4RF Aprisa XE User Manual - page 74
72 | Configuring the Terminal
Aprisa XE User Manual
Modem Performance Settings
To view or change the modem performance settings:
Select Link or Local or Remote > Terminal > Modem
Modem QPSK Coding
When the Modulation type is set to QPSK, the default QPSK Coding setting is ‘Non-Gray Coded’ but the
QPSK Coding can use ‘Gray Coded’ for interoperability with older hardware.
Modem Interleaver Mode
The Modem Interleaver improves modem bit error rate but increases the end to end link delay so the
Modem Interleaver should be enabled where a low bit error rate is required and disabled where a low end
to end link delay is required.
The ‘Default’ Modem Interleaver Mode setting is on for channel sizes of 250 kHz and greater and off for
channel sizes of 200 kHz and less. The specification of end to end link delay for both interleaver on and
off is given in the relevant RF Specification section. For ETSI Link Delays, see ‘Link Delays ETSI’ on page
292.
When you change the Modem Interleaver Mode in an operational terminal, traffic across the link will be
interrupted.
Both terminals must be set to the same Modem Interleaver Mode.