Guide to Meter Usage of ANT20E

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Edited by Optical Network technical support department Document version

Guide to meter usage of ANT20E

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Reviewed by: Date:

Reviewed by: Date:

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Huawei Technologies Co, Ltd

All Rights Reserved


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Guide to meter usage of ANT20EConfidentiality Level:

Internal Use Only

2005-02-24 Huawei Confidential. No disclosure without permission. Page 2 of 19

Revision Records

Date Revised version Description Author


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Contents

Chapter 1 Acceptance Test Instruction.......................................................................................... 5


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Keyword:

The meter use of ANT20E

Summary:

The meter use of ANT20E

Abbreviation list:

None.

Reference list:

None.


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Chapter 1 Acceptance Test Instruction

Objective: now there are already instructions on acceptance test available from

the product engineering department, but such instructions provide mainly

theoretical guidelines for the on-site test by the project supervisor, without

mentioning how to use meters specifically which are usually borrowed to the site

test for a short time. It is the purpose of this article to help the project supervisors

to be handy with the meter in no time.Applicable range: the on-site acceptance test of SDH equipment at STM-16 level

can also serve as a reference for that of SDH equipment below STM-16 level.

1. Preparations before acceptance:Usually, 2.5G exchange belongs to the local network, so the acceptance report

of the customer should be submitted to the provincial level exchange. Thus

careful and complete preparations beforehand are a requisite, mainly including

the following points:(1) The test items should be agreed in written form with the equipment buyer in

advance, in case that an index has to be tested after the acceptance test is over,

because the equipment buyer holds that it should have been tested. To be on the

safe side, it is recommended to provide a test form to the equipment buyer at the

meeting discussing acceptance test issues, listing the test items and national

standard values, with actual test values to be filled in the test. It is advisable to

use a self-made test form instead of the acceptance form delivered with the

equipment.(2) Well plan the acceptance items, including personnel of the two sides, specific

test time, vehicle arrangement, meters needed, and the sampling ratio of boards

and circuits to be tested. The items in need of support of the equipment buyer

must be agreed upon beforehand, and tools should be made available as

complete as possible because even power plug boards may not be handy in the

branch exchange.(3) If possible, test all items yourself in advance, especially for the project whose

construction has been discontinuous, because the optical interface indexes,

being behind schedule, may change greatly comparing with the single station

commisioning data. If it is impossible to test in advance, then at least make sure

that there is no pointer justification and bit error networkwide.


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(4) Normally test of the following items takes about 3 hours, so it is advisable to

complete the test items of a station in half a day.

2. Common test items:(1) Optical interface: average optical transmitting power, max. receiver sensitivity,

receiver overload power, actual optical receiving power, max. frequency offset

permitted at input interface, output jitter and input jitter tolerance.(2) 2M electrical interface: output jitter, input jitter tolerance, mapped jitter,

combined jitter, frequency offset permitted at input interface, 24-hour bit error,

and output signal bit rate.(3) System test: switch time and orderwire phone.

Item Test requirements Preparation for test meter andequipment

Average optical transmitting power Select the wavelength, cleanconnector and tail fiber

Optical power meter and a tail fiber

Max. receiver sensitivity The same above SDH analyzer (or 2M errordetector), optical power meter,variable attenuator, and three tailfibers

Receiver overload power The same above The same above

Actual optical receiving power The same above Same as that for test of averageoptical transmitting power

Max. frequency offset permitted atinput interface

The change step of frequency offsetis around 20ppm

SDH analyzer, two tail fibers andvariable attenuator

Output jitter Input without jitter or frequencyoffset

The same above

Optical interface

Input jitter toleration Input without frequency offset The same above

Output jitter Input without jitter or frequencyoffset

PDH/SDH analyzer

Input jitter toleration Input without frequency offset The same above

Mapped jitter Input with frequency offset, andwithout jitter and pointer

The same above

Combined jitter With TU pointer and frequencyoffset

The same above

Frequency offset permitted at inputinterface

2M with frequency offset The same above

24-hour bit error The meter alone uses a powersupply

The same above

Electricalinterface

Output signal bit rate Digital frequency meterNetwork Switch time SDH analyzer

3. Test methods:(1) Average optical transmitting power: connect as shown in the following

diagram


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Graphic

Generator

Optical

powermeter

Equipment

tested

In the actual test, the optical transmitting power of the equipment can be tested

directly without using the pattern generator. Suitable wavelength should be

selected in the optical power meter, and the connector should be clean and in

good contact. The index for 1310 short-haul board is 0~-5dBm, and the index for

1550 long-haul board is 3~-2dBm.(2) Optical interface index test: connect as shown in the following diagram

