Doppler VHF Omni-directional Range Transmitter And Monitor Design

DVOR(Doppler VHF Omnidirectional Range) is one of the most commonly used communication navigation equipment for today’s civil aviation, can provide civil aviation aircraft Angle information. Monitor is one of the important part of DVOR navigation system, launches the receiving DVOR navigation system of electromagnetic signals, the demodulation signals and compared with the correct value, to determine whether the working state of DVOR navigation system is normal. This article main research content is as follows:According to the performance requirements of China’s civil aviation, this paper DVOR transmitter and monitoring system for the design.1、transmitter: It is proposed based on crystal vibration circuit and digital phase locking technique of two RF generated models, two chips of digital phase locking structure were analyzed,which solved the signal generation of carrier channel and side-band signals.2、monitor:Monitor should be in accordance with the requirements in real time with9960 Hz signal level, 30 Hz amplitude modulation and 30 Hz frequency modulation signal level, and the identification accuracy, which begins with the signal demodulation.Directly on the analog signal demodulation method is more convenient, also facilitate maintenance personnel find fault and maintenance. 9960 Hz and the AM signals’ filtering were relatively simple, this paper designed the detection circuit of signal levels.For the extraction of FM signal, we designed a pulse counting discriminator that consists of the triggers, can guarantee a good linear phase. Azimuth information acquisition using sine square wave train of thought, by phase-locked loop stability.Finally,It put forward a design idea based on microprocessor 80c186.3、The test part:It verified the feasibility,according to the measured signal hardware.For transmitter, It tested the 30 Hz and side-band waveform and level ranges with reference to the theoretical value. Especially for the impact on the signal fluctuation side-band phase, the results must be strictly locked with phase difference of 90°, and the amplitudes were equal. Finally got good synthetic composite signal. For monitor, the MATLAB simulated to contrast test results, correctly extracted signal and completed NOT detection, square wave transformation also keep the phase relationship, completedthe perspective transformation.