Right from the Lowrance Manual
FMCW = Frequency Modulated Continuous Wave The scanner transmits a ‘rising tone’ (Tx wave) with linearly increasing frequency. The wave propagates out from the transmitter retaining the frequency it had when it was transmitted. If it refl ects off an object, it will return to the receiver, still at the frequency it had when originally transmitted. Meanwhile, the transmitter continues to output an increasing frequency. The difference between both the currently transmitted and received frequencies, coupled with the known rate of frequency increase, allows a time of fl ight to be calculated, from which distance is calculated.
Additional benefi ts of FMCW radar are:
Safety
• low energy emissions. 1/5th of a mobile phone
• safe operation in anchorages and marinas
• instant power up. No warm up required