TimeSource 3000
GPS Primary Reference Source
097-72000-02
Issue 6: October 2003
Symmetricom, Inc.
2300 Orchard Parkway
San Jose, CA 95131-1017
http://www.symmetricom.com
Copyright © 1999-2003 Symmetricom, Inc.
All rights reserved. Printed in U.S.A.
All product names, service marks, trademarks, and registered trademarks
used in this document are the property of their respective owners.
Acronyms and Abbreviations
AIS alarm indication signal
E1 digital transmission (2.048 Mb/s)
ESD electrostatic discharge
ESF extended superframe
GPS Global Positioning System
LOS loss of signal
MDEV mean time deviation
pps pulse per second
PRS primary reference source
RO remote oscillator
RU rack unit (1.75 in.)
SSM synchronization status messaging
T1 digital transmission (1.544 Mb/s)
TDEV time deviation
TOD time of day
UTC U niversal Coordinated Time
What’s New in This Manual
This issue of the TimeSource 3000 user manual has the following changes from
the previous issue:
• Added “Startup”, “Bridging/Holdover Behavior” and “Time Figure of Merit”
sections to Chapter 1.
• Removed TimeScan Craft connection key (020-46700-001) from system
equipment lists in Chapter 2.
• Added section on TimeWizard software installation application to Chapter 3.
• Added Procedure H, TimeWizard Installation and Operation, to Chapter 3.
• Added TL1 command “RTRV-HDR” for NMA keep alive responses.
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Table of Contents
Chapter 1 Description
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Global Positioning System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Physical Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
IF Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Local Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Clock Extractors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
NTP TimeServer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Network Time Protocol Password Activation . . . . . . . . . . . . . . . . . . . . . . . 22
BesTime Ensemble Timing Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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T1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Eight Additional T1 Outputs (990-72010-02 Systems Only) . . . . . . . . 22
TOD Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
IRIG-B TOD Outputs (990-72010-05 Systems Only) . . . . . . . . . . . . . . 22
1 PPS Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
10 MHz Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Eight Mixed E1/T1 Outputs (990-72010-06 Systems Only) . . . . . . . . . 23
Eight Mixed T1/CCK Outputs (990-72010-07 Systems Only) . . . . . . . . . . 23
Composite Clock Outputs (990-72010-03 Systems Only) . . . . . . . . . . . . . 23
Alarm Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Communications Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Passthrough . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Alarm Programmability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Chapter 2 Engineering & Ordering
Site Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Lightning Suppressor Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Antenna Location Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Cabling Considerations for Standard Configurations . . . . . . . . . . . . . . . . . . . . 33
Antenna Cable Choices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
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Cabling Considerations for Optional Configurations . . . . . . . . . . . . . . . . . 35
IRIG-B TOD (990-72010-05 Systems Only) . . . . . . . . . . . . . . . . . . . . 35
Remote Oscillator Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
RJ-422–to–RJ-232 TOD Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Antenna-to-Shelf Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Shelf Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Rack Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
With Two T1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
With Ten T1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
With Two T1 and Eight Composite Clock Outputs . . . . . . . . . . . . . . . . . . . 42
With Two T1 and Two IRIG-B TOD Outputs . . . . . . . . . . . . . . . . . . . . . . 43
With Two T1 and Eight Mixed E1/T1 Outputs . . . . . . . . . . . . . . . . . . . . . . 44
With Two T1 and Eight Mixed T1/CCK Outputs . . . . . . . . . . . . . . . . . . . . 45
User-Supplied Tools and Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
For Antenna Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Outputs, Power, and Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
For Shelf Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Chapter 3 Installation
Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Shelf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Rack Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Power and Signal Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Frame Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Alarms Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
GPS Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Additional T1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Composite Clock (CCK) Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Mixed E1/T1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Mixed T1/CCK Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
IRIG-B TOD Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Remote Oscillator Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
DCD Shelf with Isolation Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
DCD Shelf without Isolation Module . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Source Other than DCD Shelf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
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1 PPS Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
10 MHz Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Time of Day Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
T1 Reference Inputs (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
T1 Synchronization Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Communication Port 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
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Communication Port 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Craft Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Power-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Factory-Set Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Chapter 4 TL1 Reference
Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Command Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Response Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Autonomous Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Report Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Report Event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Tasks/Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Activate User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Cancel User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Copy Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Delete Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Delete User Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Edit Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Edit Date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Edit Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Enter Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Enter User Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Initialize Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Initialize Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Initialize System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Operate Alarm Cutoff All . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Retrieve Alarm All . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Retrieve Alarm Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Retrieve Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
