Comtech EF Data SNM-1010L - Manual (Page 189)

SNM-1010L Data/Control Modem Revision 0
System Checkout MN/SNM1010L.OM
7.2.2.1.1 Modulator Checkout
Use the following procedure to check out the modulator:
1. Refer to Chapter 6 for modulator specifications.
2. Set up the modem for operation by using the Configuration Modulator and
Demodulator front panel menus.
3. Clear all TX faults by correct use of data and clock selection.(Chpater 5).
4. Measure the E
b
/N
0
with a receiver that is known to be properly operating. Refer
to Table 7-2 to check for proper E
b
/N
0
level. The (S+N)/N is measured by taking
the average level of the noise and the average level of the modem spectrum top.
5. Use this measurement for the first column on Table 7-2. Read across the page to
find the S/N and E
b
/N
0
for the specific code rate. Once the demodulator has
locked to the incoming signal, the Monitor menu will display signal level, raw
BER, corrected BER, and E
b
/N
0
. Refer to Chapter 1 for examples of BER
performance curves.
Typical output spectrum are shown in Figure 7-1and Figure 7-2.
7–9