1.1 DEPTH A/T:-
When trenching work and laying of OF Cable is completed by OFC Project
or SSA Trans wing, route is ready to offer for depth and cable A/T. They have to offer it
on ATOM. All the required information has to be filled up correctly so that it should not
be rejected by DET A/T (TR). Along with this offer they must produce Route Index
Diagram (RID) and relaxation for less depth approved by competent authority.
1-1.1 check RID for - What type of protection and for how much route length?
- Culverts, Road, Railway crossing etc. properly shown or not?
- Depth and offset from the centre of road at every 10/20 meter
mentioned or not?
- RID is signed or not? Every page by SDE and last page by
- Some important landmarks marked or not?
Proceed on the route with Rodometer and white/yellow paint, brush.
Mark the pits wherever you want, randomly two pits per km. and some culvert bed with
the help of Rodometer measuring from Km stone as a reference or where Km stone is not
available measure from MH marking or MH marking also not available then straightway
start from 0 and go on continuously up to the end of the route. In fact this is possible for
short route only. Also try to mark the pits in built up area so as to check protection in
built up area. Marking may be done by white or yellow paint at the edge of road towards
1-1.2 Depth A/T Procedure: -When pits are ready and called for, proceed on the route
with following tools.
1. Small tape of 3.0 Meter for depth measurement.
2. Long tape of 30 Meter for offset measurement.
3. Rodometer is required to measure the shifted pits due to local
Measure depth of the pit from the top of PLB pipe or from the top of protection
provided and for correct measurement holds big tape horizontally on ground level, touch
small tape vertically on the top of PLB or Protection and read depth at the crossing of two
tapes which is the exact depth A/T reading in cms.
- Now final reading = measured depth + thickness of protection.
- Note down the results in the following table.
- Measure offset (distance of trench from the centre of road)
by 30 M tape in meter.
- Note down type of soil as Rocky (R) where trenching has
been executed by blasting / chiseling. Non rocky (NR), at
some places it may be R + NR.
- If area is built up, write as B/U in remark.
- Confirm GI + CC / RCC pipe is provided in the culvert bed or not?
- If GI pipe is taken along with parapet wall then proper clamping is
provided or not?
Note down the Readings in table as below, for example,
Sr Location Depth above Offset Type of Type Remarks
no. Km / Meter PLB/ Protection In Meter Protection of soil
1 36 / 180 95 6.5 CC R B/U
2 45/ 375 160 4.5 PLB NR -------
1. HDPE (High density poly ethylene):- Diameter 75 mm or 50 mm.
2. PLB (Permanently lubricated blowing):- Diameter 50/40/32 mm.
3. Trench depth in Non Rocky soil:-165 cm , 150 cm from top of PLB.
4. Trench depth in Rocky soil: - 90 cm, trenching by Blasting / chiseling.
5. In non rocky and built up area where can not go deeper, minimum 1.0 meter
from the top of the pipe with relaxation.
6. If depth is less than 1.2 meter then suitable mechanical protection by CC or
RCC / GI pipes and latest by Cudappa in OAN routes with approval.
7. In built up area irrespective of depth, suitable protection to be provided.
8. Culverts, around bridges or places with some obstruction, if depth is less so
in small stretches of 10-15 meters OFC should be laid at the most possible
depth with protection CC or half round RCC pipes and such cases need not
be referred for relaxation.
9. In culvert bed protection like GI+CC, RCC pipe to be provided.
10. Rail / Road crossing depth should be 1.5 M and encased in RCC pipe or 65
mm GI pipe.
11. Depth tolerance is up to 8 cm is permissible i.e. 142 cm and Offset tolerance
is ± 0.5 meter
12. In any case for less depth than 1.2 meter protection is must.
1-1.4 Type of protection:-
1. CC ( Cement concreting ) of size 25 cm x 25cm, 27.5 x 27.5 or 28 x 28 cm for
single pipe, 25 x 30 cm (2), 30 x 30 cm (3 & 4), 35 x 30 cm (5 & 6) and
40 x 40 cm for 8 pipes.
2. CC mixture should be of 1:2:4 means 1:- 53 grade cement of reputed company
2 :- coarse sand and 4 :- stone of 20 mm size , reinforced with MS weld mesh
50 mm x 100 mm 12 swg, 120 cm in width in rolls of 50 M and one meter
covers 3 M of CC.
3. RCC ( Reinforced cement concrete ) pipe full round length 2 Meter, Dia 150
mm outer and 100 mm inner , every third joint will be embedded in a concrete
block of 60 cm L x 40 cm W x 25 cm H of 1: 2 : 4 i.e. ( 1- cc, 2- coarse
sand, 4- 20 mm stone )
4. GI pipe 65mm diameter.
5. RCC pipe half round
6. A combination of GI + CC or RCC pipe in culvert bed.
7. Cudappa size 300 x 1000x 40 mm in OAN routes along with sand or soft soil
for height of 20 cm.
1-1.5 Relaxation for less depth from competent authority:-
1. Less depth than 150 cm is to be certified by DET concerned.
2. In Built up areas of city/towns falling under municipal or corporation limits,
depth can be relaxed to 1.00 M in NR and 0.90 M in R and it is to be certified
by concerned DGM along with reason for not laying at 150 cms.
3. In Built up areas of city/towns not falling under any municipal or
corporation limit, a suitable depth and protection is to be certified by concerned
DGM of Project and Maintenance.
4. In Rocky soil 90 cm is further relaxed by CGM Project on specific
recommendations of GM Project and Maintenance , where blasting permission is
1-1.6 General Information:-
1. Route indicator: - Indicator embedded in a trapezium shape of concrete with
base 30 cm x 30 cm and top of 15 cm x 15 cm, Height 1.25 meter at every 200 m
for MH and approx. 2 Km for joint chamber.
It should be 30 cm above ground, color yellow for MH indicator and red for joint
indicator now changed as Orange for MH and Green for Joint indicator.
Made up of pre cast RCC base – 25 cm x 25 cm, top – 20 cm x 7.5 cm, height –
It should be designated as BSNL OFC by white color
2. RCC hand hole internal size 1.20 x 0.7 x 1.50 meter or 0.60 x 0.75 x 1.0 meter
with SFRC cover.
3. NR: - Soft soil, Murrum, soil with stone, soft rock.
4. R : - Rocky area with hard, solid stone and trenching by blasting or chiseling.
5. Depths in multiple of 5 cm e.g. 97 cm write as 95 cm or 103 cm write as 105 cm.
6. Point of measurements at a distance of 10/20 M in RID.
7. OF cable life is 40 years.
8. MH size is 3x 1x 1.65 M.
9. Joint chamber pit 2 x 2 x1.8 M with internal size 1.5 x 1.5 x 1.2 M.
10. RCC collar sealing by 1:3 where 1- 53 grade cement 3- fine sand without
impurities , in RCC pipes every third joint embedded in concrete block of
60x40x25 cm of 1:2:4 cc mix where 1- cement 2- coarse sand and 4- stone of 20
11. GI pipe 65 mm / 40 mm IS 554/1985, IS 554/ 1989, 40 mm on Bridge or culvert.
12. Various Machines used for digging are – JCB ( Joseph Cryle Bamford ),
Poclain, Chiseler or Rock breaker.
13. Lubricants of HDPE pipe :- Betonite or Betonite with Ethyle glycol or Paraffinic
14. Minimum offset 15 meter from the centre of road , in exceptional case 0.6 meter
from shoulder or 4.5 meter from centre of road and 1.2 meter below road
1-1.7 HDD (Horizontal Directional Drilling)
A new type of technique is introduced in BSNL. In this technique pipes are laid through horizontal
bore by a machine and depth of cable automatically revealed by a sensor. This type of technique is
operated in the city where manual or conventional technique is not possible, for example, below
footpath in the city. The main advantage of HDD is depth of cable is sufficient below the ground so
no question of protection is arises.
