The initial results of the Chung-Li dynasonde for RF environment surveillance and ionospheric observations

In 2004, a NOAA (National Oceanic and Atmospheric Administration) MF/HF radar or dynasonde was set up by the National Central University in Chung-Li (24.5°N, 121.0°E), Taiwan. The Chung-Li dynasonde employs an interferometric array (including four receivers) for receiving ionospherically reflected echoes, and is a fully digital research ionosonde, capable of providing high precision spatial and temporal ionospheric measurements. Utilizing a pulse set defined by four pulses transmitted at two closely spaced frequencies, the measured parameters are the time-of-flight and sixteen complex-amplitudes. Two types of observations are conducted by the Chung-Li dynasonde - an active sounding mode and a passive sounding mode. The methods are utilized in observing the local ionosphere and RF environment above Chung-Li. The active sounding is capable of transmitting HF radio pulses for remote sensing of the ionosphere. Initial results from this study have revealed various special events for observing sporadic E and spread F, along with the distribution of foF2 in a single day. These initial results will be used to confirm the surveillance of the ionosphere from other instruments, and conduct statistical comparisons between seasons. On the other hand, passive sounding receives and records signals from RF environments. It is used to monitor the MF/HF band in real time, and is contrasted with the active results when the echo is weak.