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Retrieve Condition All . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Retrieve Condition Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Retrieve Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Retrieve GPS Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Retrieve Header . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Retrieve Inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Retrieve Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Retrieve Performance Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Retrieve User Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Set Source Identifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Chapter 5 Troubleshooting
Troubleshooting with Front Panel Items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Troubleshooting with Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Card Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Repair and Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
Technical Assistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
Sales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Manual Updates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Chapter 6 Specifications
Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Communication Port 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Communication Port 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Craft Communication Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Ethernet Communication Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Remote Oscillator Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
T1 Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
1 PPS Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
T1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Eight Additional T1 Outputs (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Eight Additional Mixed E1/T1 Outputs (Optional) . . . . . . . . . . . . . . . . . . . 198
E1/T1 Common . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
E1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
T1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Eight Additional Mixed T1/CCK Outputs (Optional) . . . . . . . . . . . . . . . . . 200
T1/CCK Common . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
T1 Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
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CCK Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Eight Additional Composite Clock Outputs (Optional) . . . . . . . . . . . . . . . 201
Time of Day Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Cisco Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
IRIG-B (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
10 MHz Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Office Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Rear Panel Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
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Front Panel Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Front Panel Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Simple Network Time Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
Mechanical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Shelf Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
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10 TimeSource 3000
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Contents
Description
This chapter provides an overview of the
global positioning system, and a physical and
functional description of the TimeSource 3000.
Chapter 1
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Overview
1
The TimeSource 3000 is a Primary Reference Source (PRS) that receives and processes
signals from GPS satellites, and outputs Stratum 1 synchronization signals traceable to UTC.
TimeSource 3000 applications include synchronization for central offices, radio base
stations, transmission nodes, and other instances where a primary reference source can
improve the performance of telephony network facilities.
The TimeSource 3000 creates timing outputs by ensembling signals from several sources.
The sources include GPS signals, an onboard local oscillator, and optional T1 and remote
oscillator signals. Timing outputs created from the ensemble are composed of the most
stable and least noisy parts of each input. Synchronization outputs are delivered in a framed,
all-ones, T1 format, a 10 MHz signal, a 1 pps signal, composite clock signals (optional), and
time of day (TOD) signals.
The TimeSource 3000 minimizes timing impairments such as jitter and wander, that are
created by network and transmission systems. The synchronization timing is traceable to the
GPS, which provides the highest level of synch ronization for tele phony networks. The
TimeSource 3000 with its GPS input is a stand-alone office PRS. With the optional inputs
ensembled, overall system performance is improved, and holdover is extended if GPS
signals become disrupted.
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Global Positioning System
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The United States Government developed the GPS navigation system. It is a satellite-based,
radio navigation aid designed to provide global, all-weather, precise navigation and timing
capability to users 24 hours a day.
The satellites, circling the earth at approximately 12,550 statute miles, are arranged in 6
orbits with 4 operational satellites in each orbit. Each satellite has an orbital period of
approximately 12 hours. This configuration assures that a minimum of 4 satellites, and as
many as 12, are in view anywhere in the world at all times.
The TimeSource 3000 tracks all satellites within its field of view. The performance of each
tracked satellite is observed and compared to the others, and available for use in the timing
solution. A satellite with unacceptable performance data is dropped from the timing
solution.
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3
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Physical Description
1
The TimeSource 3000 consists of a shelf, a plug-in card, an antenna, cables, hardware, and
software. An optional factory-installed daughter card may be included to provide eight
additional T1 outputs, eight additional composite clock outputs, two additional IRIG-B TOD
timing outputs, or eight mixed El/T1 outputs.
The shelf occupies two rack mounting un its (RU), and can be mounted in a 19 inch rack or a
23 inch rack. One RU (1.75 in.) of air space above the TimeSource 3000 is required for
proper ventilation. Other than a communications connector on the front panel, all connectors
are at the rear of the shelf.
The antenna (Figure 1) is encased in weather-resistant plastic housing for outdoor
installation, usually on a roof. A single coaxial cable carries signal and power between the
antenna and the shelf.
Figure 1.Antenna
12.375 in.
1.75 in.
