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I have a wireless adapter (antennae) that I need to connect to my computer which will be 20 feet away. The adapter comes with a 5 foot extension cable, which I assume to be a passive cable, and I am purchasing a 16 foot active USB extender cable.

What is the preferred sequence: active then passive or vice versa?

computer -> active -> passive -> antenna

computer -> passive -> active -> antenna

This related question shows that it is OK to chain these Can I use an inactive USB 3.0 extender in series with an active one?

and

http://www.yourcablestore.com/USB-Cable-Length-Limitations-And-How-To-Break-Them_ep_42-1.html#maxactive

  • What active "cable" exactly are you buying? If it includes electronics to proxy USB signals at both ends (which I'd assume), the order shouldn't matter. – dirkt Oct 2 '18 at 6:48
  • If you check your own links, you will see that the functionality of combination and order of cables depends on where the "active" part is residing. Yet you didn't submit any info about what kind of active cable did you get. – Ale..chenski Oct 6 '18 at 0:01
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It'll probably be fine either way.

Er, well... honestly, after thinking about it a bit... egg on face here... if you think about how USB connectors work there is really only one possible orientation, with the passive cable nearer the "antenna" (USB-WiFi adapter). The passive cable ends with a male "B" connector (the almost-square type), no? But the active extender cable has male and female "A" connectors (the flat rectangular type), so unless you use some nonstandard gender/type adapter it really can't go the other way.

BUT: If you did have the choice, it shouldn't matter. Whichever orientation you pick, the data flowing in one direction will arrive at its destination in better condition than data flowing in the other direction, because of the not-equal cable lengths.

Consider this case:

computer-16 ft cable-hub-5 ft cable-USB wifi adapter

(The "16 foot active cable" is really just a hub with only one port and an attached cable, so I've represented it that way. Also got rid of the arrows because everything is bidirectional)

Notice that data from computer to WiFi will arrive at the WiFi adapter just 5 feet after leaving the hub (where it's been re-transmitted). Whereas data from the WiFi, after being re-transmitted by the hub, has 16 feet of cable to get through. So it will experience 3x the attenuation, distortion, noise, etc. after the hub as will data moving in the opposite direction.

Either would probably work (assuming you could physically make the connections), but the net effect is not the same for both directions. If you want symmetric effects you have to have a symmetric setup, with equal cable lengths on both sides of the repeater.

added: Here's the "diagram" with the connector types and gender added:

computerAF-AM16 ft cable-hubAF-AM5 ft cableBM-BFUSB wifi adapter

  • This is nonsense. Active USB extensions are hubs -- they retransmit all data, and do not selectively "help" data flowing in one direction. – duskwuff Oct 1 '18 at 1:47
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    @duskwuff You are correct that the hub retransmits data from both directions. But, in e.g. the computer>active>passive>antenna case, data from computer to hub will arrive at the antenna just 5 feet after the hub. Whereas data from the antenna, after being re-xmtd by the hub, has 16 feet to get through. So it will experience 3x the attenuation after the hub as will data moving in the opposite direction. As I said, either will probably work, but the net effect is not the same for both directions. If you want symmetric effects you have to have a symmetric setup. – Jamie Hanrahan Oct 1 '18 at 4:38
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    @JamieHanrahan thank you. Your comment contains a lot of useful information, so maybe it would be helpful to include it in your original post? I +1d. – RMurphy Oct 2 '18 at 1:24
  • @RMurphy Good point! – Jamie Hanrahan Oct 2 '18 at 3:38
  • @RMurphy and I guess I should have added "...done." Thanks. – Jamie Hanrahan Oct 2 '18 at 19:44
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To avoid likelihood of link flakiness and associated frustration with likely unstable connection, I would strongly advise to ditch the passive extender and get a 20-25 ft active cable, as outlined in my older answer.

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