In this method boring is achieved by pushing of GI pipe of 3 meter length at a distance of
approximately 100 to 150 meters. At the time of execution of trenching work depth reading is
noted down on RD-98 instrument which is known as radio detector. It is kept and read out where 3
meter pipe ends. When gain is maximum, display will show the depth of bore. In water Bentonite
powder is added in tanker approx 250Kg in 3000liters of water to form a channel for pulling of
• Applicable in Corporation/Municipality limits only.
• Useful for Highway/Rail crossing
• Normally 250cms depth is possible
• Bore dia 100mm for 4 PLB or less pipes and for 5-8 PLB Bore dia 200mm.
• Machine should drill maximum 1.50 meter at a time.
• Depth at the entry should be 165cms.
• Depth, deviation and offset to be provided by machine automatically with graph.
• HDD is normally deployed in soft soil.
• GI route indicators at every 200 meter manhole and 30 cm above ground level.
Depth A/T of HDD
• As usual RID should be obtained first.
• HDD machine reading duly certified by DET to be obtained
• Offset tolerance ±0.5meter
• Depth A/T to be conducted at the time of execution of trenching
• (This is the extract of newly released EI from T&D circle)
1-2 CABLE A/T
1-2.1 General : - In BSNL OF cable of various capacities from 6F to 96F. i.e. 6F, 12F, 24F, 48F
& 96Fare being used. There are near about 25-30 cable manufacturing companies with different
IOR for every make. 144F, 288F, 576F cables are as a high count cable. Please see the IOR table
as below. Please see various Optical fiber cables in Fig. 1-5 to 1-8.In one repeaters section cable of
two makes should not be used if no alternative then IOR should be the same upto maximum three
digits after decimal..
Sr.No. MAKE OF CABLE λ = 1310 λ = 1550
1 UNIFLEX 1.4670/1.4690 1.4675/1.4695
2 STERLITE 1.4670/1.4800 GPRI 1.4670 old
3 AKSH 1.4670/1.4720
4 SIECORE 1.4620
5 OPTEL 1.4620
6 SIEMENS 1.4700
7 VIKAS HYBRID 1.4670
8 HCL 1.4630
9 HFCL 1.4667
10 PLASMAC 1.4660
11 SUDARSHAN 1.4670 1.4675
12 CMI 1.4670
13 BIRLA-ERICSSON 1.4670 1.4688
14 GCEL 6F Arial 1.4676
15 ARM 1.4670
16 GOCL 1.4670
17 RPGCL 1.4670
18 TTL 1.4690 1.4671/1.4668/95
19 FINOLEX 1.4660
20 UM 1.4680 1.4688
21 TELELINK 1.4670
22 ICOMM --------- 1.4675
23 UTL --------- 1.46108
24 DEOL REWA 1.4718
25 DAEWOO 1.4630 1.4640
26 VINDHYA TELELINK 1.4670
27 STERLITE Buffer 1.4725
1-2.2 Required Meters for cable A/T :-
1. Laser source of both λs. Tests: - 1. Source loss from one end.
2. Optical Power meter 2. Splice loss from both ends.
3. OTDR 3. Manual printouts for
4. Printer section loss from one station
5. Suitable Patch Cords
6. Fibre Cleaner / Spray
1-2.3 Source Loss:-
Check termination of Optical fibre on FDF with connectors at both the stations. Measure
output power of source with power meter for both 1310 and 1550 nm window by pressing CW in
source meter. Keep power meter at station A. with A/T Officer and send source to other station or
vice versa. Ask distant station to send source, measure received power at your end on all fibre and
tabulate the results as below:-
Trans power: - 1310:- - dBm
1510:- - dBm
Sr.No Reading in dBm Loss in dB Loss in dB/Km
1 1310 1550 1310 1550 1310 1550
1-2.4 SPLICE LOSS: - Take splice distances of OFC from the installer. Connect the meter as
shown in Fig. 1-3
Set the OTDR for title, fibre number, IOR, pulse width, distance manually or in auto mode. Start
OTDR. Cable trace appears on the screen. Adjust two cursors for section loss in LSA mode. Take
out the printout in manual. Select events in Auto mode. Observe event table on display. Note down
the loss and distance of splice. Prepare a chart. Carry out same splice loss test from other end also
with print out or otherwise note down. Calculate average splice loss:-
Specifications:- Fibre loss.
1. 0.43 dB/km for 1310 nm
2. 0.33 dB/km for 1550 nm
3. Average splice loss should be less than 0.1dB, but in any case
Individual splice loss should not exceed 0.3 dB
4. If OF Cable is existing then 0.50 dB/km for 1310 nm and 0.35 dB/km for 1550 nm
5. 10 % of total splices may have loss more than 0.3 dB provided per Km loss should
be within limit.
6 For 96 F the modem section is increased to 15km for calculating specification.
7 . If OF Cable modem sections is less than 10 km then calculate specification
a) Total splice loss = no. of joints x 0.1 dB
b) FDF loss will be 0.5 dB for each FDF
c) Cable loss excluding splice loss and FDF,
= 0.38 dB x cable length in Km
d) Total cable loss = a + b + c
e) Limit for cable loss including FDF & splice
= --------------------------------- dB/km
Length of cable in Km.
f) For 1550 nm 0.25 instead 0.38.
8. Individual splice loss should not exceed 0.3 dB
9. Normally in one hop two different make cable should not be used but
due to shortage if used , arrange make of same IOR up to 3 decimals.
10.Test cable for both window i.e. 1310 and 1550.
1. 12 F colors (make Aksh):- Blue, Orange, Green, Brown, Slate, Red,
Violet, Water glazy, Pink, White, Black, Yellow.
2. Three types of measurement modes: - Manual, Full Auto, Auto.
Auto – Measurement using values which are set,
Full Auto – Distance range and pulse width automatically set by OTDR.
Manual: - Distance and pulse width to be set manually.
3. Two methods LSA – ( Least Square Approximation ) :- Line is drawn
by computing the least square of distance from all measured data.
2 PA (Two Point Approximation):- Two measured data points are
linked at two markers.
4. All termination boxes are to be encased in wooden frame with glass.
5. FDMS ( Fibre Distribution and Management System ) :- 96 F cable have 4
tubes of 24 fibers , Blue, Orange , White, White . Each 24 F are further spitted
into 12 F, called Ribbon which are to be terminated in a Tray, so 8 Trays are
required for 96 fibers.
6. Ribbon color: - Blue, orange, green, brown, slate, white, red, black, yellow,
violet. rose and aqua.
7. Find out correct IOR from cable drum as IOR is important, since optical length
of fibre changes with IOR.
8. Core: - Pure silica glass with impurity, 8/50 micron dia, IOR higher than
9. Cladding: - 125 microns dia, silica glass made, IOR lower than core.
10. Diameter of fibre with plastic color coating is 250 microns.
11. Pig tails are used to extend OF cable from termination box to FDF, Color
yellow with PVC white color coating, dia 900 microns.
