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.