FMG stands for Funkmess Gerät (radar equipment), while the numerical digits denote the model year of the device. "G" denoted that the equipment was manufactured by GEMA, "g" indicated that it operated between 335 and 440 MHz, while "O" indicated the positioning of the set atop of the forward rangefinder. FuMO stands for Funkmess-Ortung (detection radar). See Williamson, halaman 7.
