Guide Station health

Station health

View > Station health. One button ("Check station") stops the receiver, retunes the radio over a few fixed bands, measures them, and lists plain advice. Code: core/src/sweep/station_health.cpp (analysis, plain logic, tested on synthetic sweeps in tests/sweep/test_station_health.cpp), app/panels/station_health_ui.cpp (window, worker thread, report text in the interface language).

What it measures

Item	How
Noise floor per band	the sweep scanner's floor (median of the hop floors) on FM 87.5-108, airband 118-137, VHF band III 174-240, UHF 470-694, 868 ISM and ADS-B 1080-1100 MHz; bands outside the radio's range are skipped
ADC level and clipping	rms, peak and the fraction of samples at full scale in a short capture at the middle of each band
ADC margin	the noise over the whole sample rate against the quantisation noise of an 8-bit ADC (-49.9 dBFS): small = the converter, not the antenna, limits sensitivity
Reference stations	FM carriers (60-450 kHz wide), DAB ensembles (1-1.9 MHz), DVB-T channels (5.5-8.8 MHz) seen above the floor; the strongest one is compared with what a healthy antenna shows (25 / 12 / 12 dB over the floor)
Frequency error (ppm)	optional: give the frequency of a carrier you trust; a 1 kHz-bin sweep +-100 kHz around it, parabolic peak
ADS-B range	from the range statistics the ADS-B mode keeps (10 degree sectors); needs the antenna position and 50 or more positions

Everything is relative to the receiver itself: the radios are not calibrated, so there are no dBm values and no antenna gain figure.

The advice (rules of thumb)

• ADC clips (more than 0.1 % of the samples, or a peak at full scale): lower the gain. If another band is ADC-limited at the same gain, the strong band needs a band-stop filter instead (an FM notch for the FM band).
• ADC level above -12 dBFS rms without clipping: little headroom, lower the gain a little.
• ADC margin under 6 dB: raise the gain; at the radio's maximum gain: add an LNA at the antenna.
• ADC margin over 26 dB with a high level: the gain could drop (margin minus 20 dB) with no loss of sensitivity.
• A band's noise density (per Hz) more than 12 dB over the quietest band, after allowing 15 dB per decade of galactic noise below 300 MHz: a local noise source (LED lights, switching supplies, computers); move the antenna or add a ferrite.
• No FM / DAB / DVB-T found, or the strongest one weak: check antenna and cable, move it higher or outdoors, add a filter and LNA.
• More than 5 ppm of clock error: enter the number as the frequency correction in the radio's settings.
• ADS-B farthest aircraft under 60 nm (under 25 nm: bad), or a run of empty 10 degree sectors between directions that reach far: raise the antenna, look for what blocks that direction.

Export

"Save report..." writes the text (in the interface language), "Save as JSON..." the numbers and finding codes.

Limits

The ADC statistics come from one capture at the middle of each band, so a band wider than the sample rate (FM at 10 Msps) is judged by its middle part. Thresholds are heuristics, not standards. 8-bit converters are assumed (HackRF, RTL-SDR); a 12-bit radio reads a larger margin than it has.

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See also: Tutorials and guides, FAQ, Troubleshooting.