strange Wi-Fi interference with SDR RTL dongles

[natedawg1604]

Hi there,

For some time I've been using an external Wi-Fi dongle simply to get internet from a wireless router. Specifically, the dongle is a TP-LINK TL-WN722N, which connects to a USB port. The Wi-Fi dongle is connected to a dual-boot HP machine, running Windows 7 and alternatively Kali Linux. With Windows 7, everything is fine.

However, when I run any type of SDR program in Kali Linux with my Wi-Fi dongle connected, my RTL SDR dongles get massive inference, such that no SDR program can be used with the Wi-Fi dongle running. When I run rtl_test -p, it generates constant errors about missing bits or whatever. And, I can't run OP-25 or GQRX while the Wi-Fi dongle is connected, due to the massive interference. As noted earlier, as soon as I unplug the Wi-Fi dongle, everything is fine. The weird thing is, I don't have these problems when I'm running Windows 7 and DSD+, FMP, Unitrunker etc.

Would it help if I installed another USB PCI card, so the Wi-Fi dongle could run on its own USB bus? Any suggestions would be appreciated...

-Nate

 

[j0atm0n]

just tossing out a few random thoughts ,( im not a pro at this by any means )
are both devices on the same internal buss ( hub or whatever its called ) ?
have you tried plugging one say in the back of the pc and other in front ,
sounds like maybe a os driver / configuration bug ,
since you state that everything runs fine under the windows 7 enviroment

 

[natedawg1604]

just tossing out a few random thoughts ,( im not a pro at this by any means )
are both devices on the same internal buss ( hub or whatever its called ) ?
have you tried plugging one say in the back of the pc and other in front ,
sounds like maybe a os driver / configuration bug ,
since you state that everything runs fine under the windows 7 enviroment

Yeah unfortunately all the USB ports on my computer (both front and back) are routed to a single bus (USB 2.0), I verified this with lsusb.

-Nate

 

[Project25_MASTR]

I'm just going to point this out…your wifi dongle transmits. The front end on RTL dongles is non-existent (nor is it on most 802.11 devices). RTL devices do t have any shielding against stray rf.

I'd try a NooElec metal enclosure for your RTL and separate the antennas some if you can.


Sent from my iPhone using Tapatalk

 

[M105]

Since no problem occurs when running Windows I think you can rule out RF interference. I would suspect you have a hardware conflict between the WiFi adapter and the RTL dongle when running Linux. Check for conflicts such as IRQ and memory space. One shotgun cure might be to uninstall the WiFi driver then reinstall it while the RTL dongle is also installed. The installer might detect the conflict and avoid it.

 

[natedawg1604]

Since no problem occurs when running Windows I think you can rule out RF interference. I would suspect you have a hardware conflict between the WiFi adapter and the RTL dongle when running Linux. Check for conflicts such as IRQ and memory space. One shotgun cure might be to uninstall the WiFi driver then reinstall it while the RTL dongle is also installed. The installer might detect the conflict and avoid it.

Yeah I would think RF interference, as such, couldn't be the issue if it works fine in Windows. Also I have a laptop a few feet away from the desktop machine with an internal wifi card, and that doesn't seem to cause problems with anything. I guess I'll try re-installing the wifi driver on the Linux side.

 

[natedawg1604]

Update: So, I found an unused router laying around (Linksys E2500) and flashed it with DD-WRT. This allowed me to put the Router in "client mode" (a special DD-WRT option) and use it as a wifi adapter. For whatever reason, the RF problems are now totally gone. Maybe it's because the wifi device is running on the Ethernet bus, or maybe the standard ath9k_htc driver I was using has some type of strange bug, not really sure.