ABB ETL600 Instruction Manual page 330

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8.2 Equalizer for NSK600 modems with data rates of 2.4, 4.8 and 9.6 kbps
By default the long equalizer in connection with the 'Amplitude response equalization only'
setting is used for NSK600 modems with data rates of 2.4, 4.8 and 9.6 kbps. Additionally the
allpass filter has to be enabled on the transmitting equipment ('allpass filter for group delay
equalization' setting in 'Configuration' / 'System' / 'Channel Settings'). If the performance of the
modem is unsatisfactory, the equalizer mode can be changed to 'Combined group delay and
frequency response equalization'.
In order to evaluate the modem performance a BER test equipment transmitting pseudo random
data should be used. Which equalizer to choose, is based on the measured BER. Alternatively the
equalizer yielding the better signal quality (during transmission of random data) in the NSK600
status can be selected.
9 Recommended procedure to equalize a channel
1. Logon to the desired ETL600 using the HMI600 dialog 'Equipment' / 'Connect' with 'Read &
Write access' enabled, correct Equipment ID, correct password and with the checkbox
'Upload configuration' selected.
2. Start channel measurement by selecting 'Equipment' / 'Commissioning and maintenance' /
'Frequency response' / 'APLC channel X'.
3. Wait until the window 'Select equalizer' appears.
4. View the frequency response of the desired equalizer with the 'View' button. By default,
'Amplitude response equalization only' is active. With 'Equipment' / 'Commissioning and
maintenance' / 'Select equalizer' / 'APLC channel X', it is possible to go back into the
'Select equalizer' dialog box.
5. If the channel measurement is noisy, repeat the measurement with 'Equipment' /
'Commissioning and maintenance' / 'Frequency response' / 'APLC channel X' and go
back to point 4.
6. Select with 'Equipment' / 'Commissioning and maintenance' / 'Select Equalizer'/ 'APLC
channel X' the desired new equalizer with the desired group delay equalization mode and
press the 'Download' button. The equipment is reset now.
7. Wait until the equipment has restarted. The new equalizer is active now.
8. Exit.
10 Recommended procedure to change the equalizer settings
1. Logon to the desired ETL600 using the HMI600 dialog 'Equipment' / 'Connect' with 'Read &
Write access' enabled, correct Equipment ID, correct password and with the checkbox
'Upload configuration' selected.
2. Select the desired channel with 'Equipment' / 'Commissioning and maintenance' / Select
equalizer / 'APLC channel X'.
3. View the frequency response of the desired equalizer with the 'View' button. It is also possible
to change only the group delay equalization mode. With 'Equipment' / 'Commissioning and
maintenance' / 'Select equalizer' / 'APLC channel X', it is possible to go back into the
'Select equalizer' dialog box.
4. If the user doesn't want to change the equalizer settings, press 'Cancel' to exit the dialog box.
5. Select with 'Equipment' / 'Commissioning and maintenance' / 'Select Equalizer' /
'Channel X' the desired actual equalizer with the desired group delay equalization mode and
press the 'Download' button. The equipment is reset now.
6. Wait until the equipment has restarted. The new equalizer is active now.
7. Exit.
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1KHW001494-EN