Length of USB extender cables

[bogstad-e+AXbWqSrlAAvxtiuMwx3w at public.gmane.org (Bill Bogstad)]

On Mon, Sep 28, 2009 at 7:40 AM, Jerry Feldman <gaf-mNDKBlG2WHs at public.gmane.org> wrote:
> My wife has a TV tuner for he laptop, and she would like a longer USB
> cable. Currently her cable is either 2 or 3 feet. If I get a 6 ft or
> 10ft extender cable, would that cause problems with the tuner, or should
> I get an "active" cable? My gut feel is that a 6ft cable would work
> fine, but I'm not sure if a longer cable would cause problems or not.

I've used extender cables.  People who probably know
(http://www.usb.org/about/faq/ans5) say the following:

====
  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.
=====

If you have a powered (or unpowered) hub lying around you could try
that out first.  I've used both 15 foot cables and an unpowered hub
when I needed to put a printer on the other side of a room from a
computer.

Bill Bogstad