Satellite Internet forumiDirect Forum: hubs and terminals › 64APSK, 128APSK and 256APSK MODCODs for iDirect networks.

64APSK, 128APSK and 256APSK MODCODs for iDirect networks.

(Read 1414 times)
Jun 30th, 2022 at 9:09pm  
Network users of ST Engineering iDirect now have the opportunity to upgrade their Evolution® networks.

Using Universal Line Cards and new network software enables you to take full advantage of DVB-S2X efficiencies which include Adaptive Coding and Modulation (ACM) and up to 119 Msps in DVB-S2X forward carriers.

When you have high C/N, higher order MODCODs should be investigated, allowing 64APSK, 128APSK and 256APSK. These higher order modulation methods, combined with suitable FEC rates, substantially increase your bit rate for a given satellite transponder bandwidth. Since the system is adaptive this means that instead of having wastefully large C/N rain margins in clear sky you can increase the bit rate during clear sky. This also applies if you have transitioned to a more powerful EIRP satellite.

BPSK gives 1 transmission rate bit per symbol
QPSK  gives 2 transmission rate bits per symbol
8APSK gives 3 transmission rate bits per symbol
16APSK gives 4 transmission rate bits per symbol
32APSK gives 5 transmission rate bits per symbol
64APSK gives 6 transmission rate bits per symbol
128APSK gives 7 transmission rate bits per symbol
256APSK gives 8 transmission rate bits per symbol

With iDirect sharper roll off filtering your symbol rate increases towards the leased transponder bandwidth.

Your information bit rate is transmission bit rate x FEC ratio.

Contact you iDirect sales representative for more details.

More about Bandwidth, symbol rate, transmission rate and modulation method, fec rate and customer information rate.
Reply #1 - Jul 1st, 2022 at 9:33am  
I've just found the relevant technical brief document about iDirect DVB-S2X Evolution.

There is an excellent graph relating C/N and spectral efficiency (Bits per Symbol) and the improvement from going from DVB-S2 to DVB-S2X.

There is also a table showing the available modulation methods and FEC ratio options for each.

Download (pdf):
https://www.idirect.net/wp-content/uploads/2020/03/TechBrief-DVB-S2X-Evolution.p...

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