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Functional Description
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Overview
Figure 2 shows the main functions of the TimeSource 3000. The center of the TimeSource
3000 is the Ensemble Timing Generator, which uses the BesTime algorithm to analyze the
phase and frequency relationships, individually and collectively, of the timing sources. Each
type of timing source has a particular characteristic that gives it an advantage over other
sources, as listed in Table A.
The BesTime algorithm uses the best characteristic of each source to produce an output
signal with greater overall accuracy and stability than any single source. The contribution of
a source is based on its deviation from the weighted average of all the sources. The more
accurate a source, the more weight it has in the final output. Every so urce is under co nstant
evaluation and its contribution subject to periodic adjustment. The output is essentially the
best performance of the best source.
Table A. Timing Source Characteristics
Source Characteristic
Local Oscillator Short term stability
T1 Line Intermediate term stability
1
2
3
External Oscillator Intermediate term stability
GPS Signal Long term stability
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Figure 2. Block Diagram
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Antenna
The antenna housing includes a volute antenna, GPS receiver, amplifier, and intermediatefrequency (IF) downconverter.
The GPS Receiver extracts a clock signal from the GPS satellite signals. The receiver can
process the signals from all satellites in view, while simultaneously using the Earth location
of the receiver and other factors to determine an accurate clock signal.
An amplifier in the antenna provides 23 dB of signal gain.
2
A downconverter converts the L-band GPS signal to IF for long-distance transport on the
coaxial antenna cable. The antenna cable provides 125 mA power from the shelf to the
antenna, and transports GPS satellite IF signals from the antenna to the shelf.
IF Interface
3
An IF interface accepts the signals from the antenna, and provides the clock information to
the BesTime Ensemble Timing Generator.
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1
Local Oscillator
A digitally controlled, oven-controlled crystal oscillator (OCXO) develops a highly stable
local oscillator signal, independent of factors that exist outside the shelf. This signal is sent
to the BesTime Ensemble Timing Generator.
Clock Extractors
T1 signals (optional) enter on the SPAN IN #1 and #2 wire-wrap pins, and remote oscillator
signals (optional) enter on the A and B REM OSC connectors. From each external signal, a
clock extractor circuit extracts a timing signal, which is sent to the BesTime Ensemble
Timing Generator.
Power Supply
A power converter filters and converts -48 volts dc power supplied to the shelf into the
voltages required by the shelf.
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Description
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NTP TimeServer
The TimeServer is a Simple Network Time Protocol (SNTP) device. The SNTP TimeServer
function is provided via the TimeSource Ethernet interface and associated IP address. User
software requests UTC time of day via NTP protocol. The TimeSource SNTP server
responds with current UTC time. The TimeServer is compatible with the SNTP RFC-1769
format.
To enable the SNTP feature, a password must be entered using the ED-EQPT TL1
command. If a user makes a fourth attempt of an incorrect password entry, the TimeServer
will lock out the user for 1 hour.
Network Time Protocol Password Activation
Use of the Simple Network Time Protocol (SNTP) feature requires activation with a
password. Activation is accomplished through receipt of a Network Time Protocol
Activation Certificate from Symmetricom. This certificate contains the unit purchase order
number, unit model number, unit activation date, unit serial number, and unit activation key.
The unit activation key is the password that enables the SNTP feature. To activate the SNTP
feature, enter the TL l command printed on the activation certificate. Once activated, this
feature will be permanently enabled. To order the SNTP feature, contact the local
Symmetricom sales representative.
BesTime Ensemble Timing Generator
Clock signals from the IF Interface, the local oscillator, the two T1 span lines, and the two
remote oscillators are used as sources by the BesTime algorithms in the BesTime Ensemble
Timing Generator. The signals are analyzed for MTIE, TDEV, and other phase and
frequency characteristics.
The BesTime Ensemble Timing Generator uses mathematical models to analyze each clock.
The ensemble algorithms use the comparisons and analyses to generate a highly stable
timing signal, which uses the best qualities of all inputs.
T1 Outputs
The BesTime Ensemble Timing Generator provides the timing for the T1 timing signal
available at the T1 OUT A and B connectors in a framed, all-ones format, which can be set
to ESF or D4 framing.
Eight Additional T1 Outputs (990-72010-02 Systems Only)
This option provides eight additional T1 outputs at the OPTIONS I/O wire-wrap pins. These
outputs function the same as the standard T1 outputs.
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TOD Output
The BesTime Ensemble Timing Generator provides the timing for the TOD timing signal
available at the RJ-45 connector, which provides time code to devices compatible with NTP
Type 4 or Cisco format.
