Observation of VHF broadcast radio waves propagating from China

We have observed broadband VHF radio waves to investigate the propagation of distant TV broadcast waves. From the end of January to the middle of February, 2006, in the evening various radio waves at several frequency in 47.5-76.0 MHz have been often received with high intensity at Tateyama observatory(34deg59´N, 139deg54´E). Many of them are considered to come from China because their frequencies are used for TV broadcasting waves in China. As the value of foEs is high in occurring this event, we examine relationship between this event and Sporadic E layer (Es).