Comtech EF Data CDM-500 - Manual (Page 39)

Front Panel Operation CDM-500 Closed Network Satellite Modem
6–10 Rev. 1.3
6.5.19 (CONFIG, RX) BUF (Buffer size)
EDIT RX BUFFER SIZE:
+/-4096 BITS (PRESS ENT)
Edit the size of the Plesiochronous/Doppler Buffer in bits using the UP/DOWN arrow
keys. 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.
6.5.20 (CONFIG, RX) RSI (Receive spectral inversion)
SELECT RECEIVE SPECTRAL
INVERSION: OFF ON(ENTER)
Select 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.
6.5.21 (CONFIG, RX) Eb/No (Eb/No Alarm)
EDIT Eb/No ALARM POINT:
2.0 dB (PRESS ENTER)
Edit the Eb/No alarm point by selecting the digit to be edited, using the LEFT/RIGHT
arrow keys. Change the value of the digit using the UP/DOWN arrow keys. 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.
6.5.22 (CONFIG) FRAME (Framing Mode)
SELECT FRAMING MODE:
TRANSPARENT FRAMED (ENT)
The sub-branches available are:
6.5.23 (CONFIG, FRAME) TRANSPARENT
No framing is selected. No overhead is added, and the unit will be compatible with other
manufacturer’s equipment, when operating in a ‘standard’ configuration (IESS 308
filtering, V.35 scrambling, Viterbi).