Scan depth
the
maximum depth at which the sonar locator (see "Type") is able to operate effectively — in other words, how deep underwater the device is able to "see".
It is worth choosing an echo sounder according to this parameter, taking into account the actual depths at which it is planned to be used. Of course, this does not place a certain margin, but within reasonable limits (15-20%, less). For example, it hardly makes sense to specially take a model with a scanning depth of 200 m for a lake with pits of 30-40 m — such devices are expensive, while there will simply be nowhere to realize their full potential, and a powerful signal can also scare away the fish. But for marine or oceanic applications, a depth of a kilometer or more may be required; the most advanced echo sounders are quite capable of providing it.
Emitter power
The power output by the fishfinder (or fishfinder-chartplotter, see "Type") when operating.
The
more powerful the emitter, the more “long-range” the device turns out, the greater the depth at which it can work normally (see above). However, do not forget that the practical capabilities of an echo sounder depend on a number of other parameters, ranging from operating frequencies and angles (see above) to the quality of the receiver and the features of signal processing algorithms. In addition, different manufacturers may indicate different types of power in the characteristics: in some cases it is peak (maximum power at the time of a single pulse), in others it is RMS (rms power calculated over a certain period of time and obtained below peak). Therefore, we can say that the role of this parameter is usually purely reference, and when choosing, it is worth focus on moments that are closer to practice (for example, the same scanning depth).
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).
—
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.
