Although using a metal detector is a fairly simple task, some of the more technical functions may be a bit harder to understand, especially when you’re just starting.
A metal detector is a specialized device that generates and emits a magnetic field onto the soil or water, through a device called ‘transmitter coil’. When it hits a metallic object, this magnetic field will change the movement of the particles that form the atoms of the object, changing its magnetic field. In other words, the magnetic field generated by the metal detector can create a magnetic field around metal objects. Different types of metal will generate different types of magnetic fields.
After the magnetic field is generated and emitted by the transmitter coil, when you move the metal detector over the soil you are basically moving the magnetic field around, so it can reach buried objects and create magnetic fields around them. When these magnetic fields are created the metal detector can detect them through a device called ‘receiver coil’. The receiver circuit is usually connected to a speaker, and when the coil receives a magnetic field, it generates electricity that travels through the circuit and causes the speaker to emit “beep” sounds that work asa signal. The closer the transmitter coil is to the metal object, the stronger the generated magnetic field will be, and the stronger the received magnetic field. Therefore, the sound signal will be louder as the detector gets closer to the target.
This is the basic functioning of a metal detector, but these pieces of equipment usually have other types of technology to help enhance the experience. The most common ones, and possibly the most useful, are the sensitivity and discrimination modes.
If you’re new to the metal detecting world, chances are you heard the terms ‘sensitivity’ and ‘discrimination’ but have very little idea as to what they actually mean.
Are these features required in a good metal detector? Are they indispensable for metal detecting? How do they help? Do they enhance the ‘power’ of the metal detector? Are they hard to use?
These are all questions that may have crossed your mind at some point. We’ll help you better understand these concepts so you can bring your metal detecting skills to a whole new level.
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What is sensitivity?
Sensitivity is the name given to a metal detector’s ability to interact with weaker magnetic fields. I practical terms, it refers to the equipment’s ability to detect small metal and ferromagnetic and particles.
How is it useful?
Metal detectors usually have at least two sensitivity setting levels: high and low (in a more complex or advanced metal detector, there can be many levels in between). Sensitivity doesn’t increase its depth or detection range; instead, it makes the detector capable of detecting smaller particles within its range and depth.
Low sensitivity allows the detector to focus on larger objects and ignore smaller particles. It might be useful in highly mineralized or contaminated soils. Higher sensitivity, on the other hand, is a function that allows you to detect smaller particles within the metal detector’s range, by giving off signs in response to weaker magnetic fields.
So, is it okay to use the detector on the maximum level of sensitivity at all times?
Sensitivity is highly useful if you’re looking for small objects, but it shouldn’t be used on its max level all the time. For example, you should avoid using sensitivity on max in any of these conditions:
# If you’re hunting on highly mineralized soil;
# If there are power transformers nearby;
# If there are radio stations nearby.
When set on max mode, the detector will be able to detect even the smallest metal or ferrous particles and the weakest magnetic fields, so you’ll constantly have “noise” and interference. Using higher sensitivity levels in the right conditions is without a doubt a very valuable resource but using it all the time will interfere with your findings because you’ll be drowning in constant noise (what is usually referred to as ‘false signals’ or ‘false positives’).
What is discrimination?
During a hunt, every type of metal has a specific electromagnetic signal they send back for the metal detector to receive, and discrimination is based on this property. It’s akind of filter that some metal detectors have in their basic system and that can be quite useful.
How is it useful?
Basically, the discrimination mode allows the detector to filter out (or “mute”) signals related to undesired metal objects such as iron. It works by measuring the time it takes for the detector to receive the magnetic field form the target, which is usually referred to as ‘phase shift’. Larger phase shifts indicate high-conductive metals such as silver and copper, while smaller phase shifts indicate low-conductive metals such as iron.It also filters out soil minerals, preventing you from hearing “noise” when hunting in highly mineralized grounds.
The discrimination scale on most metal detectors is usually 0-10. Lower discrimination means that you will get more signals and the “noise” won’t be filtered out, while higher discrimination will prevent you from receiving signals from, say, iron objects or soil minerals.
Zero discrimination, the lower level, is also known as the “all-metal” mode since it doesn’t filter out any type of metal. It allows you to receive more signals from deeper targets, but it doesn’t change the detection depth of the metal detector. Decreasing discrimination has a similar effect to increasing sensitivity but usually doesn’t cause as much noise.
On the other hand, if discrimination is set too high, it can interfere with the signals even if the sensitivity level is high. Balancing discrimination and sensitivity is very important when using a metal detector that has both functions.
So, is it okay to use the detector on the minimum level of discrimination at all times?
The short answer is no. Although lower levels of discrimination increase the detector’s ability to detect deeper and smaller targets, having the metal detector on “all metal” mode all the time may impact your search and require much more effort from your part, since you’ll have to identify every single signal to see if it’s a desired metal or trash. Discrimination should never be too high (especially because gold is a low-conductive material), but it must be high enough to filter out some of the noise (for example, aluminum particles).
Sensitivity and discrimination are the two most important and useful functions in a metal detector. Once you understand how they work and how to use them correctly, you’ll be able to find treasures like never before. Give it a try.
