telemeter
    n 1: any scientific instrument for observing events at a
         distance and transmitting the information back to the
         observer

Telemeter \Te*lem"e*ter\, n. [Gr. ? far + -meter.]
   1. An instrument used for measuring the distance of an object
      from an observer; as, a telescope with a micrometer for
      measuring the apparent diameter of an object whose real
      dimensions are known.
      [1913 Webster]

   2. A measuring instrument which sends the information
      obtained from its sensors by radio to a distant station,
      usually to be recorded there; also, the complete system
      including measuring instrument, transmitter, and receiver.
      Such instruments are used, for example, to measure
      conditions in space or in other locations difficult of
      access for humans observers, or merely to allow one
      observer to monitor conditions in many places
      simultaneously.
      [PJC]