IRIG-B TOD Outputs (990-72010-05 Systems Only)
This option provides two additional TOD outputs in IRIG-B format at the BNC connectors
on the IRIG-B BNC adapter (secured to the shelf rear panel).
2
The BesTime Ensemble Timing Generator provides the timing for the TOD timing signal,
which provides timing code to devices compatible with IRIG-B.
1 PPS Output
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1
The BesTime Ensemble Timing Generator provides the timing for the 1 pulse-per-second
timing signal available at the 1 PPS connector, which can be used for application-specific
requirements.
3
10 MHz Output
The BesTime Ensemble Timing Generator provides timing for the 10 MHz timing signal
available at the 10 MHZ connector, which can be used for local cellular frequency or testing
purposes.
Eight Mixed E1/T1 Outputs (990-72010-06 Systems Only)
This feature enables a user to mix any combination of E1 and T1 outputs. A user can also
use any combination of framing. For El, CCS, CAS, CCS with CRC4, and CAS with CRC4
can be used per G.703 table 6. For T1, D4 or ESF can be used per ANSI T1.101. In addition,
there is support for analog (2.048 MHz) per G.703 table 10 and support for synchronization
status messaging (SSM) per TR-33 for E1 and T1.
5
Eight Mixed T1/CCK Outputs (990-72010-07 Systems Only)
This feature enables a user to mix any combination of T1 and CCK outputs. For T1, D4 or
ESF framing can be used per ANSI T 1.101. Support for SSM is per TR-33 for T1.
Composite Clock Outputs (990-72010-03 Systems Only)
This option provides eight composite clock signals available at the OPTIONS I/O wire-wrap
pins.
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Description
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Alarm Interface
The microprocessor delivers alarms to normally open dry-contact type connections. A larms
are also indicated by the front-panel status lamps, and TL1 messages reported via the
communication ports.
Ethernet
TimeSource 3000 has one physical Ethernet port with six virtual ports to carry TL1
commands, responses, and autonomous messages between the TimeSource 3000 and an
external terminal, or an Element Manager, or both. The user can configure the IP address,
subnet mask, and gateway address for the Ethernet ports.
Four ports (5001, 5002, 5003, and 5004) are configured to act as though a serial-port
communication terminal were connected to them. These ports communicate TL1 commands,
responses and autonomous messages.
Two additional ports communicate with Element Managers, which may have NMS,
TimeScan, TimePictra, or similar software. An Element Manager establishes a connection
with one port (5551) for TL1 commands and responses. Another port (5550) establishes a
connection to an Element Manager, sends autonomous messages, and closes the connection
when finished.
Communications Ports
Three RS-232 serial communications ports carry TL1 commands, responses, and
autonomous messages between the TimeSource 3000 and an external terminal.
Passthrough
The Passthrough feature of the TimeSource 3000 allows the unit to front a DCD product to
provide one management interface for a user site. Passthrough allows a user to do the
following:
• Provide a no download exclusion for the Passthrough port
• COM 1 or COM2 is connected to the DCD product
• The user port can be any unused port, including the Ethernet port
• Messages can pass from a user to the DCD product and from the DCD product to a
user through the TimeSource 3000
• The TID (SID for DCD) is used to identify commands that go to the DCD product.
The TimeSource 3000 passes any TID not its own through to the DCD product. In
the reverse direction, all commands received from the DCD product are passed
through to the user.
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Note: The TID of the TL1 command must be the SID of MIS.
• DCD is fully managed except for firmware download.
S
• The Passthrough feature is communicated via TL1 only (ie. no GUI interface).
Figure 3. shows a TimeSource 3000 Passthrough setup.
Figure 3. TimeSource 3000 Passthrough Function
Straight cable
DCD-5X TS-3000
COM 1, 2, or 3
Alarm Programmability
DCDPASSTHRU
COM1 or 2 (COM-1 is
DB-25 and COM-2 is
RJ-45)
2
User port (any port)
DCDUSERPORT
COM 1, 2, 3
IP:5001-5004
3
1
New releases of TimeSource (1.05.03 or higher) allow the user to provision the alarm
escalation parameters that were hardcoded in the previous releases of TS3000.hex. The
defaults for this release remain the same as were previously hardcoded. This feature can be
used to set the programmability for such alarms as GPS, HOLDOVER, SPAN-X, and RO-X.
