Sensitivity to long USB cable?

Post your feedback here
G4OAV
Posts: 4
Joined: Wed Sep 02, 2015 3:06 pm

Sensitivity to long USB cable?

Postby G4OAV » Wed Sep 02, 2015 10:21 pm

I'm about to set up my sdrplay and wan't to operate the PC 20m from my antenna cable termination. My question is can I run the SDR at the end of an extended USB cable, possibly using a Cat5 Ethernet cable extender? I have been using a Winradio (HF) for some time on a short USB cable and that works fine with a display bandwidth up to 30MHz. Is Sdrplay particularly sensitive to USB connection at 8MHz width?

Regards

Stan Ames
Last edited by G4OAV on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

Sideteacher
Posts: 7
Joined: Mon May 04, 2015 8:47 am

Re: Sensitivity to long USB cable?

Postby Sideteacher » Fri Sep 04, 2015 9:00 am

I am not sure how you can use a Ethernet cable extender to extend USB cable runs, unless you are talking about using a USB over Ethernet type device? Can you expend on this idea a little as I am not sure I follow your trail of thought.

In terms of extending USB cable runs the USB 2.0 specification for high speed devices limits cable runs to a maximum of 5m. In order to go further than this you would need to use powered USB hubs to act as signal repeaters or an active USB repeater cable, which is basically a single port hub. Again the USB specification limits the maximum number of hubs in any one run to 5 so that’s around 30m of distance covered. The chip set we use is USB 2.0 compliant and so the USB performance will have been tested to be compliant against this specification. The main problem you are going to encounter in doing this will be its effect on the radio performance. By extending the USB cable run you are increasing the distance between the radio and its natural ground return which is through the USB connector. In this respect it is like adding a large antenna to your ground return and I would expect this too have some impact on your sensitivity performance and the amount of pickup you are going to get. You might be able to experiment with locally grounding the device at the antenna end or adding some ferrites to isolate the ground return currents which may help your performance. You are more likely to be successfully at the lower frequencies rather than the higher frequencies with this approach. Generally speaking I would recommend sticking to a shorter USB cable length if at all possible

You might want to open this question up for discussion on the facebook page. I think there were some people playing around with remote PC’s and streaming the data over Ethernet.
Last edited by Sideteacher on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

GalloCosta
Posts: 2
Joined: Sun Aug 16, 2015 10:13 am

Re: Sensitivity to long USB cable?

Postby GalloCosta » Sat Sep 05, 2015 11:30 am

I am using a 10m active USB cable (cheap on Ebay) + the 2m connection from the cable's end to the SDRPlay and that works perfectly fine.
Last edited by GalloCosta on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

m0phe
Posts: 7
Joined: Thu Aug 13, 2015 6:54 pm

Re: Sensitivity to long USB cable?

Postby m0phe » Sat Sep 05, 2015 8:28 pm

"I am using a 10m active USB cable"

Interesting to know. I'll give it a go.
Last edited by m0phe on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

G4OAV
Posts: 4
Joined: Wed Sep 02, 2015 3:06 pm

Re: Sensitivity to long USB cable?

Postby G4OAV » Wed Oct 14, 2015 10:47 am

Firstly sorry for the delay in replying.
Thanks for the replies, they are very helpful. I was thinking of using the system that employs a length of Cat 5 cable with usb converters at each end. There are some that claim to be USB2. The aerials terminate in my "shack" one side of the house and my office, where I would like to be able to monitor the SDRplay, is on the other side. I already have a an Ethernet connection between the two which makes the usb converters desirable. They are not hugely expensive so I might just suck it and see! I will report back but any other suggestions would be welcome.

I suppose another solution would be to use "team view" that allows one pc to remotely operate another.

Stan
G4OAV
Last edited by G4OAV on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

G4OAV
Posts: 4
Joined: Wed Sep 02, 2015 3:06 pm

Re: Sensitivity to long USB cable?

Postby G4OAV » Fri Nov 06, 2015 6:58 pm

Further to my earlier message I have tried the standard USB over Cat5 cable extender and it does not work. I'm thinking that it might not be a matter of data transfer speed but power available at the far end to operate the SDR, the two converters that are likely to draw a little current. I have found a cheap 30m "active" USB2 extender cable and several quite expensive USB2 over Cat5 devices. I would be very interested to hear if anyone else has solved this problem.

Stan Ames
Last edited by G4OAV on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

G4OAV
Posts: 4
Joined: Wed Sep 02, 2015 3:06 pm

Re: Sensitivity to long USB cable UPDATE

Postby G4OAV » Mon Nov 30, 2015 11:35 pm

I have tried a version if the USB2 over Cat5 cable adapters which has an external power supply at the end remote from the PC. I found that this worked after a fashion but the FM audio was very noisy and unreadable, the AM audio was only slightly better. My next move is to try a screened network cable with earthed connectors at each end.

I would be interested to hear of any further experiences.

Stan
G4OAV
Last edited by G4OAV on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

k1xd
Posts: 2
Joined: Thu Feb 02, 2017 5:08 pm

Re: Sensitivity to long USB cable?

Postby k1xd » Thu Feb 02, 2017 5:20 pm

Stan (or others)...

I wonder if you tried a screened (shielded) cable as you mentioned. I want to try a similar setup here. The SDRPlay works great, but... it picks up locks of junk from network cables, HD TV and a multitude of interfering devices in my home. I attempted to add noise suppression devices...relocate things, etc.. My conclusion is that it's easier to move the antenna away from the house. I did this with my HF loop antenna. It's now about 75 feet from the house and spurious junk is almost non-existent.

My thought is now to tackle the VHF-UHF region. I have a discone antenna and would like to locate on top of my detached garage.. probably about 150-200 foot cable run. I could locate the SDRPlay in the garage and extend the USB as you tried or run Coax (low-loss---expensive).

Any thoughts?

Dave
K1xd
Last edited by k1xd on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

jon
Posts: 260
Joined: Tue Jan 06, 2015 10:48 am

Re: Sensitivity to long USB cable?

Postby jon » Fri Feb 03, 2017 8:58 am

The only worry about very long coax lengths at VHF and above is that the losses in the cable become more significant, the higher the frequency - this table illustrates the numbers involved - http://www.w4rp.com/ref/coax.html

Reason: No reason

k1xd
Posts: 2
Joined: Thu Feb 02, 2017 5:08 pm

Re: Sensitivity to long USB cable?

Postby k1xd » Fri Feb 03, 2017 12:57 pm

My thought was to use a long USB cable (150 feet) rather than coax and locate the SDRPlay basically at the antenna. If I use coax, LMR400 or LMR600, the loss is not too bad, but price is way more than shielded CAT6.

Dave
K1xd
Last edited by k1xd on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason


Return to “New Users' experiences”

Who is online

Users browsing this forum: No registered users and 1 guest