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Troubleshooting

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ralphl edited this page Aug 2, 2026 · 2 revisions

Troubleshooting

Common problems and the actual fixes. If you don't see your issue here, check the FAQ or open an issue.

SDR not detected

The Device dialog shows no devices, or your device isn't in the list.

Confirm the vendor driver works first. If rtl_test, hackrf_info, airspy_info, LimeQuickTest, etc. can't see the device, NyxScope won't either. See Hardware-Setup for vendor-tool instructions.

If the vendor tool works but NyxScope doesn't:

  1. Restart NyxScope. The Device dialog enumerates at app start; if you plugged the device in after launch, restart.
  2. Try a different USB port. USB 3.0 ports occasionally have driver-layer issues that USB 2.0 ports don't. Swap and retest.
  3. Check the cable. Charge-only USB cables look identical to data cables. A short, known-good USB cable rules this out.
  4. Run NyxScope as Administrator once to check for a permissions issue. If it works as admin but not normal user, the driver install needed admin and didn't get it. Re-run Zadig as admin.
  5. For SoapySDR devices: NyxScope bundles SoapySDR and the device modules — do not install them yourself. If you have PothosSDR or another system-wide SoapySDR stack installed for other software, it can shadow the bundled one on versions before 1.33.4 (or if the SOAPY_SDR_ROOT environment variable is set). Unset SOAPY_SDR_ROOT, update NyxScope, and only the device's vendor driver / API service should remain installed.
  6. SDRplay specifically: the device silently never appears unless the SDRplay API Service is installed and running (Services.msc → SDRplay API Service).

RTL-SDR stops working after Windows Update

Windows Update occasionally replaces the WinUSB driver Zadig installed with the original DVB-T driver Windows ships. The dongle reverts to its "fake TV tuner" role and NyxScope can't talk to it.

Fix: re-run Zadig and re-install the WinUSB driver. Takes 30 seconds.

To prevent recurrence (best you can do — Windows is going to Windows):

  • Set the dongle aside and don't plug it in until after an update.
  • Or use the device on a dedicated machine that doesn't get Windows-Updated frequently.

No audio

You can see the spectrum, the VFO shows activity, but no sound.

Check in order:

  1. Master volume. Top bar → master volume slider. Mute is a separate state.
  2. VFO mute. Each VFO card has its own mute toggle. Yours might be muted.
  3. Squelch. If squelch is set higher than the signal, audio gates. Lower squelch (left panel) or right-click the VFO → Set squelch to here.
  4. Mode. If the mode (NFM, AM, USB, LSB, WFM) doesn't match the signal, the demod produces silence or noise. Right-click the VFO → set the correct mode.
  5. Output device. Settings → Audio → Output device. Default is the Windows system default; if you've connected headphones since launch they might not be selected.
  6. DSD override active. If HD Radio or a digital-voice decoder is muting the analog FM path on this VFO. Look for HD/DSD indicators on the VFO card.

Scanner stuck on one frequency

The scanner stops sweeping and holds on one channel even though squelch should release it.

Likely causes:

  • Hold time too long. Right-click the scan range → Edit → Hold time. Default is 2 seconds; longer values keep you on a signal after squelch closes.
  • Auto-squelch mis-calibrated. Run Calibrate auto-squelch from the left panel — it samples the noise floor across the band and resets thresholds.
  • A protocol decoder is holding it. Trunking voice channels, pager monitor, ACARS, and similar "lock and decode" modes intentionally hold the SDR. Check the right dock for which decoder is active.
  • Skip list isn't catching this signal. If you've already marked the frequency as Skip but the scanner keeps stopping, the skip list might be storing an off-by-channel-step frequency. Right-click the locked frequency → Skip again to be sure.

P25 voice is garbled

P25 voice should be intelligible whenever NyxScope holds a sync (94–96% IMBE frame recovery on weak signals). If voice is garbled:

  • Radio slightly off frequency. The single biggest cause of "strong signal, garbled or no audio" on digital voice. 1.36+ corrects for this automatically (AFC); on older versions, measure and set the PPM correction in device settings.
  • Simulcast system on an old version. LSM/CQPSK simulcast P25 systems decode from 1.35 onward and need the system type on Auto. Before that they sync but never decode.
  • Check Phase 1 vs Phase 2. Look for the orange P2 badge in the Trunking dock. Phase 2 is more fragile to multipath, and Phase 2 voice is still being finished — see Trunking-Configuration for the honest status.
  • Encrypted call? Check for the lock icon. Encrypted audio is silenced, not garbled — if you're hearing garbled audio with the lock icon, the encryption detection is mis-firing on a flaky Crypto Control decode. Mark the system as default_encrypted=false if you know it's clear.
  • CC and voice channel coverage differ. The control channel reaches you but the voice channel doesn't. Try a higher-gain antenna or a closer site.

HD Radio: metadata works but no audio

nrsc5 was built without FAAD2 support. Metadata is plain text and decodes; audio is AAC and needs FAAD2 to decode. See HD-Radio-Setup → Metadata works but no audio for the fix.

Pager monitor isn't decoding

You started Pager Monitor mode, FFT channels are being discovered, but multimon-ng isn't producing FLEX/POCSAG decodes.

