Aiming at the problem that iridium satellite communication has the disadvantages of low security and high cost

while Beidou radio determination satellite service（RDSS） has the limitation on transmission speed and coverage range

a dual-mode communication system which combines Iridium satellite communication and Beidou RDSS is designed for smart float.After the smart float completes data acquisition of a profile

shore station control system can freely choose Beidou RDSS or Iridium to communicate with smart float according to sensitivity of data and the intensity of satellite signals

and while one communication mode break down

it can switch to another communication mode.This method can effectively enhance security of data transmission

improve communication efficiency and enhance robustness of system.