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OM25
User Manual
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ATL OM25 User Manual

OM25
USER GUIDE
ATL Part No 1/356/001/610
Issue: 03 Nov 2004
Disclaimer
The information contained in this document is confidential to ATL Telecom Ltd. and may not be disclosed or reproduced in whole or in part without their written consent.
Note: The information contained in this document is supplied without liability for errors or omissions.
ATL Telecom Limited reserves the right to make changes to this document at any time without notice.
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COMPLIANCE NOTES & SAFETY INSTRUCTIONS
Caution: - Hazardous voltages inside the equipment
Safety Instructions:
This apparatus must be installed and maintained by SERVICE PERSONNEL only
There are NO user serviceable parts inside the modem.
The mains plug on the equipment serves as the disconnect device, therefore a socket outlet shall be installed near the equipment and shall be easily accessible
Caution: - Electrostatic sensitive devices inside the equipment
Electrostatic discharge (ESD) Warning:
Antistatic precautions should be observed at all times.
Power Rating Information - AC unit:
Voltage Range 85V-250V
Current Range 50mA
Frequency Range 50/60Hz
Power Rating Information - DC Unit:
Voltage Range -18V to -72V
Current Range 200mA
Safety Statements classification - NON traffic ports
The AC Mains input has a safety status of PRIMARY CIRCUIT
The OM25 AC unit is defined as a class 1 equipment and must be connected to a reliable earth connection.
If the mains earth cannot be guaranteed to be PROTECTIVE EARTH, then a PROTECTIVE EARTH conductor must be connected to the M3 stud on the rear panel of the unit.
The DC input has a safety status of TNV-2
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The OM25 DC unit is defined as class II equipment, an EARTH conductor must be connected to the M3 stud on the rear panel of the unit when using the G.703 interface in accordance with ITU­T G.703 requirements.
Statement Safety Statements traffic ports:
The Optical Interface has a safety status of CLASS 1 LASER PRODUCT
The Terminal Port has a safety status of EARTHED SELV.
The G.703 Port Connection Port has a safety status of SELV when connected to Unexposed Environments:
The G.703 Port Connection Port has a safety status of TNV-1 when connected to Exposed Environments:
Definitions:
Exposed Environment
A TELECOMMUNICATIONS NETWORK is considered to be an exposed environment if one or more conditions for an unexposed environment are not fulfilled.
Unexposed Environment
A TELECOMMUNICATIONS NETWORK is considered to be an unexposed environment if the following conditions apply to all parts of the network.
a) The possible effect of indirect lightning has been reduced by measures described in IEC 61312-
1.
b) The possibility of having different earth potentials has been reduced by connecting all equipment within the network to the same equipotential bonding system (see HD 384).
c) The possibility of power cross/contact has been reduced (see HD 384).
d) The possibility of induced transients and voltages has been reduced.
Manufacturers Declaration*
