§  90.735   Station identification.

   (a) Except for nationwide systems authorized in the 220–222 MHz band,
   station identification is required pursuant to § 90.425 of this part.

   (b) Trunked systems shall employ an automatic device to transmit the
   call sign of the base station at 30 minute intervals. The
   identification shall be made on the lowest frequency in the base
   station trunked group assigned to the licensee. If this frequency is in
   use at the time identification is required, the identification may be
   made at the termination of the communication in progress on this
   frequency.

   (c) Station identification may be by voice or International Morse Code.
   If the call sign is transmitted in International Morse Code, it must be
   at a rate of between 15 to 20 words per minute, and by means of tone
   modulation of the transmitter, with the tone frequency being between
   800 and 1000 hertz.

   (d) Digital transmissions may also be identified by digital
   transmission of the station call sign. A licensee that identifies its
   station in this manner must provide the Commission, upon its request,
   information (such as digital codes and algorithms) sufficient to
   decipher the data transmission to ascertain the call sign transmitted.

   [ 56 FR 19603 , Apr. 29, 1991, as amended at  62 FR 15997 , Apr. 3, 1997]