TM 11-5820-803-12
Figure 2-15. (Eb/No) as a function of signal/noise meter reading.
2-11. Special Applications
(2) The bit-error rate performance with
external coding depends upon the type of external
a. The PSK modem input and output digital user
coder/decoder used.
interfaces are compatible with each other. The interface
signals normally connected to a digital user may be
(3) The PSK modem may be used in
connected directly to another PSK modem to implement
conjunction with other than rate one-half coder/decoders;
a ground relay configuration, as shown in figure 2-17. If
e.g, a rate three-fourths coder/decoder. In this case,
the two earth terminals are widely separated, the PSK
however:
modem may also be interfaced with another PSK
(a) The coder section must be capable
modem over a shielded cable or a line-of-sight (LOS)
of operating with only one clock input at the input data
microwave link.
For detailed information on cable
rate, and must produce an output clock at the output
interface, refer to paragraph 2-9 b. All coding options
symbol rate.
may also be used in a relay configuration.
(b) The decoder section must be
b. In the external coding mode, the PSK modem is
capable of operating with only one clock input at the
intended for normal operation with an external rate one-
symbol rate, and must produce an output clock at the
half Viterbi coder/decoder (KY-801/GSC). However, the
output data rate.
modem may be used in conjunction with other types of
(c) The
PSK
modem
operating
coders/decoders, within the following constraints:
procedures must be revised to reflect the appropriate
(1) The interface levels (line drivers and
data rate to symbol rate relationship.
receivers) must be compatible (see paragraph 2-6 for
further information on interface levels).
2-16
