Jitter-wander Measurements Guide

Jitter and Wander Measurement Guide Jitter and Wander Jitter and wander are essentially short and long term signal rate movements across networks. SONET/SDH are, by definition, synchronous systems which require phase stability in clock and data signals throughout the network. Network elements (NE) are subject to a number of interference factors that can affect synchronisation and transmission quality, resulting in bit errors, slips and data loss. Jitter and wander measurements are deployed to quantify these errors and enable network operators to maintain synchronicity within acceptable limits. International compatibility To achieve international compatibility at network interfaces, the ITU-T along with other standardisation bodies, define maximum permissible limits for jitter and wander. These limits apply to network interfaces in which system components are incorporated into a complete network. Examples can be found in ITU-T Recommendations G.823, G.824 and G.825.

It is essential that developers of system components study and understand how NEs are likely to behave as individual elements under ideal conditions. By so doing, requirements can be better defined in accordance with and incorporated into standards for system components such as ITU-T recommendation G.783. The right test solution ± Acterna ANT-20 Advanced Network Tester In the fiercely competitive telecommunications arena, technological and economic excellence is crucial to commercial success.Acterna,with its firm commitment to sustained leadership in all aspects of the communications network life cycle, is dedicated to helping customers rise to the market's challenges in order to ensure economic value in their businesses. With technologies developing rapidly the Acterna ANT-20 advanced network tester is designed to meet customers' future needs. This flexible platform enables customers to adapt to technological change and can accommodate the DSn, SONET, SDH and/or ATM requirements, as well asnewstandards, higher bit rates and the intelligent system components of the future.

These requirements can be broken down into three categories: ± Jitter and wander at output interfaces ± Jitter and wander tolerance of input interfaces, and ± Jitter and wander transfer functions

Although precision test equipment can provide immediate results on how specific components measure up to these requirements, various components require distinctly different instrument set-ups. This guide is intended to provide support in setting up the Acterna ANT-20 jitter test instrument.

Contents 1

Jitter measurement 3 Measuring jitter 3 Output jitter measurement, instrument set up and application settings 3 Peak to peak jitter 4 RMS jitter 5 Phase hit measurement 7 Mapping jitter measurement 7 Combined (pointer) jitter measurement 9 Maximum tolerable jitter (MTJ) 13 Fast maximum tolerable jitter (FMTJ) 15 Jitter transfer function (JTF) 16

2

Wander Measurement 18 How to measure wander 18 Instrument setup 19 MTIE/TDEV offline wander analysis 20 Wander measurement of clock source 21 Wander generation and measurement of device under test (DUT) 22 Wander measurement for synchronous signals 22 Wander measurement for asynchronous signals 22 Wander tolerance measurement 24 Pointer wander measurement 25

3

Jitter and wander test equipment 29

2

Jitter measurement Measuring jitter To measure jitter effects, the incoming signal is regenerated to produce a virtually jitter-free signal for comparison purposes (figure 1). No external reference clock source is required for jitter measurement. The maximum measurable jitter frequency is a function of the bit rate that ranges at up to 80 MHz.

Data Tx/Rx electrical bal. electrical unbal. electrical electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12], Tx [13] 1.5 to 155 Mbps Rx [14], Tx [15] 622 Mpbs Rx [16] 2.5 Gbps Rx [43], Tx [46] 10 Gbps Rx [114], Tx [104] 52, 155, 622 Mbps Rx [17], Tx [18] 2.5 Gbps Rx [44], Tx [47] 10 Gbps Rx [113], Tx [103]

Table 1 Recommended interfaces dependent on signal under test Tx DUT Rx Jitter measurement ANT-20

Instrument and application setup Virtual instruments (VI) required ± Signal Structure ± O.172 Jitter Generator/Analyzer

Figure 1 Basic principle of jitter measurement

The unit of jitter amplitude is measured in unit intervals (UI). 1 UI corresponds to an error measuring one bit or one bit clock period. Test times on the order of minutes are necessary to accurately measure jitter.

Output jitter measurement, instrument setup and application settings Output jitter (jitter generation) measurement is used to determine the amount of jitter on a data signal. Here, the signal under test is connected to the receiver of the Acterna ANT-20 Advanced Network Tester (figure 2). The test duration is not defined according to specific standards but is dependent on the application. In most cases however, a measurement time of 60 seconds is recommended. The maximum Peak-to-Peak Jitter (UIpp) and RMS value (UIrms) ± or the number of Phase Hits (PH) during the test interval ± are the most important parameters. Table 1 shows the recommended interfaces for use dependent on the signal under test.

Step 1 Add the VIs required to the list of those used in the Application Manager. Step 2 Click on the ªJITº button (figure 3) in the Application Manager to open/activate the O.172 Jitter Generator/Analyzer window.

Figure 3 Application manager

Measurement setting Step 1 In the Mode menu, select either PP+RMS or PP+PH command for measuring jitter peak values and rms values or number of phase hits. The O.172 Jitter Generator/Analyzer window will open (figure 4).

Tx Network element Rx Jitter measurement ANT-20

Tx Network Rx Jitter measurement ANT-20

Figure 2 Output jitter measurement setup

Figure 4 O.172 Jitter Generator/Analyzer window showing output jitter results screen

3

Step 2 In the Settings menu, select the General ... command (figure 5).

Figure 5 O.172 jitter general settings dialog box

The root mean square (RMS) integration period can be set to measure RMS values via the Rx section (an integration period of 1 second is sufficient in most cases). The average function may be used to acquire a quieter, current display of the peak-to-peak indication. The Hit Threshold amplitudes allow the tolerable +/± peak levels, beyond which the unit detects phase hits, to be specified. Step 1 Start the measurement by pressing function key F5 or clicking the green traffic signal icon in the Application Manager. ITU-T G.783 ITU-T G.811 ITU-T G.812 ITU-T G.813 ITU-T G.823 ITU-T G.825 ANSI T1.105.03 ANSI T1.102 ANSI T1.101 Telcordia GR-253 Telcordia GR-499 ETSI EN 302 084 ETSI EN 300 462-3-1 ETSI EN 300 462-5-1 ETSI EN 300 462-6-1 ETSI EN 300 462-4-1 ETSI EN 300 462-7-1

Characteristics of SDH equipment functional blocks Timing characteristics of PRCs Timing requirements of SSU slave clocks Timing characteristics of SDH equipment slave clocks (SEC) Jitter and wander within networks based on 2048 kbps Jitter and wander within networks based on the SDH SONET-Jitter at network interfaces Digital Hierarchy- Electrical interfaces Synchronization interface standards for digital networks SONET transport systems common generic criteria Transport systems generic requirements The control of jitter and wander in transport networks The control of jitter and wander within synchronization networks Timing characteristics of slave clocks suitable for operations in SDH Timing characteristics of primary reference clocks Timing characteristics of slave clocks suitable for synchronization supply to SDH and PDH equipment Timing characteristics of slave clocks suitable for synchronization supply to equipment in local node applications

Table 2 List of recommendations for jitter generation (output jitter) measurements

4

Important ± Ensure the optical level lies between the ±10 and ±12 dBm range. ± Always use the lowest possible measurement range. ± Ensure the correct filter setting is being used. ± Allow a warm up time of at least 30 minutes.

Peak to Peak (UIpp) jitter For this procedure, the signal under test is connected to the receiver of the Acterna ANT-20 Advanced Network Tester. A measurement time of 60 seconds is recommended to produce an adequate output jitter result for the data signal under test. During the test interval, peak-topeak jitter (UIpp) is the important parameter. The distance between the highest and lowest jitter value is therefore refered to as as the jitter amplitude. Interpretation of results The test set determines the positive and negative values for a phase variation (leading and lagging edges) and the results updated continuously as Current Values. In addition to this, the Maximum Values occurring during a measurement interval are also recorded and displayed. Measured values should not exceed those recommended under ITU, ANSI, ETSI and Telcordia regarding requirements for network interfaces and equipment. Figure 6 shows a tabular view of an output jitter result.

Figure 6 Tabular view of output jitter result

The Jitter versus time screen provides a graphical display of the measured jitter values and records the +/± peak, peak-to-peak or RMS value of the jitter versus time (figure 7). This presentation format is particularly useful for long-term in-service monitoring and for troubleshooting.

!

Peak to peak view

!

! Figure 7 Graphical representation of output jitter result (jitter versus time)

Manual peak-peak correction method The manual correction method can be used for measuring very low jitter values to improve the accuracy of the measurement result. This is achieved by reducing the influence of intrinsic jitter caused by the ANT-20. If the value measured is in the range of the intrinsic jitter noise floor (intrinsic jitter approximately 4 - 30% of the measured result), it is recommended that the residual component caused by Rx be subtracted. Diagram 1 below outlines a potential method for reducing the influence of intrinsic jitter on a measurement result.

Step 1 Loop back the ANT-20 (connect TX output to RX input) Step 2 Set the appropriate signal structure ensuring the optical input levelis within the range expect at the DUT output. Step 3 Read the jitter result/value. In the example below, the value represents the total amount of intrinsic jitter ± Rx and Tx ± for the particular signal structure. 0.045 UIpp at OC-192 Step 4 As the actual TX portion is unkown the jitter value should be reduced by the typical Tx value of approximately 0.02 UIpp for OC-192. In this example, the factor C can be used as a correction value for subsequent DUT measurements. C = 0.045 UIpp ± 0.020 UIpp = 0.025 UIpp Step 5 Measure at DUT output. For example: 0.080 UIpp Step 6 Subtract the correction value for intrinsic jitter C from the result. In the example below, the value is a realistic estimation of the DUT output jitter for this indidual case. 0.080 UIpp ± C = 0.080 UIpp ± 0.025 UIpp = 0.055 UIpp IMPORTANT: If the measurement result of the DUT does not differ significantly from the intrinsic result, this may be an indication of correlation between the DUT and the intrinsic jitter. In this case, it is recommended not to apply the described correction method. Potential method for reducing the influence of intrinsic jitter on a measurement result.

