In other words, the fish is not only looking for where it is deeper, but also where it is better for it to spend the night, hunt, disguise, and feed. Therefore, the primary task of the echo sounder is to determine the depths of the reservoir and study the bottom topography.
A block diagram that explains the design and operation of the echo sounder is shown in fig. 1. Clock generator G1 controls the interaction of the device nodes and ensures its operation in automatic mode. The short (0.1 s) rectangular pulses of positive polarity generated by it are repeated every 10 s.

With their front, these pulses set the digital counter PC1 to zero and close the receiver A2, making it insensitive to signals for the duration of the transmitter. The falling clock pulse triggers the transmitter A1, and the emitter-sensor BQ1 emits a short (40 µs) ultrasonic probing pulse towards the bottom. At the same time, the electronic key S1 is opened, and oscillations of the reference frequency of 7500 Hz from the generator G2 are fed to the digital counter PC1.

At the end of the transmitter, the receiver A2 opens and acquires normal sensitivity. The echo signal reflected from the bottom is received by the sensor BQ1 and, after amplification in the receiver, closes the key S1. The measurement is completed, and the indicators of the PC1 counter highlight the measured depth. The next clock pulse again translates the counter PC1 to the zero state, and the process repeats.

principled echo sounder circuit with a depth measurement limit of up to 59.9 m is shown in fig. 2. Its transmitter is a push-pull generator based on transistors VT8, VT9 with a transformer T1 tuned to the operating frequency. The positive feedback necessary for self-excitation of the generator is created by the circuits R19C9 and R20C11. "The generator generates pulses with a duration of 40 μs with radio frequency filling. The operation of the transmitter is controlled by a modulator consisting of a single vibrator on transistors VT11, VT12, which forms a modulating pulse with a duration of 40 μs, and an amplifier based on a transistor VT10 The modulator operates in standby mode, the triggering clock pulses come through the capacitor C14.

echo sounder receiver assembled according to the direct amplification scheme. Transistors VT1, VT2 amplify the echo signal received by the emitter-sensor BQ1, transistor VT3 is used in the amplitude detector, transistor VT4 amplifies the detected signal. A single vibrator is assembled on transistors VT5, VT6, which ensures the constancy of the parameters of the output pulses and the sensitivity threshold of the receiver. The receiver is protected from the transmitter pulse by a diode limiter (VD1, VD2) and resistor R1.

The receiver uses a forced shutdown of the receiver's single vibrator using the VT7 transistor. A positive clock pulse enters its base through the diode VD3 and charges the capacitor C8. Opening, the transistor VT7 connects the base of the transistor VT5 of the receiver's single vibrator to the positive power wire, thereby preventing it from being triggered by incoming pulses. At the end of the clock pulse, the capacitor C8 is discharged through the resistor R18, the transistor VT7 gradually closes, and the single-shot receiver acquires normal sensitivity. The digital part of the echo sounder is assembled on DD1-DD4 microcircuits. It includes a key on the element DD1.1, controlled by an RS flip-flop on the elements DD1.3, DD1.4. The counting start pulse is supplied to the trigger from the transmitter modulator through the VT16 transistor, the end pulse is from the receiver output through the VT15 transistor.

The pulse generator with an exemplary repetition rate (7500 Hz) is assembled on the element DD1.2. A negative feedback circuit is made up of resistor R33 and coil L1, leading the element to a linear section of the characteristic. This creates the conditions for self-excitation at a frequency determined by the parameters of the L1C18 circuit. The generator is tuned exactly to the specified frequency with a coil trimmer.

The reference frequency signal is fed through the key to a three-digit counter DD2-DD4. It is set to the zero state by the edge of the clock pulse coming through the VD4 diode to the R inputs of the microcircuits.

The clock generator that controls the operation of the echo sounder is assembled on transistors of different structures VT13, VT14. The pulse repetition rate is determined by the time constant of the R28C15 circuit.

The indicator cathodes HG1-HG3 are powered by a generator based on transistors VT17, VT18.

Button SB1 ("Control") is used to test the device. When you press it, the VT15 key receives a closing pulse and the echo sounder indicators highlight a random number. After some time, the clock pulse switches the counter, and the indicators should show the number 888, which indicates that the echo sounder is working.