12. one micron = 10 -6 meter
1-3 OFC System Acceptance Testing
1-3.1 Various types of Meters required for OFC A/T
Sr.No Meters Type of Models
1. Power Meter 1. EXFO Fibre Optic Tester FOT-50, FOT-10 A
2. Radiant Tech. Optical Power Meter FTM-220/10101329
3. WWG Optical Power Meter OLP-18 C +26 dB Max
Germany BN 229143, OLP- 6 Germany OPN- 7 BN 2256
4. Silicomp Optical Power Meter-01-7 Hills
5. Acterna Optical Power Meter OLP-8, OLP-6 Germany
6. Optiwave Photonix PHM-501
2. Optical Source 1. EXFO FLS 2100-7 Hills 1310 and 1550 nm
2. Anritsu Stabilized Light Source MG 9001 A 1310, 1550
3.FOTEK Source 1310 nm
3. Variable Attenuator 1.EXFO Variable Attenuator FVA- 60 A or 60 B
2.EXFO Variable Attenuator FVA- 3100
3. Anritsu Optical Attenuator MN 9605 C
SMF 1.3/1.55 M 5848
4. Kingfisher international Optical Attenuator KI 7010 A
5. Acterna Optical Attenuator OLA-156
4. OTDR:- 1.Anritsu MW 910 C with rotating Knob
Optical Time 2. Anritsu MW 9070 A
Domain Reflector 3.Ando AQ 7250 P
4. Agilent E 6000 Series mini OTDR
6. Wavetek media test set N 292
7. HP OTDR
5. DTA set:- 1. Anritsu 1520 K PDH Analyzer (Tx & Rx combined)
Digital Transmission 2. Anritsu DTA Transmitter ME 520 B
Analyzer 3. Anritsu DTA Receiver ME 520 B
4. HP 37721 A
5. Radart 8303 M
6. Victor plus 2.048/64 Sl.No. LF/ 03369
Trend communication Spain
7. PCM Link Tester SBOM-Swan Electronics Thane 2.048 Mb
Model no. A-88 or PCM LP-3
8. BER Tester Sunlite E1 (Sunrise Telecom) with 4 Hrs.
9. MAC-390 B
6. SDH Analyzer 1. W & G ANT-20 E BN 3035/71 Germany.
(With Jitter Analyzer/ Generation Module)
2. W & G ANT-20 E (Without Jitter)
3. Acterna ANT- 20 SE with Jitter
4. ICT Victoria Jitter/ Wander YB 0065 (Portable)
5. Anritsu MP 1550 B PDH/SDH Analyzer with
Jitter & Wander.
6. WAVETEK Media Test set N 292
7. HP BER 717 with jitter up to STM-4, no 37717 C
7. Frequency Counter 1. HP M/W Frequency Counter HP-5350 B
2. Anritsu M/W Frequency Counter MF 76 A
8. Jitter Modulator Anritsu MH 370 A (Frequency and Amplitude by rotating
9. Optical Connectors & 1. FC: - Ferule connector
Patch cords 2. SC: - Straight/ Subscriber/Standard connector
3. LC: - Lucent/ Local / Light connector
4. D3, D4 connectors
5. ST: - Straight Tip
6. APC- Angle Pencil Cut
7. FC- PC (Ferule core- Physical contact or pencil cut)
8. SC- PC (Straight connector-Physical contact or pencil cut)
9. LC- FCPC patch cord
10. Different length & different combinations with above
10. Digital Multimeter any make
11. Fiber cleaners 1.MOLY-GRAPH 1/0402 Optical fibre cleaner
2. ESO Propyle alcohol with tissue paper or buds
3. MOLY KOTE Electric contact cleaner
4. Philips head cleaner
5. OFC connector cleaner Japan NTT-ME Corp.
CLETOP REEL Type A
1-3.2 Brief about ANT-20 (Advance Network Tester)
Make: - 1] W & G. (Walter and Golterman) Germany.
2] ACTERNA, Germany.
Models: - 1. ANT-20 and ANT-20 E in W& G
2. ANT-20 SE in ACTERNA. Fig. 1-9
The following Meters are available in above ANT-20 models which can be added or
removed as per our requirement.
1. Anomaly/Defect analyzer
2. Anomaly/Defect insertion
3. PDH Generator/ Analyzer.
4. Jitter Generator/ Analyzer.
5. Performance Analysis
6. Pointer Analyzer
7. Pointer Generator
8. Overhead Analyzer
9. Overhead Generator
Signal structure (Mapping) is to be done for every test as follows, just for example,
If started then W & G – ANT -20 – untitled.
Auto, Time, Edit, Interface, Laser, Channel,
Application – Instrument- Measurement- Configuration- Help.
EDIT MODE SDH MAPPING PDH PDH MODE SETTING
1] Tx NML STM-1 VCH 140 Unframed PRBS-23
Then Tx = Rx O.K
2] Tx Optical STM-1 VCH 140 Unframed PRBS-23
AU-4 Then Tx = Rx O.K
3] Tx Electrical STM-1 VCH 2M Unframed PRBS-15
Then Tx = Rx O.K
If Unbalance ports (75 Ω) with transformer are using then go to interface, change
Balance to Unbalance or otherwise 120 Ω (Balance) cords are available with Meter.
1. To monitor the BER, select PERF and Performance Parameters on table.
2. For O/P jitter, I/P jitter tolerance select, jitter (JIT) Generator and Analyzer
3. For mapping and various type of signal click on
4. Offset change can be done in signal structure only
5. Select performance Analysis- Hierarchy setting, menu, View.
6. For BER- Anomaly/Defect Analyzer- View- Graph/ Table Select table number
TSE –Reading of BER displayed.
7. For O/P Jitter and I/P Jitter tolerance, see procedure in STM-1 & 4
8. Alarms: - There are many LEDs on LHS of ANT-20 but some important alarms are as
LHS side LEDs shows History and RHS side LEDs shows current alarms.
1-3.3 OFC: - General
The best of all and most stable media is OFC. Optical fibre cables have
brought a revolution in the history of DOT and BSNL. If you look in to the past of DOT,
Our systems were working on Overhead lines, Co-axial cables and M/W systems.
Overhead line was very old media and was frequently interrupted so communication was
always remaining unreliable, Co-axial cable systems were having many repeaters with
limited bandwidth , during cable fault restoration was time consuming and it was prone
to lightning faults also , so maintenance of long route was a very cumbersome job. In
Microwave systems, due to the path loss, fading effect, rain attenuation and antenna
de-orientation, Receive level was not always stable, so effect was, calls were getting
disturbed, data was getting corrupted. When OFC media was introduced in BSNL
systems are most steady, reliable provided that OF cable is laid at proper depth and
proper protection is provided. Therefore in OFC systems all types of benefits are
derived and our transmission network has become most reliable with larger bandwidth
on demand which no other media was able to support. The OFC media is free from any
The OFC system A/T is to be carried out in the following sequence:-
1. Depth A/T
2. Cable A/T
3. Local A/T of system
4. Through A/T of system and
1-3.4 Some important abbreviations of SDH systems
Sr.no Abbre. Full forms
1 AC-1 Add/Drop Cross connections of first order
2 AC-4 Add/Drop Cross connections of fourth order
3 ADM Add & Drop Multiplexer
4 ALS Automatic Laser Shutdown
5 ALR Automatic Laser Restart
6 AUG Auxiliary Unit Groups
7 BER Bit Error Rate
8 CMCC Control Management & Communication Controller
9 DCC Data Communication Channel
10 DDF Digital Distribution Frame
11 ECC Embedded Communication Channel
12 EOW Engineering Order Wire
13 FDF Fibre Distribution Frame
14 HDB-3 High Density Bipolar-3
15 L11 Line Interconnect Module
16 LOF Loss Of Frame
17 LOS Loss Of Signal
18 MS Multiplex Section
19 MS-SP Ring Multiplex Section Shared Protection Ring
20 MSP Multiplex Section Path Protection
21 NSAP Network Service Access Point
22 PS Power Supply
23 PDH Plesiochronous Digital Hierarchy
24 RCF Rack Interconnection Field
25 R11 Ring Interconnect Module
26 SDH Synchronous Digital Hierarchy
27 STM Synchronous Transport Module
28 SDXC Synchronous Digital Cross Connect
29 SEC Synchronous Equipment Clock
30 SNCP Sub Network Connection Protection
31 SIM Section Interface Module
32 SPIM Synchronous Path Interface Module
33 TM Terminal Multiplexer
34 TEX Tributary Extension Module
1-3.5 A/T of Infrastructure:-
1. Verify all items as mentioned in infrastructure A/T schedule,
e.g. Availability of fire detectors, fire extinguisher and Antistatic flooring, adequacy
of Power plant, Battery, E/A, rigidity of the rack, fill up all information in schedule.
