Comtech EF Data CDM-550T - Manual (Page 53)

CDM-550T Satellite Modem Revision 3
Front Panel Operation MN/CDM550T.IOM
(CONFIG: RX) BUF (Buffer size)
Edit the size, in bits of the Plesiochronous/Doppler Buffer. The value is changed
using the [
↑] [↓] arrow keys. The user should then press ENTER. Values of
± 256, 512, 1024, 2048 and 4096 bits are possible. If the buffer is disabled, a
warning message will be displayed if this screen is entered.
EDIT RX BUFFER SIZE:
+/-4096 BITS (PRESS ENT)
6.2.3.2.7 (CONFIG: RX) RSI (Receive spectral inversion)
Select either OFF or ON, using the [
←] [→] arrow keys, then press ENTER.
This should normally be in the OFF position. When in the ON position, the receive spectrum is
inverted (which is the same as reversing the direction of phase rotation in the demodulator).
Note: In BPSK mode, the demodulator will automatically synchronize to either the normal time-
ordering of bits FEC codeword pairs, or the inverted ordering used by certain other
manufacturers.
SELECT RECEIVE SPECTRAL
INVERSION: OFF ON(ENTER)
6.2.3.2.8 (CONFIG: RX) Eb/No (Eb/No Alarm)
Edit the Eb/No alarm point. This is accomplished by selecting the digit to be edited, using the
[
←] [→] arrow keys. The value of the digit is then changed using the [↑] [↓] arrow keys. The
user should then press ENTER.
The range of values is from 2.0 to 16.0 dB. The user may select a value here, and if the Eb/No
falls below this value, a receive traffic fault will be generated.
EDIT Eb/No ALARM POINT:
2.0 dB (PRESS ENTER)
6–17