It is well known that there's a Duna pyramid that makes an SSTV signal(sound that can be made into image).   Three years ago, it was found by @Holo that if you go 10,000 peta meters from kerbol, another signal appears.  @holo was unable to do it again.  It is possible it only works once per install- so have recording software ready.  It also must be an actual vessel, not a part ejected by a bug.