Number of frequencies
The number of individual radiation frequencies that can be operated by a device with echo sounding function (see "Type").
The features of the frequencies themselves are described in detail below, but here we note that different models may provide different options for distributing frequencies over individual beams (see "Number of radiation beams"). So, in some devices, each beam has its own frequency, in others, individual emitters can be switched, choosing the best option depending on the characteristics of the situation. In general, more frequencies indicate greater versatility, but it significantly affects the price.
Radiation frequency
The frequency(s) of radiation at which the device with the echo sounder function is capable of operating (see "Type").
The higher the frequency, the better the resolution and noise immunity of the device, the better it is suitable for working at high speeds, but the range and coverage suffer. Low-frequency (up to 200 kHz) sensors, on the contrary, "reach" deep and cover a wide angle, but are sensitive to interference and do not work well with fine terrain details and small objects. Accordingly, the first option is considered optimal for shallow depths and high-precision topographic measurements, while the second option is for deep water bodies, as well as for searching for fish and other tasks that require wide coverage.
Models with several radiation beams (see “Number of radiation beams”) often provide different frequencies for individual beams, which allows you to combine the advantages of different options in one device and compensate for their disadvantages.
Display
— Screen size. Diagonal screen size in inches. The
larger the screen, the more information can be displayed on it and the more detailed this information can be. On the other hand, this parameter noticeably affects the dimensions of the device, and large screens are expensive, especially since you need the appropriate resolution for normal image quality (see below).
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Touch. The presence of a sensor in the design of the display. This feature allows you to control the device by touching the icons on the screen — similar to how it is done in smartphones and tablets. Touch control provides more options than the classic one, using buttons and switches, besides it is more visual — however, such devices are more expensive.
— Display resolution. Display size in dots (pixels) horizontally and vertically. The higher the resolution, the more detailed image the screen is able to produce, the smaller objects can be clearly displayed on it and the more comfortable viewing. At the same time, the specificity of echo sounders is such that too high resolution is not required even for high-end models: for example, modest by the standards of smartphones or tablets 640x480 with a 5" screen are considered quite sufficient even for an advanced device.
— Colour. The ability of a screen to display colours. In this case, the simplest division is used:
Monochrome.... Displays that display information only in shades of one colour. Theoretically, the main colour can be any, but in this case, the vast majority of monochrome screens are black and white. Their advantages are low cost and energy consumption, as well as good visibility in the sun; at the same time, such an image allows you to work with quite a variety of types of data, which is enough even for very advanced echo sounders (see "Type"). However, this variety is not as wide as for colour displays, as a result, for chartplotters (see ibid.), such an image is not suitable — if it is impossible to display different colours, some of the important information on the maps is lost.
Coloured. Screens capable of working with multiple colours. The variety of colours can be quite small, but the image still turns out to be more informative than black and white: different colours can indicate different depths on the map, water temperature changes, etc. Due to this, this type of display is found in all types of navigation devices (see above). Its main disadvantage can be called a higher cost than that of monochrome screens.
— Backlight. The screen has its own backlight system. This feature makes the display independent of ambient light and allows you to see the information on it even in complete darkness. At the same time, the backlight increases power consumption, which is important during long-term operation from an autonomous source (for example, a boat battery). Therefore, it can be turned off.Ice fishing sensor
The presence
of a sensor for winter fishing in the scope of delivery of the device with the function of an echo sounder (see "Type").
This feature allows the device to be used on ice-covered water bodies. Usually, the sensor itself is made in the form of a float and is designed to be placed directly in the hole. At the same time, some models are also able to “see” directly through the ice to some extent, but this function is usually auxiliary and is intended more for a general assessment of the depth, and not for a detailed display of the situation; and the working depth during such work is less than the regular one. There are two things that are common to all winter sensors: the absence of mounts found in conventional sensors (on the bottom of the boat, transom, etc.), as well as increased resistance to low temperatures.
Key backlight
The presence of a
key illumination system in the design of the device.
The role of this function is similar to the backlight of the display (see "Display"): it makes the keys visible even in complete darkness, allowing you to accurately control the device's functions. Yes, even in twilight conditions, the backlight can come in handy — not all buttons have markings that are clearly visible in low light.
Dust and water protection
The presence in the design of the device protection against dust and moisture.
This function is realized due to the body of the appropriate design, which prevents the ingress of moisture and dirt on the sensitive elements of the device. It is practically mandatory for modern fish finders and chartplotters (see "Type"), as such devices are originally designed to work near water, where the likelihood of splashing is very high. At the same time, note that the specific degree of dust and water protection may be different.
The IP standard is often used to describe it. The classic designation according to this standard includes two digits, one of which corresponds to the degree of protection against dust and foreign objects, the other against moisture (IP54). Here are the most common options for the first digit in modern devices:
- 4 — protection against objects more than 1 mm (most wires, tools, bolts and nails, etc.)
- 5 — full protection against solid objects, dust resistance (some dust may get inside, but it does not interfere with the satisfactory operation of the device).
- 6 — full protection against dust ingress into the case.
For the second digit, the options are:
- 4 — resistance to water splashes from any direction;
- 5 — resistance to water jets of medium power from any direction (protection against powerful splashes during storms);
- 6 — resistance to powerful water jets from any direction (protection agains...t sea waves)
- 7 — resistance to complete immersion in water to a shallow depth and for a relatively short time — but not less than half an hour to a depth of 1 m.
- 8 — resistance to prolonged immersion in water to a depth of more than 1 m. Possibility of submerged operation.
A specific option is a marking with one number and the letter "X" in place of the second — this means that certification has not been carried out for this parameter. In the case of fish finders and chartplotters, "X" is usually put first — for example, IPX4. This is due to the fact that dust resistance for this class of devices plays a secondary role, and many manufacturers prefer not to spend money on certification of this parameter.
It should also be said that dust and moisture resistance is indicated for the main unit of the device placed on board; external sensors that are lowered into the water during operation must, by definition, be waterproof, so they are not discussed in this case.
Power source
The supply voltage required for the normal operation of the device. This parameter allows you to determine compatibility with the intended power supply.
Note that usually a certain voltage range is indicated in this paragraph, which ensures versatility. Of course, it is impossible to go beyond this range: too low a voltage can simply “not start” the device, and too high a voltage can damage the electronics. And even seemingly normal operation with a “non-native” voltage (for example, when an unsuitable power source is accidentally connected) is not an indicator in this case: an abnormal mode anyway will accelerate the failure of the device, and besides, it can lead to displaying incorrect readings .
