Aky dlhy usb kabel?

[T@poX]

Chcem spojit dva Pc pomocou usb zariadenia. Su od seba cca 150 m priama viditelnost. Podporuju Ad-hoc cize AP mi netreba, ale potrebujem jednu tu usb srandu dostat dalej od pc tak cca 6 - 10 m. Zaujimalo by ma ci sa to da Existuje nejaky usb predlzovaci kabel a ak ano tak aky dlhy moze byt

[Jezevec]

Jo, do 10ti metru by to melo fungovat.

[simhap]

Osobne jsem se setkal s pasivnimi prodluzkami max. 5 m. Cokoli nad uz byly jen aktivni za pomerne dost penez (1000+ Kc). S aktivni prodluzkou lze dosahnout az 25 m. Nikdy jsem ale nezkousel treba spojit dve pasivni prodluzky co by to udelalo.

Norma pripousti max. 5m pro USB 1.1 a max. 3m pro USB 2.0 (resp. pro jeho max. rychlost). Pomoci aktivniho prodlouzeni lze dosahnout az 25 m.

Vice treba na oficialni strance USB.ORG...

Q3: Why can't I use a cable longer than 3 or 5m?
A3: USB's electrical design doesn't allow it. When USB was designed, a decision was made to handle the propagation of electromagnetic fields on USB data lines in a way that limited the maximum length of a USB cable to something in the range of 4m. This method has a number of advantages and, since USB is intended for a desktop environment, the range limitations were deemed acceptable. If you're familiar with transmission line theory and want more detail on this topic, take a look at the USB signals section of the developers FAQ.

[T@poX]

Osobne jsem se setkal s pasivnimi prodluzkami max. 5 m. Cokoli nad uz byly jen aktivni za pomerne dost penez (1000+ Kc). S aktivni prodluzkou lze dosahnout az 25 m. Nikdy jsem ale nezkousel treba spojit dve pasivni prodluzky co by to udelalo.

ze sa tak blbo pytam ale mozes mi vysvtelit rozdiel medzi pasivnou a aktivnou predlzovackou

[simhap]

Osobne jsem se setkal s pasivnimi prodluzkami max. 5 m. Cokoli nad uz byly jen aktivni za pomerne dost penez (1000+ Kc). S aktivni prodluzkou lze dosahnout az 25 m. Nikdy jsem ale nezkousel treba spojit dve pasivni prodluzky co by to udelalo.

ze sa tak blbo pytam ale mozes mi vysvtelit rozdiel medzi pasivnou a aktivnou predlzovackou

Aktivni prodluzovacka vyuziva napajeni z USB root hubu pro casovou synchronizaci a upravu elektrickych parametru usb signalu (napetove urovne), proste je na jednom konci takova krabicka .

[Jezevec]

Jednoduseji receno, je tam "zesilovac". , ale podobne jako u site by to melo jet s nejakou rezervou. Za rychlost nerucim.

[simhap]

No chtel jsem jen rici, ze takovy kabel proste nekoupi a bude si ho muset udelat. Ted jsem koukal na to trochu podrobneji a upravil bych tvrzeni s temi peti metrama pasivni prodluzky. Nejdelsi co jsem v ceniku nasel tak je 2m (A-male na A-female), 5m je jen klasicky USB kabel A-male na A-male. Takze asi nejjednodusi je koupit 5m klasickej USB kabel a k tomu 2m prodluzku a zkusit to . Celkem by me to zajimalo, tak dej vedet jak jsi dopadl

[simhap]

Jednoduseji receno, je tam "zesilovac". , ale podobne jako u site by to melo jet s nejakou rezervou. Za rychlost nerucim.

Podle developer fora na USB.org je vylouceno dostat se nad 5m bez regenerace timingu, 5 metru je max a prodlouzeni byt jen o 5 cm uz ma za nasledek nefunkcnost.

1. Why are there cable length limits, and what are they?

A: The cable length was limited by a cable delay spec of 26ns to allow for reflections to settle at the transmitter before the next bit was sent. Since USB uses source termination and voltage-mode drivers, this has to be the case, otherwise reflections can pile up and blow the driver. This does not mean the line voltage has fully settled by the end of the bit; with worst-case undertermination. However, there's been enough damping by the end of the bit that the reflection amplitude has been reduced to manageable levels. The low speed cable length was limited to 18ns to keep transmission line effects from impacting low speed signals.

2. I want to build a cable longer than 5 meters, why won't this work?

A: Even if you violated the spec, it literally wouldn't get you very far. Assuming worst-case delay times, a full speed device at the bottom of 5 hubs and cables has a timeout margin of 280ps. Reducing this margin to 0ps would only give you an extra 5cm, which is hardly worth the trouble.

[T@poX]

Dufam ze sa k tomu dnes dostanem, ak ano tak zajtra napisem ako to dopadlo.. Keby to nahodou neslo, ako by sa to dalo potom zosietovat. Staci kupit nejaku wifi sietovku + extrenu antenu Ako som pisal vysie vzdialenost je okolo 150 m len je potrebne antenu vyviest trochu vyssie aby bola priama vidielnost...

[Gappa]

My máme USB WiFi adaptér na 5+m kabelu a funguje to.
Je tam 5m kabel z adaptéru + další prodlužka - teď ale nevim kolik měří , ale každopádně je to delší než 5m, to vim na beton.