Sec.  5.115   Station identification.

   Each  class  of  station  in  the  experimental services shall, unless
   specifically exempted by the terms of the station authorization, transmit
   its assigned call sign at the end of each complete transmission: Provided,
   however,  that  the  transmission  of the call sign at the end of each
   transmission is not required for projects requiring continuous, frequent, or
   extended use of the transmitting apparatus, if, during such periods and in
   connection with such use, the call sign is transmitted at least once every
   thirty minutes. The station identification shall be transmitted in clear
   voice or Morse code. All digital encoding and digital modulation shall be
   disabled during station identification.