3.5 New developments for GNSS precise positioning and timing

Abstract

: The latest developments in the GNSS precise positioning and timing receivers from JAVAD GNSS include the option to replace the classical TCXO (Temperature Compensated Crystal Oscillator) by an OCXO (Oven Controlled Crystal Oscillator). This internal OCXO delivers an unmachted short term frequency stability 2x10-12 (@1sec) and 5x10-12 (@10sec). The position and timing signals measured using this OCXO will have great advantages, especially for flight test measurements with high dynamics or ionosphere scintillation measurements both requiring high update rates for raw measurement and positioning (up to 200Hz supported). For the long term frequency stability, the latest JAVAD GNSS receivers have the ability to precisely synchronize the internal receiver clock with external 1 PPS signal without any additional equipment. In this mode the receiver uses the external frequency as the reference, but the time offset between 1 PPS and 10 MHz signal is measured inside the receiver and can be recorded. All the observations are performed in the epoch defined by an incoming 1 PPS signal. Receiver synchronizes its internal time scale to input 1 PPS signal with accuracy less or equal 0.4 ns, without any external time interval counter. This is the optimal solution for network timing or to synchronize FTI.