RMS jitter To perform this measurement, the signal under test must be connected to the ANT-20s receiver. The RMS value of the jitter signal provides a clear indication of the jitter noise power. The significant parameter here is the RMS value (UIrms) during the test interval. 5

Interpretation of results The test set determines the RMS in UI and results are updated every second (GUI refresh time) according to the set integration period (figure 8). Measured values should not exceed those recommended under ITU, ANSI, ETSI and Telcordia regarding requirements for network interfaces and equipment.

Whereas peak values are momentary values, RMS values represent an indication of the jitter noise power during a certain integration period. The relation between RMS and peak to peak values is not fixed and depends on the time function of jitter. The relationship between noise-like signals that include small and high peak amplitudes in particular appear to be hightened when compared with the commonly known relationship of sinusoidal signals. The relationship of a typical jitter signal is described in equation 1 in which RMS jitter is defined for a integration period of T. ÐÐÐÐÐÐÐÐÐÐÐÐÐ

JRMS =

H 1T $[ j(t)] dt T

2

0

Equation 1

Here, the square root is calculated over the mean value of the squared signal. This procedure is illustrated in table 3 for a noise-like (random) jitter signal with small peaks of +1 UI. 1.50

Current RMS

1.00 Squared Signal

Figure 8 Tabular view of output jitter results ± RMS 0

The jitter versus time RMS presentation also illustrates the change in RMS value over the measurement time and records the +/± peak, peak-to-peak or RMS value of the jitter versus time. This presentation format is particularly useful for long-term in-service monitoring and for troubleshooting.

Jitteramplitude

0.50

0.00

0

20

40

60

80

Noise-like Jitter 2 UIpp

±0.50

±1.00

±1.50

Figure 10 RMS value of random jitter

!

RMS view

! Figure 9 Graphical representation of output jitter ± RMS

6

RMS 120 Value 0.25 UIrms

Integration Time T

RMS Value

!

100

p-p-Random

Time Square of Random

The red curve represents a jitter signal with a peak-peak amplitude of 2 UIpp. The squared signal is shown in yellow. The square root of the area below the yellow curve yields an RMS value (blue line) of approximately 0.25 UIrms. The relation between UIpp and UIrms in this example is 2 UIpp/0.25 UIrms = 8. Practical experience has shown that such relationships lie predominantly between 5 and 10 for noise-like jitter. The same calculation can also be made with a typical sinusoidal jitter test signal. Assuming an amplitude of 2.0 UIpp ± leading to a squared signal of 1.0 UIpp ± the square root of the area below the 1.0 UIpp squared amplitude curve would yield an RMS value (blue line) of approximately 0.71 UIrms. The relation between UIpp and UIrms in this б example is 26H2 , which equals 2.83.

Phase hit measurement Phase hits occur when a definable jitter +/± peak threshold is exceeded. Events of this kind are recorded using a counter. The current counter reading indicates how often the phase hit threshold has been exceeded from the time measurement commenced. Both positive and negative counts can be monitored with the ANT-20 Jitter Analyzer. A phase hit measurement records how often the tolerable jitter amplitudes (adjustable +/± limits) are exceeded. Based on a count of phase hits (PH), the user is able to better assess the jitter behavior.

Mapping jitter measurement Mapping jitter is jitter caused by the mapping processes in synchronous network elements (NE). Bit stream gaps caused by the bit stuffing procedure lead to variations in the plesiochronous tributary signal. Phase locked loop (PLL) circuits used in the desynchronizer of NEs are help to smooth out the phase steps. Remaining phase modulation is observed as mapping jitter at the PDH interfaces. In order to test mapping jitter, the ANT-20 transmits a plesiochronous signal to the tributary interface of the DUT in the event of full channel measurement (figure 12). This signal is then mapped into a synchronous signal structure, demapped and fed into the measurement instrument that thenchecks for phase modulation. Once this measurement setup has been established, the offset of the transmitted signal must be tuned to allow for the highest amount of jitter to be measured on the receiver side. Additional pointer actions can lead to additional amounts of jitter. Therefore, it is essential that both the measurement instrument and DUT are synchronized to the same reference clock. REF Ref. clock in [25]

Offset variation W E ADM S T

ANT-20

E STM-N loop A S T E1 tributaries

Jitter measurement

E1 E1

Figure 12 Analysis of mapping jitter at tributary ouputs ± full channel measurement

Display of current threshold transgression count Phase hit measurement is interrupted and counters stopped if either the synchronization or AC line supply fails. Counting resumes once the instrument resynchronizes itself after the interruption.

Figure 11 Output jitter result screen illustrating phase hits

The yellow warning icon indicates an interruption in the measurement.

The jitter vs. time +/± peak presentation is also able to illustrate the distribution characteristics of phase hits (homogenously or in bursts) over the measurement time. 7

Table 3 outlines the interfaces recommended for use in full and half channel measurements.

Bit rate (kbps) 1 544

Full channel measurement electrical bal. 1.5 to 2 Mbps Rx [12], Tx [13] electrical unbal. 1.5 to 155 Mbps Rx [14], Tx [15] ref. clock in [25] 1.5/2 Mpbs, 1.5/2 MHz Half channel measurement, additional electrical 155 Mbps Tx [15] electrical 2.5 Gbps Tx [46] electrical 10 Gbps Tx [104] optical 52, 155, 622 Mbps Tx [18] optical 2.5 Gbps Tx [47] optical 10 Gbps Rx Tx [103]

2 048

6 312 34 368 44 736 139 264

Table 3 Recommended interfaces dependent on signal under test

Jitter measurement bandwidth Measurement mode High pass filter W 10 Hz H 8 kHz W 20 Hz H1 (only for certain 700 Hz national use) H2 18 kHz W 10 Hz H 3 kHz W 100 Hz H 10 kHz W 10 Hz H 30 kHz W 200 Hz H 10 kHz

Low pass filter 40 kHz 40 kHz 100 kHz 100 kHz 100 kHz 60 kHz 60 kHz 800 kHz 800 kHz 400 kHz 400 kHz 3.5 MHz 3.5 MHz

Table 4 Mapping jitter measurement bandwidth

Instrument and application setup Virtual instruments (VI) required ± Signal structure ± O.172 Jitter Generator/Analyzer Measurement setting To set the clock source, the ANT-20 must be set to an external clock source to to avoid unforeseen pointer adjustments and wander activities in addition to the set signal offset. Step 1 Select Settings... in the Interface menu in the Signal Structure VI. Step 2 Select the external reference source format to be used for interface [25] within the Clock Source dialog box (1.5 Mbps, 2 Mbps, 1.5 MHz, or 2 MHz are supported). When setting the measurement bandwidth, different jitter weighting filter combinations are used depending on the bit rate (figure 12). For each particular measurement, a wide band (W) and a high band (H) filter combination of high-pass and low-pass filters are specified (table 4).

When setting the mapping offset range, mapping jitter measurements need to generate SONET/SDH signals with different bit rate offsets in the mapped payload signal. To obtain the maximum mapping jitter, the mapping offset should be varied in the entire allowed offset range of a particular bitrate. The measurement must then be repeated with varying offset values to determine the worst case offset. This variation must however be within the values permitted in accordance recommendation G.783. Table 5 provides an overview of the permissable payload mapping offset ranges. Bit rate (kbps) 1 544 2 048 6 312 34 368 44 736 139 264

Max. mapping offset range (ppm) +50 +50 +33 +20 +20 +15

Proposed mapping offset step width (ppm) 5 5 3 2 2 1

Table 5 Permitted payload mapping offset ranges

Figure 14 Signal structure ± Tx offset

Figure 13 Filter bandwidth settings

8

Interpretation of results The maximum peak to peak results are important when judging the mapping jitter behavior of the DUT. The most important results for the mapping jitter measurement are the peak to peak values measured with the worst case offset and the correct filter settings (figure 15).

Combined (pointer) jitter measurement

Figure 15 Mapping jitter results

The ITU-T, ANSI, ETSI and Telcordia standards define the maximum peak to peak jitter values caused by mapping jitter (table 6). Table 8 outlines recommendations covering mapping jitter measurements. Bit rate (kbps)

1 544

Jitter Maximum peak-to-peak mapping jitter (UIpp) measurement bandwidth ITU-T ANSI ETSI Telcordia G.783 T1.105.03 EN 300417-1-1 GR-253 W * 0.7 * 0.7 H 0.1 * -

2 048

W H

* 0.075

n.a. n.a.

* 0.075

n.a. n.a.

6 312

W H

* 0.1

1.0 -

n.a. n.a.

-

34 368

W H

* 0.075

n.a. n.a.

* 0.075

n.a. n.a.

44 736

W H

0.4 0.1

0.4 -

* *

0.4 -

139 264

W H

* n.a. 0.075 n.a. (proposed)

* 0.075

n.a. n.a.

