Sec.  73.297   FM stereophonic sound broadcasting.

   (a) An FM broadcast station may, without specific authority from the FCC,
   transmit stereophonic (biphonic, quadraphonic, etc.) sound programs upon
   installation of stereophonic sound transmitting equipment under the
   provisions of  Sec.  Sec. 2.1001, 73.322, and 73.1590 of the Rules. Prior to
   commencement of stereophonic sound broadcasting, equipment performance
   measurements must be made to ensure that the transmitted signal complies
   with all applicable rules and standards.

   (b) Each licensee or permittee engaging in multichannel broadcasting must
   measure the pilot subcarrier frequency as often as necessary to ensure that
   it is kept at all times within 2 Hz of the authorized frequency.

   [ 48 FR 28454 , June 22, 1983, and  48 FR 38479 , Aug. 24, 1983]