TimeSource 3600
GPS Primary Reference Source
097-72060-01
Issue 2
FCC Regulatory Notice
Warning: This equipment generates, uses, and can radiate radio
frequency energy, and if not used in accordance with the instruction
manual, may cause interference to radio communications. It has
been tested and found to comply with the limits for a Class A
computing device pursuant to Subpart B of Part 15 of FCC rules,
which are designed to provide reasonable protection against such
interference when operated in a commercial environment. Operation
of this equipment in a residential area is likely to cause interference
in which case the user at his own expense will be required to take
whatever measures may be required to correct the interference.
Symmetricom, Inc.
2300 Orchard Parkway
San Jose, CA 95131-1017
http://www.symmetricom.com
Copyright © 1999–2001 Symmetricom, Inc.
All rights reserved. Printed in U.S.A.
Symmetricom is a registered trademark of Symmetricom, Inc. BesTime, DCD, and TimeSource are
trademarks of Symmetricom, Inc. All other product names, service marks, trademarks, and registered
trademarks used in this document are the proper ty of their respective owners.
2
TimeSource 3600
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
SSM synchronization status messaging
TDEV time deviation
TOD time of day
UTC Universal Coordinated Time
Contents
3
This page intentionally left blank.
4
TimeSource 3600
Description
Chapter 1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Global Positioning System . . . . . . . . . . . . 19
Physical Description . . . . . . . . . . . . . . . . . 20
Roof Antenna . . . . . . . . . . . . . . . . . . . 22
Mechanical Window Antenna . . . . . . 23
Self-Adhesive Window Antenna . . . . 24
Wall Antenna . . . . . . . . . . . . . . . . . . . . 25
Functional Description . . . . . . . . . . . . . . . 26
Overview . . . . . . . . . . . . . . . . . . . . . . . 26
Antenna . . . . . . . . . . . . . . . . . . . . . . . . 28
IF Interface . . . . . . . . . . . . . . . . . . . . . . 28
GPS Receiver . . . . . . . . . . . . . . . . . . . . 28
Local Oscillator . . . . . . . . . . . . . . . . . . 28
Clock Extractors . . . . . . . . . . . . . . . . . 29
Power Supply . . . . . . . . . . . . . . . . . . . . 29
BesTime Ensemble Timing Generator 29
E1 or Analog Outputs . . . . . . . . . . . . 29
Eight Additional E1 or Analog Outputs
(990-72060-02 Systems Only) . . . 30
TOD Output . . . . . . . . . . . . . . . . . . . . 30
IRIG-B TOD Outputs
(990-72060-05 Systems Only) . . . 30
1 PPS Output . . . . . . . . . . . . . . . . . . . 30
Contents
5
Description
Chapter 1
(cont’d)
10 MHz Output . . . . . . . . . . . . . . . . . 31
Two ESCIU Por ts
(990-72060-04 Systems Only) . . . 31
Alarm Interface . . . . . . . . . . . . . . . . . . 32
Communication Ports . . . . . . . . . . . . 32
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . 32
Engineering &
Ordering
Chapter 2
Antenna Guidelines . . . . . . . . . . . . . . . . . 36
Roof Antenna Location and
Cabling Guidelines . . . . . . . . . . . . . 38
Roof Antenna Earth Ground Location
Guidelines . . . . . . . . . . . . . . . . . . . . 42
Roof Antenna Cable Choices . . . . . . 43
Window and Wall Antenna
Location Guidelines . . . . . . . . . . . . 45
Window and Wall Antenna
Cable Choices . . . . . . . . . . . . . . . . 47
IRIG-B TOD
(990-72060-05 System Only) . . . 48
RJ-422–to–RS-232 TOD Converter . 48
Shelf Considerations . . . . . . . . . . . . . . . . 49
Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Standard System (Two T1 Outputs) 50
With Eight Additional E1 or
2.048 MHz Outputs . . . . . . . . . . . 51
6
TimeSource 3600
Engineering &
Ordering
Chapter 2
(cont’d)
With Two E1 Synchronization
Insertion (ESCIU) Ports . . . . . . . . 51
With Four IRIG-B TOD Outputs . . . 52
Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Roof Antenna . . . . . . . . . . . . . . . . . . . 53
Mechanical Window Antenna . . . . . . 53
Self-Adhesive Window Antenna . . . . 54
Wall Antenna . . . . . . . . . . . . . . . . . . . . 54
User-Supplied Tools and Materials . . . . . 55
For Roof Antenna Installation . . . . . . 55
For Mechanical Window Antenna
Installation . . . . . . . . . . . . . . . . . . . . 56
For Self-Adhesive Window Antenna
Installation . . . . . . . . . . . . . . . . . . . . 56
For Wall Antenna Installation . . . . . . 56
For Shelf Installation . . . . . . . . . . . . . . 57
Installation
Chapter 3
Outputs, Power, and Miscellaneous . 58
Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . 60
Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Roof Antenna . . . . . . . . . . . . . . . . . . . 61
Mechanical Window Antenna . . . . . . 67
Self-Adhesive Window Antenna . . . . 70
Wall Antenna . . . . . . . . . . . . . . . . . . . . 73
Contents
7
Installation
Chapter 3
(cont’d)
Rack Mounting . . . . . . . . . . . . . . . . . . . . . 77
Output Module Installation . . . . . . . . . . . 78
Power and Signal Cabling . . . . . . . . . . . . 80
Frame Ground . . . . . . . . . . . . . . . . . . . 82
Power . . . . . . . . . . . . . . . . . . . . . . . . . . 84
GPS Antenna . . . . . . . . . . . . . . . . . . . . 85
10 MHz Output . . . . . . . . . . . . . . . . . 85
E1 or Analog Synchronization
Outputs . . . . . . . . . . . . . . . . . . . . . . 86
Expansion Bus . . . . . . . . . . . . . . . . . . . 87
1 PPS Output . . . . . . . . . . . . . . . . . . . 87
E1 or Analog Reference Inputs . . . . . 88
Module for Additional E1 or
Analog Outputs
(990-72060-02 System Only) . . . 89
Module for IRIG-B TOD Outputs
(990-72060-05 System Only) . . . 90
Module for ESCIU Ports
(990-72060-04 System Only) . . . 91
Cutover Procedures for
Out-of-Service Equipment . . . 92
Cutover Procedures for
In-Service Equipment . . . . . . . . 94
Time of Day Output . . . . . . . . . . . . . 96
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . 99
8
TimeSource 3600
Installation
Chapter 3
(cont’d)
Communication Port 1 . . . . . . . . . . . 100
Communication Port 2 . . . . . . . . . . . 101
Alarms . . . . . . . . . . . . . . . . . . . . . . . . . 102
Craft Port . . . . . . . . . . . . . . . . . . . . . . . 103
Power-Up . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Factory-Set Values . . . . . . . . . . . . . . . . . . 118
TL1 Reference
Chapter 4
Conventions . . . . . . . . . . . . . . . . . . . . . . . 122
Command Format . . . . . . . . . . . . . . . . . . 124
Response Format . . . . . . . . . . . . . . . . . . . 125
Parameters . . . . . . . . . . . . . . . . . . . . . . . . 127
Autonomous Messages . . . . . . . . . . . . . . 131
Report Alarm . . . . . . . . . . . . . . . . . . . 132
Report Event . . . . . . . . . . . . . . . . . . . . 133
Tasks/Commands . . . . . . . . . . . . . . . . . . . 134
Commands . . . . . . . . . . . . . . . . . . . . . . . . 136
Activate User . . . . . . . . . . . . . . . . . . . . 137
Cancel User . . . . . . . . . . . . . . . . . . . . . 138