* = for further study ** = Pointer sequence C n.a. = not applicable Table 6 Maximum peak-to-peak mapping jitter as defined by ITU-T, ANSI, ETSI and Telcordia

Important ± Always use the lowest possible measurement range. ± Ensure the correct filter settings and the worst case offset on the tributary Tx side are being used. ± Ensure a warm up time of at least 30 minutes. ITU-T G.783 ANSI T1.105.03 Telcordia GR-253 ETSI EN 300 417-1-1

Characteristics of SDH equipment functional blocks SONET jitter at network interfaces SONET transport systems common generic criteria Definitions and terminology for synchronization networks

Table 7 List of recommendations for XXX mapping jitter measurements

Jitter generated by the simultanous occurance of two effects ± mapping jitter and pointer jitter ± is refered to as combined jitter. In addition to the mapping effect, pointer action can also cause phase jumps on the tributary side. To simulate and measure combined jitter, the DUT must be stimulated with defined pointer sequences together with the worst case offset on the plesiochronous payload of the SONET/SDH signal. This signal is then applied to a synchronous signal, demapped and measured at the tributary output by the jitter measurement instrument (figure 16). Combined jitter only occurs at the tributary interfaces of SONET and SDH NEs. Table 8 outlines the interfaces recommended for use with signals under test. REF [25] Pointer simulation (+ offset variation) STM-N including E1

ANT-20

Jitter measurement

E1

W E S T

ADM

E STM-N loop A S T

E1 tributaries

Figure 16 Combined (pointer) jitter measurement setup

Data Tx/Rx electrical bal. electrical unbal. electrical unbal. electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12], Tx [13] 1.5 to 155 Mbps Rx [14] 155 Mpbs Tx [15] 2.5 Gbps Tx [46] 10 Gbps Tx [104] 52, 155, 622 Mbps Tx [18] 2.5 Gbps Tx [47] 10 Gbps Tx [103]

Reference clock TX ref. clock in [25] Table 8 Recommended interfaces for signal under test

Instrument and application setup Combined jitter measurement must be carried out under worst case conditions, that is with the offset on the tributary signal ± within recommended values ± generating the highest jitter. The offset causing the highest jitter on the tributary side must first be determined in accordance with the steps set out in chapter 1.3 Mapping jitter measurement. The measurement time should be 60 seconds or at least the length of the pointer sequence used. Virtual Instruments (VI) required ± Signal structure ± O.172 Jitter Generator/Analyzer ± Pointer generator ± PDH generator 9

To set the transmitter, the various signal structures for the interfaces at Rx and Tx must also be set as appropriate. Combined (pointer) jitter measurement is performed via half channel measurement. Figure 17 illustrates the effects of an E1 PDH signal connected to Rx OC-192 Tx, and a signal that has been fed into a DUT.

The most important results in combined (pointer) jitter measurement are the peak to peak values measured with the appropriate filter settings. Different jitter weighting filter combinations are used depending on the bit rate. For each particular measurement, a wide band (W) and a high band (H) filter combination of high pass and low pass filters are specified (table 8). Bit rate (kbps) 1 544 2 048

Fig 17 Signal structure for combined (pointer) jitter measurement

In order to set the clock source, the ANT-20 must be synchronized to an external clock/data signal to avoid unforeseen pointer adjustments and wander activities in addition to the set pointer sequence.

6 312

Step 1 Select Settings... in the Interface menu in the Signal Structure VI. Step 2 Select the external reference source format to be used for interface [25] within the Clock Source dialog box (1.5 Mbps, 2 Mbps, 1.5 MHz, or 2 MHz are supported). Step 3 The worst case mapping jitter offset should then be determined as described under: Chapter 1.3 Mapping jitter measurement

139 264

Combined jitter measurement results should include both, mapping jitter and pointer jitter. It is therefore advantageous to first evaluate the mapping offset value for which the maximum mapping jitter is obtained (figure 18).

34 368 44 736

Jitter measurement bandwidth Measurement mode High pass filter W 10 Hz H 8 kHz W 20 Hz H1 (only for certain 700 Hz national use) H2 18 kHz W 10 Hz H 3 kHz W 100 Hz H 10 kHz W 10 Hz H 30 kHz W 200 Hz H 10 kHz

Low pass filter 40 kHz 40 kHz 100 kHz 100 kHz 100 kHz 60 kHz 60 kHz 800 kHz 800 kHz 400 kHz 400 kHz 3.5 MHz 3.5 MHz

Table 8 Jitter measurement bandwidth (G.783, GR-253, EN 300 417-1-1)

As part of step 2, the combined (pointer) jitter measurement should then be performed to should include the worst case mapping offset as well as additional introduced pointer sequences. ITU-T, ANSI, ETSI and Telcordia standards specify the various pointer sequences for each tributary bit rate. Table 9 gives an overview of the pointer sequence types required in accordance with ITU-T recommendations O.172 and G.783. The equivalent recommendations from ITU-T, ANSI, Telcordia and ETSI can be found in table 10. G.783 Pointer test sequence SDH tributary bit rate (kbps) and SDH unit 1 544 2 048 6 312 34 368 44 736 139 264 ID Description TU-11 TU-12 TU-2 TU-3 AU-3 AU-4 a Single alternating X X X b Regular + double X X X c Regular + missing X X X d Double alternating X X e Single X X X f Burst X X X g1 Periodic 87-3 X X g2 Periodic 87-3 with add X X g3 Periodic 87-3 with cancel X X h1 Periodic X X X h2 Periodic with add X X X h3 Periodic with cancel X X X Table 9 G.783 Pointer test sequence types

Figure 18 PDH offset settings

10

Pointer sequence

ITU-T G.783 Fig. 10-2 Single alternating a Regular + double b Regular + missing c Double alternating d Single e Burst f Phase transient burst fp Periodic 87-3 g1 Periodic 87-3 with add g2 Periodic 87-3 g3 with cancel Periodic h1 Periodic with add h2 Periodic with cancel h3

ANSI T1.105.03 ± ± ± ± A1 (Fig.2) A2 (Fig.3) A3 (Fig.4) A4 (Fig.5b) A5 (Fig.5c) A5 (Fig.5d)

Telcordia GR-253 ± ± ± ± Fig. 5-29 Fig. 5-30 Fig. 5-31 Fig. 5-33 b Fig. 5-33 c Fig. 5-33 d

A4 (Fig.6b) A5 (Fig.6c) A5 (Fig.6d)

Fig. 5-34 b Fig. 5-34 c Fig. 5-34 d

ETSI EN 300 417-1-1 B D E C ± ± ± ± ± ± ± (D) (E)

Table 10 Pointer test sequences as defined by ITU-T, ANSI, Telcordia and ETSI

Pointer sequence test procedure Complete test sequences for specific bitrate and pointer sequence consist of several defined periods. In order to prime the pointer processor and prepare the equipment for the test sequence, initialization and cool-down periods must be applied prior to starting the measuring procedure.

Initialization 60 s

Cool-down 41 period

Measurement 460 s or 41 period

Cool-down period After the initialization period and in the case of single and burst pointer tests, it is recommended that a 30-second cool-down period be allowed where no pointer activity is present in the test signal. For periodic test sequences (both continuous and gapped) a 30-second cool-down period is recommended during which the periodic sequence is applied so that a steady state condition is maintained. If necessary, the period should be extended to include an integral number of complete sequences. Measurement period During the measurement period, the jitter of the tributary output is measured for the recommended 60 seconds. If necessary, the period can be extended to include at least one complete pointer test sequence. In general two consecutive measuring periods are required, one for wide-band jitter and one for high-band jitter. The result at the end of the measuring period is the maximum peak-peak jitter. Selecting the pointer sequence The Pointer Generator enables the generation of test sequences in accordance with ITU-T G.783 and ANSI T1.105.03 for AU/STS or TU/VT pointers. Both pointers can be generated simultaneously or independently of each other.

time INC

87-3 INC

87-3 INC

87-3 INC

time

The time parameters are related to the ANT-20 settings of the Pointer Generator VI. Table 11 shows the default values for each pointer test sequence and the corresponding range requirement.

Figure 19 Example pointer procedure for 87-3 INC periodic test sequence

Initialization period To ensure that jitter on the demultiplexed tributary signal is nevertheless affected in the event of single and burst sequences, it is important that pointer movements are not absorbed by the pointer processor. With periodic sequences, the pointer processor must be in the same steady-state condition it would be in if continual pointer movements had always been present. For single and burst test sequences, the initialization period should consist of pointer adjustments applied at a rate higher than that of the test sequence but lower than 3 pointer adjustments per second in the same direction as the subsequent test sequence. The initialization period should last at least until a response is detected in the jitter measured on the demultiplexed tributary signal. For this purpose it is recommended that a 60 second initialization period be used.

11

Pointer sequence

ID

ANT-20 setting Single alternating ªINC/DECº Regular + double ªINCº or ªDECº Regular + missing ªINCº or ªDECº Double alternating ªINC/DECº Single ªINCº or ªDECº Burst ªINCª or ªDECª Phase transient burst ªINCº or ªDECº Periodic 87-3 ª87-3 Incº or ª87-3 Decº Periodic 87-3 with add ª43-44 Incº or ª43-44 Decº Periodic 87-3 with cancel ª86-4 Incº or ª86-4 Decº Periodic ªINCº or ªDECº Periodic with add ªINCº or ªDECº Periodic with cancel ªINCº or ªDECº

b

ANT-20 parameters Default values Proposed ranges n T1 1 10 s 0.75 ... 30 s 40 n.a.

c

40

n.a.

d

2

e

1

10 s 0.75 ... 30 s n.a.

f

3

n.a.

fp

6

n.a.

g1

n.a.

n.a.

g2

n.a.

n.a.

g3

n.a.

n.a.

h1

1

n.a.

h2

1000

n.a.

h3

1000

n.a.

a

T2 n.a.

T3 n.a.

0.75 s 34 ms ... 10 s 0.75 s 34 ms ... 10 s 0.5 ms 0.5 ms ... 1 s n.a.

2 ms 0.5 ms ... 1 s n.a.

2 ms 0.5 ms ... 1 s 0.5 s 0.1 ... 1 s 34 ms 34 ms ... 10 s 34 ms 34 ms ... 10 s 34 ms 34 ms ... 10 s n.a.

n.a.