2. Main test is voltage drop. Take voltage reading at Battery
point by putting off Float, measure voltage at rack input at full load, the difference
between two readings is voltage drop which should always be within the limit of 1.0
volt, then measure voltage section by section and find out due to which section it is more
and check for cable gauge and for proper termination and if required recommend for
replacement of cable with higher gauge .
3. See whether system is Q/A stamped or labeled or Q/A
Certificate is available, if not ask for Q/A approval of the system.
4. Check of earthing system, note down the reading of Earth
resistance which was taken within six months.. Also carry out Earth measurement. Now-
a- days we have to carry out Earth Audit also.
5. Check of documentation, hardware software conformity. As
per the bill of material/purchase order confirm the Hardware installed and also confirm
Software on the computer and license with their expiry period .All licenses are to be
required in BSNL name.
6. Demand Approved equipment room layout. Check rack,
Sub-rack, DDF is properly earthed or not.
7. Check the DDF and FDF termination and availability of
8. Check room temperature which should be between 22º to
25º C (Air conditioning system)
9. Whether sufficient light arrangement in equipment room is
available or not?
10. Check sign writing on equipment as well as on DDF, FDF.
11. Emergency light available or not?
12. Check earthing of individual rack/sub rack and DDF.
- If it is TM card then only one port but if it is ADM card check trans
power of both the ports. Limit pl see table.
4. Receiver sensitivity / Dynamic range:-
Optical Variable attenuator
DTA SET 2
Make set up as above in Fig. 1-11. In variable attenuator keep minimum10dB attenuation
and observe loop on DTA .If loop not getting check all the connections and also clean
port and patch cords by applying fibre cleaner. If loop is ok then increase attenuation up
to 35 dB for STM-1 then gradually increase just to notice single Error (EC=1) on DTA
display, stop to increase the attenuation, now remove Rx cord from attenuator and
connect power meters to Rx port of attenuator by patch cord. Read power meter which
shows the exact receiver sensitivity of that port. Reconnect the removed patch cord to
variable attenuator. Please see table for Rx sensitivity Limits of STM 1,4,16 and if it is
not within limit then replace card. Now increase attenuation further so as to get the
minor, major, degraded signal, excessive error etc. alarm and at last LOS (loss of signal).
This alarm can be monitored in craft terminal in Fault- Current problem list by
continuous clicking ‘Refresh’. After LOS, go back towards loop condition on variable
attenuator and proceed towards higher attenuation side at maximum level say-2dBm,
system again shows no error, again remove patch card and connect power meter as above
and get maximum level at which OLT shows no error.
(Normally there is no error at 0 dBm in Fibcom/ ITI systems.)
The difference between minimum to maximum level is a dynamic range of the system,
which is always better than 27 dB.
N.B. - Don’t move attenuator so fast, reach to 2dB less than the prescribed sensitivity
limit and then move gradually so as to get correct reading of single error.
- If it is ADM card, carry out this test for both ports.
5) Laser Bias Current: - Note down Laser Bias Current from Craft Terminal in
Performance Monitoring. E.g. 81.9 %.
6) Check of Laser safety:-
Auto Laser shutdown (ALS) – This facility is provided to protect the eye of
person working on fibre or equipment. In case of break of fibre (Los), laser shut down
automatically. On craft terminal go to Fault- optical port- select port under test –click
ALS√- , the Trans power on power meter which was available now goes off again click
ALS, power will restore. In ALS disable, the Laser power is continuously available. This
is a forced on condition, and OFF power is -10 dBm. OK / NOT OK.
Manual Re-start – Laser restarts after 9 sec for ALS activated in normal
condition and 90 sec. for test, mtce purpose i.e. at the time of power measurement. The
normal condition of Laser sets back after 9 or 90 sec.When fault restores. ALS enable-
disconnect Rx input – click 2/90 test restart –OK- laser restores for the selected duration-
watch on power meter. OK/NOT OK.
Auto. Laser Re-start (ALR) – Automatically Laser restart after 2or 9 or 90sec
and this facility is provided on optical port. Feed 2 Mb data in any tributary and get local
loop –ALS enabled – disconnect optical I/P fibre for a moment and reconnect- data
should restore after WTR ( Wait to restore ) period. OK/NOT OK.
7) BER Test on 2Mb Electrical interface:- In the above setting of meter keep some
Attenuation say 30 dB so as to get loop OK. First of all check all 63 Trbs on DDF for
continuity, just to check the cable from system to DDF. Select one tributary from each
TEX Card e.g. Trb1 slot 15 , Trb 22 slot 21 and Trb 43 slot 9 in a sub rack, and Monitor
BER for 5 minutes each for 0, +50 & -50 PPM . Total time for the BER Test would be
45 minutes. The Result should be 0.00 E-9 i.e. No Error.
8) Combined Jitter: - It is the combination of Mapping jitter and Pointer jitter. Mapping
of signals to be carried out by synchronous structure and pointer adjustment, both
suffered in generation of SDH. Mapping jitter is always present in low or high grade in
synchronous signals, so when pointer movement occurs this jitter is added to pointer
Method: - On the above same set up of BER Test, Open O/P Jitter on Anritsu DTA Set
Select filters as HP1 and HP2 and change offset as +50 & -50 PPM. Note down the
readings for HP1-LP and HP2-LP filters as follows: - for example,
+ 50 PPM 0.069 0.024
- 50 PPM 0.075 0.027
In ANT-20 E: - Open jitter –AM off-select HP1-LP (20 Hz – 100 KHz) and
HP2 -LP (18 KHz – 100 KHz) read current
value of jitter peak –peak .Repeat for both offset and Trb 1, 22, 43.
Limit:- HP1-LP :- ≤ 0.4 UIpp HP2-LP :- ≤ 0.075 UIpp
9) Alarms:- The following alarms can be created and monitored on alarm module LEDs
also go in craft terminal and open –fault-current problem list-continuous clicking on
Single Error at a level of - 41 dBm Minor Please Note, Levels are written
Excessive Error ---“------- - 42 dBm Minor for only reference, need not to
Degraded Minute---“----- - 43 dBm Minor write in schedule, only monitor.
Loss of signal ----“------- - 45 dBm Major
Now before proceeding for through A/T, get all the pending points
of local A/T be cleared. If it is a SDH Ring then confirm whether OF Cable A/T and
depth A/T in all hops had been Completed in the past or not ? If in any hop cable A/T is
pending then ask installer to offer for cable A/T. After completion of cable A/T then start
1] Receive Power: - Note down no of Tx and Rx fibre, Route length, cable distance
.Here optical length is important i.e. OTDR distance, so as to calculate fibre loss.
Connect power meter to Rx fibre on line side as below Fig. 1-12
Line Eqpt. ATTENUATOR
Power Meter Power Meter
Note down the reading and calculate fibre loss according to the distances. If it is not
within limit clean fibers at both end and take accurate reading. Still it is not within limit;
declare that fibre for more loss. Measure receive power after connector or if 10 dB
attenuator provided then after attenuator Replace attenuator if its loss is more, also
measure the receiver power on patch cord which is to be connected to Rx part of OLT
cord, so as to check the patch card loss. Now the minimum Rx power limit for each
system is given below with 6 dBm maintenance margin out of which 3 dBm for
equipment and 3 dBm for fibre..
System Minimum Receive power Mtce. Margin
STM-1 -31 dBm -6dBm
STM – 4 - 22 dBm - 6 dBm
STM – 16 - 22 dBm - 6 dBm
There are two conditions:- (With Anritsu set )
a) Both Transmitter and Receiver at one station. Then take loop from other station.
. Make Meter connection as above. Loop getting OK. Anritsu Set – Press frequency on
Jitter modulator and take 20 Hz press amplitude and move the wheel to increase
amplitude up to such a point that single error starts in DTA receiver, carry out in the same
way for 93Hz, 700Hz and 100 KHz, and Tabulate the reading. Repeat test for other Trbs
22 and 43, this test is taken on loop.
b) Jitter modulator and transmitter at one station and receiver available at other station.
