Длина кабеля для соединения двух устройств по шине USB 2.0 может составлять не более 5 метров.

скорость максимальная ~30мбит

Но уж поверь, на 2м USB-кабеля и 1.5 вольта не затухнут

Википедия не пруф, увольте.

Да, видимо в Институте Радиоэлектроники им В.А. Котельникова РАН одни дибилы работают - один Вы умный...

В твоем компе, уж поверь, не будет 480мбит USB выдавать. Примерный Максимум я назвал.

Повторюсь - не верите, осциллограф в руки и вперед!

Странно у меня около 45мб/с выдает при копировании фаила в 5гб без проблем а это уж никак не сказанные мах ~30мбит (те 4мб/с)
+ не забывайте что таже видимая скорость копирования всегда ниже реальной скорости передачи данных по шине

Хорошо раз не вики то вот такой пруф про затухание устроит ? www.ruscable.ru/info/lan/LAN-el.html

Сами цифры подставите ? таже витая пара же ...
(особое внимание на Переходные затухания)

А ничего что витая пара не от нечего делать сделана ВИТОЙ парой?

Излучение протяженного квадруполя вам, эникейщикам, о чем-нибудь говорит?

Q1: How long of a cable can I use to connect my device?
A1: In practice, the USB specification limits the length of a cable between full speed devices to 5 meters (a little under 16 feet 5 inches). For a low speed device the limit is 3 meters (9 feet 10 inches).

Q2: Why can't I use a cable longer than 3 or 5m?
A2: 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.

Cables and Long-Haul Solutions

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.

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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.

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3. What about using USB signal repeaters to make a cable longer than 5 meters?

A: Don't bother. The best solution is self-powered hub with a fixed 10m cable that had a one-port bus powered hub in the middle. The maximum range will still have to deal with the timeout, so any out of spec tweaking of the terminations between the two hubs and the timing budget still won't yield more than 5cm of extra distance. A better solution is described in the following question.

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4. I really need to put a USB device more than 30 meters away from my PC. What should I do?

A: Build a USB bridge that acts as a USB device on one side and has a USB host controller at the other end. Use a long-haul signaling protocol like Ethernet or RS-485 in the middle. Using cables or short-haul fiber, you can get ranges upwards of a kilometer, though there's no reason why the long-haul link in the middle of the bridge couldn't be a pair of radio transceivers or satellite modems.
Embedded host solutions capable of doing this already exist. Also, two PCs connected via USB Ethernet adapters are essentially a slave/slave version of this master/slave bridge.

Сигнал в кабеле не ЗАТУХАЕТ, а ИСКАЖАЕТСЯ.

Иначе б на сетевых картах еще б и дальность писали

Наверное я тебя сильно удивлю, но таки дальность у них есть - максимальная длина обычно около ста метров, дальше сигнал затухает.

Зачем в шахту то?