Question about USB and using long USB cables

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Discussion Overview

The discussion centers around the latest USB standards, specifically USB 3.0 and USB 3.1, and the feasibility of using long USB cables, particularly in the context of applications like telescope control. Participants explore the limitations of cable lengths, the use of hubs and extenders, and the implications for performance and power delivery.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants confirm that the latest USB standard is USB 3.1, with speeds of 10 Gbit/s, while USB 3.0 offers 5 Gbit/s.
  • There are claims that USB cables can be found in lengths of 4m or longer, but some participants note that standard USB cables have a limit of 5m, with the possibility of extending this with active cables.
  • One participant suggests using a USB hub with a separate power supply to extend cable length using two shorter cables.
  • Another participant mentions the use of USB extenders that convert USB signals to other formats (like CAT5) for longer distances, although these may not deliver power.
  • There is a discussion about personal experiences with USB cable lengths in practical applications, such as controlling telescopes from a distance.
  • Some participants express concerns about maintaining bandwidth and stability when switching from USB to WiFi for telescope operation.

Areas of Agreement / Disagreement

Participants express a mix of agreement and differing opinions regarding the maximum effective lengths of USB cables and the use of hubs or extenders. The discussion remains unresolved on the best practices for achieving long-distance USB connections while maintaining performance.

Contextual Notes

Limitations include varying definitions of "long" USB cables, potential discrepancies in performance based on cable quality, and the impact of using hubs or extenders on power delivery and data integrity.

yungman
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Hi

I have not been keeping up with the latest USB standard, is the latest one USBIII? What is the speed of this?

Also, I want to run a USB cable at least 4m long, do they have USB cable that long and still work for the fastest USB standard?

I know in the past, even for USBII, there is a limit for how long the cable can be. Say if I cannot find a 4m long USB cable, can I use a Hub to serve as a repeater so I can use two short cables with a Hub in the middle to extend the length. Matter of fact, use more than one Hub to further extending the distance.

Sorry about all these questions, someone asked me about this, I never have to use a long cable before and I don't want to give out wrong info.

Thanks
 
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yungman said:
I have not been keeping up with the latest USB standard, is the latest one USBIII? What is the speed of this?
Yes, the last one is USB 3.1 (10Gbit/s). You also have USB 3.0 (5Gbit/s). Some marketing people name them USB 3.1 gen. 2 and gen.1.
yungman said:
Also, I want to run a USB cable at least 4m long, do they have USB cable that long and still work for the fastest USB standard?
Yes, there are USB cables that long for USB 2. I have found USB 3 cables that are 3m.
yungman said:
can I use a Hub to serve as a repeater so I can use two short cables with a Hub in the middle to extend the length. Matter of fact, use more than one Hub to further extending the distance.
Yes, if you get a hub with a separate power supply.
 
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For very long USB connections it might be better with a so called 'USB extender'. These are turning the original USB to something else (CAT5 or better) and back at the other end. Usually they can't deliver power.
Random product page from the internet (up to 10km!)
 
My understanding is that 5m is the limit for a standard USB cable and you can go 5m more with an active extension cable. That's how I control my telescope from my couch.
 
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russ_watters said:
That's how I control my telescope from my couch.
YOUR COUCH!

Russ, you just destroyed my image of dedicated amateur astronomers braving the elements and mosquitoes all night to capture that elusive image.:smile:
 
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russ_watters said:
That's how I control my telescope from my couch.

anorlunda said:
YOUR COUCH!

Russ, you just destroyed my image of dedicated amateur astronomers braving the elements and mosquitoes all night to capture that elusive image.:smile:
But of course Russ is now behind the times :wink: and us truly dedicated amateur astronomers use WiFi for remoter scope operation ...

https://astronomy-imaging-camera.com/product/zwo-asiair
These things are so cool :smile:

Dave
 
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anorlunda said:
YOUR COUCH!

Russ, you just destroyed my image of dedicated amateur astronomers braving the elements and mosquitoes all night to capture that elusive image.:smile:
I do like to think of myself as pretty hardcore still...

Couch Astrophotography.jpg


It can be a rough 15 minutes setting up if it is cold outside at least.

Note: in this room/furniture configuration I'm close enough for just the one USB extension cable, which you can see hanging off the side of the white box under the scope (the shiny black thing is some sort of active female socket). I said above you're limited to 10m and 2 cables, but that may not be strictly true: the white box houses a standard USB hub with a 1m cable - the grey cable sticking out the back. So when I use two 5m cables I'm really at a total of 11m and I've never had an issue. I can't remember though if I've done that since I switched to USB 3.0.

davenn said:
But of course Russ is now behind the times :wink: and us truly dedicated amateur astronomers use WiFi for remoter scope operation ...

https://astronomy-imaging-camera.com/product/zwo-asiair
These things are so cool :smile:

Dave
Yes, very cool. I hadn't actually seen that one before, but I'll definitely consider it. My main concern though is if I'll still get the same bandwidth and stability as with my current USB3 setup. I do some processing on the fly so I really want the raw images on my laptop immediately. But there's a clear benefit; I'd like to be able to say I've never kicked/pulled out the long USB cable while imaging...
 
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