. Then send jitter on Trans at station A and ask station B to receive and listen the single
Error Buzzer at station B through order wire or ask counter part, this is jitter point for 20
Hz. Repeat test for remaining frequencies.
Tabulate these readings which were taken for 0 PPM and repeat for +50 and -50 PPM.
With ANT-20E:- Take loop from station -B. Connect ANT-20E, Tx and Rx to DDF as
shown in the following diagram and proceed as follows :-
Open jitter / MTJ-Setting (scan frequency) -select frequencies in a table 20, 93, 700
HZ and 100 KHz -O.K. – Start-Running. Scanning starts and after 5 minutes tolerable
jitter values in UIPP are displayed on screen under Max Tolerance jitters. For this click
view – table or diagram- table- for jitter mask click diagram. Repeat test for 0, +50 and
-50 PPM and trb no.s 22 & 43 .For limits Pl see table.
Trb No Frequency 0 PPM +50 PPM -50 PPM
1 20 Hz
22 20 Hz
43 20 Hz
For BER Test following Offsets are recommended:-
2 Mb (2.048) ± 50 PPM
8 Mb (8.448) ± 30 PPM
34 Mb (34.368) ± 20 PPM
140 Mb (139.264) ± 15 PPM
155 Mb (155.520) ± 20 PPM
5) AIS Frequency :- (All ones) Remove trans cord from DTA Transmitter or ask
distance station to remove 2 Mb data if fed. Connect frequency counter to Rx and
measure AIS frequency on all the three trbs. .Limit:- ± 50 PPM. (± 102 Hz)
6) Check of Order Wire:- Make a selective call i.e. by dialing the assigned O/W no
which is in 5 digits as 01122 of any station and check for Ring and Speech , carry on
OW test from both stations. Make a Omnibus call by pressing ***, all station should
response, verify speech and signaling.
Speech: - OK/NOT OK
Signal: - OK/NOT OK
Frequency allocation for various order wires and Supervisory,
A) Omnibus O/W 0.3 to 3.4 KHz
B) Express O/W 8.3 to 11.4 KHz
C) Supervisory and control 4.0 to 8.0 KHz
D) Service Channel Switching 12 to 16 KHz or 37 to 55 KHz
E) Calling Method loud speaker calling.
O/W also to be checked when BER is more than 0.00 E-3. Create this condition by
attenuating receive path by variable attenuator and verify O/W in this critical condition
for both speech and ring.
7) Check of synchronization :- The clock should be synchronized in NE management
system so as to interpret the correct sequence of a chain of events, it is necessary to
accurately control the rate at which digital signal are transmitted through out the network
and it is achieved by synchronizing the clock controlling switches. Measure Trb clock
(internal), External clock (either from SSU or from any other system 2 Mbps), In Hold
over mode if fibre disconnected, system goes to HO mode for 24 hrs, remove top priority
assigned for external clock and select DO NOT USE, as existing ref is lost, sync 1
switches to HOLD OVER mode and system works without any error. Ext.clock :- For
this test external clock is to be connected at SYNC IN in sub rack connection field- in
master node assign Top priority- Ask dist station to loop one tributary- Feed 2 Mb data
and observe loop in No error condition . Measure this external clock .Trb clock:- select
T1,T2,T3 input ref source with top priority and observe system works without error.
Limit: - 2048 kb/s ± 50 PPM Trb clock or, 2.048 MHz ± 4.6 PPM Ext clock.
8) Check of protection switching: - In STM-1 Fibcom system protection switching can
be configured in cross connection in configuration of craft terminal .There are three types
of protections. 1. EPS – Equipment protection switching, standby cards/ trbs are provided
(1+1) configuration. 2. APS –Automatic Protection Switching, extra OLT cards provided
with spare fibre.
Monitor loop in ok condition and if path is disconnected then after fraction of second of
AIS loop is getting ok i.e. traffic is shifted. 3. PPS - Path protection switching which is
operated in Ring / Mesh network, where alternate route is provided for switch over the
data in case of route failure. Here in FIBCOM Path protection can be configured in craft
terminal on port 1 and port 2. Take a loop in one direction and disconnect Rx fibre in
same direction, data should hold on switch over path.
Record time of AIS restore also. Carry out this test in any hop and confirm activation of
9) Performance Monitoring on craft terminal:-
Open Performance – Performance .monitoring – monitor points -select VC4 – port 1 –
select parameters like Trans power, Receive power, LD bias current – view data, all
relevant readings are displayed. Same may be monitored for second port also. Error
performance can be monitored for a required period in the same file.
10) Configuration management: - The craft terminal facilitates local and remote NE
configuration for all station in linear/ Ring network. Connect PC or laptop to F interfaces
with a single RS – 232 cables and a pole female plug. Double click Focus NM 2100-AC
1- as a NE type –check NE address NSAP Network service access point- which is say for
example 49000100a082f0112201 in which 490001 is a area code,00a082 unique for
Tellabs equipment and fo1122 assigned for specific equipment 01 for all Tellabs
equipment assigned no – version 4.8 ,Network ID ,Rack id, Administration, fault etc can
be checked on craft terminal also equipment actual/expected ,port allocation, monitoring
of optical port, alarms monitor / non monitor, alarm log, cross connection ,protection ,
current problem list NE reset ,local and remote loop back etc
11) Local and remote loop back: - Configuration –termination point –select port for
example 2 Mb/s 01 – click line for local loop back or terminal for remote loop back –
yes –check on DTA set loop getting ok or not.
12) Alarms :- Simulate alarm condition at distance station and observe on craft
terminal as well as on system module, like AIS, LOF, LOS, payload mismatch, degraded
signal, path unequipped, major and minor. Some alarms may be critical or major or
13)e.g. degraded signal- major. Path unequipped- critical , loss of reference source- major
, payload mismatch - critical, AIS-minor, LOF and LOS- critical, Loss of pointer –
critical, Rack Top alarms A,B, R.( Warning , major, minor )
14) Stability Test: - (48 hrs)
Arrange a loop on any 2 Mb tributary from distant station. Power ON
DTA Set on inverter supply only. Switch ON/OFF all electrical appliances and see for
any disturbance to DTA due to induction. First check getting loop ok or not, ask distance
station for break, observe break; again ask him to put back the loop. This implies that
loop is confirmed. Start DTA set for 48 hours in 12 hrs print out mode. Take proper
precaution so that nobody should disturb the DTA set, also check all connections of DTA
set and tighten them. Start meter, printer and lock DTA buttons. Read first data on a
printout. Please note that stability test to be carried out at the lowest Bit rate of the
station. Some stability reports of Anritsu, HP DTA set and ANT-20 are attached herewith
in Fig. 1-14 and 1-15 for reference only.
Limit: - At 64 Kb/s - ES – 0.018 % for 280 Km
SES - 0.00023 %
DM – 0.023 %
The stability is taken on 2 Mb port as it can not be taken at 64 Kb/s, result is to be
normalized to 64 Kbps. DM & SES which are in blocks need not to be corrected, but ES
to be normalized.
0.018 x 32 = 0.576 % is limit for ES up to the system distance of 280 Km.
N.B.:- For example one stability report is attached herewith.
General: - 1] As far as possible stability should be conducted on working day.
2] DTA must be powered on INVERTER supply only.
3] If Sync loss, AIS observed stop stability.
4] 2 Mb results are to be divided by 32 to normalize for 64 Kbps.
5] Make all connection tight to avoid disturbance to stability.
6] Restart stability with the permission of DET A/T TR if stability fails third
time and first sort out the problem and then only start stability.
7] Stability parameters are related to seconds, so AS should be checked -
If stability taken for 12 hrs then 43200 seconds
“ 24 hrs then 86400 seconds
“ 48 hrs then 172800 seconds
and “ 96 hrs then 129600 seconds.
