Sensitivity is one of the important functions that determine the depth of underground metal detectors, and the other is the operating frequency of underground metal detectors. The working frequency determines whether the underground metal detector can detect the target object, and the sensitivity determines the distance, that is, the depth, at which the underground metal detector detects the target.

The maximum sensitivity value needs to be tested in practice, and different manufacturers have different settings for the maximum sensitivity value. For underground metal detectors based on the principle of ultra-low frequency magnetic wave induction, such as VLF magnetic wave probes like Garrett 350 and Fisher F44. The sensitivity settings do not seem to exceed two meters, which means that the actual detection depth cannot exceed two meters. As for the reason, it is still unknown. The sensitivity values set by all manufacturers do not exceed two meters, so we can only accept the fact that the depth of the magnetic wave underground metal detector will not exceed two meters. Although there are large values of sensitivity, which may lead to different depths due to differences in large values, the large values of sensitivity have no practical significance due to the influence of electromagnetic interference, host performance, and recognition function. Regarding electromagnetic interference, please visit our website's special article on underground metal detector electromagnetic interference. Here we mainly discuss the impact of host performance and recognition capabilities on sensitivity values. During the detection process, as the depth of the target increases, the detected signal becomes unstable in the order of stable signal - unstable signal - no signal. The sensitivity value is highest in the process from unstable signal to no signal. The reason why we purchase underground metal detectors is to obtain stable signals when detecting targets. When the target is at this depth of unstable signal, we cannot determine whether there is metal here. This is still in all metal mode, and if single item recognition exclusion is enabled, the depth will also experience attenuation at the same sensitivity. So manufacturers have developed various response strategies to deal with unstable signal areas, such as Fisher's VCO voltage controlled oscillator, V-Break variable breakpoint system, Garrett's enhanced iron recognition, and France XP's all metal independent audio system. All of them are aimed at maintaining a large detection depth with equal sensitivity in all metal mode. You should know that in the depth area of unstable signals, the initial host can still display numerical values vaguely. If it goes deeper, it can rely on an independent audio system, which means it can hear sound but not see numerical display. At this level, only experienced treasure hunters can distinguish it. For newcomers, this is already the limit of detection, and it has not yet reached the maximum sensitivity. In other words, without experienced and professional treasure hunters, we cannot determine whether the signals given by the detector are true before reaching the maximum depth. So the maximum depth was meaningless from the beginning.

Since the sensitivity range does not exceed two meters horizontally or vertically, does it mean that sensitivity does not need to be considered when purchasing underground metal detectors? That's a big mistake. The limit of sensitivity may be similar for everyone, but the grading of sensitivity can vary greatly. As mentioned above, the high sensitivity value is rarely used in practical detection, and those who have seen electromagnetic interference should also understand that sensitivity is difficult to reach a high value. The first issue we need to deal with when adjusting sensitivity is electromagnetic interference. Firstly, we need to reduce the sensitivity to a level that can eliminate electromagnetic interference. Whether we can adjust it to this state precisely reflects the role of sensitivity grading. For example, if one meter is the maximum sensitivity value, one machine divides it into 10 levels, each level being 10cm, and another machine divides it into 100 levels, each level being 1cm. If the exact point we need is at the 85cm position, then the first machine can only be set at level 8, which is 80cm. Choosing the 90cm level will cause interference, while the second machine can be accurately set at the 85cm level, which is 5cm more than the first machine. So underground metal detectors that can classify sensitivity more accurately can eliminate electromagnetic interference and retain a larger depth.

The more sensitivity levels there are, the more accurate it is to eliminate interference and preserve depth. When purchasing an underground metal detector, it is important to determine how many levels the detector can be divided into. The more levels there are, the deeper the depth after excluding electromagnetic interference will be.