RTL-SDR troubleshooting: busy sticks, dropped samples and overload

Most RTL-SDR trouble falls into a few groups. The app’s messages name the group; here is what to do about each.

The stick is not in the browser’s list

• Check the browser: Chrome, Edge or Opera on a computer, Chrome on Android. Safari and Firefox have no WebUSB and say so on the connect card.
• Try another USB port and cable, without a hub. On Android, check the OTG adapter and try a powered hub.
• The list only shows RTL2832U sticks with the usual USB IDs. A stick that reports something else will not appear.

“Windows is using its TV driver for this stick”

The browser can see the stick but cannot open it. Install WinUSB with Zadig as described in getting started, then plug the stick back in.

“The stick is busy”

Another program, or on Linux the dvb_usb_rtl28xxu kernel driver, has the stick open. Close rtl_tcp, GQRX, SDR++ or any other SDR program, or blacklist the kernel driver (the error offers to copy the command), then try again. Only one program can use the stick at a time, and that includes a second browser tab.

Dropped samples

If the stick or the USB link cannot keep up, the stream loses samples: audio stutters, the status strip shows how much is lost, and a message offers a lower sample rate. Run Device info and USB test to see which rates your stick and port really manage. Above 2.56 MS/s many sticks drop data; 1.8 to 2.4 MS/s is safe on most. A busy computer, a slow hub, a long passive extension or a USB isolator can all cause it. Note that USB isolators built on the common ADuM3160 chip are full-speed only and cannot carry the stream at all.

Overload

The Overload badge means the stick’s converter is clipping. Lower the gain, or set it to Auto. If one strong source keeps doing it, usually FM broadcast or a nearby transmitter, a band-stop filter for that band works better than less gain everywhere. Moving the antenna away from the source helps too.

The stick disconnected

A loose cable, a hub that runs out of power or a revoked permission stops the stream. The app shows when it happened and keeps your settings and bookmarks; a recording that was running is saved up to that moment. Plug the stick back in and press Reconnect: the app looks for the same stick and opens it in the same mode.

“RTL2832U found, tuner not recognised”

The stick answered but its tuner is not an R820T, R820T2 or R828D. Continue with basic mode gives you the spectrum and recording at a fixed gain, without tuning or gain control. Sticks with an E4000, FC0012, FC0013 or FC2580 tuner end up here. Copy details collects what the app saw if you want to report it.

Noise everywhere

A raised noise floor across the whole spectrum is usually local interference, not the stick. Put the stick on a USB extension, away from the computer and its power supply, try a ferrite on the USB lead, and move the antenna outdoors or at least away from screens and chargers. Turn on Remove DC spike under Source if a spike sits at the centre of the spectrum.