The echo sounder is mounted in a box glued from high impact polystyrene. Most of the parts are placed on three printed circuit boards made of foil fiberglass with a thickness of 1.5 mm. On one of them (Fig. 3) the transmitter is mounted, on the other (Fig. 4) - the receiver, on the third (Fig. 5) the digital part of the echo sounder. holes for the power switch Q1 (MT-1), the button SB1 (KM1-1) and the socket VR-74-F of the coaxial connector XI were drilled on the cover, and a window for digital indicators was cut out.

The echo sounder uses MLT resistors, capacitors KLS, KTK and K53-1. Transistors KT312V and GT402I can be replaced with any other transistors of these series, MP42B - with MP25, KT315G-with KT315V. Chips of the K176 series are interchangeable with the corresponding analogs of the K561 series, instead of the K176IEZ (DD4) chip, you can use K176IE4. If the echo sounder will be used at a depth of no more than 10 m, the DD4 counter and the HG3 indicator can be omitted.

The windings of the T1 transformer are wound with PELSHO 0.15 wire on a frame with a diameter of 8 mm with a ferrite (600NN) trimmer with a diameter of 6 mm. Winding length - 20 mm. Winding I contains 80 turns with a tap from the middle, winding II - 160 turns. The T2 transformer is made on a ferrite (3000NM) ring of size K16X10X4.5. Winding I contains 2X 180 turns of wire PEV-2, 0.12, winding 11-16 turns of wire PEV-2, 0.39. Coil L1 (1500 turns of wire PEV-2 0.07) is wound between the cheeks on a frame with a diameter of 6 mm made of organic glass. The diameter of the cheeks is 15, the distance between them is 9 mm. Trimmer - from the armored magnetic circuit SB-1a made of carbonyl iron.

The ultrasonic emitter-sensor of the echo sounder is made on the basis of a round plate with a diameter of 40 and a thickness of 10 mm from barium titanate. Thin (0.2 mm in diameter) lead wires are soldered to its silver-plated planes with Wood's alloy. The sensor is assembled in an aluminum cup from an oxide capacitor with a diameter of 45 ... 50 mm (height - 23 ... 25 mm - is specified during assembly). In the center of the bottom of the glass, a hole is drilled for a fitting, through which a coaxial cable (RK-75-4-16, length 1 ... 2.5 m) will enter, connecting the sensor with the echo sounder. The sensor plate is glued with 88-N glue to a 10 mm thick soft microporous rubber disk.

During installation, the cable braid is soldered to the fitting, the central conductor - to the output of the sensor lining glued to the rubber disk, the output of the other lining - to the cable braid. After that, the disk with the plate is pushed into the glass, passing the cable into the fitting hole, and the fitting is fixed with a nut. The surface of the titanate plate should be deepened into the glass 2 mm below its edge. The glass is fixed strictly vertically and poured to the edge with epoxy. After the resin has hardened, the sensor surface is ground with fine-grained sandpaper until a smooth plane is obtained. Solder the counterpart of the XI connector to the free end of the cable.

To establish an echo sounder, you need an oscilloscope, a digital frequency meter and a 9 V power supply. Turning on the power, check the operability of the counting device: if it is working, then the indicators should display the number 88.8. When you press the SB1 button, a random number should appear, which, with the arrival of the next clock pulse, should again be replaced by the number 88.8.

Next, set up the transmitter. To do this, a sensor is connected to the echo sounder, and an oscilloscope operating in standby sweep mode is connected to winding 11 of transformer T1. On the screen of the oscilloscope with the arrival of each clock pulse, a pulse with RF filling should appear. The trimmer of the transformer T1 (if necessary, select the capacitor C10) achieve the maximum amplitude of the pulse, which should be at least 70 V.

The next stage is the establishment of an exemplary frequency pulse generator. To do this, the frequency meter through a resistor with a resistance of 5.1 kOhm is connected to pin 4 of the DD1 microcircuit. At a frequency of 7500 Hz, the generator is tuned with a coil trimmer L1. If at the same time the trimmer takes a position far from the average, capacitor C18 is selected.

The receiver (as well as the modulator) is best tuned for echoes as described in [I]. To do this, the sensor is attached with a rubber band to the end wall of a plastic box with dimensions of 300X100X100 mm (in order to eliminate the air gap between the sensor and the wall, it is lubricated with technical petroleum jelly). Then the box is filled with water, the VD3 diode is removed from the receiver and an oscilloscope is connected to the output of the receiver. The criterion for the correct setting of the receiver, transmitter modulator, as well as the quality of the ultrasonic sensor is the number of echo signals observed on the screen, resulting from multiple reflections of the ultrasonic pulse from the end walls of the box. To increase the visible number of pulses, resistors R2 and R7 are selected in the receiver, capacitor C13 in the transmitter modulator and the position of the trimmer of the transformer T1 is changed.