WG

ANT20E

TX

RX

RX

T

X

Variable

attenuator

Attenuator

optix

Signal lo

The above connection is used to test bit error on the optical channel. Bit error

can also be tested on 2M tributary, but in consideration of convenient connection

for test of the following indexes, test on optical channel is recommended. It

should be noted that the (optical) receiving of the equipment and meter must be

tested with attenuation taken into consideration, in case of overload, and usually

the receiving is to be several dBs under-10dB. In terms of signal loopback, usePTP: BID, 8F, 0, 1 command to loop back ASP board externally, or use the

default feed-through of X16, i.e. shut down the high-speed frame PWS board,

unplug SCC unit, and turn on the switch on PWS board, then boards in the

high-speed frame will not be in service.Key points for setting: as shown in Figure 2, select Instruments in the top-level

menu and click Signal Structure, edit signal structure to be optical transmitting

and optical receiving at STM-16, and stop demultiplexing at VC4 level, i.e. select

BULK, as shown in the following figure.


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Figure 2

If the setting is confirmed, select TX=RX and click OK, the meter is set as desired.

If the connection is correct now, the meter should have no alarm, and in the case

of loopback with 8F, there will be alarms such as HP-TIM at the equipment side,

but they do not affect the test at all. If the method of default feed-through is used,

neither of the above two will alarm. The method of default feed-through is

recommended, so that the equipment will not mistake the alarm as a real one or

forget to remove the loopback.

After the above steps are completed, select Instruments, click Performance

Analysis, then click the green indicator in the top-level menu to start testing biterror. Adjust the attenuator carefully until bit error is detected on the meter. Take

down the optical receiving power of R16, which is the max. sensitivity of the

receiver. Then adjust the attenuator in the reverse direction to reduce the

attenuation until the meter detects any bit error; take down the optical receiving

power of R16, which is the overload optical power.After the overload optical power is measured, set the optical receiving power to

be several dBms under --10 by adjusting the attenuator, then it is ready to test

other indexes of the optical interface.


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Max. Input frequency offset permitted: there is a setting box of TX-OFFSET in

Signal Structure of Figure 1, which, when selected, can change the frequency

offset of STM-16.Different values can be selected to look for bit error in

Performance Analysis when the frequency offset changes. Drastic changes of

the frequency offset may easily cause bit error, which may be avoided if the

change is within 30PPMs once.Output jitter: set the frequency offset of STM-16 to 0 without input jitter. Select

Instruments in the top-level menu and click Jitter Generator/Analyzer, to pop the

following diagram.

Select AM OFF instead of TX ON, then select 2UI in RX: RANG, always set LP in

the meter to 20.0MHz, and select 5kHz in HP, then the test is ready. The meter

displays include Current Values or Max. Values, and the latter is not shown

unless the Measurement Start in the top-level menu is selected. The test

values also include the item of Phase Hit, which is usually of no interest to the

equipment buyer. In ITU recommendations, B1 is specified to be 0.5UI.Input jitter tolerance: select FMTJ (Fast Max. Tol Jitter) or MTJ. The two are

almost the same except that the former tests fewer points than the latter. Usually

the former is selected. It should be noted that the test should be performed


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without frequency offset, in case that the test of the low-frequency part fails. No

specific value but OK is displayed in the test result displayed on the meter. Click

Start for automatic test. Note: the test fails if the meter alarms.

(3) Electrical interface test: except the combined jitter, almost all other indexes

are set to 2M receiving and transmitting in the meter. As shown in the following

figure, the frame structure of the 2M should be set to Unfrm, otherwise there will

be LOF/LCD alarm with the meter. After the setting is completed, select TX=RX

and click OK in the end. At this time, TX-OFFSET shows 2M frequency offset.

Loopback at the 2M opposite end or on the optical channel is necessary;

otherwise AIS alarm will occur to the meter.

2M electrical signal

electrical signal

WG

ANT

OPTIX


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Max. frequency offset permitted at input interface: same as the 2.5G test for this

index, i.e. to view the performance while modifying the frequency offset value.Output jitter: transmit without frequency offset while testing the output jitter value.

HP1 is 20HZ, HP2 is 18K, LP is 100K and the measurement range is 2UI.Mapped jitter: transmit with frequency offset to test the output jitter value.

