PURPOSE: To obtain an integrated altimeter and Doppler speed sensor apparatus using linear FM modulation in an altitude measuring function and using sine FM modulation in a Doppler navigation detecting function.

CONSTITUTION: A transmitter 1 has an altimeter transmitter 3 using linear FM modulation and a Doppler transmitter 5 using sine FM modulation. Transmission signals are alternately supplied to an antenna 11 via a switch 9 and transmitted. Reception signal is input from the antenna 11 to a mixer 21, mixed with the part of the transmission signals supplied from a coupler 23, and transmitted to an altimeter signal processor 17 and a Doppler signal processor 19 via a switch 25. The switches 9, 25 are controlled by a computer 27, and interlocked to be operated. The outputs of the processors 17, 19 are input to the computer 27, integrally processed with other navigation signal AHRS/INS to become the final outputs of altitude and speed of an aircraft body.