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CDM-600 Satellite Modem Revision 7
ESC++ MN/CDM600.IOM
13–2
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 Baud rates available
64 to 127.999 kbps 1200, 2400, 4800
128 to 191.999 kbps 1200 to 9600
192 to 255.999 kbps 1200 to 14400
256 to 383.999 kbps 1200 to 19200
384 to 511.999 kbps 1200 to 28800
512 kbps and above 1200 to 38400
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 Overhead ratio (percentage) Eb/No degradation
64 kbps to < 768 kbps 19/17 (11.76%) 0.48 dB
768 kbps to 1.5 Mbps 12/11 (9.09%) 0.38 dB
> 1.5 Mbps to 2.5 Mbps 29/27 (7.4%) 0.31 dB
> 2.5 Mbps to 7 Mbps 19/18 (5.56%) 0.23 dB
> 7 Mbps 64/63 (1.58%) 0.07 dB
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.