The TS3000 alarms can be programmed for GPS and HOLDOVER types of events. The
SPAN-X alarms can be programmed for AIS, ERROR, and LOS types of events. The RO-X
alarms can be programmed for ERROR and LOS types of events.
The user can set the parameters for SEVERITY1 and SERAFF1 which initially come into
effect when the condition is detected. The user can also set the parameters for SEVERITY2
and SERAFF2 which come into effect after TIME (another user programmable parameter).
Startup
When the TimeSource starts up, the CRIT lamp lights. The CRIT lamp remains on for
approximately 50 seconds to 60 seconds and then shuts off.
During startup, the TimeSource performs several self-tests to verify the integrity of the
hardware and software. Neither communication nor outputs are possible at this time, and the
CRIT lamp is switched on. Once the self-tests are done, a connection to the system can be
made and the events viewed.
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Two events are initially provided. These events are:
• "Power Up Restart"
1
• "Settling Period"
In the "Power Up Restart" event, which lasts for approximately 2 minutes, the system does
additional checks and starts all the various tasks within the system.
The "Settling Period" event is an informational message that lasts until the TimeSource’s
BesTime engine reaches the highest possible stable point. The time taken to reach this point
depends on satellite availability, type of oscillator, ambient temperature, etc. and may take
up to 20 hours to clear. Since "Settling Period" is independent of the quality of the output
and is the normal behavior of the system, it is generated as an event rather than an alarm. If
"Settling Period" is not cleared after 24 hours, another "Settling Period" event is generated
as a marker. This is still Non-Service-Affecting.
As soon as the "Power Up Restart" message is cleared, the "BT3 Warmup" event is
generated. This is also an informational message that lasts till the time it takes the system to
acquire the satellites, warm up the oscillator, and start giving out valid outputs. It may take
up to 2 hours for the message to clear, but typically takes approximately 40 minutes. During
the "BT3 Warmup" time, the outputs will generally be squelched. If the outputs are enabled
using the TL1 command
(ED-EQPT::TS3000:ctag:::ALMCOND=ALW;) they may not be within the PRS mask. In
case the system is not able to acquire sufficient number of satellites and/or discipline the
oscillator within 2 hours, the event escalates into a Non Service Affecting Minor alarm.
Once the warm up is complete, the system generates valid outputs and the event is cleared.
Bridging/Holdover Behavior
In the TimeSource 3000, alarms are designed with a built-in hysteresis. This means that an
alarm is not announced as soon as some error condition is detected. There is a preintegration time during which the error must persist in order for the alarm to be announced.
On the flip side, the error must be clear for a certain time for an alarm condition to be
cleared. This ensures that intermittent conditions are not flagged unnecessarily.
During the normal working of the TimeSo urce 3000, it is a very co mmon occurrence that the
GPS satellites may not be visible during certain parts of the day, depending on the
installation of the antenna. This is particularly true with wall and, especially, window
antenna installations. The TimeSource 3600 has been designed to work around this situation.
The TimeSource 3000 enters "Bridging" mode when all satellite locks are lost. There is no
TL1 annunciation that the system has entered "Bridging" mode. This is "Non Service
Affecting" and the outputs are not affected. The system runs of f i ts internal oscillator and the
outputs are kept within the PRS mask by the BesTime engine.
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When "Bridging" mode persists for more than 30 minutes, the system enters "Holdover"
mode and a "Holdover" event is generated. This may or may not affect the outputs
depending on the alarm integration parameters that can be set by the user.
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The system allows the user to set various parameters for GPS error, Holdover error, and
SPAN error conditions. These parameters are:
• Initial Severity
• Initial Service Affecting state
2
• Integration Time
• Final Severity
• Final Service Affecting state
The system also allows the user to set a parameter to define how outputs should behave in an
alarm condition. Outputs can be set to AIS, Squelch, or SSM on an alarm. Outputs can also
be set to ignore alarm conditions.
When the "Holdover" event is announced, it is announced with the Initial Severity and
Initial Service Affecting state. If the "Holdover" event persists for the length of the
Integration Time, the alarm is escalated to the Final Severity and Final Service Affecting
state.
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1
The "Holdover" event/alarm is cleared when the satellites are visible again.
