Comtech EF Data CDM-550T Manual page 49

CDM-550T Satellite Modem
(CONFIG, RX) BUF (Buffer size)
(CONFIG, RX) RSI (Receive spectral inversion)
(CONFIG, RX) Eb/No (Eb/No Alarm)
Rev. 1.3
EDIT RX BUFFER SIZE:
+/-4096 BITS (PRESS ENT)
Edit the size, in bits of the Plesiochronous/Doppler Buffer. The value is changed
using the UP/DOWN 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.
SELECT RECEIVE SPECTRAL
INVERSION: OFF ON(ENTER)
Select either OFF or ON, using the LEFT/RIGHT 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 that 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.
EDIT Eb/No ALARM POINT:
2.0 dB (PRESS ENTER)
Edit the Eb/No alarm point. This is accomplished by selecting the digit to be
edited, using the LEFT/RIGHT arrow keys. The value of the digit is then changed
using the UP/DOWN 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.
Front Panel Operation
6–19