8] AS – Available seconds AM - Available minutes
US – Unavailable seconds DM – Degraded minutes
TS – Total seconds
ES – Errored seconds
SES – severely Errored seconds
9] If stability is taken on other bit rate then to normalize the result to 64Kbps
Divide result by N, Where N = 1 for 64 kb/s, = 32 for 2 Mb, = 132 for 8 Mb, = 537 for
34 Mb, = 2176 for 140 Mb and = 2430 for 155 Mb
10] The Transmission system are classified as Class 1, 2, 3, and 4.
Class - 1:- CXL, OFC, D/M/W 34/140 MB
-2 :- OFC PDH
-3:- 120 chl UHF,
-4:- 30 chl /10 chl UHF.
Hypothetical Reference Digital Section is 280 km for class 1 & 2, and 50 km for 3 &4
system. OFC system is class -1 and performance limits are as above.
11] High grade system – Above level TAXS (D/M/W, CXL, OFC)
Medium grade system – level 1 TAX and local Exchange
(D/M/W, OFC, Cable PCM &UHF)
Local grade – Between local Exchange and subscriber,
(D/MARR, D/Sub, VHF and PCM)
1-3.11 Stability Important Terms:-
Error :- 0 & 1 transmitted from one end should be detected as 0 &1 only at the
other end ,when 0&1 are not detected exactly at receiver end , it is an Error due to which
communication gets affected.
BER: - It is the measure of Transmission quality.It is the ratio of bit errors to the
no of total bits received in one second, or the no.s of false bits to the total no of bits in a
second in digital data stream. Called BER. It is generally shown as a negative exponent,
e.g. 10 -7 which means
1 bit out of 10,000,000 bits is errored. Please note 1x 10 -6 is better than 1x10 -5.
e.g. EC = 10 in 5 seconds at 2.048 Mb then BER = --------------------- = 0.00097x 10 -6
2048 x 5 x 10 6
23 259x 10 -8
EC = 23 in 43200 seconds, BER = ------------------ = ------------ = 2.59 x 10 -10
2048x 43200x10 6 10 4
% US: - It is a period of unavailable time, it is a measure of % of time the circuit is
not available. if error continue for a significant period of time ,say 10 sec or more then
circuit is US.US starts when error ratio exceeds 10 -3 for 10 consecutive seconds, for any
Stability full time should be counted. % US =------------------ x 100
% ES: - It is a period of one second in which at least one error is detected or any
second which contain an error. ES is indicative of background errors.
S (errored) e.g. 18 errors in 12 hours then, 18x 100
% ES = ----------------- x 100 % ES = -------- = 0.0416
S (available) 43200
% SES: - It is a second in which error is worse than 10 -3 or any second during
which error exceeds 10 -3
% SES = ----------------- x 100
% DM: - It is a group of 60 consecutive seconds in which error worse than 10 -6.
DM x 60 Note that SES and DM are indicative
% DM = ------------------- x 100 of burst errors.
AS – ES TS - AS
% EFS = 100 - % ES = ------------------ % AS = ---------------
The various STM-4 systems are as follows:-
1) ITI / Fibcom
2) Tejas / ITI and
The Tejas sub rack comprises of ADM cards having two optical ports, in two slots
5 and 10. There are many versions of the sub rack i.e. with/without STM-1 Electrical /
Optical ports and Ethernet ports.
Before starting A/T:-
- Ask installer for trunking diagram of Ring Network along with hop
Distances, fibre no.s for Trans and Receive direction used in Ring
- Confirm whether OF cable in all hops acceptance is tested or not?
Commissioned or not?
- What about depth A/T?
- Whether A/T for 1550 nm window had been carried out or not in
the past? if not pl. carry out cable A/T for 1550 nm
- Get details of no. of tributaries dropped at each ADM station.
- Obtain approved layout of each station.
For example one Ring network is shown in Fig. 1-16.
Various versions of STM-4 system:-
1) With STM-1 Optical port.
2) 3X21 Trbs cards, 4+4 Ethernet port
3) With 2 STM-1 Optical port + 3X21 Trbs card, 4+4 Ethernet card.
4) With only 3X21 Trbs cards.
5) With 3X21 Trbs cards and one Ethernet port.
Here STM-4 make Tejas/ITI Ring Network is described on example basis.
STM-4 Mux card Trbs are as follows:-
1] Slot No. No. of Trbs
5, 10 L4.2 port 1 and port 2
2, 11, 12,13,14,15 21 Trbs per slot
2] STM-1 Optical/ electrical slot, slot no. 1 STM-1 optical port
3] Ethernet card with 4 ports.
Slot 3 -8 Ethernet ports of 10 mbps each or1for100 mbps or all 8 for 10mbps each
can be configured.
N.B. As such there is no tester to test Ethernet ports, so A/T can not be conducted.
One of TEJAS version:-
Slot 2 - 21 Trbs
Slot 3 - 28 Trbs
Slot 11, 12,13,14,15 - 28 x 5 Trbs Total 189 Trbs.
Slot 1 - 4 x STM-1 Optical port
Slot 5 - 4 x STM-1 Optical port
Slot 10 - 4 x STM-1 Electrical port.
1-4.3 Through A/T of STM-4 System.
Through A/T should be conducted in both directions:-
1. - Measure Receive power in both directions on fibre side of FDF i.e. before
attenuator and measure after attenuator (If provided for shorter distance).
- Compare reading for limit as 0.30 dB/Km. If not, write the (Maximum
Rec level should be -25 dBm) deviation to the installer.
- Note down Trans and Receive fibre no. which are worked out for both
directions, along with distances.
2. BER Test: - Ask 2 Mb loop from other station i.e. in A B direction. Check all
63 Trbs dropped, for continuity and BER on one Trb per card for 0, ±50 PPM
and monitor for 5 Min each.
3. STM-1 Optical port: - Take loop from distance station on this port and test it on
ANT-20E for BER 0, ± 20 PPM for 5 minutes each.
4. O/P jitter: - Make a set up of ANT-20 get loop of one Trb,
Mapping- Jitter- AM OFF-Select filter HP1- LP and HP2-LP filler.
Note down jitter reading for Trb 1, 22, 43 out of 63 Trbs.
Limit: - Please see the table.
5. I/P Jitter tolerance: - On a loop from other station, open. Jitter generator and
anomaly detector, MTJ- set- MTJ setting (Scan frequency)
- Select required frequency i.e. 20Hz, 93Hz, 700Hz and 100 KHz- O.K-
Start, observe running then scanning of jitter.
- Note down jitter values under maximum tolerance UI in table, for table
click view- diagram shows you jitter mask.
- Limit: - Please see table
- Repeat test for 0, ±50 PPM for Trb 1, 22, 43 or whatever dropped at a
6. STM-1 optical port: - Carry out BER O/P Jitter and I/P jitter tolerance test as
mentioned above by mapping AN-20E. Frequency for I/P jitter tolerance: -
500 Hz, 6.5 KHz, 65 KHz and 1300 KHz
Limit: - Please see table.
7. AIS frequency: - Ask distant station to remove loop and measure AIS frequency
On Rx which should be 2.048 MHz ± 102 Hz.
8. O/W check: - check O/W for ring and speech by dialing assigned no.s of the
stations, also check for speech when BER goes to 10-3, by inserting pad in Rx
9. Remote loop back: - Connect ANT-20 on any one Trbs for loop. Land on distant
station on laptop by IP address- go to node –nml- operation,facility,Terminal –
select Terminal-OK- view- mtce- PDH loop back, put maintenance E1-1-2-1.
Select Trb Select terminal and O.K you will get loop on Trb.
LP back mode- NML operation (disconnected) failure LP back
10. Protection Switching: - MS path protection :- Take a loop from any station in
the ring and observe loop is O.K Remove Rx fibre at the station of slot 10, again
see whether loop is disconnected or still exist, loop should remain exists. Take
disconnection from other station and monitor loop and confirm protection
switching takes place or not?
11. Synchronization test :- Measure 2 Mb clock at clock O/P 1 or 2 port ( 9 pin
connector ) in ADM sub rack, provided it is extracted from any other Ring or
system and connected in clock I/P 1 or 2 . Limit: - 2048 KHz ± 4.6 PPM.