ATL Telecom Limited declares that this product is in conformity
with the essential requirements of the 'R&TTE directive 1999/5/EC'.
*A copy of the Declaration of Conformity is available upon request from ATL Telecom Ltd.
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ATL User Guide
OM25 OOptical MModem
1 INTRODUCTION 9 2 EXAMPLE APPLICATIONS 10 3 CONSTRUCTION 11
3.1 FRONT PANEL 11
3.1.1 LEDS 11
3.1.1.1 STATUS 11
3.1.1.2 OPTICAL 11
3.1.1.3 INTERFACE 11
3.1.1.4 MASTER (GREEN) 12
3.1.1.5 TEST (RED) 12
3.1.1.6 LOOPS (AMBER) 12
3.1.2 BUTTONS 12
3.1.3 TERMINAL PORT 12
3.2 REAR PANELS 12
3.2.1 DC VARIANT 12
3.2.2 AC VARIANTS 13
3.2.3 REAR CONNECTORS COMMON TO AC & DC VARIANTS 13
4. INSTALLATION 14
4.1 PROTECTIVE EARTH 14
4.2 POWER ON SEQUENCE 14
4.3 DEFAULT SETTINGS 15
5. INTERFACES & TIMING OPTIONS 16
5.1 V.35 INTERFACE 16
5.1.1 USER RATE 16
5.1.2 END TO END SIGNALLING 16
5.1.3 SIGNALLING CIRCUIT OPTIONS 16
5.1.4 EXTERNAL TIMING 16
5.1.5 ENABLE LOOPS 17
5.1.6 FUNCTIONAL OPERATION 17
5.2 G.703 INTERFACE 18
5.2.1 TIMING MODES 18
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5.2.1.1 THROUGH TIMING 18
5.2.1.2 LOCAL TIMING 18
5.2.1.3 LOOP TIMING 19
5.2.2 FRAMING MODES 19
5.2.2.1 UNSTRUCTURED MODE 19
5.2.2.2 STRUCTURED MODE 19
5.2.3 PERFORMANCE 20
6. CONFIGURATION VIA THE TERMINAL PORT 21
6.1 LOGIN 21
6.2 LOGOUT 24
6.3 MENU SCREENS 25
6.3.1 NAVIGATION SCREENS 25
6.3.2 INFORMATION SCREEN 26
6.3.3 CONFIGURATION SCREENS 27
6.3.3.1 ENTERING INFORMATION 27
6.3.3.2 MOVING BETWEEN CHECK BOXES 27
6.3.3.3 TURNING FUNCTIONS ON AND OFF 27
6.3.3.4 HOW RADIO BUTTONS WORK 28
6.4 MENU STRUCTURE 29
6.5 ALARMS 30
6.5.1 ALARM STATUS SCREEN 30
6.5.2 ALARM HISTORY SCREEN 32
6.6 CONFIGURATION 34
6.6.1 MASTER/SLAVE CONFIGURATION 34
6.6.2 USER PORT CONFIGURATION 36
6.6.2.1 V35 USER PORT 36
6.6.2.2 G703 USER PORT 37
6.6.3 REBOOT 38
6.6.4 SYSTEM 39
6.6.5 SUBSYSTEM NAMES 40
6.6.6 MONITORING 41
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6.6.7 SERIAL COMMUNICATIONS 43
6.6.7.1 PROCEDURE TO FOLLOW WHEN CHANGING SETTINGS 44
6.6.8 FRONT PANEL 45
6.7 INFORMATION 46
6.8 PERFORMANCE 47
6.8.1 PERFORMANCE OPTICAL LINES 47
6.8.2 PERFORMANCE USER PORT 48
6.9 SECURITY 49
6.10 TEST 50
7. CONFIGURATION VIA THE FRONT PANEL BUTTONS 51
7.1 INTRODUCTION 51
7.2 OPERATION 51
7.2.1 GENERAL 52
7.2.2 G.703 OPTIONS 53
7.2.3 V.35 OPTIONS 54
7.3 KEYPAD LOCK 54
7.4 AUXILIARY PORT OPERATION 54
8. SPECIFICATIONS 55
8.1 DIMENSIONS 55
8.2 TRANSMISSION PERFORMANCE 55
8.2.1 JITTER 55
8.2.2 TRANSMISSION RANGE 55
8.3 AC POWER INLET 55
8.4 DC POWER INLET 56
8.5 DC MAINS CABLE 56
8.6 OPTICAL CONNECTIONS 57
8.6.1 SAFETY WARNING 57
8.6.2 OPTICAL CONNECTOR CLEANING 57
8.6.3 FC.PC CONNECTOR 57
8.6.4 SC CONNECTOR 58
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8.7 INTERFACE CONNECTIONS 58
8.7.1 G.703 120 OHM INTERFACE 58
8.7.2 G.703 75 OHM INTERFACE 58
8.7.3 V.35 INTERFACE 59
8.7.4 V.35 EXTERNAL TIMING ADAPTOR CABLE PINOUT 60
8.8 TERMINAL CONNECTION 61
8.9 ENVIRONMENTAL 62
8.9.1 TRANSPORTATION 62
8.9.2 STORAGE 62
8.9.3 OPERATIONAL 62
9. ORDERING INFORMATION 63
9.1 OM25 AC POWERED 63
9.2 OM25 DC POWERED 63
9.3 ACCESSORIES 63
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OM25 OOptical MModem
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1 INTRODUCTION

