Unusually low audio modulation on XEPPM Radio Educación Mexico 6185 AM 8 Sept 2015 0438 UTC. One of the few remaining great shortwave broadcasters with diverse programming, but for some reason XEPPM has had unusually low audio modulation this year despite a pretty strong carrier. The S7-S9 carrier over very modest QRN has modulation comparable to only an S2-S3 signal. Reminiscent of Radio Cairo several years ago, which also boasted a strong carrier but very weak modulation.
Video recording off-speaker audio, switching between Radio Shack Optimus cube and Palstar SP30 speakers.