DCD-LPR

TMSL 097-45100-02
Issue 10: Apr 01
DIGITAL CLOCK DISTRIBUTOR
LOCAL PRIMARY REFERENCE
FUNCTIONAL DESCRIPTION
CONTENTS
PAGE
1. GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . .
1
2. SYSTEM DESCRIPTION . . . . . . . . . . . . . . . .
A. Output Signals . . . . . . . . . . . . . . . . . .
B. Input Reference Signals . . . . . . . . . .
C. SSM . . . . . . . . . . . . . . . . . . . . . . . . . . .
D. Fuse and Alarm . . . . . . . . . . . . . . . . .
E. Power . . . . . . . . . . . . . . . . . . . . . . . . .
F. GPS Timing Antenna/Receiver (GTR)
G. LORAN-C Antenna. . . . . . . . . . . . . . .
2
5
5
5
6
6
6
9
3. CARD DESCRIPTION . . . . . . . . . . . . . . . . .
A. GTI Card . . . . . . . . . . . . . . . . . . . . . .
B. LTI Card. . . . . . . . . . . . . . . . . . . . . . . .
C. LOU Card . . . . . . . . . . . . . . . . . . . . . .
9
9
12
15
4. SPECIFICATIONS . . . . . . . . . . . . . . . . . . . .
16
5. INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
Distributor - Local Primary Reference (DCD-LPR)
System.
1.02 This section was reissued for the following reasons. Additions and changes are marked by change
bars.
• Removed references to analog capability for the
GTI-18 card.
• Revised information on SSM in paragraph 2-20.
• Added Table B, Signal Output for GTI-17 and
-18.
• Removed hex code information from E1 System
Quality Levels and T1 System Quality Levels in
Table C.
1.03 All product names, service marks, trademarks,
and registered trademarks used in this document
are the property of their respective owners.
Figures
1. DCD-LPR Shelf . . . . . . . . . . . . . . . . . . . . . .
2. GTR Block Diagram . . . . . . . . . . . . . . . . .
3. GTI Card Block Diagram
(without LOU Card) . . . . . . . . . . . . . . . . .
4. GTI Card Block Diagram (with LOU Card)
5. Time-of-Day System. . . . . . . . . . . . . . . . .
6. LTI Card Block Diagram. . . . . . . . . . . . . .
7. LOU-1 Block Diagram . . . . . . . . . . . . . . .
8. LOU-2 Block Diagram . . . . . . . . . . . . . . .
2
8
10
11
12
14
15
15
Tables
A.
B.
C.
DCD-LPR Cards . . . . . . . . . . . . . . . . . . . . .
Signal Output for GTI-17 and -18 . . . . . .
DCD-LPR System Specifications . . . . . . .
3
6
16
1. GENERAL
1.01 This section provides functional descriptions
and specifications for Symmetricom’s Digital Clock
1.04 The DCD-LPR may be used in conjunction with
a DCD-ST2 or DCD-419 System, or any DCD-500 Series System equipped with appropriate oscillators.
Note: The DCD-LPR is not compatible with
Rev. C or earlier revisions of the DCD-419.
1.05 The following abbreviations are used in this
document:
ACO
BITS
CI
DCD
GPS
GRI
GTI
GTR
LORAN-C
LOU
LPR
LTI
alarm cut-off
Building Integrated Timing Supply
Clock Input
Digital Clock Distributor
Global Positioning System
group repetition intervals
GPS Timing Interface
GPS Timing Antenna/Receiver
Long Range Navigation-Version C
LPR Oscillator Unit
Local Primary Reference
LORAN-C Timing Interface
Copyright © 1994–2001 Symmetricom, Inc. All rights reserved. Printed in U.S.A.
TMSL 097-45100-02
MIS
NTP
PRC
PRS
pps
RU
SSM
SSU
ST2
ST2E
ST3E
TI
TNC
TOD
USNO
UTC
WAN
Issue 10: Apr 01
ST2, and ST2E cards, these cards are collectively referred to as rubidium clock cards.
The TNC-E and ST2E clock cards are identical in specifications, functions, controls and
indicators, and acceptance test procedures.
The TNC-E name uses ITU standard terminology; the ST2E name uses ANSI standard
terminology. The TNC-E and ST2E are interchangeable.
Maintenance Interface, System
network time protocol
Primary Reference Clock
primary reference source
pulses per second
rack unit
Synchronization Status Messaging
Synchronization Supply Utility
Stratum-2 Clock
Enhanced Stratum-2 Clock
Enhanced Stratum-3 Clock
timing interface card or slot
Transit Node Clock
Time-of-Day
United States Naval Observatory
Universal Coordinated Time
wide area networks
2. Where information is common to the TNC and
ST3E cards, these cards are collectively referred to as quartz clock cards.
2. SYSTEM DESCRIPTION
2.01 The DCD-LPR (Figure 1) provides Stratum-1
quality reference signals when used with the DCDST2, DCD-419, and DCD-500 Series Systems.
Notes:
1. Where information is common to the TNC-E,
DIGITAL CLOCK DISTRIBUTOR
LOCAL PRIMARY REFERENCE
090-45100-XX
REV. ______
DCD-LPR
–48VA
2A
LTI
MAJOR
–48VB
SELECT FAIL
41140-01
ISS ___
OUTPUT INPUT STATUS
LORAN TIMING INTERFACE
MINOR
2A
GTI
ACO
FAIL
42140-xx
ISS ___
OUTPUT INPUT STATUS
GPS TIMING INTERFACE
SLOT A
A. Front Panel
I/O A
PWR- PWR+ CMN
BATT
B
1
RTN
SIG-
SW1
0
B
PWR- PWR+ CMN
1
SIG+
J11
SIG-
NC C NO
J12
J15
AUD
VIS
J16
TB1
BATT
A
RTN
STAT
EXP1
EXP2
EXP3
RTN
DIG
GND
SIG+
FRM
GND
1 2 3 4
1
TB4
TB7
I/O B
B. Backplane
Figure 1. DCD-LPR Shelf
Page 2
COMMA COMMB
MSTR
LORAN
ANTENNA B
FRM
GND
OSCB
AUD
VIS
TB6
GTR
POWER
J10
DIG
GND
FRM
GND
FRM
GND
TB3
RTN
OSCA
LORAN
ANTENNA A
MAJ
TB5
MIN
GTR
POWER A
J9
SLOT B
J5
J6
J7
J8
Issue 10: Apr 01
TMSL 097-45100-02
2.02 Cards which may be included in the DCD-LPR
System are listed in Table A.
