Research method of the VCXO disciplined base on UTC(NTSC)

Applying the 1pps signal of the Universal Time Coordinated (National Time Service Center) (UTC(NTSC), as the reference signal, the parameters of the voltage-controlled crystal oscillator (VCXO) are estimated by using the Least Square and the frequency adjustment amount of the VCXO is calculated, so that the VCXO is adjusted properly and so as to make the VCXO get the better accuracy and the long term stability. Based on the above principle, the VCXO control circuit was design to achieve. Finally, the VCXO control circuit can be tested. The experimental results show that, the standard deviation of the clock error that is between the output 1pps of the VCXO and the UTC (NTSC) is no more than 0.5ns, the peak-to-peak of the clock error is less than 2ns, the Allan variance with 1s sampling is 4.902×10⁻¹², the Allan variance with 4000s sampling is 1.91×10⁻¹³. Therefore we can conclude that the VCXO gets the better accuracy and the long term stability, certainly the short-term stability is minimally affected. The test also proves that the Least Square is a reliable and stable to control the VCXO.