Reading the RTL-SDR status strip

With an RTL-SDR connected, a status strip runs across the receiver page under the header. It does the job the status panel does for the ATS Mini, but it says less about the signal and more about the link: is the stick there, does every sample arrive, is the input clipping. Each VFO’s signal level is in the VFO bar, not here. The strip updates quietly; only a recording’s start and save, and a warning about lost samples, are announced.

From left to right

Connection menu

A dot and USB while the stick streams. The stick’s name is in the button’s label and in Device info. Press it for Device info and Disconnect. When the stick is lost it reads Disconnected and offers Reconnect and Close the receiver. Playing an IQ file it shows the file name, with File info, Open another file and Close the file.

Frequency and mode

The active VFO’s frequency in the radio’s digit groups (145.500.000 MHz) and its mode.

RATE

The sample rate, which is also how wide a slice the stick captures. A new stick starts at 1.8 MS/s.

GAIN

AGC while the gain is on Auto, otherwise the manual gain in dB.

PPM

The frequency correction set under Source. A source without one, such as an IQ file, shows no PPM (and no GAIN).

Stream state

Stream OK, Dropping samples or No stream. On a desktop a small line beside it counts the loss: “0 dropped” while all is well, the share lost and the samples per second while dropping. While a file plays the word is Playing, Paused or Ended instead.

Lower to {rate}

Appears beside Dropping samples while the loss lasts. One press sets the lower rate it names.

Overload

A badge shown while the stick’s converter clips. Press it for what to do.

REC

Shown while a recording runs, with the time since it started.

Volume

The master volume for the whole receiver, with a mute button. Each VFO also has its own Mute in the VFO bar.

Logbook, Radio tools, UTC

The receptions you logged, the tools menu, and the time in UTC.

When the stream drops samples

The app counts the samples that arrive and compares them with what the sample rate promises. When fewer than 97 % arrive over two seconds, data is being lost between the stick and the tab, and the strip switches to Dropping samples. You hear it as stutter and see it as gaps in the waterfall. Once per stream and rate a message says “The receiver is losing samples at …” with a Use … button, and the strip keeps a Lower to … button while the loss lasts. Above 1.8 MS/s both propose 1.8 MS/s, the rate most sticks hold; at 1.8 MS/s or below they propose the next lower rate. The cost is a narrower capture.

If a lower rate does not help, look at the USB path: a hub, a long passive extension, a USB isolator or a busy computer. Troubleshooting goes through them, and Device info and USB test in Radio tools measures which rates your stick and port really manage.

The Overload badge

When more than about half a percent of the samples hit the converter’s limits, the strip shows Overload with the hint “lower the gain”. It goes away once clipping stays below a tenth of a percent for a moment. Press the badge for a short explanation and Gain settings…, which opens Source. Lower the gain, or set it to Auto. If one strong transmitter or FM broadcast keeps causing it, a filter in front of the stick does more than any setting; the workspace guide has more on gain.

REC and saving

While any recording runs, a scheduled one included, the strip shows REC and a timer. After you stop it reads saving… until the file is finished. The start and the save are announced once each. Recording and IQ files covers what gets recorded and where it goes.

Radio tools

The Radio tools menu at the right end holds Scanner, Decoders, Calibrate frequency (where the source can be corrected), Device info and USB test, Preferences (playing in the background, keeping the screen awake) and Keyboard shortcuts. Below 1280 px the Logbook moves into this menu as well. Items that need a streaming stick say “Connect the receiver first” until it streams.

On a tablet or a phone

Narrower screens drop fields. A tablet keeps the connection menu, the frequency, the rate and the stream state, drops GAIN and PPM, and adds a button for the side panel. A phone’s strip has no buttons at all: the frequency, the rate, a dot for the stream (with a word when something is wrong), the Overload badge and REC. On a phone, Radio tools, Device info and the Logbook are in the More sheet, the volume is in the Radio view, and the lower rate is offered by the message only.

To connect a stick in the first place, see getting started. For the keys that go with the strip, see RTL-SDR keyboard shortcuts.