Table A. DCD-LPR Cards
CARD
NAME USED
IN THIS
SECTION PART NUMBER
REVISION
FEATURES
ANSI-STANDARD CARDS
GTIV5
GTI-17
090-42140-17
–
Input: 5 MHz or 10 MHz, from quartz, rubidium, or better quality clocks, any combination of two quartz,
rubidium, or better quality clocks, or LOU card
Output: 1.544 Mb/s (T1)
Framing format: ESF or D4
Time-of-Day
SSM capable
GTI
GTI-15
090-42140-15
A
GTIV5
GTI-15
090-42140-15
B or later
Input: 5 MHz or 10 MHz, from quartz, rubidium, or better quality clocks, any combination of two quartz,
rubidium, or better quality clocks, or LOU card
Output: 1.544 Mb/s (T1)
Framing format: ESF or D4
Time-of-Day
GTI
GTI-13
(Note 4)
090-42140-13
D or earlier
GTIV5
GTI-13
(Note 4)
090-42140-13
E or later
GTI
GTI-11
(Note 4)
090-42140-11
–
Input: 5 MHz or 10 MHz, from rubidium or better quality clocks, ST2E or ST2 cards only
Output: 1.544 Mb/s (T1)
Framing format: ESF or D4
LTI
LTI
090-41140-01
–
Input: 5 MHz from rubidium or better quality clocks,
ST2E or ST2 cards only
Output: 1.544 Mb/s (T1)
Framing format: ESF or D4
Input: 5 MHz or 10 MHz, from quartz, rubidium, or better quality clocks, any combination of two quartz,
rubidium, or better quality clocks, or LOU card
Output: 1.544 Mb/s (T1)
Framing format: ESF or D4
ITU-STANDARD CARDS
GTIV5
GTI-18
090-42140-18
–
Input: 5 MHz or 10 MHz, from quartz, rubidium, or better quality clocks, any combination of two quartz,
rubidium, or better quality clocks, or LOU card
Output: 2.048 Mb/s (E1)
Framing format: CCS/CAS with or without CRC-4
Time-of-Day
SSM capable
Page 3
TMSL 097-45100-02
Issue 10: Apr 01
Table A. DCD-LPR Cards (Cont’d)
CARD
NAME USED
IN THIS
SECTION PART NUMBER
REVISION
FEATURES
ITU-STANDARD CARDS (Cont’d)
GTI
V5
GTI-16
090-42140-16
–
Input: 5 MHz or 10 MHz, from quartz, rubidium, or better quality clocks, any combination of two quartz,
rubidium, or better quality clocks, or LOU card
Output: 2.048 Mb/s (E1)
Framing format: CCS/CAS with or without CRC-4
Time-of-Day
GTI
GTI-14
(Note 4)
090-42140-14
D or earlier
GTIV5
GTI-14
(Note 4)
090-42140-14
E or later
Input: 5 MHz or 10 MHz, from quartz, rubidium, or better quality clocks, any combination of two quartz,
rubidium, or better quality clocks, or LOU card
Output: 2.048 Mb/s (E1)
Framing format: CCS/CAS with or without CRC-4
GTI
GTI-12
(Note 4)
090-42140-12
–
Input: 5 MHz or 10 MHz, from rubidium or better quality clocks, TNC-E cards only
Output: 2.048 Mb/s (E1)
Framing format: CCS/CAS with or without CRC-4
ANSI-STANDARD AND ITU-STANDARD CARDS
LOU
LOU-1
090-42145-01
–
Source: one oven-controlled crystal oscillator with two
parallel outputs
LOU
LOU-2
090-42145-02
–
Source: two independent oven-controlled crystal oscillators, each with one output
Notes:
1. The V5 indicates that this is a Version 5 card.
2. Where information is common to all GTI cards, these cards are collectively referred to as GTI cards.
3. Where information is common to both LOU cards, these cards are collectively referred to as LOU cards.
4. Manufacture discontinued.
2.03 The DCD-LPR equipped with LOU and GTI
cards provides office PRS timing as specified by industry standards.
2.04 The DCD-LPR accepts up to two GTI or LTI
plug-in cards in any combination.
2.05 The DCD-LPR, when used in conjunction
with the DCD Shelf and its clocks (rubidium or better quality), is a network (PRS), as specified by industry standards. Using GPS and/or LORAN-C
radio navigation services, the DCD-LPR System
can provide independent and diverse timing sources for both network or office primary reference clock
applications.
Page 4
2.06 Both the GTI and LTI cards employ sophisticated ensembling to ensure the highest levels of reliability, comply with tightening PRS performance masks,
and mitigate known performance degradation effects
of GPS and LORAN-C signals.
2.07 Ensemble averaging is a mathematical treatment of network synchronization. As a process, it
treats a group of timing sources and their relative
time errors simultaneously to produce an output signal that achieves a greater overall accuracy and stability than any single source. In a timing ensemble
arrangement, each timing reference is adjusted by
the time error between itself and a weighted average
of the group.
Issue 10: Apr 01
2.08 The advantages of ensemble averaging for precise time scale determination is a significantly reduced sensitivity to internal and external noise, and
elimination of a master clock dependency. These facts
provide survivability and greater stability for the
group as a whole. This is because the ensemble averaging output provides the best performance of the
best sources in the ensemble.
2.09 The GTI is used to extract the UTC traceable
clock and mitigate the effects of GPS signal instabilities. This is accomplished in two stages:
1.
2.
Simultaneously ensemble averaging six satellites in the GTR’s field of view; a maximum of
eight satellites will be processed in a round-robin method, if visible.
Ensemble averaging the uncorrected oscillator
sources from the clocks in the DCD Shelf.
Note: If LOU cards are used, the GTI takes
the ensemble averaged GTR signal information, but does not ensemble average the uncorrected oscillator input from the LOU card.
2.10 It is the combination of the six-satellite ensemble and the short-term stability of the uncorrected oscillator sources that removes the instabilities, and
provides PRS timing.
2.11 The LTI ensemble averages all of the stations
within the two nearest Group Repetition Intervals
(GRIs), such that reliable performance is not dependent on a single station. For LORAN-C, one of the primary concerns for reliable performance is the effects
of electrical storms between the LORAN-C receiving
antenna and the LORAN-C transmit station. Ensemble averaging multiple stations can eliminate adverse
effects of electrical storms.
2.12 The LTI also uses the short-term stability of the
uncorrected oscillator sources from the DCD Shelf
clocks to output a signal fully compliant with the performance masks for a PRS.
2.13 Both the GTI and the LTI perform self-management and autonomous error checking. The DCD-LPR
constantly monitors all stages of the PRS output signal generation. If a problem occurs that cannot be resolved by the GTI or LTI, an alarm is raised and a
message is displayed on the LCD display of each timing input card. Additional information may be ob-
TMSL 097-45100-02
tained via the rear RS-232 port for debugging
purposes only when necessary.
A. Output Signals
2.14 The timing interface (TI) cards convert the timing signals provided by the (associated) antenna(s)
into two primary rate T1 or E1 timing references, and
passes them to the DCD Shelf.
B. Input Reference Signals
2.15 The DCD-LPR can accept two radio navigational frequency references (GPS and LORAN-C).
2.16 The two uncorrected oscillator sources are also
used as timing reference sources to the timing interface cards. The sources can be from the from the DCD
Shelves, from a Symmetricom cesium clock source, or
from the LOU card. The DCD Shelf clocks are an integral component of the DCD-LPR. These clocks provide true short-term stability to the GTI or LTI card
needed for PRS timing.
2.17 If the clock card installed in the ST A or TNC A
slot (the primary source) of the DCD Shelf is removed,
the TI card will automatically switch reference to the
clock card installed in the ST B or TNC B slot. When
the clock card is plugged back into the ST A or TNC A
slot, the TI card will not immediately switch reference
back to the ST A or TNC A. The switch occurs 5 minutes after the ST A or TNC A card is active and providing clock output.
2.18 Prior to switching reference, the TI card will
output a 600 ns transient pulse to cause the clock
cards to perform a phase buildout to prevent the timing output from moving. Occasionally, this may cause
the clock card to momentarily display DRIFT/
INP TOL alarms. The ST A or TNC A card will then
go into freerun. This non-service affecting condition
remains for approximately 1 minute, after which the
condition clears.
C. SSM
2.19 The DCD-LPR can deliver Synchronization Status Messaging (SSM) messages to network elements
and BITS/SSU equipment which require SSM input
signals. The GTI card delivers the appropriate SSM
message, depending on the status of the GPS system.
2.20 When the system is in a normal condition, and
locked to the GPS satellites, the GTI card generates a
Page 5
TMSL 097-45100-02
Issue 10: Apr 01
PRC/PRS SSM message, indicating that the signal
can be used as a primary reference signal. If the timing signal from the GTR degrades, or is invalid, the
output of the GTI signal will change its SSM message.
See Table B.
Table B. Signal Output for GTI-17 and -18
TL1
ATTRIBUTE
GTI
LOCK
GPS
INVALID
GTI
CARD
SSME
PRC
DNU
GTI-18
SSMEC
PRC
UNK
GTI-18
SSMT
PRS
STU
GTI-17
2.21 SSM operation is enabled by TL1 command via
the MIS card. For details on TL1 commands, refer to
the TL1 User’s Guide provided with the MIS card.
D. Fuse and Alarm
2.22 Fuse and alarm functions provide monitoring
and filtering of the input power from two –48 volts dc
office batteries from the office power distribution panel.
2.23 Depending on which alarms are activated in the
DCD-LPR, audible and visual alarm indicator outputs are activated.
2.24 Each TI card is self-contained and provides individual alarm and status information. Minimum
alarm and status information for each TI card is:
• Major alarm, form-C relay (visual and audible)
• Minor alarm, form-C relay (visual and audible)
• Status, form-C relay; reserved for future use
2.25 A front-panel ACO pushbutton, when pressed,
silences the audible alarm, and lights the ACO lamp.
E.
Power
2.26 The DCD-LPR Shelf is powered by two separate
–48 volts dc office battery inputs. Both the redundant
inputs are fused on the shelf, then bused to the cards
in the shelf. If one of the battery feeds/fuses fails, a
fuse alarm is indicated.
Page 6
2.27 The GTI also powers the GTR via a three-conductor cable. The GTR requires power because it contains active electronics (as do all GPS antennas), and
may be powered separately from the GTI.
2.28 The LTI whip antenna is passive. The preamp
associated with the LTI whip antenna (to transmit
the signal through the twinax cable) requires power
for an FET (required as a bandpass filter).
F.
GPS Timing Antenna/Receiver (GTR)
2.29 The GTR is a six-channel GPS receiver, capable
of simultaneously tracking up to eight Global Positioning System (GPS) satellites, and provides timing
information to the GTI. The GTR also provides Universal Coordinated Time (UTC) information to the
GTI for display.
2.30 The GTR is available with Time-of-Day capabilities; a version of the GTR is available with leap second capabilities. Twice a year (end of July and
December), the US Naval Observatory (USNO) decides whether or not to add a leap second. This feature
notifies timed equipment that the addition of a leap
second is pending, and that tracking of the leap second should be implemented.
Note: Contact Symmetricom Customer Assistance Center (CTAC) regarding availability of
the GTR with leap second capabilities at one
of the following numbers:
•+44 1483 510300 (U.K.)
•+1 408 428 7907 (U.S.A.)
The following toll-free number is available in
some countries to access Symmetricom’s Inside Sales and CTAC in the U.S.A.: +1 888 367
7966 (U.S.A.).
2.31 The GTR uses multiple satellites, and performs
a majority vote on the timing information obtained
from each satellite.
2.32 Majority vote is the process which validates reference sources against preset performance criteria.
The algorithm measures and compares the timing information obtained from each timing source (e.g., a
satellite). If, during the process of the individual comparisons, the computed value exceeds one of the preset thresholds, that source is disqualified.
Issue 10: Apr 01
2.33 The distinguishing feature of the voting algorithm is the ability to qualify a timing source against
a known performance threshold when viewed with respect to at least two other sources.
TMSL 097-45100-02
• Digital processor
• Phase-locked loop (PLL) subsystem
• Encoder subsystem
2.34 Using majority vote, the GTR discards unacceptable performance data results and then ensemble
averages the remaining qualified satellite information to provide a precise timing signal to the GTI card.
At any one time, the GTR can ensemble average a
maximum of six satellites , to derive an output timing
solution.
2.35 The GTR outputs a 4 kHz clock used by the GTI
to generate the disciplined timing signal for PRS accuracy, a 1 pps signal used for Time-of-Day applications (via the GTI card), and a 4 kb/s channel for
transmitting GTR status information to the GTI.
2.36 These signals are Manchester-encoded, and
transmitted over fiber optic cable. The fiber cable provides robust protection to the DCD-LPR System from
EMI effects on this data channel link.
2.37 The GTR consists of four main sections (refer to
Figure 2),
2.38 The receiver accepts the GPS radio navigational signals and sends the digitized GPS signal to the
digital processor.
2.39 The digital processor provides the processing
power required to track the satellites, position the receiver, then derive an ensemble-averaged timing correction to the phase-locked loop subsystem.
2.40 The phase-locked loop subsystem provides a
time lock to GPS by locking a local oscillator to the
digitally processed GPS signals.
2.41 The encoder takes the GTR information, and
Manchester-encodes the clocking signals and any
data messages to the GTI.
2.42 For leap second capabilities, the GTR uses an
algorithm that transmits a “leap second pending”
message twice a year (end of July and December) for
2 months.
• Receiver
Page 7
TMSL 097-45100-02
Issue 10: Apr 01
GPS TIMING ANTENNA/RECEIVER
(GTR)
GPS
SATELLITE
GTR RECEIVER
DIGITAL
PROCESSOR
PLL
ENCODER
3-CONDUCTOR CABLE
FIBER OPTIC CABLE
TO/FROM DCD-LPR
POWER
Figure 2. GTR Block Diagram
Page 8
Issue 10: Apr 01
G. LORAN-C Antenna
2.43 The LORAN-C antenna is designed to work
with the LTI (do not attempt to use an antenna from
another source). It is a 2.4 meter (8 foot), whip (omnidirectional) antenna. The preamplifier at the base of
the antenna is powered by the DCD-LPR via the twinax cable.
3. CARD DESCRIPTION
A. GTI Card
3.01 The GTI card forms the link to the roof-mounted GPS Timing Antenna/Receiver (GTR). The GTI
card takes the GPS signal information from the GTR,
and, using the oscillator inputs from a DCD-500 Series Shelf or DCD-Cs Shelf, performs an ensemble-averaged timed correction to provide the outputs.
3.02 GTI-11, GTI-13, GTI-15, and GTI-17 cards provide a T1 output frequency of 1.544 Mb/s. GTI-12,
GTI-14, and GTI-16 cards provide an E1 output frequency of 2.048 Mb/s. The GTI-18 card provides an
E1 output frequency of 2.048 Mb/s, selectable via TL1
command. In addition, framing formats are switch-selectable.
3.03 Figure 3 shows a simplified block diagram of
how the GTI card works with the DCD Shelf. Figure 4
shows how the GTI card works with the LOU card to
provide output timing to the DCD Shelf. Communication between the GTI card and the GTR is accomplished through a fiber optic link.
TMSL 097-45100-02
3.04 Information from the GTR is sent to a fiber optic receiver/transmitter in the GTI card. The transmitter and receiver are incorporated on the I/O
module located on the DCD-LPR Shelf backplane. A
lamp on the module lights green to indicate that a
4 kHz signal from the GTR is present.
3.05 The receiver accepts the GPS signal information from the GTR and sends it to an ensemble engine.
3.06 The GTI card ensemble averages the signal, using the oscillator inputs (from the DCD Shelf), or, inputs from a 10 MHz external source, and performs
time correction. The corrected signal is sent to output
drivers to provide the outputs to the timing output
cards.
3.07 On power-up, the GTI card output is AIS or
squelched (user selectable). This condition persists
until the GTI card has qualified all the GPS inputs,
correlated its position, and is ready for PRS operation.
At this point, the GTI card will have entered “GTI
LOCK” and now outputs a valid DS1 or E1 output
synchronization signal.
3.08 Typically, the GTI card sends an AIS signal or
squelches the output (user selectable) when a major
alarm is raised, e.g., loss of all inputs—both oscillators, and the GTR signal. All alarm and status messages are displayed in the LCD display, and the status
pushbutton on the front panel is used to step through
the LCD display screens to display time and status information.
Page 9
TMSL 097-45100-02
Issue 10: Apr 01
TO GTR
TO/FROM GTR
LIGHTNING
PROTECTOR
FIBER OPTIC CABLE
GTI CARD
RECEIVE/TRANSMIT
TIME-OF-DAY
DAUGHTER BOARD
(GTI-15, -16, -17, -18)
(Note)
GTR
POWER
SUPPLY
DISCIPLINED TIME SCALE
ENSEMBLE ENGINE
GTI
POWER
SUPPLY
PRIMARY RATE
DRIVER
2A
2A
FUSE AND
ALARM
PANEL
–48 V
–48 V
OSC
A
CONTROL
COMM
PORT
ALARMS AND
INDICATORS
TO MIS
(DCD-500)
OSC
B
PRIMARY
RATE
DCD SHELF
Note: See Figure 5 for a diagram of the TOD system.
Figure 3. GTI Card Block Diagram (without LOU Card)
Page 10
Issue 10: Apr 01
TMSL 097-45100-02
TO/FROM GTR
TO GTR
LIGHTNING
PROTECTOR
FIBER OPTIC CABLE
GTI CARD
RECEIVE/TRANSMIT
TIME-OF-DAY
DAUGHTER BOARD
(GTI-15, -16, -17, -18)
(Note)
GTR
POWER
SUPPLY
DISCIPLINED TIME SCALE
ENSEMBLE ENGINE
GTI
POWER
SUPPLY
PRIMARY RATE
DRIVER
2A
2A
FUSE AND
ALARM
PANEL
–48 V
OSC
A
CONTROL
COMM
PORT
ALARMS AND
INDICATORS
TO MIS
(DCD-500)
OSC
B
LOU CARD
(Notes 2 and 3)
PRIMARY
RATE
DCD SHELF
–48 V
Notes:
1. See Figure 5 for a diagram of the TOD system.
2. In the LOU-1 card, there is only one oscillator, but provides 2 parallel outputs.
3. In the LOU-2 card, both oscillators are active, but only one oscillator at a time provides timing;
oscillator A is the primary source; oscillato rB provides timing only when A has failed.
