GPS Receiver Test Bed at USNO CNS Systems

GPS Receiver Test Bed at USNO CNS Systems, Inc. Communication, Navigation and Surveillance Critical Evaluation of the Motorola M 12+ GPS Timing Receiver vs. the Master Clock at the United States Naval Observatory, Washington DC. Prepared for the 34 th Annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting December 3 -5, 2002, The Hyatt Regency, Reston Town Center, Reston, Virginia by Richard M. Hambly CNS Systems, Inc. 363 Hawick Court, Severna Park, MD 21146 -1409 Phone 410 -987 -7835, Fax 410 -987 -7836, Mobile 410 -591 -6065 e-mail info@cnssys. com, Web Site http: //www. cnssys. com/ © 2002 CNS Systems, Inc.

CNS Systems’ Test Bed at USNO CNS Systems, Inc. Communication, Navigation and Surveillance Tac 32 Plus software simultaneously processes data from four Time Interval Counters and four CNS Clocks, writing 12 logs continuously © 2002 CNS Systems, Inc. Time Interval Counters compare the 1 PPS from each CNS Clock (M 12+) against the USNO’s UTC time tick.

GPS Receiver Test Setup at USNO CNS Systems, Inc. Communication, Navigation and Surveillance CNS Clock equipped with GPS Rx module under test 1 PPS USNO-provided signals GPS 1 PPS 5 MHz © 2002 CNS Systems, Inc. GPS 1 PPS Agilent 53132 A Time Interval Counter GPS Command Status Time Interval Counter Data Tac 32 Plus running on Windows XP, 2. 4 GHz P 4 PC 1 PPS Signal Splitters 10 MHz 1 PPS Secure Internet Link to CNS Systems

Delay Calibration Data CNS Systems, Inc. Communication, Navigation and Surveillance On-Time 1 PPS 31. 7 ns 3 S Nav TSA 100 L 1/L 2 Antenna Temp Stabilized with 50 db gain preamp USNO On-Time 1 PPS 122. 2 ns FSS 150 A Cable (7 db loss) 4. 8 ns 21. 5 ns TST/Trak 6487 Pulse Distribution Amplifier 3’ RG 8 X/II … … … Start Agilent/HP 53132 A Time Interval Counter Note: 1 us bias added to M 12+ so that the counter always reads positive numbers CNS Clock Femto. Systems Special “USNO FS#1” 12. 0 ns RG-214 … … 18. 1 ns Start Bias = 26. 3 ns © 2002 CNS Systems, Inc. HP 58516 A L 1 Distribution Amplifier 13. 5 ns 3’ LMR-240 M 12+ GPS Timing Receiver … … … 4. 1 ns Stop Bias = 1224. 6 ns 0. 8 ns 1. 0 us (late) Stop 17. 6 ns Total Bias = 1198. 3 ns Serial Data To Tac 32 Plus software 4. 6 ns This Bias is removed from the data in all of the following charts.

Pre-Calibration Data Sample, Rx A Average = -84. 3 ns CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.

Individual M 12 Clock Performance (A) CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Average = -0. 6 ns

Individual M 12 Clock Performance (B) CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Average -0. 2 ns

Individual M 12 Clock Performance (C) CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Average +5. 3 ns

Individual M 12 Clock Performance (D) CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Average = +3. 4 ns

M 12+ Timing Receiver Comparison Chart CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.

Comparisons - Reference to Rx A CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.

Comparisons - Reference to Rx B CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.

Comparisons - Reference to Rx C CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.

Comparisons - Reference to Rx D CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.

Raw Noise Charts – 1 Hour CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.

Raw Noise Charts – 10 Minute Detail CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.

What Happened on 9/7/02 ? CNS Systems, Inc. Communication, Navigation and Surveillance September 7, 2002. September 8, 2002. This picture is a two hour composite of 85 different photos spanning 21: 07 thru 23: 10 EDT on Sept. 7 th (01: 07 thru 03: 10 UTC Sep. 8). This picture is a four hour composite of 140 different photos spanning 20: 00 thru 24: 00 EDT on Sept. 8 th (00: 00 thru 04: 00 UTC Sep. 9). Pictures are © Dr. Thomas A. Clark Each picture was an 87 second exposure with 3 seconds between frames. The trails on the picture all due to airplanes. The bright loop is from a plane on final approach into BWI airport. Camera = Canon D 60 shooting Hi Resolution JPEG at ISO 100 with TC-80 timer. Lens = Sigma f/2. 8 20 -40 mm set to 20 mm @ f/4. 5 © 2002 CNS Systems, Inc.

Short Baseline Test (USNO to NASA GGAO) CNS Systems, Inc. Communication, Navigation and Surveillance Data reduction by Dr. Thomas A. Clark © 2002 CNS Systems, Inc.

A Longer Term View CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc.