Comtech EF Data CDM-710G - Manual (Page 96)

CDM-710G High-Speed Satellite Modem Revision 1
Front Panel Operation MN-CDM710G
6–20
(CONFIG:) Rx
Æ SymRate
Data: DEMOD unlocked
Sym: 017.379483 Msps (E)
If the Rx Path is not locked, the message should as shown in the above example. To change the
Symbol Rate, use the
W X arrow keys to select the digit to be edited. Use the ST arrow keys to
change the value of the digit, then press
ENTER .
The Data Rate digits also change as the Symbol Rate values are edited. The value of the Data Rate
depends upon the code rate, modulation type. When programming a new Symbol Rate (or indirectly
a Data Rate) the value is not accepted unless it is within a valid range.
Note: G.703 Interface Data Rate is fixed. The user must enter the correct Symbol Rate.
See the tables under the (CONFIG:) Tx Æ SymRate menu for the valid range of Symbol/Data
Rates.
‘Demod unlocked’ appears while the Rx path is not synchronized. After synchronization the
correct Data Rate appears in the display and the demodulator has automatically resolved the
modulation type, code rate, pilots ON/OFF, FEC frame length, spectral inversion, etc. from the
DVB-S2 carrier.
The Symbol Rate is calculated using the equation SR = DR/SE , where:
SR = Symbol Rate;
DR = Data Rate;
SE = Spectral Efficiency.
The following example illustrates the Symbol Rate as calculated for 8PSK 3/4 and E3:
SR = 34.368/2.22814 = 15.424524 Msps
Refer to Tables 6-1 and 6-2 for Symbol Rate / Data Rate Range tablature.
(CONFIG:) Rx
Æ Freq
RX Freq: 0140.0000 MHz
(▲ ▼ E)
Edit the RX IF Frequency. Use the W X arrow keys to select the digit to be edited. Use the ST
arrow keys to change the value of the digit, then press
ENTER .
Note the following:
70/140 MHz
The ranges of frequencies are from 52 to 88 MHz and from 104 to 176 MHz with a
resolution of 100 Hz.
L-Band The range is 950 to 1950 MHz with 100 Hz resolution.
IMPORTANT
The bandwidth of the modulated carrier MUST stay within the IF
frequency range, or the frequency is not accepted.