To adjust the receiver turn-on delay device, the VD3 diode is soldered in place, the resistor R18 is replaced with a variable one (resistance 10 kOhm) and with its help the first two echo signals disappear on the oscilloscope screen. Having measured the resistance of the introduced part of the variable resistor, it is replaced by a constant of the same resistance. After tuning, the number of echo signals on the oscilloscope screen should be at least 20.

To measure the depth of a reservoir, it is best to fix the sensor on a float so that its lower part is immersed in water by 10 ... 20 mm. You can attach the sensor to a pole, with which it is immersed in water for a short time, while measuring depth. When using the echo sounder in a flat-bottomed aluminum boat for measuring shallow depths (up to 2 m), the transducer can be glued to the bottom inside the boat.

It should be noted that on sunny days the brightness of the digital indicators may be insufficient. It can be increased by replacing the Korund (Krona) battery with a power source with a slightly higher voltage, for example, a battery made up of eight D-0.25 batteries (this will not require any changes in the circuit and design of the device).

A bit of theory

How do we see fish with an echo sounder?
Sonar sound waves bounce off physical movable objects (i.e. places where sound speed changes). Fish are mostly water, but the difference between the speed of sound in water and the gas in the fish's air bladder is so great that it allows sound to be reflected and returned. The air bubble allows the fish to stay at a certain depth without the help of fins (submarines are built on the same principle). Therefore, with the help of an echo sounder, we “see” not the fish itself, but its air bubble, which, by and large, is all the same for the fisherman. There is a bubble - there is also a fish. But still, you need to know that each gas-filled air bubble, like a stream of air in an organ pipe, has its own natural frequency. When sound waves of the same frequency reach the bubble, it resonates, and the resonance frequency is several times higher than the frequency of the wave itself. Therefore, the "target" looks larger than it actually is.

Looking deeper, the tone of air bubbles resonating is determined by water pressure, the size and shape of the bubble, and physical obstructions within the fish itself.
These factors change as the fish moves vertically through different depths.

How does sonar show fish?
The figure shows a typical “nail oval” (arc) formed by the pattern of movement of one fish from the center to the corners or the angle of the cone when the boat is stationary. The same effect can be created if the boat is moving and the fish is stationary. But you rarely see that perfect arc, because the fish you're looking for is always moving outside of the arc, not necessarily level or center. The bigger the nail oval, the bigger the fish, right? No, not necessarily.

A fish of the same size, swimming in the center of the arc to the surface, may stay in the arc for a short time and therefore give a small imprint. If the same fish is pressed to the bottom and passes through the center of the arc, it will hit the target zone for a longer period of time and give a larger signal. Generally speaking, a fish will appear smaller the closer it is to the transducer, and larger the further away it is.
This is exactly the opposite of what our eyes see when sunlight. Variations in this ideal "nail oval" can occur for a number of reasons. The fish swims up and down, it goes through the outer edges of the arc at irregular angles, the boat moves either slowly or quickly, the fish can be so close to the bottom that it partially enters the "dead zone". For example, you will find that a school of the right fish , located in a close cluster in a horizontal layer, forms a large arc, but with angles that differ little from the mark of a single fish. So, you will see many variations of this "nail oval" shape, but remember that it is a normal display that is returned by a fish.
There is one mistake common to all fish finders that few fishermen know or even think about, and that is that everything APPEARS as if it is under the boat, when in fact it is not.

The drawing shows what is really happening underwater with our sound cone and our impression of it based on a flashing scale or a 2D image.

The figure shows how all echo sounders give an error in reading the fish between the boat and the bottom.
This is due to the fact that the device tries to line up all the fish it finds within the cone in one straight line, which convinces us that the fish is right under the bottom of the boat.
The figure also shows us what happens when two (or more) fish are found at the same distance (from the transducer) when they are actually at opposite ends of the cone.
All of them are marked by the echo sounder as being at the same distance, and therefore are shown as one fish.
Fishing with echo sounder very interesting, moreover, it adds confidence and, as a result, a catch.