The Emulation Research Of The Ionosonde

The signal reception of the ionosonde is emulated in this paper according to the process of ionospheric sounding.In order to lower the transmission power the Spread Spectrum Technique is introduced into the ionosonde. Several Spread Spectrum codes (PN code) are introduced in this paper especially the Maximal Length code (m code).On the ground of the channel statistical characteristic, this paper introduces a new wideband channel model, ITS channel model, which is used by the emulation. Based on the ITS channel model this paper theoretically discusses the fading effect of the ionosphere to the signal which is reflected by the ionosphere. With assuming the electron density distribution to be the Qps model, this paper developes the delay-frequency relation of single model.According to the ionosphere model this paper emulates the signal reception with PN acquisition algorithm. The coherent PN acquisition algorithm, non-coherent PN acquisition algorithm and automatic decision threshold level control algorithm are introduced in turn. In addition the performance of the automatic decision threshold level control algorithm is discussed mathematically.