Figure 4. GTI Card Block Diagram (with LOU Card)
Page 11
TMSL 097-45100-02
Issue 10: Apr 01
Time-of-Day
3.09 The GTI-15, GTI-16, GTI-17, and GTI-18 cards
include the Time-of-Day (TOD) feature. These cards
are similar to the GTI-13 and GTI-14 cards, with the
following exceptions:
• An additional set of configuration switches on
the GTI card daughter board are provided to set
alarm integration for TOD alarms, baud rate,
and TOD message formatting
3.10 The TOD engine and accompanying software
produce a TOD output stream on the TOD ribbon cable connectors which are routed to the adapter. There
are two RS-422 outputs from the adapter: one for
RS-422 CABLE (DB9 MALE
TO DB9 FEMALE)
DCD-LPR SHELF
ADAPTER
GTI-1 and the other for GTI-2. If required, an RS422–to–RS-232 converter can be added to provide an
RS-232 signal (Figure 5).
3.11 The TOD engine uses the synchronization input
signals from the GTR as a reference from which the
output signal is generated. The synthesizer inputs
provide a stable reference which is not phase-locked
to the GTR in the short term. The GTR signal gives
the approximate position of the 1 second mark in
time. Using these signals, the phase measurement
circuitry in the TOD engine, and the GTI phase measurements, the TOD engine can control the output
phase to track the long-term average of the GTR signal.
BNC
1 pps OUT
DATA CABLE (DB25 MALE
TO DB25 FEMALE)
RS-422–TO–RS-232
CONVERTER
RS-232 SIGNAL
RS-422 SIGNAL
(Note)
OPTIONAL: WITH MIS CARD ONLY
DCD MASTER SHELF
Note: RS-422–to–RS-232 converter not required for RS-422 signal.
Figure 5. Time-of-Day System
3.12 The TOD output at the adapter is user selectable as either a Cisco Systems proprietary TOD signal, or an NTP Type 4 signal (see Table C for signal
specifications).
Also, the user can assign output messages by TL1
command. For details on TL1 commands, refer to the
TL1 User’s Guide provided with the MIS card.
B. LTI Card
SSM
3.13 GTI-17 and GTI-18 cards are SSM capable.
SSM messages are transmitted continuously until
there is a state change determined by the GTI card.
Page 12
3.14 The LTI card forms the link to the roof-mounted
LORAN-C antenna. The LTI card takes the
LORAN-C signal information, and, using the DCD oscillator (rubidium only) inputs from the DCD-ST2,
Issue 10: Apr 01
TMSL 097-45100-02
DCD-419, or DCD-500 Series Shelf, performs an ensemble-averaged timed correction to provide the outputs.
3.17 The LTI card will only output AIS or squelch the
output when a major alarm is raised, e.g., loss of all
inputs—both DCD oscillators.
LTI Card Outputs
3.18 Figure 6 shows a simplified block diagram of
how the LTI card works. Communication between the
LTI card and LORAN antenna is accomplished
through a twinax cable.
3.15 The LTI card outputs two primary rate T1 timing references of 1.544 Mb/s which are passed to the
inputs of DCD-ST2, DCD-419, or DCD-500 Series
Shelf. In addition, framing formats are switch-selectable.
3.16 On power-up, the LTI card outputs either an
AIS signal, or the output is squelched, depending on
the user-configured setting. This condition persists
until the LTI card has qualified all the LORAN-C inputs, correlated its position, and is ready for PRS operation. At this point, the LTI card will have entered
“LTI LOCK” and outputs a valid framed all-ones output signal.
3.19 The receiver provides filtering and amplification of the LORAN-C signal to the digital processor.
3.20 The digital processor provides the processing
power required to lock to a station, and sends the frequency and phase information to a phase-locked loop
subsystem in the ensemble engine.
3.21 All alarm and status messages are displayed in
the LCD display, and the pushbuttons on the front
panel are used to step through the LCD display
screens to display time and status information.
Page 13
TMSL 097-45100-02
Issue 10: Apr 01
TO PREAMP IN
LORAN-C ANTENNA
FROM LORAN-C ANTENNA
LTI CARD
LORAN-C RECEIVER
DIGITAL
PROCESSOR
ENSEMBLE ENGINE
POWER
SUPPLY
2A
PRIMARY RATE
DRIVER
2A
FA
PANEL
–48 V
OSC
(NOTE) A
COMM
PORT
ALARMS AND
INDICATORS
TO MIS
(DCD-500)
OSC
B
PRIMARY
RATE
–48 V
CONTROL
DCD SHELF
NOTE: From rubidium or better quality oscillators only.
Figure 6. LTI Card Block Diagram
Page 14
Issue 10: Apr 01
TMSL 097-45100-02
C. LOU Card
3.22 The LOU card is typically used in applications
requiring an upgrade to the existing system (e.g., upgrading a DCD Shelf equipped with an ST3 or TNC to
PRS level), or if connecting to a BITS from a manufacturer other than Symmetricom. When used with a
DCD Shelf, the LOU card can be used as timing reference sources to the GTI card to provide office PRS
timing, as specified by the Telcordia document
GR2830.
3.23 The GTI card takes the GPS signal information
from the GTR and the uncorrected oscillator input
from the LOU card, and sends the signal to an output
driver to provide the outputs to the timing output
cards.
3.24 Two LOU cards are available: LOU-1 and
LOU-2 (Figure 7 and Figure 8). The LOU-1 card contains one oscillator with two parallel outputs, and
the LOU-2 card contains two active oscillators, but
only one oscillator at a time provides timing.
