PTF 3203A - Disciplining Algorithm

2.2. ptf 3203A GlobalTyme - Disciplining Algorithm
One of the most fundamental benefits of a GPS time and frequency system is
the attainable accuracy and stability of the generated RF frequency outputs.
The RF output is derived from an internal oscillator, and dependent upon the
requirements of the application this oscillator can be either a temperature
compensated quartz oscillator (TCXO), an oven controlled quartz oscillator
(OCXO), or a rubidium atomic oscillator.
In order to realize the benefits of the excellent long-term accuracy of the
received GPS signals, the internal oscillator is “disciplined” (controlled) by the
GPS signal, to insure it is centered on exactly the right frequency. The
narrower the bandwidth of the disciplining loop, the more accurate is control
of the local oscillator to the desired frequency, however this disciplining has to
be implemented with great care, as the noise of the incoming GPS signal can
cause the disciplining control loop to become unstable if the bandwidth of the
loop is too narrow.