Copy Memory . . . . . . . . . . . . . . . . . . . 139
Delete Equipment . . . . . . . . . . . . . . . . 142
Delete User Security . . . . . . . . . . . . . 143
Edit Communication . . . . . . . . . . . . . . 144
Edit Date . . . . . . . . . . . . . . . . . . . . . . . 148
Contents
9
TL1 Reference
Chapter 4
(cont’d)
Edit Equipment . . . . . . . . . . . . . . . . . . 150
Enter Equipment . . . . . . . . . . . . . . . . . 158
Enter User Security . . . . . . . . . . . . . . . 160
Initialize Register . . . . . . . . . . . . . . . . . 161
Initialize System . . . . . . . . . . . . . . . . . . 162
Operate Alarm Cutoff All . . . . . . . . . 163
Retrieve Alarm All . . . . . . . . . . . . . . . 164
Retrieve Alarm Equipment . . . . . . . . 165
Retrieve Communication . . . . . . . . . . 167
Retrieve Condition All . . . . . . . . . . . . 170
Retrieve Condition Equipment . . . . . 171
Retrieve Equipment . . . . . . . . . . . . . . 173
Retrieve GPS Status . . . . . . . . . . . . . . 180
Retrieve Inventory . . . . . . . . . . . . . . . 182
Retrieve Performance Monitoring . . 184
Troubleshooting
Chapter 5
10
TimeSource 3600
Retrieve User Security . . . . . . . . . . . . 200
Set Source Identifier . . . . . . . . . . . . . . 201
Troubleshooting with Front Panel Items 204
Troubleshooting with Error Messages . . 209
Card Replacement . . . . . . . . . . . . . . . . . . 216
Repair and Return . . . . . . . . . . . . . . . . . . 218
Technical Assistance . . . . . . . . . . . . . . . . . 220
Troubleshooting
Chapter 5
(cont’d)
Sales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Manual Updates . . . . . . . . . . . . . . . . . . . . 222
Specifications
Chapter 6
Antenna . . . . . . . . . . . . . . . . . . . . . . . . 224
Roof Antenna . . . . . . . . . . . . . . . . . 224
Mechanical Window Antenna . . . 224
Wall Antenna . . . . . . . . . . . . . . . . . 225
Self-Adhesive Antenna . . . . . . . . . 225
Communication Ports . . . . . . . . . . . . 226
Port 1 . . . . . . . . . . . . . . . . . . . . . . . 226
Port 2 . . . . . . . . . . . . . . . . . . . . . . . 227
Craft Port . . . . . . . . . . . . . . . . . . . . 228
Ethernet Port . . . . . . . . . . . . . . . . . . . . 229
Time of Day Outputs . . . . . . . . . . . . . 230
Network Time Protocol (NTP),vt
Type 4, Format 2 Driver Format 230
Cisco Systems Format . . . . . . . . . . 231
IRIG-B TOD Outputs
(990-72060-05 System Only) . 232
E1 Inputs . . . . . . . . . . . . . . . . . . . . . . . 233
Analog 2.048 MHz Inputs . . . . . . . . . 234
1 PPS Output . . . . . . . . . . . . . . . . . . . 235
E1 Outputs . . . . . . . . . . . . . . . . . . . . . 236
Standard . . . . . . . . . . . . . . . . . . . . . 236
Contents
11
Specifications
Chapter 6
(cont’d)
Additional E1 Outputs
(990-72060-02 System Only) . 238
Analog 2.048 MHz Outputs . . . . . . . 240
Standard . . . . . . . . . . . . . . . . . . . . . 240
Additional Analog Outputs
(990-72060-02 System Only) . 241
10 MHz Output . . . . . . . . . . . . . . . . . 242
ESCIU Ports
(990-72060-04 System Only) . . . 243
Office Alarms . . . . . . . . . . . . . . . . . . . . 244
Connector Panel Contacts . . . . . . 244
Front Panel Lamps . . . . . . . . . . . . . 244
Front Panel Control . . . . . . . . . . . . 244
Power . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Shelf Mechanical . . . . . . . . . . . . . . . . . 245
Shelf Environmental . . . . . . . . . . . . . . 246
Index
Figures
12
TimeSource 3600