OSC A
OUTPUT
DRIVER
WARM-UP
AND OSC A
DETECT
OSC A
–48 V A
–48 V B
GND
+5 V
DC/DC
+15 V
GND
Figure 7. LOU-1 Block Diagram
+15 V
–48 V B
GND
GND
OSC B
WARM-UP
AND OSC B
DETECT
OUTPUT
DRIVER
–48 V A
–48 V B
OUTPUT
TO GTI
OUTPUT
TO GTI
DC/DC
GND
OUTPUT
DRIVER
OSC A
+5 V
–48 V A
3.25 If using the LOU-2 card, oscillator A is the preferred clock. Oscillator B becomes the preferred clock
only if oscillator A fails.
OSC A
WARM-UP
AND OSC A
DETECT
OSC B
OUTPUT
TO GTI
+5 V
DC/DC
+15 V
GND
Figure 8. LOU-2 Block Diagram
3.26 If the oscillator fails in the LOU-1 card, a lamp
lights to indicate failure. If one of the oscillators fails
in the LOU-2 card, the other oscillator provides timing. Fault tolerance is achieved by using the redundant oscillators. If both oscillators fail in the LOU-2
card, or the oscillator in LOU-1 card fails, the
DCD-LPR will defer to a degraded mask output, as
specified by the Telcordia document GR2830.
Page 15
TMSL 097-45100-02
Issue 10: Apr 01
4. SPECIFICATIONS
4.01 The DCD-LPR System specifications are listed
in Table C.
Table C. DCD-LPR System Specifications
ITEM
SPECIFICATION
DCD-LPR SYSTEM
Sensitivity
Locks with signal-to-atmospheric noise level of –10 dB or better
Performance
MTIE
Observation
Time
MTIE (sec.)
TNC-E, ST2, ST2E
@ 25 °C (72 °F)
ST3E, TNC, LNC,
LOU-1, LOU-2
@ 25 °C (72 °F)
1
8 ns
8 ns
10
10 ns
10 ns
100
10 ns
10 ns
1000
30 ns
60 ns
10000
100 ns
200 ns
100000
100 ns
600 ns
Inputs
The GTI-11 card accepts 5 MHz or 10 MHz from rubidium or better quality clock
cards, from ST2E or ST2 clock cards; the GTI-12 accepts 5 MHz or 10 MHz rubidium or better quality clock cards, from TNC-E clock cards; the GTI-13, GTI-14,
GTI-15, GTI-16, GTI-17, and GTI-18 cards accept 5 MHz or 10 MHz inputs from
quartz, rubidium, or better quality clock cards, or combinations of the two clock
types, or LOU card; the LTI card accepts 5 MHz from rubidium clocks, from ST2E or
ST2 clock cards only.
Outputs
The GTI-13, -15, and -17 provide 2 outputs: 1.544 Mb/s DS1, framed all-ones,
Superframe (D4) format or ESF
The GTI-12, -14, -16, and -18 provide 2 outputs: 2.048 Mb/s E1, framed all-ones
CCS/CAS
Page 16
Issue 10: Apr 01
TMSL 097-45100-02
Table C. DCD-LPR System Specifications (Cont’d)
ITEM
SPECIFICATION
DCD-LPR SHELF
Alarm Output Audible
and Visible
Major
Minor
Status (VIS only)
Type
Format
Contact Rating
Activates if power is lost on GTI/LTI card or if any major alarm condition exists on
the GTI/LTI card (e.g., loss of all inputs, or GTI/LTI card has failed)
Activates if any minor alarm condition exists on the GTI/LTI card (e.g., a single
blown fuse or loss of a single input)
Not used
Dry contact
Normally open and normally closed
1.0 A @ 56 V dc, 0.6 A @ 125 V ac
Power
Voltage
Current
Shelf Fuses
Power Source Fuses
–40 V dc to –56 V dc
Minimum 1 A
2A
3A
Environmental
Operating Temperature
Operating Humidity
0 °C to +45 °C
0 % to 95%, noncondensing
Dimensions (HxWxD)
13.3 cm (5.25 in.) (3 RU) x 48.3 cm (19.0 in.) x 27.9 cm (11.0 in.) overall
Note: If mounting above equipment that produces heat, leave an additional 1 RU (4.4 cm [1.75 in.]) beneath the
shelf for air flow.
Page 17
TMSL 097-45100-02
Issue 10: Apr 01
Table C. DCD-LPR System Specifications (Cont’d)
ITEM
SPECIFICATION
GTI-11, GTI-12, GTI-13, GTI-14, GTI-15, GTI-16 CARDS
Input Type
GTI-11 accepts rubidium or better quality, ST2E or ST2 cards only
GTI-12 accepts rubidium or better quality, TNC-E cards only
GTI-13, GTI-14, GTI-15, and GTI-16 accept 5 MHz or 10 MHz inputs from quartz,
rubidium, or better quality clocks, or combinations of the two clock types, or LOU
card
Output Frequency
GTI-11, GTI-13, and GTI-15: 1.544 Mb/s (DS1), framed all-ones
GTI-12, GTI-14, and GTI-16: 2.048 Mb/s (E1), framed all-ones
Framing Format Switch-selectable
GTI-11, GTI-13, and GTI-15: ESF or D4 (SF)
GTI-12, GTI-14, and GTI-16: CCS/CAS, with or without CCS4
Environmental
Operating Temp
Operating Humidity
0 °C to +45 °C
0 to 95%, noncondensing
Dimensions (HxWxD)
4.92 cm (1.9375 in.) x 35.08 cm (13.8125 in.) x 19.37 cm (7.625 in.)
SSM Capable
No
GTI-17, GTI-18 CARDS
Input Type
Accept 5 MHz or 10 MHz inputs from quartz, rubidium, or better quality clocks, or
combinations of the two clock types, or LOU card
Output Frequency
GTI-17: 1.544 Mb/s (DS1), framed all-ones
GTI-18: 2.048 Mb/s (E1), framed all-ones
Framing Format Switch-selectable
GTI-17: ESF or D4
GTI-18: CCS/CAS, with or without CCS4
Environmental
Operating Temp
Operating Humidity
0 °C to +45 °C
0 to 95%, noncondensing
Dimensions (HxWxD)
4.92 cm (1.9375 in.) x 35.08 cm (13.8125 in.) x 19.37 cm (7.625 in.)
SSM Capable
Yes
Note: For details on TL1 commands, refer to the TL1 User’s Guide provided with the MIS card.
