Airspy HF+ with a USB hub

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aurgathor
Posts: 46
Joined: Wed Apr 25, 2018 8:14 am

Airspy HF+ with a USB hub

Post by aurgathor » Mon May 21, 2018 4:34 pm

Instead of a direct connection, I'm trying to plug the HF+ into a USB hub (a Radio Shack 4-port USB 2.0 hub with a 2.5A PS) and Win10 keeps telling me: "The last device you connected to this computer malfunctioned, and Windows does not recognize it"

The HF+ works fine when connected directly to the front USB port on the PC, I have not seen anything else not working with said hub before, so it's not something that is obviously broken.

Anyone seen the HF+ not working with USB hubs?

rtlsdrblog
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Re: Airspy HF+ with a USB hub

Post by rtlsdrblog » Mon May 21, 2018 10:44 pm

I've noticed that the HF+ sometimes has USB connection issues when I use long extension cables. How far away is the HF+ from the PC?

aurgathor
Posts: 46
Joined: Wed Apr 25, 2018 8:14 am

Re: Airspy HF+ with a USB hub

Post by aurgathor » Tue May 22, 2018 3:12 am

Extension cables are a little different since they have a length limit (15ft) plus some possibly significant voltage drop due to the HF+'s nearly 400 mA current consumption.

In any case, the cable between the hub and the PC is 10ft long, and the cable between the hub and the HF+ is 3ft. Will look into this more tomorrow.

rtlsdrblog
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Re: Airspy HF+ with a USB hub

Post by rtlsdrblog » Tue May 22, 2018 10:37 pm

There's also timing requirements that can get messed up with longer cables, although 10ft should be in spec. But since the HF+ transfers very high amounts of data, maybe it could be causing problems.

You might want to try asking on the airspy.groups.io forum, or on freenode IRC #airspy, as you'll find all the HF+ users hanging out there.

aurgathor
Posts: 46
Joined: Wed Apr 25, 2018 8:14 am

Re: Airspy HF+ with a USB hub

Post by aurgathor » Thu May 24, 2018 4:12 am

Hubs should alleviate the issues of longer cables as long as each segment is 15ft or less.

In any case, after some more testing this seems to be a case of a real or perceived overcurrent by the hub.
1. looks to me the HF+ is tripping the overcurrent protection of the hub, but I don't know if the hub is tripping on an under 500 mA current or on an over 500 mA current. Better hubs send a message to the host so the OS can display what happened, but this doesn't appear to be the case with this hub.
2. the HF+ may have a significantly higher in-rush current than I can measure with my cheap USB meter (380 mA).

Unfortunately I do not have access to a current probe, so I do not know who is at fault, but I think the hub is a somewhat more likely culprit. I know from past experience that USB ports on mobos can be much more forgiving than some hubs in this respect. Not sure if they just allow more current, or just don't trip on short spikes.

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