Datum Systems PSM-500L Manual de usuario descargar pdf (Pagina 4)

Datum Systems PSM-500, 500H & 500L VSAT/SCPC Modem Specification

Rev. 0.86

A-4

PSM-500 Series FEC Option Table Rev. 1.6 Firmware 0.72+

FEC

Type

Sel

(T)

FEC Type

Option

Sel

(O)

Code

Rates

Available

Sel

(C)

R-S

Option

Modulation Modes (see notes)

BPSK

QPSK

OQPSK

8PSK

8QAM

16APSK

16QAM

S-Tec 6 Any

0 1/2 0

" " " " "

Interleaver

3/5 1

" " " " "

Block Size

3/4 2

" " " " "

Option 0~4

4/5 3

" " " " "

5/6 4

" " " " "

7/8

Notes: 8QAM requires modem firmware version 0.72 and later. 8QAM with the S-Tec FEC is not

implemented yet.

16APSK modes not implemented yet, and will have added options available.

* TPC4k and TPC16 restrictions apply to that line and Code Rate only.

TPC4k M5 Mode Limits: Rate 1/2 = 2.46 Mbps, Rate 3/4 or 7/8 = 4.92 Mbps.

TPC4k CT Mode Limits: Rate 5/16 = 2.048 Mbps, Rate 21/44 = 3.2 Mbps, Rate 3/4 = 5 Mbps,

Rate 0.95 = 6.6 Mbps.

The Modulation Modes, FEC Types, Option and Code Rates plus Reed-Solomon selection form a

number completely defining that FEC Mode. The acronym for these 5 numbers is “MTOCR”.

Table 7 below shows the Spectral Efficiency of the above FEC modes in bits per Hz of occupied

bandwidth at the 3 dB occupied bandwidth point.

Table 7 – Spectral Efficiency vs. Modulation and FEC Code Rates.

Modulation

Bits/Sym !

BPSK

QPSK OQPSK

8PSK 8QAM

16QAM/16APSK

FEC Code Rate

Efficiency in Bits/Hz at 3 dB Bandwidth

5/16

0.3125 0.625** 0.9375** 1.25**

0.453

0.453 0.906 1.359 1.812

21/44

0.477 0.95 1.43 ** 1.91**

1/2

0.50 1.00 1.50 2.00

3/5

0.60 1.20 1.80 2.40

2/3

0.66 1.33 2.00 2.66

3/4

0.75 1.50 2.25 3.00

4/5

0.80 1.60 2.40 3.20

5/6

0.833 1.667 2.50 3.333

7/8

0.875 1.75 2.625 3.50

0.922

0.922 1.844 2.766 3.688

0.95

0.95 1.90 2.85 3.80

** These modes not available in any setting

Each of these FEC Types can operate up to the maximum 20 Mbps, except TPC-4K is limited to 5

Mbps and S-Tec Standard is limited to approximately 10 Mbps at all rates. The S-Tec High speed

version is capable of 20 Mbps or more in all modes.

The possible FEC operating modes has exploded in recent years because of the variety of

available and common FECs in use. The PSM-500 Series has many current modes and additional

ones in development. Below is a table showing the currently available modes depending on

modulation.

1 2 3 4 5 6 7 8 9 ... 31 32

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