Time Figure of Merit
Time Figure of Merit (TFOM) is a moving 24 hour measurement reported in nanosecond
(ns) against an ideal model. TFOM has a frequency component used to measure GPS
wander caused by multipath and a time loop component used to measure long term oscillator
wander.
The TFOM alarm threshold is set to 500 ns and is not user configurable. A TFOM below
500 ns indicates a stable clock well within PRS output performance specifications. A TFOM
between 500 ns and 800 ns is an early warning of a clock becoming unstable and in danger
of going out of PRS specification. When the TFOM exceeds 800 ns, the clock is no longer
meeting the stratum 1 MTIE mask.
TFOM is most useful for installations where the antenna has a limited view to the sky. This
is defined as any installation where fewer than 4 satellites are in view for greater than 1 hour
per day on average. This is typical for installations where the antenna is mounted in a
window or on an outside wall of a building, but can also include rooftop installations with
partial sky view blockage. TFOM’s primary use is to help troubleshoot multipath issues
associated with antenna placement and incorrect latitude, longitude, and/or altitude
(location) data entry.
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Installations with full view to the sky see 4 satellites 23+ hours a day, seven days a week. It
is relatively easy to filter out multipath signals using multiple satellites and simple voting
schemes. In addition, rooftop antennas are mounted vertically and all signals below the
horizon are obvious multipath interference and can be masked out of the system. With 4
satellites in view, the GPS timing receiver will provide an error-free lock on its location
through an automatic survey function.
With wall/window installations, voting schemes become less effective as the number of
satellites in view drop. Also, wall/window antennas are mounted horizontally and are prone
to seeing multipath signals reflected off nearby structures and the ground. Wall/window
installations also require the manual input of location data, creating the potential for errors
and the need to detect these errors.
The TimeSource has unique algorithms to account for, and defeat, the added multipath
complications and location data entry error possibilities of wall/window antenna
installations. Large amounts of multipath or major errors in location data entry are easier to
identify and are detected over a relatively short period of time. These short-term errors are
normally reported via the TimeSource tracking success rate parameter.
Small amounts of multipath or minor errors in location data entry are difficult to identify
because they mimic a true signal or an expected satellite behavior pattern. Single satellite
reception over limited periods of time complicates the ability for the internal TimeSource
algorithms to filter out these ghost signals and longer periods of time are needed to sort them
out. TFOM tracks and reports these long-term errors.
At time of installation, marginal or unacceptable TFOM readings can indicate the need to
adjust the antenna placement, the mask angle, and/or the location data. Relatively small
changes in the antenna placement can improve the ability of the system to see satellites and
therefore improve performance. The mask angle can be adjusted to block out low er
elevation portions of the sky if there is good visibility at higher elevations, thereby reducing
multipath. Correct location data is very helpful in identifying and tracking satellites.
In addition, a clock may be stable for many weeks, months, or years but could degrade
because of changes in its environment. TFOM is useful in detecting these infrequent subtle
changes including:
• Maturing foliage or seasonal foliage changes
• Installation of new transmitters nearby (i.e. wireless base station)
• New building construction
• Variations in the day-to-day temperature of the CO
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Description
Engineering & Ordering
This chapter provides antenna
installation guidelines, shelf mounting
configurations, a parts list, and a list of
user-supplied tools required for
installation.
Chapter
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Site Survey
Procedure A. Site Survey
Step Action
1 Determine the location of the grounding point for the lightning suppressor. The
lightning suppressor must be located within 15 ft. of th is point. If the grounding
2
point is inside the building, the grounding point must be within 50 cable feet of
where the antenna cable enters the building. Valid lightning suppressor grounding
points are as follows:
• •Valid roof ring ground system
• •Cad weld to building structure steel
• •Central Office ground plate
2 Determine the best location for mounting the antenna. The ideal location is where
the antenna has an unobstructed view of the sky, from the horizon to zenith, for 360°
around the horizon.
A site survey should be performed before ordering the system, as described in Procedure A.
3 Determine the shelf location.
4 Determine the cable length between the antenna, and the lightning suppressor
location determined in Steps 1 and 2.
5 Determine the cable length between the lightning suppressor and the shelf location
determined in Steps 1 and 3.
6 Determine the –48 V power source for the shelf.
7 Determine if 5 MHz signals from a Symmetricom Digital Clock Distributor (DCD)
Shelf will be used as remote oscillator inputs (optional).
