When out hunting with a metal detector, you could come across more junk than treasure. You may detect and dig up rusty nails and bottle caps in the hope of finding coins or other valuables. To resolve this issue, most detectors are equipped with a discriminator. Setting the discrimination level allows you to distinguish between good and bad tones when hunting for specific metallic objects. One of the most effective ways to use your discriminator is with a technique known as positive discrimination.
Learn the specific tones your metal detector makes when it passes over specific metal objects. Place a few different objects of different metal properties, such as a gold ring, a silver ring, a coin, a nail and a bottle cap, in a row. Pass the coil over each object and note the tone that is emitted from the detector for each one.
Set the detector to the VLF or all-metal mode.
Walk with the coil parallel to the soil, about 6 inches away. Listen for the tone.
Center the coil on the source when a tone is heard. Place the detector coil directly onto the ground at the source.
Switch the detector to the TR mode. Lift the detector coil away from the ground. If the tone decreases in strength or stays at the same pitch then you have a quality target source. A bad target source will not produce sound when the coil is lifted from the source.
Learn the specific settings of your detector. Many detectors have audible tones while others have display screens that you can read.
Only use a metal detector where you are allowed to do so. Never use a detector on private property unless you have permission from the landowner.