Advantech AMT-73 - Link Budget Analysis and Eb;No (Viterbi and Viterbi R;S); Figure 5: Fec; Mode; Rate C

AMT-70/AMT-73/AMT-75 Installation and Operation
Mode Modulation Rates
Intelsat 308/309 BPSK, QPSK
OQPSKI / OQPSKQ
Rates:
½, ¾ and 7/8 are valid along with
the option of Reed-Solomon OFF/
219 or 126
Intelsat 310 8PSK Rates:
2/3 and again with the option of
Reed-Solomon OFF/ 219 or 126
DVB-S QPSK
OQPSKI / OQPSKQ
Rates:
½, 2/3, ¾, 5/6 and 7/8
DVB-DSNG 8PSK and 16QAM Rates
2/3, 5/6 8/9 in 8PSK and ¾ and
7/8 in 16QAM.
DVB-S2S QPSK, 8PSK, 16APSK Rates
¼, 1/2. 3/5 2/3, ¾, 4/5, 5/6, 8/9
DVB-S2N QPSK, 8PSK, 16APSK Rates
1/2. 3/5 2/3, ¾, 4/5, 5/6, 8/9, 9/10,
1/4
TPC4K PSK,QPSK, oQPSK, 8PSK
and 16QAM
Rate 4/5 and 3/4
TPC16K BPSK,QPSK, oQPSK,
8PSK and 16QAM
Rate 2/5, 3/5, 8/9, 7/8 and 19/20.
OM73 BPSK, oQPSK and QPSK
and NONE
NONE, 1/2 and 3/4
Figure 5: FEC / MODE / RATE Configuration Chart
3.2.3 Link Budget Analysis and Eb/No (Viterbi and Viterbi R/S)
46
There are many satellites available that operate in C or Ku Bands with different transmission
parameters (power, bandwidth, sensitivity, etc.); different tariffs for their use; different operational
requirements and under different regulatory environments. The link budget problem normally consists
of determining the optimum economic solution for the particular network requirements, given the
satellite parameters, the price for utilization of power and bandwidth and the operational restrictions
that may apply.
The link budget should always guarantee a minimum E
b
/N
0
for worst-case conditions, as a function of
the availability requirements of the network, typically resulting in a BER of 10
-7
.
The figure on the next page illustrates the minimum E
b
/N
0
required for different bit rates and code rates
for Intelsat Viterbi with and without Reed Solomon and the DVB-S and DVB-DSNG formatted Viterbi
with RS.
Onto this value must be added link margin; this includes rain margin, pointing loss, etc. For example, if
a -3 dB rain margin is added, the link will normally be operating at better than 10
-10
BER under clear sky
conditions. The figure also shows examples of the allocated bandwidth (or channel spacing) for each of
the carrier types.
Out-of-beam emission limits or downlink emission limits as defined by the regulatory environment in the
country where the network is being installed are also an issue: there may be a limit on the minimum or
maximum antenna size to be used.