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10 feet / 3 meters USB extension cord

Posted: Wed Jul 11, 2018 10:23 pm
by Remon
Can a safely use 10 feet / 3 meters USB extension cord or will it cause problems? I want to use it in between my RTL-SDR dongle and my Raspberry Pi running rtl_tcp. My fear is it will generate buffer overflows.

I'm thinking of buying an USB 3 cable because these are rated for higher bandwidth.

Re: 10 feet / 3 meters USB extension cord

Posted: Tue Jul 17, 2018 2:57 pm
by Remon
I'm currently using my setup with the 10 feet / 3 meters USB3 extension cable without any problems.

Re: 10 feet / 3 meters USB extension cord

Posted: Tue Jul 17, 2018 5:02 pm
by snn47
It depends how cheap the extension cable is. The Data lines should work also for longer cable,
but depending on how much power is needed and how much resistance (how cheap) the power line wires are. It may or may not work, with one cable while it will not work with another. Unfortunately you cannot deduct from the diameter of a cable on the resitance, unless you measure it.
EIther use an active USB cable or add a USB Hub at the end to provide the power.

Re: 10 feet / 3 meters USB extension cord

Posted: Tue Jul 17, 2018 8:13 pm
by Username
I have an 30m extender Cable wo also work fine on my pc.

Re: 10 feet / 3 meters USB extension cord

Posted: Tue Jul 17, 2018 9:53 pm
by Remon
I'm using a passive cable. It's not that special or expensive: https://www.amazon.com/Valueline-male-U ... 00DC3L4GQ/

Re: 10 feet / 3 meters USB extension cord

Posted: Wed Jul 18, 2018 3:33 pm
by Username
I can recommend Cable from Delock the are cheap but there are better on the Marked Belkin did good one but I dont know if the still make it.

Re: 10 feet / 3 meters USB extension cord

Posted: Thu Jul 19, 2018 4:31 am
by snn47
@all Please be precise and specify if the cable you talk about are passive USB extension cables or have an active component/hub, possibly with chance to connect an external PS,
I have an 30m extender Cable wo also work fine on my pc.
is this a typo username, since I have never seen a USB cable of such length.

There is to my knowledge no standard that specifies USB cable quality, like resitance and signal loss of USB cable. However there is a limit for USB cable length, can't remember how long, which is to my knowledge for providing detectable signals at the end of the cable. The power wires should be adequate to rpovide the 5 V minus allowable tolerances at the end of the cable for upt to 500 mA current for USB 2 and 900 mA for for USB 3.
The resitance is the reason why with some short cable cable of <1m, HDD often don't work with a "thick (looking)" USB cable, while another thin cable (e.g. such as supplied for charging with cell phones) works. Manufacterer can at any time replace a "good" cable with a cheaper inferior cable when they choose to do so. Therefore recommendations for cable, even if a manufacterer number is provided are not necessarily a guaranty that the extension cable will work.

PS.: I saw a long time ago USB to LAN Adapter. Since LAN cable also employ twisted wire, they could be an alternative to using passive USB extension cable. I don't know for which purpose these LAN to USB adapter were made for. Has anyone looked into the differences between USB and LAN cable properties or knows what these adapters wer intended for?

Re: 10 feet / 3 meters USB extension cord

Posted: Thu Jul 19, 2018 8:15 am
by Remon
I will not recommend phone charging cables for SDR's since they have barely to no shielding.

Re: 10 feet / 3 meters USB extension cord

Posted: Thu Jul 19, 2018 10:04 am
by Username
https://www.delock.de/produkte/747_USB- ... kmale.html work with an ordinary SDR Dongle. :D

I will buy an Icron USB -> Fiber -> USB Adapter who is 100% isolated.

Re: 10 feet / 3 meters USB extension cord

Posted: Thu Jul 19, 2018 8:57 pm
by snn47
I will not recommend phone charging cables for SDR's since they have barely to no shielding.
I didn't propose to use such a cable, I was just trying to explain that cable diameter is not ameasure of resistance of the power lines.