This User Guide applies to the OM25 optical modem designed and manufactured by ATL Telecom Limited in the U.K. It provides guidance for installation, commissioning and operation of the modem as well as reference information covering maintenance, specification and compliance.
OM25 is an optical standalone modem providing a single V35 or G703 interface to the user. It delivers framed & unframed E1, fractional E1 and N*64kbps services. Protocol conversion (e.g. G.703 at the CO and V.35 at the CPE) is handled automatically.
The OM 25 Long Haul version can transmit data typically up to 75km. The OM25 Short Haul version can transmit data typically up to 15km.
Management control is provided locally via the RS232 connector. Alternatively the OM25 can be set-up locally using the loop buttons on the front of the unit.
Power is via a universal 85 to 250V ac connector or a -48V dc connector.
Figure 1 OM25
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2 EXAMPLE APPLICATIONS

Two OM25s may be linked via a dual fibre single mode optical link to provide end-to-end electrical interfaces, either of like type (ie G703 to G703) or of different type (G703 to V35). One of the units is configured as timing source (CO) , the other as timing sink (CPE).
Additionally, one of the units is configured as ‘master’, the other as ‘slave’. The ‘master’ unit is the source of link management and is able to configure and monitor the slave settings but not vice versa.
Either master or slave can be set to be CO.
A simple point-to-point network between two terminals is shown in Fig 2.
Figure 2
A tandem section, where the modems are connected in series with another transmission system or equipment that is the source of timing, is shown in Fig 3.
Figure 3
OM25 - CO OM25 - CPE
G.703 or V.35
Optical Fibre Cables
G.703 or V.35
Network
OM25 - CO OM25 - CPE
G.703 or V.35
Timing
Optical Fibre Cables
G.703 or V.35
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3 CONSTRUCTION

The front panel controls have a dual purpose. For normal operation, the LED indicators display status information and the push buttons are used for applying test loops. These controls can however, also be used to configure the modems without the need to plug in a VT100 terminal or PC. To do this, the front panel controls must be enabled for "Full Control" (default setting) and the unit set to Programming Mode, section 7.

3.1 FRONT PANEL

The front panel of the OM25 contains a RS232 9 way D-Type terminal connection, eight status LEDs and three front panel buttons
Figure 4 Front Panel

3.1.1 LEDS

3.1.1.1 STATUS
Red - An urgent alarm is present in the system.
Amber - A non-urgent alarm is present in the system.
Green - No alarms are present in the system.
3.1.1.2 OPTICAL
Red - An urgent alarm is present on the Optical Port.
Amber - A non-urgent alarm is present on the Optical Port.
Green - No alarms are present on the Optical Port.
3.1.1.3 INTERFACE
Red - An urgent alarm is present on the User Interface.
Amber - A non-urgent alarm is present on the User Interface.
Green - No alarms are present on the User Interface.
In the ‘green’ state the state of the received data (data output from the modem on the user interface) is indicated. The LED is green for 1’s and off for 0’s.
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3.1.1.4 MASTER (GREEN)
When lit, this LED indicates that the unit has been configured to operate as a management 'master'. The default setting is for the unit to be a 'slave', in which case the LED will be turned off.
3.1.1.5 TEST (RED)
This will be illuminated whenever a loop test is active on the unit.
3.1.1.6 LOOPS (AMBER)
These will be illuminated whenever a test loop has been selected.

3.1.2 BUTTONS

There are three buttons on the front of the OM25, Local Loop, Loop Back and Remote Loop. In Normal mode the buttons can be used to setup various test loops. In Programming mode the buttons are used to configure the OM25, refer to section 7.

3.1.3 TERMINAL PORT

The terminal port allows the OM25 to be configured via a VT100 terminal or PC running a VT100 emulation program.
Alternatively, the port may be used as an auxilary RS-232 link carried transparently across the fibre. See section 7.4.

3.2 REAR PANELS

The OM25 is supplied with either a -48V d.c. or a 110/230V a.c. power supply connector.

