Comparison Deeper Start vs Garmin Striker Plus 7sv

The type defines the general purpose of the device.

— Echo sounder. Echo sounders are devices designed to study water bodies using sonar. The principle of operation of an echo sounder is similar to that of a radar, but it does not use radio waves, but ultrasound. The initial purpose of such devices is the creation of topographic maps of the bottom of a reservoir, the determination of its topography and depth in various places. However, in addition to this, the echo sounder can be used to detect fish, and with good quality of the device and correctly set settings, you can even determine the approximate size of potential prey.

— Chartplotter. A chartplotter can be described as a dedicated GPS navigator designed for marine use and equipped with related additional features. Such functions include, at a minimum, working with sailing directions (detailed maps of water bodies, indicating depths, currents, etc.); in addition, support for meteorological services, additional equipment such as radars or specific navigation sensors, etc. can be provided. Note that the GPS receiver can be either built-in or external; see Chartplotter Specifications for details.

— Sonar chart plotter. Models that combine the capabilities of both types described above in one device. Such devices are the most versatile, however, and cost accordingly.

— Sonar fl...asher. A specific type of echo sounder, designed specifically for use in one place, without movement. Initially, such devices were generally developed for fishing from an ice hole in winter — although this is not limited to such fishing — flashers are also used in summer, including in open water when fishing from a boat. Such devices are by definition capable of displaying fish in real time (see "Functions"), however, instead of a traditional screen, a circular indicator is used, thanks to which the user can determine the direction of the detected object. And the features of this object (more precisely, the signal reflected from it) can be determined by the colour of the mark on the indicator: for example, a red mark corresponds to a strong signal, yellow to an average signal, green to a weak one. Another advantage of a flasher over a traditional fish finder is its high sensitivity, which allows you to follow even small baits. Thanks to all this, such devices are quite popular among anglers, however, they are not cheap.

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.

The number of individual beams of radiation emitted by the device with the echo sounder function (see "Type"). The general principle is as follows: the more rays, the more advanced the device is considered and the more additional features it provides. Specific features may be:

— 1. Single- beam echo sounders are the simplest variety; accordingly, one of their key advantages is low cost. On the other hand, the shortcomings of any beam — both narrow and wide — are fully realized in them (for more details, see "Total angle of radiation"), and there is no question of a detailed determination of the position of individual detected objects (for example, fish).

— 2. In models with two beams, these beams most often have a common axis, but differ in coverage angle: one is made narrow, directly for measuring depths, the other is wider, for searching for fish and other individual objects. Thus, this option combines the advantages of beams of large and small widths. However such an echo sounder is not capable of fixing the location of the fish relative to the boat.

— 3. Three- beam echo sounders have all the capabilities of the two-beam echo sounders described above, and in addition, they are also able to determine the location of a fish or other object relative to the boat (right or left).

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.

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.

The angle covered during operation by the transducer of the echo sounder (or an instrument with such a function, see "Type").

Technically, the wider the angle, the better the echo sounder is suitable for finding fish and other underwater objects, because. a large coverage area reduces the likelihood of missing prey. On the other hand, to accurately determine the depth, the beam must be as narrow as possible. This is due to the fact that the depth is determined by the maximum protruding point that fell under the beam; thus, if the size of the hole at the bottom is smaller than the spot from the beam, the device simply will not notice this hole. The smaller the angle (and, accordingly, the projection of the beam onto the bottom) — the less likely this phenomenon is.

However, it should be taken into account that all of the above is unambiguously true only for single-beam echo sounders (see "Number of radiation beams"). But multibeam models, usually, combine beams of different widths, thus compensating for the shortcomings of narrow and wide angles. In them, the total radiation angle describes only the dimensions of the space covered by the device.

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).

Sonar support for CHIRP technology.

The meaning of this technology is to use the echo sounder at the same time several frequencies. In other words, each pulse consists of several signals, each at its own frequency. According to the creators, this allows you to improve image quality, increase detail (including at great depth and high speed) and at the same time reduce the level of noise and other interference on the screen compared to single-frequency sonars. However, models with CHIRP are noticeably more expensive.

Availability of the side scan function in the echo sounder.

Devices with this feature are able to "see" the bottom and underwater objects not only directly under the vessel, but also on the sides of it. Note that different models can differ markedly in the angle of coverage of the side space. However, the side scan anyway expands the capabilities of the echo sounder and provides additional features compared to the usual bottom one.