LDG-300 radio height fixing device works in C-band, which is a pulse compression system. The sensitive device adopts heterodyne type, and the antenna terminal circulator adopts the common mode of transceiver. Before the missile is launched, power is supplied to the height fixing device, and the height fixing device is self checked and installed through the communication interface. After the missile is launched, the RF module is turned on, and the wave gate is set according to the installation height. When the installation height is met, the height fixing device outputs the height fixing instruction information and telemetry information. LDG-300 height fixing device is mature in technology. Pulse compression technology can improve the height of altimeter. It has the characteristics of wide range of height measurement. Digital pulse compression based on FPGA has the advantages of small volume, low power consumption and low cost.