earthSCAN 

Professional, computerized ,  high-sensitivity ,  multi-frequency metal detector with original, patented , no analogue technology

of space- harmonic filtering (SFT),  which allows to significantly improve the quality of the identification of objects.

The main original feature of this detector and all the other models of Aka is a "holograph" identification of targets, which allows

to define targets very easy and with an exact value. No other metal detector brand has such an identification.
There are 3 algorithms to choose from, algorithms are best described as 3 chips that control the detector in different ways

based on recovery speed and desired targets.

All 3 algorithms named MSF, SSF and MM have their own parameters, for example if you are using MM which is high trash mode

and a very fast recovery speed all you settings such as discrimination, sensitivity, audio tone , etc are all saved under that feature,

so when using another algorithm such as SSF you can save a different range of settings to suit your search requirements.
SSF is primarily for use in areas with large flat iron or heavily rusted iron plates, these are usually detected with mixed signal or

are often confused as a non-ferrous signal.

When using algorithm SSF, these errors are avoided the machine clearly identifies that the detected signal is iron.
MSF is more of an all round setting, it has a medium recovery speed which rejects or identifies most iron with ease,

this is best describes as a low to medium trash setting and will suit most people.
MM is also known as metal trash (MT), it is very dynamic and an ideal setting for working amongst high iron contamination

such as ancient sites, the audio response is very sharp and precise so a slow sweep speed is recommended for MM mode.