FarSync BERT | ![]() |
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FarSync BERT - Configuration
When the FarSync BERT is run for the first time it will default to the following setup:
In this case, when the test is run it will use
also
Note that whenever the FarSync BERT is started it will default to the configuration that was used when it was previously run.
Changing any of the configuration options during a test will cause the test to stop. Simply press the Start button (shown above) to start a new test using the new settings.
Details of the available configuration options are listed below.
The line rate to be used for the test is selected using the RATE control. The range of 8 selectable values that are displayed is dependent on the configured Interface Mode (ASYNC or SYNC) and the labels will change accordingly as and when the Interface Mode button is pressed.
If required, the values available in this range can be modified by double-clicking the RATE control to display the Rate Configuration dialog:
Select the required rate values from the dropdown lists and press OK to update the selectable values. Alternatively a custom value can be entered into any of the 8 locations. Only use custom values if you are sure that the FarSync hardware that you are using does support the customised rate. In the case that the actual configured rate is not supported by the FarSync hardware, the device will choose the closest rate available to it.
Please refer to the FarSync FAQ for details of the rates natively supported by the particular FarSync device that you are using. Note in particular that the FarSync Flex V2, and above, do not support the set of very low synchronous rates, less than 100bps e.g. 15, 25, 30, 50, 60 & 75bps, that are supported by the FarSync Flex V1.
Note that the rate need only exactly match the required rate if the BERT is generating the clock itself in SYNC mode (i.e. using Internal (INT) Clocking mode) or if Interface Mode is set to ASYNC - otherwise simply choose the closest available rate.
If you are experiencing unexpected errors or failure to synchronise whilst running a BERT test, check the Bit Rate value that is reported in the Statistics/Results Table and ensure that it is close to the Rate value that you have configured. If it is not, then you may have configured an unsupported rate. Reconfigure the rate value accordingly and rerun the test.
Refer to the Interface Type options for details of the maximum supported rate for each type.
Where the BERT is sourcing clocking (i.e. is configured for Internal (INT) clocking) at rates in excess of 1.5Mbps, the use of Terminal Timing is recommended. Where Terminal Timing is not available, the use of Invert Rx Clock should be considered as an alternative.
The test pattern to be used for the test is selected using the PATTERN control. This enables you to select a value from a range of 8 predefined patterns or 8 user-defined patterns.
If required, this range can be modified by double-clicking the PATTERN control to display the Pattern Configuration dialog:
Select the required pattern values from the dropdown lists and press OK to update the selectable values.
The currently supported patterns are detailed below.
Synchronous Line Pattenrs
The following pseudorandom patterns can be used to test synchronous lines:
The following fixed patterns can be used to test synchronous lines:
Note that the use of MK and SP patterns is not recommended if you are using Manchester (MAN) encoding.
Asynchronous Line Patterns
The following patterns are recommended for general use on asynchronous lines (see above for definitions):
The ITU specifications for some of these industry-standard patterns can found at the ITU web-site, https://www.itu.int/en/ITU-T/publications/Pages/recs.aspx.
In addition to the pseudorandom and fixed patterns provided, up to 8 of your own patterns may be selected. To add a user pattern, go to the Additional Configuration - User Patterns tab and provide the filename and filetype of the file which contains your pattern. The provided files can be in either a binary file format or a text file format (with the data stored as hexadecimal values as shown below).
The pattern length is the number of bytes of data. In the example shown below, this would be 56 bytes (448 bits).
Once you have selected a valid filename, the pattern will be made available in the Pattern Configuration Dialog with one of the default User Pattern Names USR1 – USR8, unless of course, you have changed it. Simply select the pattern to make it available on the PATTERN control.
Note that User Patterns can only be used in software mode.
The length of the test is specified using either LENGTH or TIME. In the time mode, the elapsed time doesn’t commence until initial synchronisation is achieved and thus to handle the case where synchronisation never occurs, a timeout is set using SYNC TIME.
To cycle between the different modes, double-click on the label beneath the Test Length Dial. For the TIME and SYNC TIME modes, a clock display appears above the dial showing hours, minutes and seconds in an HH:MM:SS format. The three test length modes are shown below:
Test Length - Length Control
The length of the test is selected using the LENGTH control to choose from the range of 8 selectable values. This length value determines how any bits to test in the received datastream before completing the test. Note that the count does not start until initial synchronisation is achieved.
If required, the values available in this range can be modified by double-clicking the LENGTH control to display the Test Length Configuration dialog:
Select the required length values from the dropdown lists and press OK to update the selectable values.
Test Length - Time Control
The duration of the test is selected using the TIME control. To change the duration, click and drag the TIME control in a circular motion. As the control is dragged, the green HH:MM:SS values in the Time Display will increase using a clockwise motion and decrease using an anti-clockwise motion.
The default mode for the TIME control is H:M:S, whereby the time is updated one second at a time. Alternatively, each of the hours, minutes and seconds values can be set separately by clicking on the desired value in the Time Display and then clicking and dragging the control. The currently selected value is highlighted in the Time Display along with the appropriate HOURS, MINS, SECS label which is shown beneath the TIME control.
