Comparison Fisher F22-11DD vs Fisher F44

The design of the coil(s) of the metal detector.

— Concentric. The name of this type is due to the fact that such a coil includes two separate windings — receiving and transmitting — one of which is located inside the other. It is used in metal detectors that use the principles of VLF and VLFEX (see above). The field from a concentric coil has a small width, which determined both its advantages and disadvantages: on the one hand, due to this, it is possible to determine the location of an individual find with high accuracy, on the other hand, it takes a lot of time and effort to carefully examine vast areas. This shortcoming can be partly compensated for by the elliptical shape (see below). Also note that concentric models are quite sensitive to mineralized soils.

— Mono. The simplest type of coil, having only one winding. This option is used in PI, OR and RF devices, and in the latter case, two mono-coils must be installed. The main advantages and disadvantages of this type are similar to those described above concentric.

— D.D. Also known as Double-D. Such coils have a pair of windings in the form of the letters D, turned in different directions and arranged closely so that they form a circle or an ellipse. In terms of application, DDs are similar to the concentric coils described above, but they differ in the shape of the generated field: it is a narrow plane directed along th...e line of contact of the windings. This makes it possible to cover a fairly wide band in one pass, and also reduces the sensitivity to interference from mineralized soils. Among the shortcomings, compared with concentric ones, it is worth noting the high cost and lower accuracy in the localization of individual finds (however, the latter can be compensated by the skills and experience of the operator).

— Super-D. Coils of a specific design, consisting of three windings — a central one, which plays the role of a transmitter, and two external ones, working for reception. They were developed specifically for ZVT metal detectors (see "The principle of operation"), taking into account the features of their work.

The greatest depth at which a metal detector is guaranteed to be able to detect a metal object. Note that this parameter is most often quite approximate, moreover, somewhat conditional. This is due to the fact that it is usually indicated for an perfect environment (low-mineralized soil, a fairly large object, the material of which optimally matches the frequency of detection of the coil, etc.), and even for such conditions it is difficult to derive an absolutely accurate value. Therefore, in fact, the detection depth is highly dependent on a number of additional factors (from soil characteristics to user skills) and can be significantly less than indicated in the characteristics. Nevertheless, the claimed depth describes the capabilities of the metal detector quite well, and it is quite possible to compare different models with each other.

Note that a large depth not only increases the cost of the device, but can also adversely affect its ability to detect small objects.

The deepest depth at which a metal detector is capable of detecting small coins and other objects of similar size. Many users buy a device with the intention of “hunting” for metal trifles, so manufacturers often indicate this parameter separately in the specifications. Due to the small size of the coins, their detection depth is usually much less than the total maximum detection depth (see above).

Ground balancing method provided in the design of the metal detector. By itself, such balancing is a setting of work parameters for the characteristics of a particular soil — after all, depending on its mineralization, humidity, etc. The soil affects the search signal in different ways, and the device electronics must take this effect into account for high-quality processing of such a signal. Due to the correct balancing, the detection of the desired objects is ensured and at the same time the probability of false positives is minimized; and it can be done in the following ways:

— Automatic. The most convenient type of balancing that does not require the user to manually adjust the device. Usually, tuning requires some time to move the coil up and down above the ground until the automation sets the necessary parameters. There are two types of auto tuning: preset and tracking. The first option involves balancing the metal detector for a specific type of soil before starting work, after which the device uses the same parameters until the next setting. Such a scheme is inexpensive and can be used even in fairly simple models, but it is not very reliable: even a small change in the type of soil under the coil leads to a decrease in the effective detection depth and an increase in the probability of false positives. Follow-up balancing does not have this disadvantage: devices with this function constantly monitor the characteristics of t...he soil and make the necessary corrections to the operating parameters right in the process of operation. This increases the efficiency of the search, however, the price of such devices is very high.

— Manual. As the name implies, with such balancing, the necessary parameters must be set by the user himself. This option is considered the most reliable, because. even the most advanced automatic systems do not always work perfectly; And yes, this setup is cheap. On the other hand, it requires certain skills from the operator and may not be suitable for inexperienced users.

— Manual / automatic. A variant that combines both types of balancing described above; in such models, the user can choose the way of setting as they wish.

The number of pre-installed programs for searching for various materials. Their number reflects the capabilities of a particular model, allowing you to start working right off the bat.

Regular metal detector search programs include detection of coins, all metals, jewelry and relics. In some models, this list can be expanded with "Beach" programs, custom (user) detection mode, etc.

— LCD display. The presence of its own display in the design of metal detectors. This feature makes working with the device more convenient and visual: through the display, you can display more different information than with the help of an audible alarm or indicator lights, and it is easier to perceive. On the other hand, such devices are more expensive than similar models without a screen.

— Arrow indicator. The presence in the design of the metal detector of an analogue dial indicator to display data on the search process. Such an implementation is much more modest and cheaper than the same LCD display, but an order of magnitude more convenient than without visual notification at all.

— Display backlight. The presence of a backlight allows you to use the display of the metal detector in low light conditions — up to complete darkness. Note that this function can be useful not only at dusk, but also in the daytime — for example, when searching in a dense forest in cloudy weather. See above for details on the display.

— Built-in speaker. The presence in the design of the metal detector of its own speaker. Such a speaker allows you to use the device without headphones, which are not always convenient, and sometimes unsafe (for example, when working in places where traffic can move).

— GPS module. The pre...sence of a GPS satellite navigation module in the design of the metal detector. This module allows you to determine the current geographic coordinates of the device, and the options for using this data can be different: recording search routes, fixing the places of individual finds, and even full-fledged navigation with laying routes from point to point.

— Armrest. The presence in the design of the metal detector of an additional support in the area of the operator's elbow. This support reduces the load on the hand, and also makes the hold more stable and at the same time controllable, allowing you to comfortably hold the device in one hand.

— Headphone output. The presence of a headphone output in the design of the metal detector. This can be either a standard connector that allows you to connect any compatible "ears" (for example, a 3.5 mm mini-jack output, popular in portable audio equipment), or an original proprietary interface that allows you to use only specialized "native" accessories. Anyway, headphones are often more convenient than a speaker, as they allow you to hear the signals from the device well even in a rather noisy environment.

— Headphones. The presence of headphones in the scope of delivery of the metal detector. Usually, such headphones have high quality and accuracy of sound transmission, so that the user can be guaranteed to hear all the signals and tone shades of the signals. "Ears" can be wired and wireless, and in underwater models (see "Type"), they are, respectively, made waterproof. This function is convenient because you do not have to search and purchase the best headphones for the metal detector on your own.