Figure 2-4. PSK modem theoretical bit error rate performance for various coding configurations (best case performance).

TM 11-5820-803-12

maximum bit error rate, but the satellite will not support

d. However, should the digital user require a

any increase in the C/KT, then the following situation

minimum bit error rate of 1 x 10- instead of 1 x 10 ,

-3

exists. Operating with the same link parameters, the

operation with differential coding only would not provide

resulting Eb/No,, from figure 2-5 (for an effective C/KT of

an acceptable bit error rate. In this case, using the

55 dB and a data rate of 100 kb/s,) is now 5 dB.

internal coder/decoder would result in an acceptable bit

Referring, to the performance curves of figure 2-4 the

-6

error rate of 4.4 x 10 as indicated in figure 2-4.

resulting error rates for the various options are:

e. Assuming that the digital user's data rate is

-2.

-5

(1) Differential coding only

1.2 x 10

changed to 100 kb/s, that he still requires 1 x 10

2-5