18K-100KHZ filter is OK, and test of 20HZ is unnecessary. It is required that each

frequency offset should be tested, but in consideration of the time limit in

acceptance test, it is OK to only sample several frequency bands to test.Input jitter tolerance: same as the 2.5G test for this index, i.e. to select the correct

template for automatic test.Combined jitter: the test of combined jitter involves many aspects of the meter,

so familiarity with the meter is highly recommended. The test should be

performed along with optical transmitting, otherwise, TU pointer can not be

added. See the connection in the following figure.

2.5G optical signal

Attenuator

2M electrical signal

W

G

A

N

T

O

P

TI

X


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In the test, stop the switching and configure a service, map 2M signals into 2.5G,

and the 2M output to the meter after being demultiplexed and demapped by the

equipment receives/analyzes the jitter. The following figure shows the setting of

GW3: 19 in the test.

When setting a mapping structure, set the signal structure, click OK, then click

Channel menu in Signal Structure window in the above figure, select Set

Channel to pop up the following figure for you to select the corresponding VC4

and timeslot number.


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Directly fill TS# (timeslot number) of the WG meter in the TX column in the above

figure, and click OK to complete the configuration. The test for the combined jitter

needs no loopback; add/drop of services should be normal. Actually signals ofthe meter only pass through the downlink channel in Optix equipment. Here, it

should be noted that the numerals in TX-Offs box in Signal Structure stand for

the frequency offset of STM-16 instead of that of 2M required by the test. No

alarm will occur to the meter if both the configuration and setting are correct.At this time, select Pointer Generator under Instruments to pop up the following

window for you to select TU and MS to set a specific type of TU pointer. MS

means that the numerals filled in are in the unit of millisecond, otherwise, the unit

will be frame or second.


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The left part of the figure shows that the single pointer with opposite polarity is

generated, i.e. INC/DEC is selected first, indicating the pointer with oppositepolarity. n stands for the number of repeated pointer(s), where n=1 means single

pointer. T2 stands for the interval time between two pointers having the same

polarity, and here it should not be selected after single pointer is already selected.

In Mode, Single means that the generation of the sequence ends after one cycle,

while Cont means that one such sequence is generated every T4 time.T 1 > 1 0

Pinter sequence a


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The left part of the figure shows that the regular single pointer is added with a

double pointer. INC, if selected first, stands for the positive pointer, then selectthe interval T2 between the two pointers to be 750 milliseconds. Select 14 as the

pointer number n since the cycle of the whole sequence will exceed 10 seconds,

then select Add (INC, DEC) to add a pointer, and set T3 to 2 milliseconds.T3

T2

Pointer sequence (t2>750ms, t3=2ms)


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The left part of the figure shows the regular single pointer leaving out a pointer.

Select Cancel (INC, DEC) as set in the figure, to find that the third pointer is leftout.

Pointer sequence C (T2>750ms)

After the pointer sequence is selected, 2M frequency offset is also to be selected,

and frequency offset can be added in 2M when WG ANT20E is under version6.6.

Select PDH Generator/Analyzer in Instruments menu, to add frequency offset.


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In the left part of the figure, there is a TX whose frequency offset value can befilled in manually, so fill it in and close the window directly. The frequency offset

received can be viewed in RX part when opening the window again.

After a specific pointer sequence above is selected, the frequency offset of 2M

should be changed over and over, so as to measure the max. B1 and B2 values

of the output jitter and obtain the combined jitter value in such a sequence.

Change the sequence in turn to obtain the final combined jitter value.


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Switch time measurement: the connection is the same with the test for bit error of

2M. No alarm occurs to the meter for remote loopback.

Select Aps in Time menu in Single Instruments to pop up the left figure, and click

Start. Switch the system, the meter will show the switch time and whether the

test is passed.4. About WG-ANT20E:Since ANT20E of WG is the soft meter based on PC and WIN95, it is very

convenient to print and be on-line. Now both the network adapter and printer are

ready, and they can be used directly to print out the test result.WG can be output to the printer or in the form of EXECL. It is not permitted to

change setting or shut down PC during measurement, unless the measurement

is stopped.Manual mode and Timer mode are available for measurement of WG meter. Asshown in the following figure, select the appropriate setting. To save the

measurement result, select corresponding items in Measurement menu.


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5. Supplementary description for the pointerSince three types of sequences, a, b and c are specified by ITU for the 2M test of

combined jitter, sequences other than the three need not to be tested. ANT20E

of WG is powerful in generating pointer, and when measuring the combined jitter,

it is OK to only set n, pointer polarity, T1, T2, T3, T4 and T5, whose relations are

shown in the following figure:T2

T4

T1N

Guide to Meter Usage of ANT20E

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