Performance

The S-TEC™ codec is based on a serial concatenation scheme and it achieves excellent performance for a wide range of modulations. It can be programmed for various delays and can be used in a secure point to point satellite link. The user can select small (2,520 bits), medium (10,080 bits) or large (20,160 bits) block sizes depending on the required performance. These default block sizes can be changed to any other custom defined length. The larger the block size, the lower the operating point for a target bit error rate (BER). The table below shows the typical operating point, Eb/No [dB], for large block sizes, required to achieve BERs of around 1E-9, function of the selected modulation and coding rate:

 
Coding rates
  
Modulation
 1/2 3/5 3/4 4/5 5/6 6/7 7/8 8/9 9/10 10/11 11/12 12/13
BER curves
QPSK
1.5
2.2
2.9
3.4
3.9
4.4
4.7
5.0
5.4
5.8
6.1
6.5
QPSK
8QAM
3.4
4.3
5.2
5.9
6.3
6.9
7.5
8.1
8.5
8.8
9.2
9.9
8QAM
8PSK
3.4
4.3
5.4
6.1
6.6
7.1
7.9
8.5
8.8
9.2
9.5
10.2
8PSK
16QAM
4.1
5.3
6.2
7.0
7.5
8.1
8.6
9.0
9.4
9.8
10.6
11.1
16QAM
Note: These values are measured in a 70 MHz loopback benchtest environment.

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The performance of rate 1/2 coding is the best in the market in similar testing environment. The outstanding performance of 16QAM over nonlinear channels allows bandwidth efficient satellite links of 2 bit/s/Hz at ~4 dB.
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