CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. GPS Receiver Test Bed at USNO Prepared for the 34th 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 Phone , Fax , Mobile Web Site Critical Evaluation of the Motorola M12+ GPS Timing Receiver vs. the Master Clock at the United States Naval Observatory, Washington DC.

CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. CNS Systems’ Test Bed at USNO Tac32Plus software simultaneously processes data from four Time Interval Counters and four CNS Clocks, writing 12 logs continuously Time Interval Counters compare the 1PPS from each CNS Clock (M12+) against the USNO’s UTC time tick.

CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. GPS Receiver Test Setup at USNO Signal Splitters GPS 1PPS 5 MHz 1PPS 10 MHz 1PPS GPS Secure Internet Link to CNS Systems GPS Command and Status Time Interval Counter Data CNS Clock equipped with GPS Rx module under test Agilent 53132A Time Interval Counter Tac32Plus running on Windows XP, 2.4GHz P4 PC USNO-provided signals

CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Delay Calibration Data TST/Trak 6487 Pulse Distribution Amplifier USNO On-Time 1PPS … … … M12+ GPS Timing Receiver Agilent/HP 53132A Time Interval Counter Start Stop CNS Clock On-Time 1PPS 21.5 ns 4.8 ns 3’ RG8X/II 17.6 ns 4.6 ns 0.8 ns4.1 ns HP58516A L1 Distribution Amplifier … … … 13.5 ns 3’ LMR-240 Femto- Systems Special “USNO FS#1” 18.1 ns RG-214 … … 12.0 ns 3S Nav TSA100 L1/L2 Antenna Temp Stabilized with 50db gain preamp 31.7 ns ns Start Bias = 26.3 nsStop Bias = nsTotal Bias = ns 1.0 us (late) Note: 1 us bias added to M12+ so that the counter always reads positive numbers This Bias is removed from the data in all of the following charts. Serial Data To Tac32Plus software FSS150A Cable (7db loss)

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

CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Individual M12 Clock Performance (A) Average = -0.6 ns

CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Individual M12 Clock Performance (B) Average -0.2 ns

CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Individual M12 Clock Performance (C) Average +5.3 ns

CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. Individual M12 Clock Performance (D) Average = +3.4 ns

CNS Systems, Inc. Communication, Navigation and Surveillance © 2002 CNS Systems, Inc. M12+ 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 ? September 7, This picture is a two hour composite of 85 different photos spanning 21:07 thru 23:10 EDT on Sept. 7th (01:07 thru 03:10 UTC Sep. 8). September 8, This picture is a four hour composite of 140 different photos spanning 20:00 thru 24:00 EDT on Sept. 8th (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 are all due to airplanes. The bright loop is from a plane on final approach into BWI airport. Camera = Canon D60 shooting Hi Resolution JPEG at ISO 100 with TC-80 timer. Lens = Sigma f/ mm set to 20 f/4.5

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

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