Sec. 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 Sec. 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.
[ 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]