LTI CARD
Input Type
LTI accepts 5 MHz inputs from ST2E or ST2 cards only
Environmental
Operating Temp
Operating Humidity
0 °C to +45 °C
0 to 95%, noncondensing
Dimensions (HxWxD)
4.92 cm (1.9375 in.) x 35.08 cm (13.8125 in.) x 19.37 cm (7.625 in.)
SSM Capable
No
Page 18
Issue 10: Apr 01
TMSL 097-45100-02
Table C. DCD-LPR System Specifications (Cont’d)
ITEM
SPECIFICATION
SSM
E1 System Quality Levels
Quality Level
PRC
DNU
UNK
T1 System Quality Levels
Quality Level
PRS
STU
Meaning
Primary Reference Clock
Do not use or idle code (no SSM message)
Unknown
Meaning
Primary Reference Source
Synchronized – Traceability Unknown
Page 19
TMSL 097-45100-02
Issue 10: Apr 01
Table C. DCD-LPR System Specifications (Cont’d)
ITEM
SPECIFICATION
TIME-OF-DAY (Optional)
Data Signal
Baud Rate
Format
Physical/Electrical
Data Format
1 pps Signal
Pulse Width
Valid Edge
Accuracy
Physical/Electrical
Page 20
9600 b/s
8 data bits, no parity, 1 start/stop bit
Output of Adapter:
Physical:
DB9, female
Electrical:
RS-422
Output of Converter (optional):
Physical:
DB25, female
Electrical:
RS-232
Cisco Systems:
Time format: Year/month/day, hour:minute:second
Alarm fields: Alarm severity, source, and cause where the TOD alarm codes
are defined as follows:
Alarm severity:
NR
= non-reporting
MN = minor alarm
MJ
= major alarm
Alarm source:
TOD = TOD output card
GTI = GTI
CK1 = Clock 1
CK2 = Clock 2
PW1 = primary power feed
PW2 = secondary power feed
GTR = GTR
GPS = GPS satellites
Alarm cause:
ACQ = acquiring
UNL = unlocked
FLT = fault
LOS = loss
NTP Type 4:
Time format: Year Julian-date hour:minute:second:millisecond
Alarm fields: First character, sp = insync, ? = out of sync
800 µs
Rising
<1 µs compared to UTC
Output of Adapter:
Physical:
DB9, female
Electrical:
RS-422
Output of Converter (optional), DB25:
Physical:
DB25, female
Electrical:
RS-232
Output of Converter (optional), BNC:
Physical:
BNC
Electrical:
TTL
Issue 10: Apr 01
TMSL 097-45100-02
Table C. DCD-LPR System Specifications (Cont’d)
ITEM
SPECIFICATION
LOU CARDS (LOU-1, LOU-2)
Source
LOU-1, one oven-controlled crystal oscillator; LOU-2, two oven-controlled crystal
oscillators
Accuracy
24 hours
20 years
3.0 x 10-10
1.0 x 10-6
Warm-up Time
30 min
Environmental
Operating Temp
Operating Humidity
0 °C to +45 °C
0 to 95%, noncondensing
Dimensions (HxWxD)
4.92 cm (1.9375 in.) x 35.08 cm (13.8125 in.) x 19.37 cm (7.625 in.)
BLANK PANEL
Dimensions (HxWxD)
4.92 cm (1.9375 in.) x 35.08 cm (13.8125 in.) x 7.93 cm (3.125 in.)
ANTENNA/RECEIVER (GTR)
Type
Stable phase centered active patch
Power
16 to 32 V dc at 6.5 W
Fiber cable wave length
850 nm
Power cable between
GTR and power source
Minimum 242.7 m (minimum 1,200 ft) with GTI card providing power
Minimum 242.7 m (minimum 1,200 ft) with an external power source
Cable types
For single lightning protector installations: one shielded 3-conductor cable, 1.47 mm
(16 AWG) with a 1.47 mm (16 AWG) built-in drain wire and one shielded 3-conductor
cable, 1.47 mm (16 AWG)
For dual lightning protectors: two shielded 3-conductor cables, 1.47 mm (16 AWG),
with a 1.47 mm (16 AWG) built-in drain wire; and one shielded 3-conductor cable,
1.47 mm (16 AWG)
200 µ multimode fiber optic cables to connect the GTR to the DCD-LPR Shelf.
Environmental (GTR)
Operating Temp
Storage Temp
Relative Humidity
Operating: –40 °C to +70 °C (cannot be started at temperatures below –20 °C)
Storage: –50 °C to +100 °C
Up to 100%
Dimensions
29.8 cm (11.75 in.) diameter; 16.5 cm (6.5 in.) total height
Page 21
TMSL 097-45100-02
Issue 10: Apr 01
Table C. DCD-LPR System Specifications (Cont’d)
ITEM
SPECIFICATION
LORAN-C ANTENNA
Type
Active whip
Preamp
FET type, bandpass filter, powered from receiver
Cable types
Type 1 Lightning Protectors
For single lightning protector: two twinax cables, RG-108A (or equivalent) as plenumrated cables are required. One cable must have TROMPETER TWINAX BNC connector plugs #PL30-55 (or equivalent) on both ends; one cable must have a TROMPETER TWINAX BNC connector plug #PL30-55 (or equivalent) on one end, and a
spade lug connector to fit 1.02 mm (18 AWG) wire, 6.35 mm (0.25 in.) wide, and fit to
a #6 stud on the other end.
For dual lightning protectors: three twinax cables, RG-108A (or equivalent) as plenum-rated cables are required. Two cables must have TROMPETER TWINAX BNC
connector plugs #PL30-55 (or equivalent) on both ends; one cable must have a
TROMPETER TWINAX BNC connector plug #PL30-55 (or equivalent) on one end,
and a spade lug connector to fit 1.02 mm (18 AWG) wire, 6.35 mm (0.25 in.) wide,
and fit to a #6 stud on the other end.
Type 2 Lightning Protectors
For single lightning protector: two twinax cables, RG-108A (or equivalent) as plenumrated cables are required. One cable must have a TROMPETER TWINAX BNC connector plug #PL30-55 (or equivalent) on one end, and a spade lug connector to fit
1.02 mm (18 AWG) wire, 6.35 mm (0.25 in.) wide, and fit to a #6 stud on the other
end; one cable must have a spade lug connector to fit 1.02 mm (18 AWG) wire,
6.35 mm (0.25 in.) wide, and fit to a #6 stud on both ends.
