ABB ETL600, Instruction Manual

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A EN 3/6
1KHW001494-EN
equalization' enabled only (in 'Configuration' / 'System' / 'Channel Settings' ). The default
setting is 'Amplitude response equalization only' enabled.
Always check the amplitude response of the short equalizer in the pilot channel if used in
conjunction with external protection system before activation through instructed personnel.
3.3 Medium equalizer
The medium equalizer compensates the amplitude response of the channel with additional delay.
This additional delay can be viewed in the
'Select equalizer' box.
If 'Amplitude response equalization only' is selected, no group delay equalization is performed.
The resulting amplitude response is good.
If 'Combined group delay and frequency response equalization' is selected, a combined
amplitude and group delay equalizer is activated. Due to the additional group delay equalization,
the equalized channel amplitude response could have quite a ripple. Group delay distortion up to
1.5 ms can be equalized.
Please note that the additional group delay equalization must only be activated if there is a modem
present on that channel and the performance is better than with
'allpass filter for group delay
equalization' enabled only (in 'Configuration' / 'System' / 'Channel Settings' ). The default
setting is 'Amplitude response equalization only' enabled.
Always check the amplitude response of the medium equalizer in the pilot channel if used in
conjunction with external protection system before activation through instructed personnel.
3.4 Long equalizer
The long equalizer compensates the amplitude response of the channel with additional delay. This
additional delay can be viewed in the
'Select equalizer' box.
If 'Amplitude response equalization only' is selected, no group delay equalization is performed.
The resulting amplitude response is excellent.
If 'Combined group delay and frequency response equalization' is selected, a combined
amplitude and group delay equalizer is activated. Due to the additional group delay equalization,
the equalized channel amplitude response can have a ripple. Group delay distortion up to 2 ms can
be equalized.
Please note that the additional group delay equalization must only be activated if there is a modem
present on that channel and the performance is better than with
'allpass filter for group delay
equalization' enabled only (in 'Configuration' / 'System' / 'Channel Settings' ). The default
setting is 'Amplitude response equalization only' enabled.
Always check the amplitude response of the long equalizer in the pilot channel if used in
conjunction with external protection system before activation through instructed personnel.
)
Note: The equalizer is applied on the receive signal whereas the allpass filter is
applied on the transmit signal. As a consequence the equalizer has to be
configured on the receiving equipment and the allpass filter on the transmitting
equipment.
4 Establishing a new equalizer
To establish a new equalizer, use the following step-by-step procedure:
1. Measure the frequency response of the channel to equalize ( 'Equipment' / 'Commissioning &
maintenance' / 'Frequency response' ).
2. Check the equalized frequency response with the 'View' button in 'Select Equalizer' of the
desired channel. If you are not satisfied with all new equalizers, repeat the measurement. If you
decide not to change the running equalizer, quit the
'Select Equalizer' dialog box with the
'Cancel' button.
3. Activate the chosen equalizer with the 'Download' button in 'Select Equalizer' . The new
settings are downloaded, stored in the EPROM and the equipment is reset.