[IchMe]

Une expression du SNR moyen là

[Divico]

Hello,
De retour de la Toscane (Siena), je reprends au vol le topique.

Lignes mouillées

Mon information est tirée du bouquin "Fundamentals of DSL Technology", Auerbach 2006 (P. Golden, H. Dedieu, K. S. Jacobsen). Voici un extrait du passage en question :

1.5.3 Potential Effect of Wetting Current on DSL

The moast obvious effect of wetting current on DSL is the need to add a DC current-providing feature at the line interface at the exchange DSL equipement. Furthermore, on DSL equipement at the customer end will need to be able to sink whatever DC current is determined necessary. It should be noted that wetting current does not need to be continuously applied; its benefecial effects can result when it is applied over relatively short periods [Beaumont 2001]. Indeed, most existing wetting current generators for older digital services have a "flash" feature that initialy pulses the loop with a high current value to clear splice oxidation [Reeve 1999]. The application of pulses rather than continuous current has clear advantages with regard to power consumption. Traditionally, levels of wetting current have been set between 6 mA and 20 mA. These current levels are predicted to limit the contact resistance of cooper contacts to around 30 Ohm and 10 Ohm, respectively [Beaumont 2001]. While it is applied, however, it may cause harmful noise in the transmission frequency spectrum, and changes in the contact resistance may alter the properties of the transmission path at a rate such that the DSL transmission is adversely affected [Beaumont 2001]. Hence, there is a compromise between the positive effect on the physical properties of the cable and the negative effect on the performance of the DSL. These issues are currently under study in DSL standardization commitees, and the use of wetting currant is currently an option in such symmetric DSL standards as ETSI TS 101 524.

Marge de bruit

LoiCiol a en fait donné la réponse à sa question :

[loiCiol]

[loiCiol]

[loiCiol]

[pilou254]

[pilou254]

Je reviens quand même à l'origine du sujet pour vous informer:
j'ai mis la boucle locale sous tension (53 v =) pendant plusieurs jours et je n'ai observé aucunes modifications, bonne ou mauvaise, de mes conditions de raccordement, qui ne tente rien ... A part ça, pour l'heure, je n'ai pas d'autres éléments à vous communiquer. Encore merci pour votre dévouement. A bientôt.