34 ms 34 ms ... 10 s 34 ms 34 ms ... 10 s

0.5 ms 0.5 ... 2 ms n.a.

n.a. n.a.

0.25 s (T2/2) 0.05 ... 0.5 s n.a. 0.5 ms 0.5 ... 2 ms n.a. n.a.

T4 20 s (2 x T1) 1.5 ... 60 s 30 s (40 x T2) 10 s ... 60 s 30 s (40 x T2) 10 s ... 60 s 20 s (2 x T1) 1.5 ... 60 s 30 s 10 s ... 60 s 30 s 10 s ... 60 s 30 s 10 s ... 60 s 3.06 s (90 x T2) 3.06.. 900 s 3.06 s (90 x T2) 3.06 ... 900 s 3.06 s (90 x T2) 3.06 ... 900 s 1s 34 ms ... 10 s 34 s (1000 x T2) 30 s ... 60s 34 s (1000 x T2) 30 s ... 60 s

Table 11 ANT-20 time parameter settings ± default values and ranges

For some time parameter settings, fixed relations are preconfigured in the ANT- 20. These relations or conditions are listed in table 12. Pointer sequence a b c d fp g1 g2 g3 h2 h3

Relations and conditions between time parameter settings T1 given: T4 = 2 x T1 T2 and T4 given: n = T4/T2, where n = Integer, T3 5T2 T2 and T4 given: n = T4/T2, where n = Integer, T5 = T4/2 T1 given: T4 = 2 x T1, T2 5 5T1 T2 and T4 given: T3 = T2/2, T2 5 5T4 T2 given: T4 = 90 x T2 T2 given: T4 = 90 x T2, T3 5T2 T2 given: T4 = 90 x T2 T2 and T4 given: n = T4/T2, where n = Integer, T3 5T2 T2 and T4 given: n = T4/T2, where n = Integer, T5 = T4/2

Table 12 Relations and conditions between time parameter settings

Instrument and application set-up Step 1 Click the STS/AU button in the toolbar. Step 2 Select 87/3 INC from the STS/AU Pointer box. Step 3 Set the distance between the two pointer actions in the T2 entry box. Step 4 Set the desired sequence length in the Mode box and select whether single sequence or continuous repetition (T4) should be used. Step 5 Click on the AU/STS ON button to activate the pointer sequence. Step 6 Start the measurement by pressing F5 or by clicking the green traffic light signal in the Application Manager 12

Figure 20 Example periodic 87-3 pointer sequence

T5 n.a. n.a. 15 s (20 x T2) 5 s ... 30 s n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 17 s (500 x T2) 15 ... 30 s

Interpretation of results The peak to peak results are necessary to evaluate the combined (pointer) jitter behaviour of the DUT. The maximum peak to peak jitter values caused by combined jitter are defined by standards bodies including ITU-T, ANSI, ETSI and Telcordia (Table 13). Bit rate (kbps)

1 544

Jitter Maximum peak-to-peak mapping jitter (UIpp) measurement bandwidth ITU-T ANSI ETSI Telcordia G.783 T1.105.03 EN 300417-1-1 GR-253 W 1.5 1.3 * 0.7 (1.9 ****) H * * -

2 048

W H

0.4 0.075

n.a. n.a.

0.4 0.075

n.a. n.a.

6 312

W H

1.5 *

* -

n.a. n.a.

-

34 368

W

0.4 (0.75 **)

n.a.

H

0.4 n.a. (0.75 ***) 0.075 n.a.

0.075

n.a.

44 736

W H

* *

* *

0.4 -

139 264

W

0.4 n.a. (proposed) 0.075 n.a. (proposed)

0.4 (0.75 **)

n.a.

0.075

n.a.

H

1.3 -

* = for further study ** = Pointer sequence C (EN 300 417-1-1) *** = Pointer sequence d (G.783) **** = Pointer sequence A5 (T1.105.03) n.a. = not applicable Table 13 Maximum peak-to-peak combined jitter

Important ± Always use the lowest possible measurement range. ± Make sure the correct filter settings and worst case payload offset on the Tx side are selected ± Apply the required pointer sequence ± Ensure a warm up time of 30 minutes. ITU-T G.783 ANSI T1.105.03 Telcordia GR-253 ETSI EN 300 417-1-1

Characteristics of SDH equipment functional blocks SONET Jitter at network interfaces SONET transport systems common generic criteria Definitions and terminology for synchronization networks

Table 14 List of Recommendations XXX for combined (pointer) jitter measurement

Maximum tolerable jitter (MTJ) Maximum tolerable jitter measurement is used to determine the jitter amplitude on electrical and optical line and tributary inputs which causes errors and alarms. Here, the ANT transmits a specific test pattern with sinusoidal jitter at a defined frequency (figure 21). The jitter amplitude of this signal is increased with a half interval progression until errors occur at the output of the DUT. This amplitude is the MTJ result for the defined frequency. This measurement is repeated for different frequencies with results used to form the MTJ graph. Table 15 lists the interfaces for use dependent on the signal under test.

Jitter stimulation Tx

Network element

Rx Error detection ANT-20

Figure 21 Maximum tolerable jitter set

Data Tx/Rx electrical bal. electrical unbal. electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12], Tx [13] 1.5 to 155 Mbps Rx [14], Tx [15] 2.5 Gbps Rx [43], Tx [46] 10 Gbps Rx [114], Tx [104] 52, 155, 622 Mbps Rx [17], Tx [18] 2.5 Gbps Rx [44], Tx [47] 10 Gbps Rx [113], Tx [103]

Table 15 Recommended interfaces for useage depending on signal under test

Instrument and application setup Virtual instruments (VI) required ± Signal structure ± O.172 Jitter Generator/Analyzer MTJ measurements must be performed under worst case or 1dB optical penalty conditions as described in G.823, GR-253 or T1.105.03. Here, the DUT receiver should function with a level 1 dB that is higher than the sensitivity limit. An adjustable attenuator is inserted between the output (Tx) of the test set and the input (Rx) of the DUT. The optical level is set so that a limit bit error rate of for example 1±10 is obtained. As an example, at 10 Gbps this BER corresponds to one bit error per second. When the level is increased by 1 dB, bit errors should not occur. The MTJ measurement is most commonly performed with an error threshold of 1 (TSE) and a gate time of 1 s. Appendix III of G.823 states that ª...The attenuation function is needed for optical interfaces to be able to determine the 1 dB sensitivity penalty (in terms of optical power) at a certain bit error ratio.º 13

Measurement settings Follow the steps below using the O.172 Jitter Generator/ Analyzer VI. Step 1 Select the MTJ command in the Mode menu, or click on the corresponding button in the toolbar. Step 2 Select the error source in the Error Source list field to be counted during the gate time. Step 3 Enter the error threshold in the Error Threshold field. This field provides a decision criterion for the MTJ algorithm. Step 4 In the Settling Time field, enter a delay for each measurement to allow the DUT to settle on the jittered signal before measurement (error count) commences. Step 5 Enter the required gate time in the Gate Time box for the test intervals. Step 6 In the Settings menu select MTJ or click on the SET symbol.

Important ± Check that the instrument is set to the correct wavelength. ± Assure matching optical input power levels according to the 1 dB penalty approach. Interpretation of results Results can be generated in table (figure 23) or graphic (figure 24) format.

Figure 22 MTJ Settings dialog box

These steps will open the Settings dialog box that contains both the measurement frequencies for MTJ measurement and the characteristic data for the tolerance mask (figure 22). Step 7 Predefinesd setting can be used or, if necessary, scan frequencies selected and the tolerance mask values modified according to individual test needs needs. Step 8 Confirm the input with OK. Step 9 Press Start to commence measurement. Although measurement stops automatically, it can be halted at any time by clicking on Stop.

14

Figures 23 and 24 Maximum tolerable jitter result screen

Table format ± Measurement results are displayed in the table under UI. ± Measurement results ± where tolerable jitter of the DUT is greater than the maximum amplitude that can be set on the jitter generator ± are indicated by the greater than sign (4), for example 464 UI. ± Measurement results that are below the tolerance mask are marked with an exclamation mark (!) in the table. Graphic format ± Measurement results are marked with a ª+º on the graphics. ± Measurement results where the tolerable jitter of the DUT is greater than the maximum amplitude that can be set on the jitter generator are marked with ª~º on the graphics (instead of the ª+º). ITU-T G.823 ITU-T G.824 ITU-T G.825 ANSI T1.105.03 Telcordia GR-253 Telcordia GR-499 ETSI EN 302 084

Jitter and Wander within networks based on 2048 kbps Jitter and Wander within networks based on 1544 kbps Jitter and Wander within networks based on the SDH SONET jitter at network interfaces SONET transport systems common generic criteria Transport systems generic requirements The control of jitter and wander in transport networks

Table 16 List of Recommendations for MTJ measurements

Instrument and application setup Virtual Instruments (VI) required ± Signal structure ± O.172 Jitter Generator/Analyzer It is recommended that FMTJ measurement be performed under worst case condition or, 1 dB optical penalty as it is refered to. In this case, the receiver of the DUT should work with a level 1 dB higher than the sensitivity limit. An adjustable attenuator is inserted between the output (Tx) of the test set and the input (Rx) of the DUT as illustrated in figure 25. The optical level is set so that a limit bit error rate of for example 1 ±10 is obtained. As an example, at 10 Gbps this BER corresponds to one bit error per second. When the level is increased by 1 dB, bit errors should not occur. Measurement Settings Follow the steps below using the O.172 Jitter Generator/ Analyzer VI. Step 1 Select the Fast MTJ command in the Mode menu or click on the corresponding button in the tool bar (figure 26).