For dual lightning protectors: three twinax cables, RG-108A (or equivalent) as plenum-rated cables are required. One cable must have a TROMPETER TWINAX BNC
connector plug #PL30-55 (or equivalent) on one end, and a spade lug connector to fit
1.02 mm (18 AWG) wire, 6.35 mm (0.25 in.) wide, and fit to a #6 stud on the other
end; two cables must have a spade lug connector to fit 1.02 mm (18 AWG) wire,
6.35 mm (0.25 in.) wide, and fit to a #6 stud on both ends.
Distance between
antenna and LTI
Environmental
Operating Temp
Storage Temp
Relative Humidity
Dimensions (Height)
Page 22
Minimum 1,219 m (minimum 4,000 ft)
–40 °C to +70 °C (cannot be started at temperatures below -25 °C)
–50 °C to +100 °C
Up to 100%
3.3 m (10.5 ft) overall (2.4 m [8 ft] antenna, 178 mm [7 in.] conduit-T, 0.6 m [2 ft] pipe
section)
Issue 10: Apr 01
5. INDEX
A
Advantages, ensemble averaging 5
Antenna, LORAN 13
Availability, Selective 5
Averaging, ensemble 4
B
Backplane, DCD-LPR Shelf 9
Block Diagram, LOU-1 15
Block Diagram, LOU-2 15
Block diagram, LTI card 13, 14
C
Card, clock 5
Card, GTI 4, 5, 6, 7, 9, 15
Card, GTI/LTI 17
Card, GTI-11 3, 9, 16, 18
Card, GTI-12 4, 9, 16, 18
Card, GTI-13 3, 9, 12, 16, 18
Card, GTI-14 4, 9, 12, 16, 18
Card, GTI-15 3, 9, 12, 16, 18
Card, GTI-16 4, 9, 12, 16, 18
Card, GTI-17 3, 9, 12, 13, 16, 18
Card, GTI-18 3, 9, 12, 13, 16, 18
Card, LNC 16
Card, LOU 4, 5, 9, 15, 16, 18
Card, LOU-1 4, 15, 16, 21
Card, LOU-2 4, 15, 16, 21
Card, LTI 3, 5, 13, 16, 18
Card, MIS 6, 18
Card, ST2 2, 16, 18
Card, ST2E 2, 16, 18
Card, ST3 15
Card, ST3E 2, 16
Card, TI 5, 6
Card, TNC 2, 15, 16
Card, TNC-E 2, 16, 18
Cards, clock 5
Cards, GTI 4
Cards, GTI-15 16
Cards, LOU 5
Cards, LTI 4
Cards, TI 5
Cards, timing output 9
Clock card 5
Clock card, quartz 16
Clock card, rubidium 16
Clock card, ST2 16
Clock card, ST2E 2, 16
Clock card, TNC-E 2, 16
Clock cards 5
Clock cards, quartz 2
TMSL 097-45100-02
Clock cards, rubidium 2, 16
Clock, quartz 18
Clock, rubidium 18
Clocks, DCD Shelf 5
Clocks, rubidium 16
D
DCD Shelf 4, 5, 9, 15
DCD Shelf clocks 5
DCD-500 Series Shelf 9
DCD-Cs Shelf 9
DCD-LPR Shelf 6, 21
DCD-LPR Shelf backplane 9
DCD-LPR System 4, 7
E
E1 System Quality Levels 19
Ensemble averaging 4
Ensemble averaging advantages 5
Ensemble averaging output 5
Ensemble, GTI card 9
Ensemble, LTI 5
G
GPS signal information 15
GR2830, Telcordia document 15
GTI card 4, 5, 6, 7, 9, 15
GTI card ensemble 9
GTI card output 9
GTI cards 4
GTI/LTI card 17
GTI-11 card 3, 9, 16, 18
GTI-12 card 4, 9, 16, 18
GTI-13 card 3, 9, 12, 16, 18
GTI-14 card 4, 9, 12, 16, 18
GTI-15 card 3, 9, 12, 16, 18
GTI-15 cards 16
GTI-16 card 4, 9, 12, 16, 18
GTI-17 card 3, 9, 12, 13, 16, 18
GTI-18 card 3, 9, 12, 13, 16, 18
L
Lightning Protectors, Type 1 22
Lightning Protectors, Type 2 22
LNC card 16
LORAN antenna 13
LOU card 4, 5, 9, 15, 16, 18
LOU cards 5
LOU-1 Block Diagram 15
LOU-1 card 4, 15, 16, 21
LOU-2 Block Diagram 15
LOU-2 card 4, 15, 16, 21
LTI card 3, 5, 13, 16, 18
LTI Card block diagram 14
Page 23
TMSL 097-45100-02
LTI card block diagram 13
LTI cards 4
LTI ensemble 5
M
MIS card 6, 18
O
Oscillator input, uncorrected 15
Output, ensemble averaging 5
Output, GTI card 9
Q
Quartz clock 18
Quartz clock card 16
Quartz clock cards 2
R
Rubidium clock 18
Rubidium clock card 16
Rubidium clock cards 2, 16
Rubidium clocks 16
S
Selective Availability 5
Shelf, DCD 4, 5, 9, 15
Shelf, DCD-500 Series 9
Shelf, DCD-Cs 9
Shelf, DCD-LPR 6, 21
Page 24
24 Pages
Issue 10: Apr 01
Signal information, GPS 15
ST2 card 2, 16, 18
ST2 clock card 16
ST2E card 2, 16, 18
ST2E clock card 2, 16
ST3 card 15
ST3E card 2, 16
System Quality Levels, E1 19
System Quality Levels, T1 19
System, DCD-LPR 4, 7
T
T1 System Quality Levels 19
Telcordia document GR2830 15
TI card 5, 6
TI cards 5
Timing output cards 9
TL1 User’s Guide 6, 13, 18
TNC card 2, 15, 16
TNC-E card 2, 16, 18
TNC-E clock card 2, 16
Type 1 Lightning Protectors 22
Type 2 Lightning Protectors 22
U
Uncorrected oscillator input 15
User’s Guide, TL1 6, 13, 18