Airspy Noise coming from USB ?

Hi there
IS there anyone that could eliminate the USB noise of the airspy ?
if yes can you describe what you have done ?

Im interested specially in using the receiver with internal antenna attached directly to it
in this setup it receive a lot of noise

Any solution is welcome
Thanks Forward
Ronen - 4Z4ZQ
Ronen Pinchooks (4Z4ZQ) WebSite

There is extensive discussion about this on the yahoo airspy group. Some have sanded down joining portions of the case and done other mods. I tried some and none had any effect. The quality of the cable used has been the biggest factor that I have seen.

My usual test for USB lead (or any lead) radiation is simply to grab tight hold of the lead and see if the received noise chages. If it does, it may indicate that adding a couple of ferrites could help. Indoor antennas are a major problem even without your own PC radiation as there is so much general noise radiated from power wiring, TV, lighting etc.
When I first got my Wellbrook loop aerial I tried to use it here in the shack, but the noise was crazy. As soon as I mounted it on the rear external wall of the house about 20 ft up all the noise vanished.

Thank you all for the info
May you point me on the yahoo group ? if possible by link ?
as for the noise when using internal antenna (it is not only a home problem it is every setup i use for portable (say on the field) when i make compartment to a VX7 radio with internal antenna at same place the difference is between a clear reception on the VX7 and totally no reception with the AirSpy
it is defenetly not a cable problem and ferite dont help I tried few good quality cable's none solve the problem and also inserted few ferites i suspect its a design problem
If there is anyone that can get the receiver working in good sensitiovity with internal antenna ill be more then happy to hear what have he done in order to do it
Thanks Forward
Ronen - 4Z4ZQ
Ronen Pinchooks (4Z4ZQ) WebSite

There are a few Airspy Yahoo groups but the one below is the busiest, and there's an alternate dedicated forum which is linked right off the website\

https://uk.groups.yahoo.com/neo/groups/airspy/info

Airspy Support | airspy.com

Mike

I haven't used the Airspy, but one of these on each end of the usb cable reduced the noise picked up by my HackRF & rtlsdr stick considerably. They come in a variety of sizes so you may want to measure the diameter of the usb cable you intend to use & order the appropriate size.

Amazon.com : URBEST®UF35B 5mm Inner Diameter Black Core Ferrite Cable Clip 10 Pcs : Car Electronics

You can actually get them for less on the Airspy.US website.

Voyager said:

You can actually get them for less on the Airspy.US website.

Click to expand...

$6.75 for 10 on Amazon vs $2.45 a piece on Airspy?

Ooops. Didn't notice they were 10 for that price. Pic only showed one. Sorry.

Hi Ronen,

I think this is not the typical use you would expect from such a device.

Any SDR used in a IT environment will radiate some amount of noise and carriers.
Even if it is made as clean as possible there is no way you will be able to eliminate all re-radiation or travelling of current through cable shields.

The only way I've been able to completely eliminate RFI from such a setup was to faraday-cage both SDR and Computer, replace the PSU's by transformer types, use extensive mains filtering and connect the SDR via a wifi server application to a client program.

There is a lot gained by using SDR but there are some inevitable compromizes too.
The antenna as far away as possible from computers and devices connected to it will always lead to much better results unless you are able to faraday cage everything (including monitor, mouse, keyboard, usb speakers, anything) connected to such a system.

73
Paul

Had the same problem with my RTL- SDR had to put the antenna out side........

Dear Paul
Thank you for the answer
I have made some tests and it looks like the problem is not the Noise radiated from the computer as i have mentioned that the noise is only start when i press the Play button (start) of the SDRSHARP
so i suspect that the noise is coming from the USB cable and entering directly to the antenna
since i Have replaced few cables and tried ferrite too and not much results i suspect that the noise travel (or even generated ) from the data line (after all 480MHZ 5V Square wave produce harmonics and noise that can exceed micro volts easily) and even with good EMI Filter in the receiver it pass to the antenna input
if thats the case i dont think that a farady cage is the solution because the noise that present inside the receiver on the USB data line is already there however i can make test and put the receiver inside metal box and see how the noise floor is
I know that some things done by few persons that reduced the noise
one of them is scrapping the paint and making the box more Electrical conductive and by that not allowing signals to enter the receiver not via the antenna
I also read that someone else put copper RFI tape on the USB connector shield inside the receiver and attached it to the ground and that also reduced the noise im looking for the actual ways that really solved the problem by peoples who did it and succeed and thats why i have asked it here to get the experience of the peoples that could eliminate (or reduce) the noise
As for SDR with Computer i have no experience with say FlexRadio or RFspace SDR but it looks to me that if there was a problem with them i would hear it already and i didnt hear peoples say that the receiver pick up noise
so i think that SDR can work with computer and give sensitive reception with internal antenna
honestly im quiet disappointed from the results with internal antenna the 10 MHZ wide was a big advantage but if i cant use it in the field then a regular receiver can do the job for me much better
and the receiver behave with external antenna is far from being good it tend to overload very quick
So i hope someone read it and could use the receiver with the setup i have and succeed to get reasonable results
73's
Ronen - 4Z4ZQ
Ronen Pinchooks (4Z4ZQ) WebSite

A "regular receiver" usualy *is* a farady cage, with all RF and CPU parts in the same enclosure.

Computers, USB ports, external devices in an IT system all have clocks and exchange data with high bandwidth. It is virtually impossible to eliminate all radiation. The RFI norms for these devices are way higher than our weak-signal wishes.

On every SDR system I've built, extensive measures were needed to seperate the IT system noise from the receiver.

Yes, some devices may cause more RFI than others.
The wider the sampling bandwidth the more chance for re-radiation.
Caging sometimes even makes things worse, by groundloop induced noise;
You solve RFI on one frequency but a new interference pops up on another.

RF is like water in a leaky drainage
That is the downside of SDR.