Nom | Support | Langue | Disponibilité | Date d'édition | Prix | ||
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PDF |
Anglais |
Active |
01/01/2018 |
27,00 € |
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Détails
The purpose of this test is to measure bit error ratio (BER) of downstream (forward path) broadband telecommunications QAM signals. This procedure will address mainly pre-forward error correction BER results for 64- and 256-QAM.
It is important to rely upon both the pre-FEC and post-FEC BER results. In North America, most 64- and 256-QAM signals incorporate ITU-T J.83 Annex B FEC encoding. It is therefore important to reference the post-FEC result, but extremely dangerous to rely solely upon it. BER suffers from what is commonly known as a "cliff effect" in which the post-FEC BER remains error free up to a point and then begins to rapidly decline. Referring to the pre-FEC BER result can yield insight as to how much margin is available prior to reaching the cliff.
Informations supplémentaires
Auteur | Society of Cable Telecommunication Engineers |
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Edité par | SCTE |
Type de document | Norme |
Nombre de pages | 14 |
Remplace | SCTE 121 2011,SCTE 121 2006 |
Mot-clé | SCTE 121 2018 |