6.
Crystal Control
Section 95.651 provides that transmitters in the Personal Radio Services, with certain
exceptions, must be crystal controlled.
The Commission adopted this requirement to ensure that personal radio transmitters utilize a stable and accurate transmit frequency-determining method. In the early years of CB Radio Service, some operators used radios with coil and capacitor based variable frequency oscillators (VFOs) — electronic circuits that generate an alternating current or voltage -- as the frequency-determining method. VFOs of this type are susceptible to greater frequency inaccuracy and variation with time and temperature, relative to crystal oscillators.
Today’s personal radio transmitters utilize a digital frequency synthesizer to generate the transmitted signals.
These synthesizers have at their heart a crystal time base which ensures that frequencies of the transmitted signals are stable and accurate, and such synthesizer-based radios satisfy the crystal control requirement.
Synthesizer technology is also less expensive to manufacture than the older VFO technology and has largely, if not entirely, supplanted it. In view of the evolution in technology, we seek comment on whether section 95.651 is necessary, or whether frequency tolerance and stability requirements discussed supra alone are sufficient. If section 95.651 is retained, we seek comment on whether the rule should be revised to clarify that crystal-based frequency synthesizers satisfy the rule
