§ 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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