  • Check sample rate. Pager monitor negotiates the smallest sample rate (2.4M / 3.2M / 4.8M) that covers 80% of your band width. If your CPU can't keep up with 4.8M × 16 VFOs, decimation starves and decodes drop. Lower max VFO count or shrink the band.
  • Channel grid alignment. Channels snap to a 12.5 kHz grid by default. If the pager network in your area uses an offset grid (some do), you'll see strong FFT peaks but no decodes. Adjust channel grid in Pager Monitor settings.
  • FFT threshold too low. If too many noise peaks are tuning idle VFOs, real signals starve. Raise the threshold.
  • VFO preemption hits a pinned channel. Pinned frequencies don't get preempted. If you've pinned more channels than your max VFO count, the scanner can't tune new ones.

Verify pager decode is working in general by switching to Quick Mode → Pagers (a single dedicated band). If decodes happen there but not in monitor mode, it's a monitor-mode tuning issue.

ADS-B map is empty

Aircraft aren't showing up on the map.

  • Frequency: 1090 MHz (ADS-B) or 978 MHz (UAT). Make sure you're using Quick Mode → ADS-B or have a scan range covering 1090 MHz.
  • Antenna: 1090 MHz needs a 1090-tuned antenna (or at least an antenna with reasonable gain at that frequency). Generic wideband dipoles work poorly here.
  • Indoor reception: ADS-B is line-of-sight at the L-band. Indoor reception is unreliable. Move the antenna to a window or, ideally, outside.
  • Geographic coverage: in some areas, ADS-B traffic is sparse. Check FlightAware to see if there should be traffic right now.

rtl_433 silent or restarting

Symptom: ISM sensors not decoding even on a known-good frequency (433 MHz / 915 MHz), and the rtl_433 process keeps restarting every ~30 ms.

Cause (fixed in v1.25.0): rtl_433 25.02 and newer treat the -G flag as fatal even though the help text calls it "deprecated." NyxScope used to pass -G to enable extended decoders, which would crash rtl_433 immediately on the new version, causing a restart loop. NyxScope now discovers the starred protocols from rtl_433 -R help output and passes them as -R N instead.

Fix: update to v1.25.0 or later.

Verify your rtl_433 version: open a command prompt at src-tauri/binaries/ and run rtl_433-x86_64-pc-windows-msvc.exe -V. Should be 25.02 or later.

Still zero decodes on 433.92 with sensors you know are transmitting: update to 1.36. Two more causes were fixed there — the sample feed could slice the scan step so that 433.92 MHz sat outside the decoded passband, and rtl_433 25.02 exits silently when fed on stdin (NyxScope now feeds it over an internal rtl_tcp bridge instead).

Sidecar decoders silently dead (Aero / HD Radio / UAT)

On Windows 11 with Smart App Control (or a WDAC policy) enabled, unsigned helper programs can be blocked at spawn (OS error 4551). The app runs, but decoders that live in separate sidecar processes — Aero, HD Radio's nrsc5, UAT's dump978, and similar — produce nothing and log a spawn failure. Check Settings → About → logs for "os error 4551". Until the sidecars are code-signed, the workaround is allowing the app's install directory in Smart App Control, or running with Smart App Control off (it can only be disabled at Windows install time).

License won't activate / network unreachable

Symptom: license dialog shows "FCC API request failed: error sending request" or similar.

The endpoint is i-c.biz/api/v1. If you can't reach it:

  1. Confirm the Windows host can reach it — from PowerShell: 
    curl.exe -v https://i-c.biz/api/v1/heartbeat
    Should return HTTP 200 with JSON.
  2. Corporate firewall / proxy. If your network filters outbound HTTPS, ask IT to whitelist i-c.biz. NyxScope respects HTTPS_PROXY env var if you have an outbound proxy.
  3. Antivirus blocking unsigned binary. Some AV products block outbound HTTPS from newly-installed unsigned binaries. Add NyxScope's install directory to the AV's allow list.
  4. DNS: if nslookup i-c.biz fails, fix DNS first.

Offline behavior reminder: NyxScope never gates execution on network availability. The license validates from the signed key alone; the heartbeat is informational (revocation list refresh + update check). You can run NyxScope indefinitely offline — see the FAQ section on offline behavior.

App is slow / high CPU

Single-VFO use is typically under 5% CPU on a modern Intel laptop. 16 concurrent VFOs at 4.8 MHz can hit 45% on a 24-thread machine (the licensed tier allows up to 32). If you're seeing more than that:

  • Whisper transcription is the most expensive thing NyxScope does. Disable per-VFO transcription if it's not needed, or downgrade the model size in Settings → Transcription.
  • Pager monitor at 4.8 MHz × 16 VFOs is genuinely CPU-bound. Lower max VFOs or shrink the band.
  • Multiple SDRs — the multi-SDR backend is in place but each additional SDR roughly linearly adds CPU cost.
  • Waterfall FPS. Settings → Display → Waterfall FPS. Default 30 fps. Lower to 15 fps to save 5–10% CPU.

FCC / RadioReference lookup fails

Lookup from the right-click menu or Trunk Discovery returns an error.

  • FCC lookup requires the FCC ULS API endpoint to be reachable. If you see "error sending request for url," that's a network issue on the Windows host — see License won't activate above.
  • RadioReference lookup requires username + password + zip code in Settings → Lookup → RadioReference. Premium membership is required for the API. Without RR credentials, FCC ULS lookup still works.
  • Empty result vs. error: an empty result (zero matches) means the database has nothing in your tolerance window; that's not a bug. An error message means the request failed.

The endpoint URL is overridable in Settings → Lookup → FCC API endpoint. Point it at your own mirror or change the path if needed.

Still stuck? Open an issue with:

  • The exact error message
  • Your OS + NyxScope version
  • The SDR model and driver versions
  • What you've already tried from this page

Most "doesn't work" bug reports are missing one of these and we end up going back and forth. Include them up front and we'll be much faster.

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