Check that the system should work on hold over mode. Remove external clock,
system should go to hold over mode.
Check Trb clock Limit: - 2048 Kb /s ± 50 PPM.
12. Craft terminal: - There is no craft terminal monitoring of Trans and Receive
powers in Siemen’s and Tejas system. This monitoring is available in ITI/Fibcom only.
Check following parameters for each ADM and REG in Ring network.
1) Performance monitoring ,
2) Configuration management,
3) Alarm monitoring for Local and Remote, create alarms at distant station
and monitor on craft terminal.
Note: - All these through A/T test to carry out for other directions or between the
station where Trbs are dropped.
13. Stability test: - Configure software loop of one Trb to other so that whole ring
route should come in to the picture.
- Arrange physical loop on any 2 Mb trb, check loop and
- Set DTA set for 48 Hours and start stability.
14. Compare the results with stability parameters (Please see the table 8.2.)
- Demand for a trunking diagram of the Ring and No. of ADM’s REG information.
- Verify all ADM’s and REG’s for their correct ID.
- Configure how many 2Mb trbs, 140 Mb, and 155.52 optical ports and where they
are dropped as per T.T.O
- Get fiber allocation in each station and their in availability of fibre and some no.s
are worked out or not?
- Take all ADM/REG station approved equipment room layout diagrams.
- Confirm capacity and adequacy of power plant, E/A and battery, note down the
load of each ADM/REG at that station
- Check air condition availability and room temperature.
1-5.2 Local A/T o STM-16 ITI/Fibcom.
Infrastructure A/T please see STM-1 and STM-4, all parts are to be checked. Note down
all information as mentioned at the top of the test schedule.
1. Voltage drop: -Measure voltage at battery O/P and Bay I/P and the difference of two
readings is voltage drop. Limit: - 1.0 V. and I/P-40 to -60 V; Nominal -48 V
O/P voltages: - Measure O/P voltages on PSU card +5.0 V and -5.2 V.
Limit ± 0.25 (+4.75 to +5.25) and ± 0.26 V (- 4.94 to – 5.46)
Check proper MCB / Fuse rating. .
2. Trans power: - Connect craft terminal to CMCC card by RS -232 cable. Log in NM
2100 AC-4 version.
- Connect power meter to port 1 with a FCPC patch cord and measure the trans power of
port-1 Limit +1 to -4 dBm. Click- ALS-Disable, Power should go off. Same Procedure
adapt for port no. 6. If power is not within limit, Clean optical parts of SIM 1 & 6, also
clean patch cord and power meters adaptor and get trans power of each port within limit,
if not replace SIM card.
- Insert optical attenuator between trans and receive fibre of the system
- Connect one 140 Mb on one 155-52 Mb to port 1 of SIM Module.
- Map the SDH structure on ANT-20 in Signal structure as below.
- Tx optical STM-16- AU4-VC4-140 Mb-framed- PRBS-23-Tx = Rx.
- Observe Mapping on display as below Fig. 1-21
PRBS 23 140 VC-4 STM-16
` AU-4 DUT
3. Connect ANT-20 to sub rack 155 Mb optical or 140 electrical port and observe loop
- If it is not getting OK then Check all patch cords, 2 Mb cords, Clean and reconnect,
check mapping also and get loop O.K..
- Now increase attention up to the point where signal error maintained for a BER
of 1 X E-10
- Remove Rx cord of attenuator and get actual level from where error starts.
It should be ≤ -28 dBm.
- Reconnect attenuator and move to higher side but don’t cross overload point, So
as to avoid damage of SIM card, and get single error.
- Difference between higher and lower power will show the dynamic range which
should be better than 20 dB.
- Repeat same test for port-6, and note down all results.
1. Check of Laser Safety, Manual restart, automatic Laser shutdown and automatic
Laser restart; carry out as mentioned in STM-1 system.
2. Measurement of BER on Several ports of Sub rack i.e. STM-!/ 140 Mb
With the same set as above test BER on PDH 140 Mb ports and SDH STM-1
For 5-5 minutes for different offsets as below and on both ports 1 and 6. Total 16
Electrical ports should be checked in random.
140 Mb/S electrical ± 15 PPM
155 Mb/S Optical ± 20PPM
Limit: - 0.00E -12
3. Combined jitter on 2Mb Electrical port
- Get 2 Mb loop O.K after proper configuration and signal structure mapping
- Open jitter generation and analyzer
- Check AM OFF and
- Select HP1+ LP and HP1+ LP filler as 20 Hz + 100 KHz and 18 KHz+ 100 KHz
- Select +50 PPM offset
- Note down both readings for +50 PPM then change -50 PPM and repeat reading
- Limit:- as mentioned in table
4. Alarms: - In set up of receiver sensitivity increase attenuation further so as to get
the following alarms in craft terminal/ NMS in current problem list also observe
Major, Minor and critical on alarm module.
- LOS: - Loss of signal
- LOF: - Loss of frame
- Path unequipped, degraded signal MS port
- Path unequipped, degraded signal RS port
- These alarms can be created by ANT-20 using alarm insertion menu.
- AU-4 LOP: - Loss of pointer AU-4
- MS AIS: - Multiplex section AIS
- HP- UNEQP:-Higher order path unequipped
5. Local A/T of TMs: -
- Configure TEXT module 2 Mb Tributaries in cross connection and allots all 2
Mb, 63 Trbs. On different STM-1. Electrical port in both directions.
- Test 2 Mb tributary terminated on DDF, by arranging loop on concerned STM-1
Electrical 75 Ω loop.
- Carry out BER test on trb1, 22, and 43 in each STM-1 for ±50 PPM for 5 Minutes
each and carry out continuity test for all Tributaries.
- Monitor BER and any error in TMS.
9. 1-5.3 Local A/T and Through A/T of STM-16 REG:-
- Check of Power supply, Voltage drop and all other relevant information are to be
- Check Trans power of both ports and Limits :- +1 to -4 dBm
- Check of receiver sensitivity and dynamic range.
- Make a test set up as shown in Fig. 1-23.
- Insert, SPIM, CMCC of ADM and SYNC Card.
- In REG there is no Spim and SYNC Card.
- Make Mapping in signal structure for STM-16 optical and monitor loop.
- Increase attenuation and observe single error in performance.
- Limit is ≤ -28 dBm.
- In same manner go to higher side to check overload but don’t go beyond -9.0
- Difference between two readings is dynamic range.
- Monitor alarms, Minor, Major, Critical and Warning.
10. Through A/T of REG
- Receive power: - Measure receive level from both directions, maximum limit
should be -22 dBm so that 6 dB maintenance margin should be kept.
- Note down fibre details in both direction.
- Calculate fibre loss as per 0.30 dB/Km in each hop, If not try by cleaning or
changing the FDF connector, otherwise ask installer to improve it.
- Mostly fibers in the ring are existing and they were not tested for wavelength
1550 ŋ m, So test these fibers for λ= 1550 by OTDR and Source loss.
11. O/W: - Check O/W in both directions for speech and ring. Note down O/W No.
- Note down performance monitoring reading of craft terminal for Trans power,
Receive power and laser Bias current.
- Test all alarms local/ remote.
- Note down Receive power in performance monitoring of Craft terminal also for a
reference in view data and refresh.
1-5.4 Through A/T of ADM-16
1. Receive power:- Carry out as per written in REG through A/T
2. BER test: - Conduct BER test between ADM to ADM as per the allocation of
2 Mb or 140 Mb on STM-1. Carry out BER for 0 PPM and offsets as below :-
Electrical 2Mb 0 and ± 50 PPM
Electrical 140Mb 0 and ± 15 PPM
Electrical 155Mb 0 and ± 20 PPM
Ask loop from distant station on required electrical port,( because mostly one
DTA set available ) these tests are to be carried out by loop method only. BER
Limits: - 140 Mb / 155 Mb 0.00 E-11 or otherwise ask distant station to feed
140/155 Mb data ( If transmitter is available at distance station ) With 0 offset and
receive, monitor same without any error for 5 minutes repeat test for ±15, ± 20
PPM accordingly E.g. slots and Trbs are as below: -
Slot 2, STM-1/1, 140 Mb 2.3.4
Slot 3 STM-1/1,140 Mb 2,3,4
3. AIS frequency Measurement:-
Ask distant station to remove 140/155 Mb data or if loop is taken, ask him to
remove loop, Connect frequency counter to Rx port, Measure AIS frequency.