Fast maximum tolerable jitter For Fast MTJ (FMTJ) measurements, given combinations of jitter frequencies and jitter amplitudes that lie on the limit curves as defined in standards, can be set on the jitter generator. Each measurement point is classified as either ªOKº or ªFailedº thus indicating whether the DUT has met the limit curve. Table 17 lists the interfaces to be used dependent on the signal under test.

Jitter stimulation Tx

Network element

Rx Error detection ANT-20

Figure 25 FMTJ setup

Data Tx/Rx electrical bal. electrical unbal. electrical electrical optical optical optical

Figure 26 FMTJ measurement VI

1.5 to 2 Mbps Rx [12], Tx [13] 1.5 to 155 Mbps Rx [14], Tx [15] 2.5 Gbps Rx [43], Tx [46] 10 Gbps Rx [114], Tx [104] 52, 155, 622 Mbps Rx [17], Tx [18] 2.5 Gbps Rx [44], Tx [47] 10 Gbps Rx [113], Tx [103]

Table 17 Recommended interfaces for useage depending on signal under test

Step 2 Select the error source in the Error Source list field to be counted during the gate time. Step 3 In the Error Threshold field, enter the error threshold above which the DUT would be considered as having failed the test. An error threshold cannot be entered if an alarm is selected from the Error Source list box.

15

Important ± Check that the instrument is set to the correct wavelength. ± Assure matching optical input power level in accordance with the 1 dB penalty approach. Interpretation of results Each setting, respective of the measurement, is classified as OK or Failed (figure 28). Table 18 lists the Recommendations for FMTJ measurements.

Figure 27 FMTJ settings dialog box

Step 3 In the Settling Time field, enter a delay for each measurement to allow the DUT to settle on the jittered signal before measurement (error count) commences. Step 4 In the Settings menu, select MTJ or click on the SET icon (figure 27). Step 5 If required, select individual frequency and amplitude combinations or use the predefined recommendations for performing the measurement. Step 6 Confirm entries by clicking OK. Step 7 Click Start to commence measurement. Measurement will stop automatically on completion or when the Stop icon is clicked.

ITU-T G.823 ITU-T G.824 ITU-T G.825 ANSI T1.105.03 Telcordia GR-253 Telcordia GR-499 ETSI EN 302 084

Jitter and Wander within networks based on 2048 kbps Jitter and Wander within networks based on 1544 kbps Jitter and Wander within networks based on the SDH SONET jitter at network interfaces SONET transport systems common generic criteria Transport systems generic requirements The control of jitter and wander in transport networks

Table 18 List of Recommendations for FMTJ measurements

Jitter transfer function (JTF) Jitter transfer function (JTF) measurements are of particular importance when dealing with regenerators (equation 2). Checks are carried out to demonstrate that the jitter gain of a regenerator is below a predefined value and attenuated above a defined cut-off frequency. If this is not the case, jitter accumulation occurs after several regenerators. JTF is measured by applying a signal with jitter that is constant over frequency or adjusted to the maximum tolerable jitter (MTJ). The jitter analyzer measures the resulting jitter amplitude at the output of the DUT at various TX jitter frequencies (figure 29). The log of the ratio gives the jitter gain or attenuation. For maximum measurement accuracy a calibration measurement is necessary and recommended. Table 19 lists the interfaces to be used dependent on the signal under test. Jitter transfer function:

H (f) = 20 log

output jitter input jitter

Equation 2 Tx 2 1

ANT-20

Figure 28 FMTJ result screen

16

DUT

Rx

Figure 29 Jitter transfer measurement setup

1. Calibration measurement 2. Measurement with DUT

Data Tx/Rx electrical bal. electrical unbal. electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12], Tx [13] 1.5 to 155 Mbps Rx [14], Tx [15] 2.5 Gbps Rx [43], Tx [46] 10 Gbps Rx [114], Tx [104] 52, 155, 622 Mbps Rx [17], Tx [18] 2.5 Gbps Rx [44], Tx [47] 10 Gbps Rx [113], Tx [103]

Table 19 Recommended interfaces for useage depending on signal under test

Instrument and application setup Virtual Instruments (VI) required ± Signal structure ± O.172 Jitter Generator/Analyzer Measurement Settings Follow the steps below using the O.172 Jitter Generator/ Analyzer VI Step 1 Select JTF in the Mode menu or click on the corresponding button in the tool bar (figure 30).

Figure 31 JTF settings dialog box

Step 5 To use the results of a previous MTJ measurement for scan frequencies and amplitudes, click the MTJ Adaptation button. The MTJ results are then automatically matched to the permissible ranges (measurement and frequency) of the jitter meter. If no MTJ results available, the button is grayed out. Step 6 Select whether single calibration measurement (internally stored), or calibration measurement before every JTF measurement are required. For maximum measurement accuracy, calibration measurement should be carried out before every JTF measurement. Step 7 Click Start to commence measurement. Measurement will stop automatically on completion or when the Stop icon is clicked. Interpretation of results Measurement results are displayed in two separate windows. The default values for the scan frequencies and the tolerance masks in the JTF-Settings window are set in the window with the table display (figure 32).

Figure 30 JTF measurement VI

Step 2 In the Settling Time field, enter an appropriate settling time for the various measurements steps so that analysis starts once the DUT has settled. Step 3 Use the predefined settings or click on the Set button to individually confirm the scan frequencies and amplitudes (figure 31). Step 4 To perform measurements using a constant amplitude for all scan frequencies, mark the Fixed Amplitude check box and enter the required amplitude in the box below it.

For example: ANT-20 looped Mask exceeded!

Figure 32 JTF result screen ± table format

17

Default values are dependent on bit rate and change automatically when the bit rate is altered. Measurement results are displayed in the table under dB. Measurement results that are below the tolerance mask are marked with an exclamation mark (!) in the table. Measurement values are indicated in the graph by a plus (+) character. See table 20 for a full list of recommendations for jitter transfer function measurements.

++++++++++++++

+

For example: ª+º ANT-20 looped ª+º DUT connected Note: Only one result can be shown!

Wander measurement Measuring Wander Wander test equipment requires extremely precise external reference clock sources. The same input jacks are used for the signal under test as with other ANT-20 measurements such as anomaly/defect analysis or performance and pointer tests making it possible to perform these measurements in parallel on all relevant interfaces. The wander reference clock has a separate jack and can accept clock signals at 1.5 MHz, 2 MHz, 5 MHz and 10 MHz as well as data signals with bit rates of 1.5 Mbps and 2 Mbps (figure 34). Unlike jitter results which are given in UI, TIE values are given as absolute values in seconds (s) or nano seconds (ns). In addition to this, the extremely low frequency components in the mHz/mHz range require test times of up to several hours or days.

+

+

TIE

+

+

DUT

REF ANT-20

Figure 33 JTF result screen ± graph format

Important ± Set the instrument to the correct wavelength. ± Make sure that the optical level is in the range between ±10 and ±12 dBm. ± Ensure a warm up time of 30 minutes. ITU-T G.705 ITU-T G.783 ANSI T1.105.03 Telcordia GR-253 Telcordia GR-499

Characteristics of PDH equipment functional blocks Characteristics of SDH equipment functional blocks SONET jitter at network interfaces SONET transport systems common generic criteria Transport systems generic requirements

time

Figure 34 Basic principle of wander measurement

The time interval error (TIE) value represents the time deviation of a clock/data signal under test relative to the reference source (figure 35). TIE measurement forms the basis for further maximum time interval error/time deviation (MTIE/TDEV) calculations.

TIE

Table 20 List of recommendations for jitter transfer function measurements

TIE

Observation Intervals Test period T

Figure 35 Determining TIE value

18

time (t)

Instrument setup and application settings Instrument and application setup Virtual Intruments (VI) required ± Signal structure ± O.172 Jitter Generator/Analyzer ± Pointer Generator (for pointer wander measurement only) Step 1 Add the VIs required to the list of those used in the Application Manager (figure 35). Step 2 Click on the JIT button to open/change to the O.172 Jitter Generator/Analyzer window.

Figure 36 Application Manager

Step 3 To define the TIE measurement setting, select TIE in the Mode menu. The wander display (TIE vs. Time) will appear in the O.172 Jitter Generator/Analyzer window.

Figure 39 Measurement settings dialog box

Step 4 In the Settings menu select TIE and configure the instrument in accordance with the references. Then set the connector to be used and the frequency or bit rate of the reference signal.

!

Current MTIE * and TIE values * max. TIE value in reference to the observed measurement time

!

!

Figure 37 TIE result screen

Different connectors are used dependent on the different bitrates at the measurement interface. These include: Up to 622 Mbps ± BAL [34] or UNBAL [35] 2488 Mbps ± UNBAL [54] 9953 Mbps ± BAL [121] or UNBAL [122]

Figure 38 Wander Settings dialog box

Step 5 Select the sample rate required. The low-pass filter is set automatically. For most cases a sampling rate of 30 samples per seconds is recommended. Step 6 Click OK to confirm. Step 7 To set the measurement time, click on the Aplication Manager and choose Measurement Settings from the menu (figure 39). Then set the appropriate measurement time in the gate time window. 19

Step 8 Press the function key F5 or click the green traffic signal icon in the Application Manager to commence measurement. Important ± For reliable results the accuracy of the measurement reference clock should be approximately ten times as accurate as the accuracy of the DUT. ± Ensure the optical level is between the range of ±10 and ±12 dBm when measuring optical signals. ± Ensure the recommended sampling rate is being used. ± Allow a warm up time of 30 minutes. ± It is recommended that a short term measurement be carried out prior to any very long term measurements to prevent ineffective use of measuring time through offset and mask exceed failures for example.

line with recommendations outlined in ETSI EN 300462, EN 302084, ITU-T G.811, G.812, G.813 and ANSI. Instrument application and setup Step 1 Starting the MTIE/TDEV Analysis program from the O.172 Jitter Generator/Analyzer VI. After displaying the TIE results the MTIE/TDEV software can be directly initiated by pressing the TDEV button in the TIE measurement window. Results of the TIE measurement are automatically loaded. Step 2 Click on the MTIE/TDEV button. The MTIE/TDEV analysis software will open and display the TIE graph (figure 40). Step 3 Click the MTIE/TDEV button in this window to enable TDEV if required. The values will then be calculated and displayed. A range of pre-defined tolerance masks from the Masks list box can be selected. They can be used to give a quick overview of whether the measured values meet the tolerance requirements. Step 4 Click on Analysis to display the measurement results are displayed together with the selected masks. Possible evaluations The check boxes at the lower left of the MTIE analysis window can be used to select the values for display (Zoom Marker functionality. The displayed graph can be printed out and MTIE/TDEV results exported in CSV file format via the Export menu (figure 41).