1. Shelf . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2. Roof Antenna . . . . . . . . . . . . . . . . . . . . 22
3. Mechanical Window Antenna . . . . . . 23
4. Self-Adhesive Window Antenna . . . . 24
5. Wall Antenna . . . . . . . . . . . . . . . . . . . . 25
Figures
(cont’d)
6. Block Diagram . . . . . . . . . . . . . . . . . . . 27
7. ESCIU Signals . . . . . . . . . . . . . . . . . . . . 32
8. Antenna Field of View . . . . . . . . . . . . . 39
9. Antenna Location Examples . . . . . . . . 40
10. Sample Rooftop Antenna Mount . . 42
11. Antenna Mask Angle . . . . . . . . . . . . . 46
12. Rack Mounting Options . . . . . . . . . . 49
13. Roof Antenna-to-Shelf Cabling . . . . 62
14. Mechanical Window Antenna-to-Shelf
Cabling . . . . . . . . . . . . . . . . . . . . . . . . 67
15. Attaching the Mechanical Window
Antenna . . . . . . . . . . . . . . . . . . . . . . . 69
16. Mechanical Window Antenna Pivot
Screw . . . . . . . . . . . . . . . . . . . . . . . . . 69
17. Self-Adhesive Window Antenna-to-Shelf
Cabling . . . . . . . . . . . . . . . . . . . . . . . . 70
18. Attaching the IF Converter . . . . . . . 72
19. Wall Antenna-to-Shelf Cabling . . . . . 73
20. Hole Spacing . . . . . . . . . . . . . . . . . . . . 75
21. Wall Antenna Mounting . . . . . . . . . . 76
22. Rack Mounting Options . . . . . . . . . . 77
23. Options I/O Connector . . . . . . . . . . 79
24. Connector Panel and Front Panel
Connectors . . . . . . . . . . . . . . . . . . . . 81
Contents
13
Figures
(cont’d)
25. Connector Panel Terminal Block
Connections . . . . . . . . . . . . . . . . . . . 82
26. E1 or Analog Output Wire-Wrap
Connections . . . . . . . . . . . . . . . . . . . 86
27. E1 or Analog Input Wire-Wrap
Connections . . . . . . . . . . . . . . . . . . . 88
28. Eight E1 or Analog Outputs
Connections . . . . . . . . . . . . . . . . . . . 89
29. IRIG-B TOD Output Connections . 90
30. Connector Layout of ESCIU Modules 91
31. ESCIU Cutover without Jacks
(Out-of-Service) . . . . . . . . . . . . . . . 93
32. ESCIU Cutover with Jacks
(In-Service) . . . . . . . . . . . . . . . . . . . . 95
33. RS-422–to–RS-232 TOD Converter
Mounting Plate . . . . . . . . . . . . . . . . . 97
34. RS-422–to–RS-232 TOD Converter
Connections . . . . . . . . . . . . . . . . . . . 98
14
35. Alarm Connections . . . . . . . . . . . . . . 102
36. Command Format . . . . . . . . . . . . . . . 124
37. Completed Response Format . . . . . 125
38. Deny Response Format . . . . . . . . . . 126
39. Controls and Indicators . . . . . . . . . . 205
40. Front of Shelf . . . . . . . . . . . . . . . . . . . 217
TimeSource 3600
Ta b l e s
A. Timing Source Characteristics . . . . . . 27
B. TOD Connector Pinouts . . . . . . . . . . 96
C. Converter DB-25 Connector Pinouts 98
D. Ethernet 10base-T RJ-45 Connector
Pinouts . . . . . . . . . . . . . . . . . . . . . . . . 99
E. COM1 Connector Pinouts . . . . . . . . . 100
F. COM2 Connector Pinouts . . . . . . . . . 101
G. Craft Terminal Connector Pinouts . . 103
H. Parameter Factor y Settings . . . . . . . . 118
I. Parameter Definitions . . . . . . . . . . . . . . 127
J. Commands for Tasks . . . . . . . . . . . . . . . 134
K. Front Panel Items . . . . . . . . . . . . . . . . . 206
L. Message Troubleshooting . . . . . . . . . . 209
Contents
15
This page intentionally left blank.
16
TimeSource 3600
Description
This chapter provides an overview of the
global positioning system, and a physical
and functional description.