End of Procedure
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Lightning Suppressor Guidelines
• Mount the lightning suppressor within 15 feet of a valid, direct, low impedance, low
resistance, earth ground connection point. Valid earth grounds include the roof ring
ground system, building structural steel, or a Central Office ground plate. If the
grounding point is inside the building, mount the suppressor within 50 feet of the
cable entry into the building.
Warning: Metal clamps that form a complete metal circle ar ou nd the antenn a cable or
the cable conduit are not allowed. The ring clamp acts like a choke coil to induce
currents, which resists current flow and hampers proper lightning protection.
Warning: Place the lightning suppressor away from electrical devices or cabling that
may induce arcing.
Note: Keep all impedances as low as possible, otherwise the grounding scheme may be
defeated.
2
3
• Route the ground wire as straight as possible (bends in the ground wire increase
impedance at lightning frequencies), in accordance with local company practices.
2
• Treat all exposed connections with an electrically conductive anti-corrosion
compound (Kopr-Shield or equivalent).
Warning: Avoid small-radius turns and unnecessary turns.
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Antenna Location Guidelines
DANGER: Do not select an antenna location that could be an electrical or physical
hazard to work persons or equipment. Avoid proximity to all high-voltage sources. Mount
in an easily maintainable location.
The ideal antenna location provides a clear, unobstructed view of the sky from the zenith to
the horizon line, and 360 degrees around the horizon.
A compromise often must be made between location and satellite field of view. The smaller
2
the field of view, the fewer the number of satellites that can be used in the timing solution
for GPS derived time. With fewer satellites, the TimeSource 3000 may experience GPS
events (temporary loss of contact with four or more GPS signals).
Signals closer to the horizon are often subject to multipath effects, which degrade the timing
solution. The TimeSource 3000 can be set to ignore, or mask, all signals from the horizon to
a chosen angle of elevation (mask angle). (See Figure 4.)
Note: Due to the geometry of the GPS satellite orbits, more satellites are visible in the
direction of the equator than the poles. If possible, place the antenna so that the antenna has a
clear view toward the equator (toward the south in the northern hemisphere, or toward the
north in the southern hemisphere). Up to 60 degrees of arc, centered at the pole, may be
blocked with little effect in the temperate latitudes. This note is less applicable in latitudes
nearer the equator.
Figure 4 Antenna Field of View
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Observe the following guidelines during the placement and installation of the antenna:
• Total of obstructions above the mask angle must not obscure more than 25 percent
of the total field of view (90 degrees of azimuth) (Figure 5).
• No single obstruction may block more than 12.5 percent of the view (45 degrees of
azimuth).
Notes:
1. Place the antenna high enough on the tower that obstructions are below the mask angle;
mount the antenna more than 3 feet away from the tower, and far below the interference
of the antennas at the top of the tower. Tower mounting is the least desirable location
because of the potential for severe multipath, and difficulty in troubleshooting and
maintenance.
2. Place the antenna high enough that the roof structure and tree are below the mask angle,
and the water tower does not block more than 12.5 percent of the sky.
Figure 5 Antenna Location Examples
2
2
3
5
Note: The most important objects are within 1/4 mile (400 yards) of the antenna.
Obstructions may include, but are not limited to, towers, buildings, other construction, trees,
and high-voltage power lines.
• Be aware of transmitting antennas in the area. The direction of transmission, power
level, and frequency may cause interference.
• The minimum horizontal distance from other receiving ante nnas is 3 feet.
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• The minimum horizontal distance from vertical reflective structures (e.g., heating
ducts, equipment housings, etc.) is twice the height of the structure or 10 feet
(Figure 6).
Figure 6 Sample Rooftop Antenna Mount
2
• The minimum vertical distance above parapets, obstructions, or horizontal metallic
reflective surfaces is 4 feet.
• Do not locate the antenna within 30 degrees azimuth of the transmission direction of
any transmitting antenna (to avoid overpowering the GPS reception, even though
the transmitting antenna may operate at a different frequency).
• Do not locate the antenna underneath high power lines. If this cannot be avoided,
ensure the antenna is placed at least twice as far from the power line as the power
line is high (to avoid danger to personnel and multipath effects).
• Mount the antenna in a location with easy and safe access for future maintenance
purposes.
• Mount the antenna on a mast of 1 inch diameter galvanized metal pipe
(recommended). Do not use metal as a cable conduit.
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