Figure 40 TIE analysis screen ± MTIE/TDEV offline software

MTIE/TDEV offline wander analysis The MTIE/TDEV Offline Analysis software provides precise time domain analysis of MTIE and TDEV with reference to the captured TIE vs. Time graph. The program evaluates TIE values measured using the Acterna ANT-20 test set, includes the mask for a variety of signal sources and is in

Storing results To store results, the Export menu must be selected followed by either MTIE or TDEV. This will open the Save As dialog box. The target directory must then be chosen and the CSV format set to ensure interoperability with calculation ore spreadsheet software such as Microsoftâ Excel. Click Save to start the export process.

!

MTIE values

!

TDEV values Selection of

20

!

!

Figure 41 MTIE analysis result screen

Passed/Failed indication

Interpretation of MTIE/TDEV results MTIE and TDEV may yield different results depending on the type of interference signal (table 21). As well as the obvious effects due to frequency offset and drift, the typical noise processes encountered in oscillators are also listed. As the table shows, the MTIE calculation is the only method described that can detect the important (and frequently occurring) case of frequency offset. The TDEV calculation also gives information about frequency drift or oscillator noise. If, for example, the slope of the TDEV curve corresponds to the square root of s, this would indicate phase modulation with white noise. Buffers are used in digital switches, synchronous crossconnects and add-drop multiplexers to compensate for phase variations. The MTIE value is useful for configuring the buffer, in other words, the buffer is dimensioned according to the specified limit value for MTIE. If this value is not exceeded it can be safely assumed that no buffer overflows will occur and hence frame slips will be absent. If results appear to include a phase ramp (consistantly increasing or decreasing) this may be eliminated via the MRTIE function. See section 2.5 Wander measurement for asynchronous signals for further information. Process

Reference For example TSR-37

PRC

Wander reference

Rx

ANT-20

Figure 42 Verifiying accuracy of a PRC

Maximum tolerable interval error (MTIE) provides a measure of the long-term stability of a clock signal. In contrast, time deviation (TDEV) analysis is a calculation of the clock signal's short-term stability. TDEV curves are used for assessing oscillator performance. Table 22 gives an overview of recommendations for jitter and wander measurement. Data Rx electrical balanced electrical unbalanced electrical electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12] 1.5 to 155 Mbps Rx [14] 622 Mpbs Rx [16] 2.5 Gbps Rx [43] 10 Gbps Rx [114] 52, 155, 622 Mbps Rx [17] 2.5 Gbps Rx [44] 10 Gbps Rx [113]

Wander reference wander ref. clock wander ref. clock wander ref. clock

up to 622 Mbps [34] or [35] 2.5 Gbps [54] 10 Gbps [121] or [122]

Frequency offset

Slope of Possible causes MTIE TDEV s Clock not from PRS

Frequency drift

-

s2

Delay variations due to temperature changes

White noise Phase Modulation (WPM) Flicker Phase Modulation (FPM) White noise Frequency Modulation (WFM) Flicker Frequency Modulation (FFM) Random Walk Frequency Modulation (RWFM)

-

s-1/2

-

s-0

Typical parasitic noise processes in different types of oscillators

s1/2

Table 22 Interfaces for use dependent on signal under test and reference

-

s

-

s3/2

Instrument and application setup Follow the instrument application and setup procedure under Measuring wander on pages 18 to 20.

Table 21 MTIE/TDEV interpretation

Wander measurement of a clock source (TIE/MTIE/TDEV) The wander measurement of a clock source is used for verifying the accuracy of a primary reference clock or a DUT (figure 42). Here, the clock signal to be measured is compared with an external reference clock. To ensure reliable measurement results it is important that the accuracy of the reference clock is essentially better than the accuracy of the DUT.

Important ± For reliable results the accuracy of the measurement reference clock should be approximately ten times as accurate as the accuracy of the DUT. ± Ensure the optical level is between the range of ±10 and ±12 dBm when measuring optical signals. ± Ensure the recommended sampling rate is being used. ± Allow a warm up time of 30 minutes. ± It is recommended that a short term measurement be carried out prior to any very long term measurements to prevent ineffective use of measuring time through offset and mask exceed failures for example. ± For reliable wander measurement, the minimal measurement time must be at least twelve time the length of the required TDEV mask. 21

ITU-T O.172 ITU-T G.810 ETSI EN 300 462-1-1 ETSI EN 300 462-3

Jitter and Wander measuring equipment for SDH signals Definitions and terminology for synchronization networks Definitions and terminology for synchronization networks The control of jitter and wander within synchronization networks (specifies MTIE and TDEV masks)

Table 23 Overview of recommendations for jitter and wander testing

Wander generation measurement of DUTs (TIE/MTIE/TDEV) Every SDH network element (NE) commonly makes use of an internal clock (SEC/SMC). This clock source may be synchronized via an external synchronization signal or via the data signal on the line input. To check the quality of the internal clock source, the clock of the reference source is compared with that of the transmitted data signal. The difference is referred to as wander. The ANT-20 can be used to perform measurements on all interfaces of the instrument. Figure 43 illustrates wander generation with a DUT and with synchronization via an external synchronization input. Table 24 gives and overview of the recommendations for wander generation measurement testing.

SEC DUT

T4

Reference For example TSR-37

OC-N/STM-N

Wander reference

Rx

ANT-20

Instrument and application setup Follow the procedure in section Instrument setup Important ± For reliable results the accuracy of the measurement reference clock should be approximately ten times as accurate as the accuracy of the DUT. ± Ensure the optical level is between the range of ±10 and ±12 dBm when measuring optical signals. ± Ensure the recommended sampling rate is being used. ± Allow a warm up time of 30 minutes. ± It is recommended that a short term measurement be carried out prior to any very long term measurements to prevent ineffective use of measuring time through offset and mask exceed failures for example. ± For reliable wander measurement, the minimal measurement time must be at least twelve time the length of the required TDEV mask ITU-T O.172 Jitter and Wander measuring equipment for SDH signals ITU-T G.810 Definitions and terminology for synchronization networks ETSI EN 300 462-1-1 Definitions and terminology for synchronization networks Table 25 overview of recommendations for wander generation measurement testing.

Wander measurement at network interfaces with synchronous signals (TIE/MTIE/TDEV) The wander measurement for synchronous signals is used for verifying the wander performance of synchronous data signals (figure 44). Here, the data signal to be measured is compared to an external reference clock. To acquire reliable measurement results it is important that the accuracy of the reference clock is essentially better than the expected accuracy of the synchronous signal. Table 26 lists the interfaces recommended for use dependent on the signal under test and references.

Figure 43 Wander generation with DUT PRC

Data Rx electrical balanced electrical unbalanced electrical electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12] 1.5 to 155 Mbps Rx [14] 622 Mpbs Rx [16] 2.5 Gbps Rx [43] 10 Gbps Rx [114] 52, 155, 622 Mbps Rx [17] 2.5 Gbps Rx [44] 10 Gbps Rx [113]

Wander reference wander ref. clock wander ref. clock wander ref. clock

up to 622 Mbps [34] or [35] 2.5 Gbps [54] 10 Gbps [121] or [122]

Reference For example TSR-37

Signal source For example 2 Mbps

Network

ANT-20

Table 24 Interfaces for use dependent on signal under test and reference Figure 44 Wander measurement at network interfaces

22

Wander reference

Rx

Data Rx electrical balanced electrical unbalanced electrical electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12] 1.5 to 155 Mbps Rx [14] 622 Mpbs Rx [16] 2.5 Gbps Rx [43] 10 Gbps Rx [114] 52, 155, 622 Mbps Rx [17] 2.5 Gbps Rx [44] 10 Gbps Rx [113]

Wander reference wander ref. clock wander ref. clock wander ref. clock

up to 622 Mbps [34] or [35] 2.5 Gbps [54] 10 Gbps [121] or [122]

measurement, the frequency offset is determined and subtracted from the result so that only the network wander is displayed. Figure 45 illustrates the instrument application setup for wander measurement with asynchronous signals. Asynchronous clock source for example +50 ppm

Signal source For example 2 Mbps

Reference For example TSR-37

Network Wander reference

Rx

Table 26 Interfaces for use dependent on signal under test and reference

Instrument and application setup Follow the instrument application and setup procedure under Measuring wander on pages 18 to 20. Important ± For reliable results the accuracy of the measurement reference clock should be approximately ten times as accurate as the accuracy of the DUT. ± Ensure the optical level is between the range of ±10 and ±12 dBm when measuring optical signals. ± Ensure the recommended sampling rate is being used. ± Allow a warm up time of 30 minutes. ± It is recommended that a short term measurement be carried out prior to any very long term measurements to prevent ineffective use of measuring time through offset and mask exceed failures for example. ± For reliable wander measurement, the minimal measurement time must be at least twelve time the length of the required TDEV mask ITU-T O.172 ITU-T G.810 ITU-T G.823 ITU-T G.824 ITU-T G.825 ETSI EN 300 462-1-1 ETSI EN 302 084