Chapter
Chapter
1
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Overview
The TimeSource 3600 is a Primary Reference Source (PRS) that
receives and processes signals from GPS satellites, and outputs
Stratum 1 synchronization signals traceable to UTC. TimeSource
3600 applications include synchronization for central offices,
wireless base stations, transmission nodes, and other cases where
a primary reference source can improve the performance of a
telecommunications network infrastructure.
The TimeSource 3600 is also ideal for installation in environments
where receiving GPS signals is difficult. Examples of environments
hostile to GPS signals include urban canyons which have a very
limited view of the sky because of blockage from nearby buildings,
and high interference zones where GPS signals are jammed by
competing over-the-air signals.
The TimeSource 3600 creates timing outputs by ensembling
signals from several sources. The sources include GPS signals, an
onboard rubidium local oscillator, and optional E1 or analog.
Timing outputs created from the ensemble are composed of the
most stable and least noisy parts of each input. The performance
of the E1 sources can be monitored and classified using standard
measures. Synchronization outputs are delivered in a framed, allones, E1 format or 2.048 MHz analog signal, a 10 MHz signal, a 1
pps signal, and a choice of time of day (TOD) formats.
18
The TimeSource 3600 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 synchronization for telephony
networks. The TimeSource 3600 with its GPS input is a standalone office PRS. With the optional inputs ensembled, holdover is
extended if GPS signals are disrupted.
TimeSource 3600
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Global Positioning System
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 20,197 km, 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 3600 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.
GPS antennas must have line-of-sight access to the transmitting
satellites. Any structure that interferes with, or blocks, the view of
the satellites disrupts the reception of the signals, and can
adversely impact the timing performance of a receiver.
The TimeSource 3600 bridges frequent GPS outage periods with
BesTime algorithms, its ultra-stable Rubidium local oscillator and
advanced holdover technology. The technology anticipates the
outages and uses BesTime-generated predictor values to optimize
the performance of timing without direct satellite input.
1
2
3
4
Description
5
19
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Physical Description
The TimeSource 3600 consists of a shelf, plug-in card, antenna,
cables, hardware, and software. Optional system configurations
include eight additional E1 or analog outputs, two E1
synchronous clock insertion unit (ESCIU) ports, or four IRIG-B
TOD timing outputs.
The shelf (Figure 1) can be mounted in a 48 cm rack or an ETSI
53.5 cm rack. Other than a communications connector on the
front panel, all connectors are at the connector panel.
Four types of antennas are available:
• roof antenna for installation outdoors, usually on a roof
• mechanical antenna for installation indoors, mounted on a
window sill or wall for reception through a window
• self-adhesive antenna for installation indoors, adhered directly
to a window
20
• wall antenna for installation outdoors, through a hole in the wall
TimeSource 3600
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Figure 1. Shelf
22 cm
43.8 cm
990-72060-01, -02, -05 Systems
1
2
8.2 cm
3
22 cm
43.8 cm
990-72060-04 Systems
Description
4
8.2 cm
5
21
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Roof Antenna
The roof antenna (Figure 2) is encased in weather-resistant plastic
housing for outdoor installation, usually on a roof. A single coaxial
cable carries signals and power between the antenna and the
shelf.
Figure 2. Roof Antenna
31.4 cm
22
4.4
cm
TimeSource 3600
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Mechanical Window Antenna
The mechanical window antenna (Figure 3) may be attached to a
window sill or wall, in any position that allows the antenna to be
moved flush against the window. The antenna can be swung away
from the window for window maintenance, and returned to its
original position.
A single length of coaxial cable carries signals and power between
the antenna assembly and the shelf.
Figure 3. Mechanical Window Antenna
Coaxial Cable
Mounting Assembly
IF Converter
1
2
Antenna
3
43 cm
4
to TimeSource 3600 Shelf
Coaxial Cable
(not included with
antenna assembly)
Description
5
23
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Self-Adhesive Window Antenna
The self-adhesive window antenna assembly (Figure 4) consists of
the antenna and two pieces of self-stick hook-and-loop fabric
fasteners (Velcro brand or equivalent). The hook-and-loop fabric
attaches directly to a window. Coaxial cables carry signals and
power between the antenna and the IF converter, and between the
IF converter and the shelf.
