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Do passive USB extenders (25ft) introduce more or less latency than a repeater cable?

S

Spellbinder2050

Junior Member
I'm trying to get my hands on a 25ft USB extender cable, along with an HDMI cable, to run from my PC in the room into the living room and then attach a USB hub to it, so I can use a wireless keyboard / mouse / PS4 controller to use on my LCD screen. I plan to do gaming with keyb/mouse, but also with the game-pad.

I'm getting mixed information. The spec for USB 2.0 says that setups beyond 5 meters (approx 16 ft 5in) will not work. It also says that "repeaters" beyond that spec will "regenerate the USB signal."

3 important questions about this:

1. When they say that USB is limited by 5 meters, are they talking about the power that can go through that cable or the data itself? (I don't really know how a USB cable works internally, but I'm assuming there's a data + power rail on it)

2. which aspect of whats traveling through the cable will be "regenerated" by a repeater?

3. Practically speaking, and in terms of input delay (latency), would I be better off with a 25 ft cable with or without a repeater if I plan to put a USB hub with 4 ports at the end of it?

What if I choose to only use the PS4 pad without a USB hub, which cable would be preferable?

Thanks to anyone who takes the time to read this. 🙂
 
1) The data. It's transmitted by a very high frequency signal. High frequencies are attenuated by long cables. Above a certain length, the data is attenuated so much that the receiver can't hear it.

2) The data.

3) A 25ft passive cable, assuming that the signal travels at 70% of the speed of light, will introduce about 36 nanoseconds of latency. That's so small it may as well be nothing. A repeater will introduce more latency than that, but I doubt it will be significant.
 
Mr Evil said:
1)

3) A 25ft passive cable, assuming that the signal travels at 70% of the speed of light, will introduce about 36 nanoseconds of latency. That's so small it may as well be nothing. A repeater will introduce more latency than that, but I doubt it will be significant.
Click to expand...

I've actually used a USB hub and there was perceivable keyboard and mouse delay. It was this one:

https://www.amazon.com/Targus-4-Por...0046TOQ8S/ref=cm_cr_arp_d_product_top?ie=UTF8

It could have been the quality of the hub.

I heard that repeaters act as a single USB hub. This is one of the reasons why I'm worried about using a repeater + a hub together.
 
As an engineering rule of thumb, signal delay is about 1 nanosecond per foot of wire.

Also, the USB spec talking about 5 meters is "official", but higher quality cables with larger diameter wire will be able to carry the signal further without degradation.
 
Last edited:
videogames101 said:
As an engineering rule of thumb, signal delay is about 1 nanosecond per foot of wire.

Also, the USB spec talking about 5 meters is "official", but higher quality cables with larger diameter wire will be able to carry the signal further without degradation.
Click to expand...

Is the signal delay irrespective to the technology used and based solely on cable length?

Because I'm now looking at USB to Cat5 (Ethernet cable) adapters. They have a greater maximum distance, but that would be irrelevant if the latency would be the same or higher (if I use a longer cable).

A USB to Ethernet adapter, 25ft Ethernet cable, and USB hub would seem to have less input delay than a 25ft USB cable with a HUB and no repeater.
 
Maybe try this one from monoprice.com ... $8.71

http://www.monoprice.com/product?p_id=6149

61491.jpg
 
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