§ 95.637   Modulation standards.

   (a) A GMRS transmitter that transmits emission types F1D, G1D, or G3E must
   not  exceed  a peak frequency deviation of plus or minus 5 kHz. A GMRS
   transmitter  that  transmits  emission type F3E must not exceed a peak
   frequency  deviation of plus or minus 5 kHz. A FRS unit that transmits
   emission type F3E must not exceed a peak frequency deviation of plus or
   minus 2.5 kHz, and the audio frequency response must not exceed 3.125 kHz .

   (b) Each GMRS transmitter, except a mobile station transmitter with a power
   output of 2.5 W or less, must automatically prevent a greater than normal
   audio level from causing overmodulation. The transmitter also must include
   audio frequency low pass filtering, unless it complies with the applicable
   paragraphs of § 95.631 (without filtering.) The filter must be between the
   modulation  limiter and the modulated stage of the transmitter. At any
   frequency  (f  in  kHz)  between 3 and 20 kHz, the filter must have an
   attenuation of at least 60 log10 (f/3) dB greater than the attenuation at 1
   kHz. Above 20 kHz, it must have an attenuation of at least 50 dB greater
   than the attenuation at 1 kHz.

   (c) When emission type A3E is transmitted, the modulation must be greater
   than 85% but must not exceed 100%. Simultaneous amplitude modulation and
   frequency or phase modulation of a transmitter are not permitted.

   (d) When emission type A3E is transmitted by a CB transmitter having a TP of
   greater  than 2.5 W, the CB transmitter must automatically prevent the
   modulation from exceeding 100%.

   (e) Each CB transmitter that transmits emission type H3E, J3E or R3E must be
   capable  of  transmitting  the  upper sideband. The capability of also
   transmitting the lower sideband is permitted.

   (f) DSRCS-OBUs are governed under subpart L of this part.

   [ 53 FR 36789 , Sept. 22, 1988. Redesignated and amended at  61 FR 28769 ,
   28770, June 6, 1996, and further redesignated at  61 FR 46567 , Sept. 4, 1996;
    69 FR 46446 , Aug. 3, 2004]

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