3.2.1 DC VARIANT

The DC unit
Figure 5 OM25 DC G.703 75ΩΩwith SC Optical Connectors
Ω
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3.2.2 AC VARIANTS

Figure 6 OM25 AC G.703 120ΩΩwith FCPC Optical Connectors
Figure 7 OM25 AC V.35 with SC Optical Connectors
3.2.3 REAR CONNECTORS COMMON TO AC & DC VARIANTS
Optical Connector (depending on variant)
User Data Ports (depending on variant)
OM25 Long Haul G.703 75 ohms FC/PC & 2*BNC
OM25 Long Haul G.703 120 ohms FC/PC & RJ45
OM25 Long Haul V.35 FC/PC & 34 way MRAC
OM25 Short Haul G.703 75 ohms SC & 2*BNC
OM25 short Haul G.703 120 ohms SC & RJ45
OM25 Short Haul V.35 SC & 34 way MRAC
Ω
ATL User Guide OM25 OOptical MModem
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4. INSTALLATION

This chapter describes the basic steps that are required to set up a system using the OM25 Optical modem.
It is recommended that if two desktop units are to be connected they should be tested back to back to check for operation before deployment.
Choose a cool, dry location away from direct sunlight. A cold, air conditioned room will give maximum service life.

4.1 PROTECTIVE EARTH

If a G.703 port needs to be connected to a circuit that is defined as TNV, then a protective earth must be connected to the earth bond stud on the rear panel. See the Safety Statements at the front of this User Guide.

4.2 POWER ON SEQUENCE

The power up sequence will begin after power is applied.
Desktop units require a -48V dc or 110/230V ac input (depending on the variant).
The unit must be connected to a protective earth using a suitable bonding conductor.
On the desktop unit, there are eight LED’s: Status, Optical, Interface, Master, Test, Local loop, Loop back and Remote loop. When power is applied to the unit, the front panel LED’s are illuminated as follows;
1. Test LED will illuminate for around 5 seconds.
2. Test LED extinguished, Status and Optical LED’s should then be illuminated. The Master LED may be illuminated if the unit is set to master. Plus the Interface LED may be illuminated if 1’s are present.
The unit will then be in a ready state for customer configuration.
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4.3 DEFAULT SETTINGS

The OM25 is supplied set with the following default settings.
General
Mode Slave CPE
User Port Rate n = 32, 2048kbps
V.35 Interface
Enable Loops Enabled
End to End Signalling Off
Circuits 106, 107 & 109 On
Timing Loop
G.703 Interface
Timing Through
Frame Unframed
TS0 Regenerated
Channelisation Disabled
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5. INTERFACES & TIMING OPTIONS

5.1 V.35 INTERFACE

5.1.1 USER RATE

User rates from 64K to 2304K (n = 1 to 36) can be configured; however, if the remote end is using G703, the maximum data rate at the V35 end is 2048K (n = 32).

5.1.2 END TO END SIGNALLING

When On
Circuits 105 and 109 are transmitted end-to-end across the link, ie the state of 105 at one end is mirrored by the state of 109 at the other.
When Off
Circuits 105 and 109 are not transmitted across the link. Their states are only relevant to the local unit.
5.1.3 SIGNALLING CIRCUIT OPTIONS
106 Normal / Set On
107 Normal / Set On
109 Normal / Set On
Circuits 106, 107 and 109 can act according to X21bis V35, or can be set permanently ON.

5.1.4 EXTERNAL TIMING

Tandem sections require an adaptor cable (not supplied, wiring information shown in section 8.7.4) so that two OM25s can be plugged together back to back via their user interfaces. Selecting External Timing ON on one of the units will then allow the two CO’s to lock timing.
Fig 8 - External Timing
OM25
16
Terminal
G703 / V35
OM25 CPE
Fibre
CO
Ext timing
Adapter
cable
OM25 CO
Fibre
OM25 CPE
G703 / V35
Terminal
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5.1.5 ENABLE LOOPS

When OFF, loop activation via control lines 140 and 141 is disabled. Also incoming V54 patterns from the fibre are ignored. This allows end to end loop activation in tandem sections. For example, the two modems connected by an adaptor cable in Fig 8 would have this option set to OFF, so that the far left-hand modem could set a remote loop on the far right-hand unit via V54.
Loop activation is still possible via front panel / VT100.