Jitter and Wander measuring equipment for SDH signals Definitions and terminology for synchronization networks Jitter and Wander within networks based on 2048 kbps Jitter and Wander within networks based on 1544 kbps Jitter and Wander within networks based on the SDH Definitions and terminology for synchronization networks The control of jitter and wander in transport networks

Table 27 Overview of recommendatios for Wander measurement at network interfaces with synchronous signals (TIE/MTIE/TDEV)

Wander measurement for asynchronous signals (MRTIE) Maximum relative time interval errors (MRTIE) measurement is used if the source is not available during wander analysis due to spatial separation for example. In this case, MTIE analysis can have a frequency offset superimposed on it. It is a function of the clock difference between the signal and the reference used for measurement. In MRTIE

ANT-20

Figure 45 Wander measurement with asynchronous signals

Data Rx electrical balanced electrical unbalanced electrical electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12] 1.5 to 155 Mbps Rx [14] 622 Mpbs Rx [16] 2.5 Gbps Rx [43] 10 Gbps Rx [114] 52, 155, 622 Mbps Rx [17] 2.5 Gbps Rx [44] 10 Gbps Rx [113]

Wander reference wander ref. clock wander ref. clock wander ref. clock

up to 622 Mbps [34] or [35] 2.5 Gbps [54] 10 Gbps [121] or [122]

Table 28 Interfaces to be used dependent on signal under test and reference

Instrument setup and application Follow the instrument application and setup procedure under Measuring wander on pages 18 to 20. MRTIE calculation The MTIE/TDEV Offline Analysis software provides precise time domain analysis of MTIE and TDEV in reference to the captured TIE vs. Time graph. The program evaluates TIE values measured using the Acterna ANT-20. Evaluation is performed acording to ETSI EN 300462, EN 302084, ITU-T G.811, G.812, G.813 and ANSI T1.101 recommendations, and include the masks for the various signal sources. This software also includes MRTIE calculation. Table 29 lists the recommendations for performing wander generation measurements.

23

Step 1 After displaying the TIE results, the MTIE/TDEV software can be started immediately by pressing the TDEV button in the ANT-20 jitter VI when the unit is in TIE measurement mode. Results from the TIE measurement are loaded automatically (table 29). Step 2 The offset must be removed (click eliminate in the frequency offset window) to acquire the MRTIE.

± If there are doubts as to whether the traffic signal to be measured is synchronous to the reference clock, perform a short TIE measurement and check for offset first. ITU-T G.823 ETSI EN 302 084

Jitter and Wander within networks based on 2048 kbps The control of jitter and wander in transport networks

Table 29 Recommendations for wander generation measurement

Wander tolerance measurement/Maximum Tolerable Wander (MTW) The Maximum Tolerable Wander (MTW) function is used to perform automatic wander tolerance measurements that conform to ITU-T G.823, G.824, G.825, O.172 and ETSI EN302084 recommendations. Here, the DUT is stressed with a wander amplitude of a given frequency and the DUT output checked for definable errors (figure 48). The measurement is repeated for different frequencies and the results (OK/failed) displayed.

Figure 46 TIE result screen ± the blue line illustrates TIE with eliminated offest

Step 3 Click the MTIE/TDEV button. Then select analysis in the next window to display the MRTIE (figure 47).

Table 30 lists the recommendations for performing MTW measurements. Reference For example TSR-37 Ref. clock in [25]

Tx DUT Rx

ANT-20

Figure 48 Wander tolerance measurement setup

Figure 47 MRTIE analysis result screen

Important ± For reliable results the accuracy of the measurement reference clock should be approximately ten times as accurate as the accuracy of the DUT. ± Ensure the optical level is between the range of ±10 and ±12 dBm when measuring optical signals. ± Ensure the recommended sampling rate is being used. ± Allow a warm up time of 30 minutes. ± It is recommended that a short term measurement be carried out prior to any very long term measurements to prevent ineffective use of measuring time through offset and mask exceed failures for example. 24

Data Tx/Rx electrical bal. electrical unbal. electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12], Tx [13] 1.5 to 155 Mbps Rx [14], TX [15] 2.5 Gbps Rx [43], Tx [46] 10 Gbps Rx [114], Tx [104] 52, 155, 622 Mbps Rx [17], Tx [18] 2.5 Gbps Rx [44], Tx [47] 10 Gbps Rx [113], Tx [103]

Reference clock TX ref. clock in [25] Table 30 Interfaces to be used dependent on signal under test and reference

For this measurement, the input level must be 1 dB higher than the sensitivity level of the interface. The sensitivity level must be determined by decreasing the signal level of the TX signal without wander modulation until a BER of 10±10 occurs. This is the sensitivity level of the DUT. Once this has been determined, the power level should be increased by 1 dB for the tolerance measurement. The error threshold should be one error.

The ANT-20's generator is normally synchronized externally in MTW mode. This is performed by connecting an appropriate reference signal to socket [25]. An appropriate message will be displayed once MTW measurement commences and if the internal clock source is used for MTW measurement. Variable combinations of wander amplitudes and wander frequencies are set once measurement is initiated. The output signal is modulated for one period of the wander frequency for each combination of values. The measurement point is then marked as OK (no alarms or bit errors detected) or Failed (alarms or bit errors detected). Instrument setup and application Follow the instrument application and setup procedure under Measuring wander on pages 18 to 20 and apply the following additional steps described: Step 1 Synchronize the measuring instrument to the same reference used by the DUT to avoid unforeseen wander or pointer activity due to synchronization differences. Step 2 Click on interface/settings in the signal structure window (figure 49). In the interface settings dialog box, set the clock source format provided to be connected to the reference clock in [25] interface.

NB:

The MTW function can only be activated once the generator has been set to wander (TX WAN). The generator must be set back to jitter (TX JIT) to enable use of other automatic jitter measurement functions such as MTJ, F-MTJ, JTF, after performing MTW measurements.

Step 3 Select the error source (for example, TSE, Test Sequence Error) in the Error Source list box. Step 4 In the Error Threshold box, enter the error threshold above which the result will be assessed as Failed. An error threshold cannot be entered if an alarm was selected in the Error Source box. Step 5 In the Settling Time box, enter the time allowed for the DUT to settle after each frequency/amplitude setting is activated before counting errors (Gate Time). Step 6 Select the MTW command from the Settings menu or click on the SET icon in the toolbar (figure 50). If required, user specified frequency/amplitude combinations can be used for the measurement by simply double clicking on the values to be changed or selecting one of the pre-defined values as recommended by the standards. Click OK to confirm entries.

Figure 49 Interface settings dialog box

Figure 50 MTW settings dialog box

Use the following procedure to select the settings in the O.172 Jitter Generator/Analyzer window.

Step 1 If required, the Tx bitrate offset can be set to the maximum value allowed. An example of the signal structure virtual instrument can be seen in figure 51.

Step 1 Select the Wander command from the TX menu in the O.172 Jitter Generator/Analyzer window, or click on the TX WAN icon in the toolbar. Step 2 Select the MTW command from the Mode menu or click on the MTW icon in the toolbar. Figure 51 Signal Structure VI

25

Step 2 Click Start to commence measurement. Measurement stops automatically once all measurement points have been tested. It can also be stopped manually at any time by clicking on Stop. Important ± Measurement times may be quite long due to the frequency settings. ± Thoroughly check the optical level for the DUT input. Interpretation of results Depending on the alarm/error monitoring result, each setting is classified as OK or Failed.

Pointer wander measurement Pointer wander is the simultaneous occurrence of mapping and pointer wander in synchronous network elements at plesiochronous interfaces when the DUT is stimulated with definable pointer actions at the SONET/SDH interface according to G.783, T1.105.03 and GR-253. Both types of wander occur only at tributary interfaces of SONET and SDH network elements. Figure 53 illustrates a typical setup to perform pointer wander measurement. Table 32 gives and overview of the interfaces to be used dependent on the signal under test and reference. Reference For example TSR-37

DX

Tx

Ref. clock in [25]

Wander Reference [in] Rx

ANT-20

PDH tributary DS1/DS3

LP filter, e.g. DS1 ± 100 Hz DS3 ± 10 Hz

Figure 53 Pointer wander measurement setup

Figure 52 MTW result screen

Table 31 gives an overview of recommendations for MTW measurement ITU-T O.172 ITU-T G.812. ITU-T G.813 ITU-T G.823 ITU-T G.824 ETSI EN 302 084 ETSI EN 300 462-4-1

Jitter and Wander measuring equipment for SDH signals Timing requirements of SSU slave clocks Timing characteristics of SDH equipment slave clocks Jitter and Wander within networks based on 2048 kbps Jitter and Wander within networks based on 1544 kbps The control of jitter and wander in transport networks Timing characteristics of slave clocks suitable for synchronization supply to SDH and PDH equipment ETSI EN 300 462-5-1 Timing characteristics of slave clocks suitable for operation in SDH equipment ETSI EN 300 462-7-1 Timing characteristics of slave clocks suitable for synchronization supply to equipment in local node applications Table 31 Overview of recommendations for MTW measurements

26

Data Tx/Rx electrical bal. electrical unbal. electrical electrical electrical optical optical optical

1.5 to 2 Mbps Rx [12], Tx [13] 1.5 to 155 Mbps Rx [14], Tx [15] 622 Mpbs Rx [16] 2.5 Gbps Rx [43], Tx [46] 10 Gbps Rx [114], Tx [104] 52, 155, 622 Mbps Rx [17], Tx [18] 2.5 Gbps Rx [44], Tx [47] 10 Gbps Rx [113], Tx [103]

Wander reference wander ref. clock up to 622 Mbps [34] or [35] wander ref. clock 2.5 Gbps [54] wander ref. clock 10 Gbps [121] or [122] Reference clock TX ref. clock in [25] Table 32 Interfaces to be used dependent on signal under test and reference

Instrument setup and application Follow the instrument application and setup procedure under Measuring wander on page 20 and apply the following additional steps described:

In order to set up pointer wander measurement, the transmitter pointer generation needs to be configured to the appropriate signal structure with the required sequences. The receiver must also be configured to wander measurement (TIE vs. Time). Setting the transmitter To set the transmitter the different signal structures for the interfaces at Rx and Tx must be set as applicable. Pointer wander measurement is performed via half channel measurement.