Figure 4. Self-Adhesive Window Antenna
GPS WINDOW
ANTENNA
24
TimeSource 3600
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Wall Antenna
The wall antenna (Figure 5) is mounted on the outside of a
building wall. The antenna attaches magnetically to the mounting
bracket. The cable from the antenna is routed through a hole
drilled in the wall. Coaxial cables carry signals and power between
the antenna and the IF converter, and between the IF converter
and the shelf.
Figure 5. Wall Antenna
7.5 cm
1
2
Antenna Mounting Bracket
Antenna
3
Coaxial Cable
Description
4
5
25
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Functional Description
Overview
Figure 6 shows the main functions of the TimeSource 3600. The
center of the TimeSource 3600 is the BesTime 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 source is under constant evaluation and its
contribution subject to periodic adjustment. The output is
essentially the best performance of the best source.
26
TimeSource 3600
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Al
Figure 6. Block Diagram
arm
Interface
Alarms
1
Clock input & dc
power to antenna
Antenna
input
Optional source s
E1 Span
Input #1
E1 Span
Input #2
–48 V A
–48 V B
IF
Interface
Local
Oscillator
Clock
Extractor
Clock
Extractor
Power
Supply
Power to
shelf
Micro-
processor
BesTime
Ensemble
Timing
Generator
COM ports
Ethernet port
Status lamps
E1/analog output A
E1/analog output B
1 pps output
TOD output
10 MHz output
8 E1/analog
outputs
4 IRIG-B
TOD outputs
2 ESCIU ports
Optional ports
2
3
4
Table A. Timing Source Characteristics
Source Characteristic
Local Oscillator Short term stability
E1 Line Intermediate term stability
GPS Signal Long term stability
Description
5
27
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Antenna
The antenna types include a roof antenna, mechanical window
antenna, self-adhesive window antenna, or wall antenna. All
antennas include a 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.
The downconverter converts the L1-band GPS signal to IF for
long-distance transport on the coaxial antenna cable. The antenna
cable provides current from the shelf to the antenna, and
transports GPS satellite IF signals from the antenna to the shelf.
IF Interface
An IF interface accepts the signals from the antenna/IF converter,
and provides the clock information to the BesTime Ensemble
Timing Generator.
28
GPS Receiver
The GPS Receiver continuously tracks up to eight satellites, using both
carrier and code lock. The recovered pseudo-range measurement data
is processed to determine precise time and frequency state estimates
for the local oscillator. The receiver software is optimized to track and
update state estimates, when as few as one satellite is in view.
Local Oscillator
A rubidium oscillator, based on a digitally controlled servo-loop,
provides an ultra-stable local oscillator signal, which is sent to the
BesTime Ensemble Timing Generator.
TimeSource 3600
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Clock Extractors
A clock extractor circuit extracts a timing signal from each
external reference source. (External sources, other than the GPS
antenna, are optional.) The extracted timing signal 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 circuitry.
BesTime Ensemble Timing Generator
Clock signals from the GPS antenna (via the IF interface), local
oscillator, and two optional E1 span lines are used as sources by
the BesTime algorithms in the BesTime Ensemble Timing
Generator. The signals are analyzed for MDEV, 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.
1
2
3
4
E1 or Analog Outputs
The BesTime Ensemble Timing Generator provides the timing for
the E1 or analog (2.048 MHz) timing signal available at the E1
OUT A and B connectors. E1 is provided in a framed, all-ones
format, which can be set to CAS, CAS4, CCS, or CCS4 framing.
2.048 MHz is provided in accordance with G.703/10.
Description
5
29
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS
Eight Additional E1 or Analog Outputs (990-72060-02 Systems Only)
This option provides a module for eight additional E1 or analog
(2.048 MHz) outputs. The module mounts in the OP TIONS I/O
mountings on the connector panel. These outputs function the
same as the standard E1 outputs.
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 (990-72060-05 Systems Only)
This option provides a module for four additional TOD outputs in
IRIG-B format. The module mounts in the OPTIONS I/O
mountings on the connector panel.
30
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
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. This signal is not squelched during an alarm.
TimeSource 3600
Loading...