does anyone know of a site that has pictures of sonar screens with the various interfence signals,such as electrical or turbulance? that would be a big help to boaters-fisherman such as myself. maybe, if there are none, someone with more skills than myself could look into it. good idea?,or is it better for us laymen to just tuff it out, and keep going with the trial and error method.... retired butcher but wish i was a retired sonar repair specialist !!!