Comparison Lowrance HDS-9 Live vs Lowrance HDS-9 Gen3

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 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.

Echosounder support for special bottom scanning technologies.

"Viewing" the space under the bottom of the boat is a classic sonar mode and is supported by all models by definition. However, in normal mode, the sound beam propagates in the form of a cone, and the area of the bottom that falls under the beam has the shape of a circle. This degrades the accuracy and does not allow you to achieve a detailed image. Thus, many echo sounder manufacturers have developed special technologies to improve the performance of the instrument; Lowrance has DSI, Hummingbird has DI, Garmin has DownVü. The nuances of these technologies may differ, but the basic principle of operation is the same: the echo sounder beam narrows and goes not in a cone, but in a strip. Due to this, the resolution of the device is significantly increased; at shallow depths, such an echo sounder can “draw” even individual stalks of algae, making it possible to distinguish underwater thickets from schools of fish. Some models combine a narrow beam with a classic cone to further expand detection capabilities. However, such devices are expensive.

The presence of a digital data processing system (DSP) in the design of the echo sounder.

Digital processing allows you to separate the received signal into extraneous noise and useful data. Of course, such a division is not 100% reliable; however, the level of noise in the filtered signal is still significantly reduced, and the screen receives a maximum of useful information and a minimum of extraneous information. The disadvantage of this function is traditional: echo sounders with DSP are somewhat more expensive than usual ones.

— 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.

— Ethernet. This standard is also known as LAN or RJ-45. Its original purpose is the construction of general-purpose wired computer networks; however, Ethernet can also be used in special networks — including used by navigation equipment. Note that this interface is technically capable of providing a higher data transfer rate than NMEA, so it can be used for tasks that require the transfer of a large amount of data — for example, connecting to the Internet via a satellite module.

— NMEA. Abbreviation for "National Marine Electronics Association", "National Marine Electronics Association". This interface is used to interconnect various "marine" electronics, mainly navigation — echo sounders, chartplotters, radars, VHF radios, gyrocompasses, sensors in engines, etc. Accordingly, its support allows you to connect the device with other specialized devices and sensors. Note that there are several versions of NMEA. The most popular at the moment is NMEA 0183, it is this standard that is supported by most special equipment. A more advanced version is NMEA 2000, which is not yet widely used. More information about the different versions and their compatibility can be found in special sources.

— Output for external GPS antenna. This function can occur regardless of whether the device has a built-in GPS receiver (see above). If such a receiver is not available,...then the ability to connect an external antenna (more precisely, a whole GPS module) is almost mandatory for devices with the chartplotter function (see "Type") — otherwise they will not be able to effectively perform their tasks. However, for models with their own receiver, an external antenna may come in handy — it is usually more sensitive than the internal one and allows you to more accurately determine the location of the device, especially in difficult conditions (atmospheric interference, navigation through narrow fjords, etc.). At the same time, such an antenna can be chosen at will, choosing the best option for price and functionality. One has only to take into account that different types of connectors can be used to connect external equipment — therefore, before buying an antenna, it would be useful to clarify its compatibility with a specific model of the device.

— Wi-Fi. A wireless interface, originally designed to connect to local computer networks, and more recently also used to directly connect various devices to each other. It can be used in echo sounders/chartplotters for various purposes — both for integration into the onboard network and for connecting external equipment (wireless sensor, remote control tablet, etc.); specific functionality depends on the model.

— Bluetooth. A wireless interface used to connect different devices to each other. The Bluetooth standard includes many separate protocols for different types of data and formats of operation; in fact, the possibilities of this connection in each particular case depend on what protocols the echo sounder / chartplotter supports. The most common features include, in particular, connecting wireless sensors (see above), exchanging data with a tablet, laptop or other gadget (for example, to download new maps and routes), connecting wireless headsets to work with sound alarms, etc. P.

— Video input. Connector for connecting an external video signal to the echo sounder / chartplotter. This feature allows you to use the display to display a "picture" from another device, such as an external camera. Note that video inputs are found mainly in models with large colour displays — without such a display, the whole point of this function would be lost.

— Video output. Connector for video signal output from echo sounder/chart plotter. This function allows you to duplicate the image from the display of the device on an external large screen — for example, the main monitor of the on-board computer — which makes viewing more convenient.