Telecommunication Laboratories Jia-Lun Wang, Shinn-Yan Lin, Yi-Jiun Huang, Huang-Tien Lin and Chia-Shu Liao APMP 2012 November 26, 2012 MSL Wellington, New Zealand National Time and Frequency Standard Lab., Telecommunication Laboratories(TL), Chunghwa Telecom Co. Ltd., Taiwan GPS Receiver Calibration Demostration

Telecommunication Laboratories GPS Receiver Calibration Exercise  Introduction  The Procedure for GPS Receiver Calibration System Setup (Hardware & Software) Data Record & Analysis Observation Data at MSL  Calibration Trip in Asia GNSS Receiver Calibration Trip  Detailed Principle and Data Analysis  Summary and Discussion

Telecommunication Laboratories Introduction  GPS time and frequency is one of the most accurate techniques for comparison of remote clocks.  To implement GPS calibration periodically is necessary for providing accurate time transfer. Absolute Calibration Differential Calibration Link Calibration  In this report, the GPS exercise demonstration and detailed calibration procedures are presented.

4 GPS Calibration System Architecture Telecommunication Laboratories

GPS Calibration System Accessories  GNSS receiver Septentrio PolaRx4 PRO  Antenna CRG2-DM-mini-GG choke ring  Antenna cable About 45m long  Personal Computer For data record  Time Interval Counter  Aluminium Tripod

Telecommunication Laboratories Antenna Mounting & Cable Setup (I)

Telecommunication Laboratories Antenna Mounting & Cable Setup (II)  Mounting Location Considerations Choose a location for the GPS antenna assuring maximum visibility of the satellites The optimum location must not shaded by any structure or by other antennas  Spacing to Other Antennas & Equipment Ensure a proper spacing from other antennas to avoid desired signal degradation because of interference Avoid installing antenna or routing cable around other communications equipment generating frequencies harmonic

Telecommunication Laboratories Antenna Mounting & Cable Setup (III)  Cable considerations Minimizing the length of the cable from the antenna to the receiver for maximum signal strength Using low loss type cable as GPS antenna cable (ex. CFD400- LW 16.8 GHz )

Telecommunication Laboratories GNSS Receiver  Multi-constellation GPS 、 GLONASS 、 Galileo  Multi-frequency GPS L1/L2/L2C/L5 GLONASS L1/L2 Galileo E1/E5a/E5b/E5  External 10 MHz reference To synchronize the GNSS measurements  Networking, remote operation, and data logging

Telecommunication Laboratories GNSS Receiver Setup  Connect the antenna cable to the N-type connector of receiver  Use a RG-58 cable to input external 10 MHz as frequency reference input of receiver  Use a RG-58 cable to connect 1PPS out of receiver to the input of counter  Connect USB cable to PC  Power on the receiver

Telecommunication Laboratories Time Interval Counter Setup  Connect 1PPS output of the receiver and Device under test to the counter input of A and B, separately  Make time interval measurement

Telecommunication Laboratories Cable Dealy Measurement  First, connect BNC T-Connector to time interval counter (TIC)  Second, Connect 1PPS output of the time source to one side of T-connector  Finally, Connect the other side of T-connector to TIC  Make time interval measurement (Cable Delay) 1PPS input Cable under-test

Telecommunication Laboratories Software Setup (Receiver, TIC)  Receiver software - RxControl Control receiver Log data Monitor navigation solution  Time Interval Counter software Measurement data record with time tag

Telecommunication Laboratories Data Record & Analysis Rinex to CGGTTS Rinex File CGGTTS File Data Analysis

Telecommunication Laboratories Common Clock Tests (Polax4_965- Polax4_966)

Telecommunication Laboratories Common Clock Tests (TWTF- Polax4_965)

Telecommunication Laboratories Observation Data at MSL

Telecommunication Laboratories Calibration Trip in Asia Ref. from ministry of foreign affairs republic of CHINA (TAIWAN)