I have this machine IN STOCK, (Antiques Detectors), it reads on the box "Powered by Digital VFLEX Technology". VLFEX Single Frequency Sine Wave.
VFLEX is "Uses state of the art digital and mixed-signal components to enhance standard single frequency technology by replacing most analogue circuitry with digital signal processing. Every time the detector starts up, the micro-controllers in the control box and he coil establish communication through a digital data link ".