5.1.6 FUNCTIONAL OPERATION

When circuits 105 and 109 are being transferred across the link (End to End signalling ON), the behaviour is as follows:
Table 1 - V35 operation
'Tx sig' refers to the state of the signalling bit sent on the fibre to the remote end. Similarly, 'Tx data' refers to the state of the data sent on the fibre to the remote end.
'Rem' is used to denote the state of the appropriate signal at the remote end.
For '106 Set On', 106 is ON in all cases. This is the factory default. When 106 is following 105, there is a delay of 16ms in the OFF-to-ON transition.
For '107 Set On', 107 is ON in all cases. This is the factory default.
For '109 Set On', 109 is ON in all cases. This is the factory default.
When circuits 105 and 109 are not transferred across the link (End to End signalling OFF), 109 and Tx sig are ON in line 5. This is the factory default.
Switching circuit 140 ON triggers a V54 sequence to activate a remote loop. Circuit 141 activates a local loop.
Circuit 142 is active when local loop or loopback is active and also at both ends when remote loop is active.
Conditions V.35 Outputs Line Outputs
Loop
Loc
In
105
Case 106 104109107 Tx Sig Tx Data
Sync
X OffOnX1 105 103105On Off 1 X OnOnYes2 105 103105On Rem 105 Rem 103 X OnOffYes3 Off 1OffOff Rem 105 Rem 103 X OffOffNo4 Off 1OffOff X X X OffOffYes5 105
Back
Loop
On 105 103
105
103
Rem
Rem
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5.2 G.703 INTERFACE

5.2.1 TIMING MODES

There are three timing modes - Through, Local and Loop.
5.2.1.1 THROUGH TIMING
Through mode is plesiochronous - the two directions have independent timing and can transfer at differing rates. The connected terminals are the source of timing. Each modem receives timing from its terminal and passes it to the far end.
Fig 9 - Through timing
5.2.1.2 LOCAL TIMING
In Local timing mode, the clock source inside the CO is the reference clock for the system. Transmission on the fibre is locked to this clock. Both terminals lock to this clock and return the clock to the OM25s.
Fig 10 - Local timing
Timing source
Terminal
G703
Tx
Rx
CO
CPE
G703
Tx
Rx
Timing source
Terminal
Timing looped
Terminal
G703
Tx
Rx
Timing source
CO
CPE
G703
Tx
Rx
Timing looped
Terminal
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5.2.1.3 LOOP TIMING
In Loop timing mode, the reference clock for the system is provided by the terminal (or network) connected to the CO.
Fig 11 - Loop timing
The timing mode in the CPE depends on that selected in the CO:
CO Through CPE Through
CO Local CPE Local
CO Loop CPE Local

5.2.2 FRAMING MODES

There are two framing modes - unstructured and structured.
5.2.2.1 UNSTRUCTURED MODE
In unstructured mode, the user data passes transparently through the system. There are no Loss of Frame Alignment (LOFA), Alarm Indication Remote (AIR) or Alarm Indication Signal (AIS) alarms. The only alarm relevant to this mode is the Loss of Signal (LOS).
5.2.2.2 STRUCTURED MODE
In structured mode, the modem aligns to the incoming G703 frame from the terminal and extracts the data from the selected timeslots. It also generates a G703 frame towards the terminal and inserts the data payload into the selected timeslots.
LOFA is raised if the modem cannot achieve frame lock. Recognition of this alarm complies with G706.
AIS is raised if there are less than 3 zeros in 512 bits on the G703 interface.
AIR is raised if bit 3 in the Not Frame Alignment Word (NFAW) is set to 1 for 3 consecutive occurrences.
CRCs may be enabled or disabled. When enabled, errored blocks are indicated back to the terminal by use of the E bits in timeslot 0. The CRC Fail alarm is active if CRC multiframe alignment cannot be attained.
Timing
G703
looped
Timing source
Terminal
Tx
Rx
CO
CPE
G703
Tx
Rx
Timing looped
Terminal
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