Available Baud Rates; Configuration; Effect On Eb/No Performance - Comtech EF Data CDM-600 Installation And Operation Manual

CDM-600 Satellite Modem
ESC++
13.3

Available Baud Rates

At the lowest data rates, the 11.76% overhead may not allow all baud rates. The
following table shows available rates:
Data rate
64 to 127.999 kbps
128 to 191.999 kbps
192 to 255.999 kbps
256 to 383.999 kbps
384 to 511.999 kbps
512 kbps and above
13.4

Configuration

To use this mode, the user should select ESC++ from the CONFIG, MODE menu. The
baud rate and async character format are then selected from the CONFIG, MISC,
HIGH-RATE ESC menu. This is described in Chapter 6 (Front Panel Operations).
13.5

Effect on Eb/No performance

Because, particularly at lower data rates, where the percentage overhead is large, the
increase in transmitted data rate will cause a decrease in the Eb/No performance.
Therefore, all of the published data concerning BER versus Eb/No needs to be modified
according to the table below:
Data rate
64 kbps to < 768 kbps
768 kbps to 1.5 Mbps
> 1.5 Mbps to 2.5 Mbps
> 2.5 Mbps to 7 Mbps
> 7 Mbps
The degradation is simply 10 * log (Overhead ratio)
The Eb/No displayed by the modem (MONITOR, RX-PARAMETERS) takes this into
account in the value that is calculated.
Baud rates available
1200, 2400, 4800
1200 to 9600
1200 to 14400
1200 to 19200
1200 to 28800
1200 to 38400
Overhead ratio (percentage)
19/17 (11.76%)
12/11 (9.09%)
29/27 (7.4%)
19/18 (5.56%)
64/63 (1.58%)
13–2
Revision 7
MN/CDM600.IOM
Eb/No degradation
0.48 dB
0.38 dB
0.31 dB
0.23 dB
0.07 dB