Measurement of single INC/DEC sequence for the STS pointer The Pointer Generator enables test sequences (in accordance with ITU-T G.783 and ANSI T1.105.03 recommendations) to be generated for AU/STS or TU/VT pointers. Both pointers can be generated simultaneously or independently of each other (figure 56).

Figure 54 illustrates an OC-192 Tx signal being fed into a DUT and E1 PDH signal for Rx.

Figure 54 OC-192 Tx signal being fed into a DUT and E1 PDH signal for Rx

When setting the clock source, the ANT-20 must be set to an external clock/data signal to avoid unforeseen pointer adjustments and wander activities in addition to the set pointer sequence. Step 1 Click on Settings in the Interface menu in the Signal Structure VI. Step 2 Select the external reference source format for interface [25] to be used from the Clock Source box and click OK to confirm (figure 55). Figure 56 Pointer generator dialog box

Step 1 Click the AU/STS button in the toolbar. Step 2 Select INC/DEC from the AU/STS Pointer box. Step 3 Set the distance between two pointer actions in the T2 entry box. Step 4 Set the desired sequence length in the Mode box, then select either single sequence or continuous repetition. Step 5 Click on the STS/AU ON button to activate the pointer sequence.

Figure 55 Interface settings dialog box

For detailed descriptions of all available pointer sequences, please read part 7 Technical Background of the ANT-20 manual.

Step 3 To select a sequence, pointer generation must first be configured.

27

To set the receiver for TIE measurement, follow the procedure described below. Step 1 In the Wander Settings dialog, set the frequency or bitrate of the reference signal, connector to be used and the sampling rate (figure 57).

Cool-down period After the initialization period and in the case of single and burst pointer tests it is recommended that a 30-second cool-down period is allowed where no pointer activity is present in the test signal. For periodic test sequences (both continuous and gapped) a 30-second cool-down period is recommended during which the periodic sequence is applied so that a steady state condition is maintained. If necessary, the period should be extended to include an integral number of complete sequences.

Figure 57 Wander settings dialog box

Step 2 The low-pass filter is set automatically. For DS1 measurements, 300 samples/s (LP filter = 100Hz) are required. DS3 measurements for example should be performed with 30 samples/s (LP filter = 10 Hz). Pointer sequence test procedure Complete test sequences for specific bitrate and pointer sequence consist of several defined periods. In order to prime the pointer processor and prepare the equipment for the test sequence, initialization and cool-down periods must be applied prior to starting the measuring procedure. The following sections explain the rationale for these different periods.

Initialization 60 s

Cool-down 41 period

Measurement 460 s or 41 period time

INC

87-3 INC

87-3 INC

87-3 INC

time

Figure 58 Example pointer procedure for 87-3 INC periodic test sequence

Initialization period To ensure that wander on the demultiplexed tributary signal is nevertheless affected in the event of single and burst sequences, it is important that pointer movements are not absorbed by the pointer processor. For periodic sequences, the pointer processor must be in the steady-state condition it would be in if continual pointer movements had been constantly present. For single and burst test sequences, the initialization period should 28

consist of pointer adjustments applied at a rate exceeding that of the test sequence, but lower than 3 pointer adjustments per second, in the same direction as the subsequent test sequence. The initialization period should last at least until a response is detected in the jitter/wander measured on the demultiplexed tributary signal For this purpose it is recommended that a 60 second initialization period be used.

Measurement Period During the measurement period the wander (TIE) of the tributary output is measured. The recommended measuring period is 100 seconds. If necessary, the period can be extended to include at least one complete pointer test sequence. Table 33 gives an overview of recommendations covering pointer sequence for pointer jitter/wander measurements. Important ± For reliable results the accuracy of the measurement reference clock should be about ten times better than the accuracy of the device under test. ± If measuring optical signals make sure that the optical level is in the range between ±10 and ±12 dBm. ± Make sure that you are using the recommended sampling rate. ± Ensure a warm up time of 30 minutes. ± For very long-term measurements it is recommended to make a previous short term measurement to prevent ineffective use of measuring time by failures (e.g. offset, mask exceed). Interpretation of results An overrun of the recommended masks indicates an error of the desynchronizer. Telcordia GR-253 (2000), SONET transport system common generic criteria Section 5.7 ANSI T1.105.03 (2002) SONET jitter at network interfaces ITU-T G.783 (2000) Characteristics of SDH equipment functional blocks Table 33 List of recommendations covering pointer sequences for pointer jitter/wander measurements

Jitter and wander test equipment PLL bandwidth also determines the lower limit frequency for jitter measurement that is to say, components below this frequency are not detected. An external reference is therefore used for wander measurements.

A jitter/wander test set consists of the following functional blocks: ± Pattern clock converter ± Reference clock generator ± Phase meter ± Weighting filters ± Peak value detector (with possible rms & phase hit determination).

The voltage fluctuations at the output of the phase meter are proportional to the phase fluctuations. Put another way, the output signal corresponds to the jitter/TIE vs. time curve. Standardized weighting filters connected after this limit the frequency spectrum of the jitter signal. The positive and negative peak values of the filtered signal are measured and displayed as the jitter result in UIpp (additional alternatively RMS or PH).

The pattern clock converter generates the clock signal from the digital signal, with all its attendant phase deviations. This clock signal is then compared to the reference clock in the phase meter provided either by the reference clock generator (jitter measurement) or an external reference (wander measurement).

The filtered signal is available at a demodulator output for further external processing. Further time and frequency domain analysis of the jitter is thus possible by using an oscilloscope, selective level meter or spectrum analyzer for example.

The reference clock generator provides a phase reference by slowly tracking the jittered input clock with the aid of a phase locked loop (PLL). The PLL has a lowpass filter with a cutoff frequency in the range of 1 Hz (ANT-20: 0.1 Hz) so that high-frequency jitter components are filtered out. The

Clock with jitter/wander

Figure 59 illustrates the principle of jitter/wander analyzers. Output voltage proportional to phase difference between signal clock and reference clock

Jitter-free reference clock

Demodulator output Digital signal (with jitter and wander)

Pattern Clock Pattern clock converter

Ext. reference clock input (for wander measurement)

HP

j

Ext.

LP

UIpp

U Int.

Phase detector

UIrms Peak-to-peak and RMS evaluation

Jitter weighting filters

Result evaluation and display

LP PLL

PLL 10 Hz Internal reference clock generation

TIE

MTIE

Lowpass

Figure 59 Block diagram of a jitter/wander analyzer

29

Acterna AdvantageSM ± adding value with global services and solutions From basic instrument support for your field technicians to management of complex, company-wide initiatives, Acterna's service professionals are committed to helping you maximize your return on investment. Whatever your needs ± product support, system management, education services, or consulting ± we offer programs that will give you the competitive edge. To learn more about how Acterna Advantage can help your business be more successful, visit the services section on your local web page at http://www.acterna.com/.

Worldwide Headquarters

Regional Sales Headquarters

12410 Milestone Center Drive Germantown, Maryland 20876-7100 USA

North America 12410 Milestone Center Drive Germantown, Maryland 20876-7100 USA Toll Free: 1 866 ACTERNA Toll Free: 1 866 228 3762 Tel: +1 301 353 1560 x 2850 Fax: +1 301 353 9216

Acterna is present in more than 80 countries. To find your local sales office go to: www.acterna.com

Latin America Av. Eng. Luis Carlos Berrini 936/8ë e 9ë andares 04571-000 S›o Paulo SP-Brazil Tel: +55 11 5503 3800 Fax: +55 11 5505 1598

Asia Pacific 42 Clarendon Street PO Box 141 South Melbourne Victoria 3205 Australia Tel: +61 3 9690 6700 Fax: +61 3 9690 6750 Western Europe Arbachtalstraûe 6 72800 Eningen u.A. Germany Tel: +49 7121 86 2222 Fax: +49 7121 86 1222

Eastern Europe, Middle East & Africa Elisabethstraûe 36 2500 Baden Austria Tel: +43 2252 85521 0 Fax: +43 2252 80727 Prospect Mira, 25, stroenie 5 RF 129090 Moscow Russia Tel: +7 095 937 88 04 Fax: +7 095 775 26 05

Acterna is the world's largest provider of test and management solutions for optical transport, access, and cable networks, and the second largest communications test company overall. Focused entirely on providing equipment, software, systems, and services, Acterna helps customers develop, install, manufacture, and maintain optical transport, access, cable, data/IP, and wireless networks.

ã Copyright 2003 Acterna, LLC. All rights reserved.

Note: Specifications, terms and conditions are subject to change without notice.

Acterna and its logo are trademarks of Acterna, LLC. All other trademarks and registered trademarks are the property of their respective owners. Major Acterna operations sites are ISO 9001 registered.

JITWAND/AG/OPT/04-03/AE/PDF ONLY