Patents Assigned to Parvin Riddle
  • Depth sound indicator
    Patent number: 4097836
    Abstract: An audible tone depth sounder indicator apparatus changes the repetition rate of its audio output to indicate deviation in actual water depth from a selected reference depth. A change in tone of the audible output distinguishes positive and negative deviations from the reference depth, and there is no audible signal when actual depth equals the selected reference depth.
    Type: Grant
    Filed: February 10, 1977
    Date of Patent: June 27, 1978
    Assignee: Parvin Riddle
    Inventors: Parvin Riddle, Christopher I. Reynolds