The maximum test duration that can be set is 99 hours, 59 minutes and 59 seconds.
Test Length - Sync Time Control
The Synchronisation Time sets the timeout to wait for synchronisation to occur. If synchronisation doesn’t occur within the specified time, the test is stopped.
To change the duration, click and drag on the SYNC TIME control in a circular motion. As the control is dragged, the red HH:MM:SS values in the Time Display will increase using a clockwise motion and decrease using an anti-clockwise motion.
The default mode for the SYNC TIME control is H:M:S, whereby the time is updated one second at a time. Alternatively, each of the hours, minutes and seconds values can be set separately by clicking on the desired value in the Time Display and then clicking and dragging the SYNC TIME control. The currently selected value is highlighted in the Time Display along with the relevant HOURS, MINS, SECS label which is shown beneath the SYNC TIME control.
The maximum test duration that can be set is 99 hours, 59 minutes and 59 seconds.
The configuration buttons provide a convenient way to select some of the BERT more frequently used options. The same options are also available within the Additional Configuration dialog.
The BERT can perform both Bit Error Rate Tests (BER) and Round Trip Delay Tests (RTD). Use the Test Function (F) button to switch between the two types of test. In the Round Trip Delay mode, the Pattern Control is disabled and the unused Interface Mode (M and Errors (E) buttons are greyed out as shown below.
The test can be run in either ASYNC or SYNC mode. Use the Interface Mode button to toggle between these two values.
The Errors Counter (see below) will display the number of Bit Errors, Block Errors, Errored Seconds, Parity Errors, Framing Errors or All Errors. Pressing the Errors (E) button cycles round the available values.
The type of interface that the FarSync port is connected to is configured using
the Interface Type button. The supported values include:
Pressing the button cycles round the available values.
The maximum supported rates for each type of interface are as follows:
Interface Type | Maximum Rate |
V.24 | 64Kbps * |
X.21 | 10Mbps † |
V.35 | 2.048Mbps |
RS530 | 10Mbps † (16Mbps if HighSpeed-V2 Flex is used) |
RS449 | 10Mbps † (16Mbps if HighSpeed-V2 Flex is used) |
RS485 (4-wire point-to-point) | 10Mbps † |
* If Terminal Timing is used then the maximum rate for V.24 is 128K
† Flex devices, other than the HighSpeed-V2, support
a maximum rate of 2 Mbps
Note that if an encoded mode is used, for example FM0 or FM1, then the Maximum Rate is reduced from 16 Mbps to 10 Mbps.
The FarSync port can be configured to
use INTERNAL,
EXTERNAL, INTERNAL+TT,
EXTERNAL+TT or
BIDIRECT (where TT is Terminal Timing and BIDIRECT is bidirectional
clocking).
Pressing the clocking (C)
button cycles round the various options.
Note that if the Advanced Clocking
option is selected in the Additional Configuration dialog, it overrides
and disables this Clocking setting.
It is recommended that Terminal Timing
is used for line speeds of 2Mbps and above. This can eliminate potential clock
phase problems related to propagation delays when using a single clock.
Note: Terminal Timing is not supported
when using NRZI encoding or by the Flex(V1).
The BERT should be connected
to the peer/network via a KCR1-V2 cable when using Terminal Timing in RS232 (V.24), V.35 and RS530
(RS422) interface modes.
The FarSync port to be used can be selected by pressing the Port button. If you have multiple FarSync devices/cards or multiport cards installed, this button enables you to cycle round the available FarSync ports. The value of ANY will enable the FarSync BERT to simply select the first detected FarSync port. More information on selecting specific ports can be found here.
The FarSync BERT Errors counter displays a count of the errors detected. Use the Errors button to select the required counter value. The options include:
Note that the Error Seconds, Bit and Block counters are available simultaneously, via the statistics table, using the Table button.
The Errors selection can be set before or during test execution.
The Secs counter, when coloured yellow, displays the total number of seconds that the test has been running for. At the beginning of the test it is coloured red and displays the number of elapsed seconds before the first synchronisation is achieved (BER only)
The DTE output states can be set before or during test execution. In addition to line signal states, the Signals Pane also shows the state of the FarSync BERT's auto inversion (IV) support. If the Auto Invert (RIV) option is enabled, and then during a test the FarSync BERT fails to synchronise with the inbound data stream for 2 seconds, the BERT will invert the receive data signals to see if perhaps the peer and/or cabling has been inverted. Whilst the FarSync BERT has the receiver inverted, the RIV indicator will be highlighted.
Whilst a test is active, you can request that the FarSync BERT inject errors into its outbound data by pressing the ERR button (shown above). Pressing the button by itself once will inject a single bit error. If one of the host PC number keys ('1'..'8') is pressed at the same time as the ERR button then the corresponding number of bit errors will be generated in a single burst.
For details on further configuration options available in the Additional Configuration dialog (displayed via the More button) click here
Details of how to use the FarSync BERT in script mode can be found here
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