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 21146-1409 Phone
410-987-7835, Fax 410-987-7836, Mobile 410-591-6065 e-mail
[email protected], Web Site http://www.cnssys.com/ Critical
Evaluation of the Motorola M12+ GPS Timing Receiver vs. the Master
Clock at the United States Naval Observatory, Washington DC.
Slide 2
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 USNOs UTC time tick.
Slide 3
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
Slide 4
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 122.2 ns
Start Bias = 26.3 nsStop Bias = 1224.6 nsTotal Bias = 1198.3 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)
Slide 5
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Pre-Calibration Data Sample, Rx A Average =
-84.3 ns
Slide 6
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Individual M12 Clock Performance (A) Average
= -0.6 ns
Slide 7
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Individual M12 Clock Performance (B) Average
-0.2 ns
Slide 8
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Individual M12 Clock Performance (C) Average
+5.3 ns
Slide 9
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Individual M12 Clock Performance (D) Average
= +3.4 ns
Slide 10
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. M12+ Timing Receiver Comparison Chart
Slide 11
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Comparisons - Reference to Rx A
Slide 12
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Comparisons - Reference to Rx B
Slide 13
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Comparisons - Reference to Rx C
Slide 14
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Comparisons - Reference to Rx D
Slide 15
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Raw Noise Charts 1 Hour
Slide 16
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. Raw Noise Charts 10 Minute Detail
Slide 17
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. What Happened on 9/7/02 ? September 7, 2002.
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, 2002. 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/2.8 20-40 mm set to 20 mm @ f/4.5
Slide 18
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
Slide 19
CNS Systems, Inc. Communication, Navigation and Surveillance
2002 CNS Systems, Inc. A Longer Term View