A comparotive study of GPS P3 and GPS L3

More recently, GPS carrier phase measurement using geodetic receivers is widely conducted for accurate time and frequency comparisons. Time transfer experiments were conducted using the Ashtech Z12T receivers whose internal frequency is provided by an external 20 MHz clock and an external 1 pps (pulse per second) of a reference clock. The results of time comparison has shown that the stability of time transfer using carrier phase is better than that of GPS common-view time transfer using GPS C/A or P3. The self-developed processing software was used to the cycle slip detection and ambiguity resolution determination. The objective of this paper is to compare the GPS P3 and GPS L3 time transfer. The GPS P3 and L3 data have been obtained using an Ashtech Z12T at NTSC and an Ashtech ZIIX3 at NICT. The main results and analysis are given in Section 3 and Section 4. For a long baseline comparison, the RMS of L3 is better than that of P3. The stability of frequency of L3 is better than that of P3 for short term tau>6d, however, for tau< 6d the stability of L3 and P3 is almost at the same level