Limit ± 15 or ± 20 PPM
4. BER on 2 Mb port:-
Map 2 Mb signal structure on ANT-20 as
PRBS 2MB Unframed DUT Unframed 2MB PRBS
Ask distant station to send 2 Mb data 0PPM, Receive and monitor for 5 minutes each and
for ± 50 PPM also.
- Limit: - No error i.e. 00.E-9
- Test all 63 Trbs for continuity by taking loop on each Trbs from distant station.
5. AIS frequency:- Ask distant station to remove data/loop and measure 2 Mb at Rx
Port. Limit ± 50 PPM
6. O/P Jitter Measurement: -
- Ask distant station 140/155 Mb data or loop and receive.
- Select HP1 + LP and HP2 + LP fillers as per given in the table.
- Note down both peak-peak reading in UIPP on all ports.
- Carry out same test on 2 Mb selected 1, 22, and 43 no. Trbs out of 63 Trbs and
note down UIPP reading for both filters.
7. I/P Jitter tolerance
- Either on loop from distant station or 140 Mb data from distant station.
- Select jitter frequencies 200 Hz, 500 Hz, 10 KHz and 3.5 MHz in ANT-20 as
jitter- Set- Frequency table- select above frequency- O.K- table with selected
frequency - Start- running- after say 5 minutes jitter values will be displayed.
In same fashion, map 155.52 Mb and 2 Mb, Select corresponding frequencies and
get me /P Jitter tolerance reading and note down.
Limit: - 200- 500 Hz ≥1.5 UIPP
10 KHz- 3.5 MHz ≥ 0.075 UIPP
If jitter frequencies are sending from the distant station, ask him to increase amplitudes so
as to observe single error at your end, note down the reading, repeat procedure for all
other frequencies and tributaries.
For 155 MB I/P jitter frequencies are: - and for 2 Mb
500 Hz 20 Hz
6500 Hz 93 Hz
650000 Hz 700 Hz
1300000 Hz 100 KHz
8. O/W check: -
Selective calling: - After lifting the O/W handset listen dial tone and dial five digit O/W
no. of distant station, verify for ring back tone, speech quality. Ask distant station to call
and observe ring speech.
Omnibus calling: - Press xxx and all station should respond on your calling.
Check O/W for BER 1 X 10-3: -
This condition simulate by inserting attenuator in receive fibre, and test O/W response for
speech and ring.
9. Check of synchronization: -
External clock: - Connect external clock from SSU from 2.048 Kbps at SYNC ‘IN’ port
in SCF and assign top priority to external clock at master station, or otherwise node is
synchronized with the clock extracted from tributary. First measure external clock from
SSU which should be 2.048 Kbps ± 4.6 PPM
Now ask distant station to loop 2 Mb Tributary feed 2 Mb data and receive loop back in
DTA. There should not be any error on displace.
- Tributary clock: - Check that the system is working without any error whenT1, T2
or T3 Input reference source with top priority is selected.
- Holdover Mode: -
a. There is no synchronization reference clock
b. Remove top priority assigned to external clock by, ‘ DO NOT USE’ (DNU)
c. When reference is lost, SYNC- 1 shifted on switches to ‘HOLD OVER’ Mode,
and in this condition system should work without error.
d. This situation can be verified by taking loop on 2 Mb and monitor it for no error.
10. Protection switching:- There are two types of protection as 1. Linear 2. Ring
Linear protection is provided when two separate OF cable paths are made
available between one ADM section.
- In STM-16 MS Sp Ring protection is adapted. i.e. [Multiplex section protection
Ring]. It is of two types. 1. 2F Unidirectional Self Healing Ring ( USHR), 2.
2F/4F Bidirectional i.e. BSHR. MS SP RING: - Multiplex section shared
protection Ring or BSLR (Bidirectional Line switched Ring) It is a protection
Scheme in which the total capacity in a multiplex section is divided equally in to
working and protection traffic.
- The protection is provided when: - Signal failure, Signal degradation, User
- Bidirectional: - Both the head end and network element receiver tail end
networks element receiver switches to the alternative receiver on receiving an
alarm. Check Protection by simulating the conditions at each ADM, card
protection is a licensed feature.
- Protection mode unidirectional: - Only the head and network element‘s Receiver
switches to the alternate receiver on receiving alarm.
11. Performance Monitoring on NMS: -
NMS: - Network management system: -
It is a computer in which all nodes of ring with a map can be configured. It
does installing, Creating of NE with NSAP (Network service Access points) addresses
and configurations of DCN (Data communicate channel). It is a channel which transports
a management data.
Connect NMS by RS -232 serial cables to ‘F’ interface.
All the NE’s in both directions can be managed and monitored by NMS.
In NMS the following jobs are to be managed and monitored,
- Configuration- Termination ports.
- Cross connection- Performance Monitoring of Tx, Rx and laser bias current
- Temperature. - Synchronization- Fault alarms log, current problems List- NE ID,
Addresses- OHA, DCN Management and NE Reset – 2Mb clock monitor,
Maximum 255 NEs with a single NMS.
- The configuration management, and security management can be observed by
- Connect NMS by RJ-45 Ethernet on interface F or Craft.
- All tests in Local and Through A/T of STM-16 Make -Fibcom, Siemens and
Icomm. Are same except some parameters and electrical port configurations,
alarms, and power supplies etc.
- The various types of alarms at distant station and monitor on NMS, different types
of remote alarms like LOS, LOF, A, B, Warning, Remind, Critical, Major, Minor
- Local and remote loop back can be checked through craft / NMS in termination
point by selecting required port , Local or Remote.
12. Stability test: - As mentioned in STM-1, Put on stability on 2Mb port so that whole
ring should come into the picture. Stability period is 48 Hrs and so large network, total
hop distance or if it is a National ring then all precautions are to be taken, with
intimations to all concerned OFC station In-charge, So that it should not be disturbed, nor
Many times it is observed that stability fails due to following reasons: -
a. Break in inverter supply.
b. Disturbed power supply.
c. Tubes and lights are frequently ON/OFF.
After 48 Hrs are over compare the results with stability parameters.
1-5.5 O/P Jitter & Stability parameters as per G.921: -
STM-1 500 Hz-1.3 MHz ≤ 1.5 UIPP
65 KHz- 1.3 MHz ≤ 0.15 UIPP
STM-4 1 KHz- 5 MHz ≤ 1.5 UIPP
20 KHz- 5 MHz ≤ 0.15 UIPP
STM-16 5 KHz- 20 MHz ≤ 1.5 UIPP
1 MHz- 20 MHz ≤ 0.15 UIPP
As per Siemens STM-16 Field trial
140 Mb/s HP1+ LP ≤ 1.5 UIPP
HP2+ LP ≤ 0.075 UIPP
I/P Jitter tolerance as per G.823 at 2 MB/s port.
20 Hz- 2.4 KHz ≥ 1.5 UIPP
18 KHz- 100 KHz ≥ 0.075 UIPP
140 Mb/S -
200 Hz -500 Hz ≥ 1.5 UIPP
10 KHz- 3.5 MHz ≥ 0.075 UIPP
STM-1 500 Hz- 6.5 KHz ≥ 1.5 UIPP
65 KHz- 1.3 MHz ≥ 0.15 UIPP
Stability Parameters of OFC system at the Bit Rate of 2 Mbps.
% ES : - 0.018
% SES : - 0.00023
% DM : - 0.023