Abstract
Russian Alpha radio navigation system (RSDN-20) emits F1=11.9kHz signals
into the magnetosphere which propagate as whistler-mode waves. Observed
by waveform continuous burst mode from EMFISIS on Van Allen Probes, a
case is presented and featured with ducted propagation, multiple
reflections and triggered emissions. Both risers and fallers appear in
the triggered emissions. We use a ray-tracing method to demonstrate
ducted propagation, which has a similar wave normal angle near
$150^{\circ}$ as the observation. The arrival time
of reflected signals is estimated using propagation analysis and
compared with the observed signal arrival time. To test the non-linear
cyclotron resonance theory, the order of chirping rate in triggered
emission is estimated. The estimated order agrees with the observation.