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Substation configuration: band_defaults

The 8 settings under band_defaults, each with the type, default and limits its schema declares.

Templates of settings for types of radio service, keyed by type name. A band inherits a template's settings by naming it in type.

A template of settings shared by one type of radio service, such as DMR, TETRA, or PMR.

A band names its template in type and inherits the settings the template gives, such as the radio channel spacing and modulation that every DMR band shares. A band overrides an inherited setting by giving it itself. Every setting in a template is optional, and a template passes on none that it leaves out or sets to null. Each band must still end up with the settings a band requires.

channel_spacing in band_defaults.<name>

Type
number or null
Default
null
Limits
above 0

Spacing between radio channel centre frequencies, in Hz, for example 12.5 kHz for PMR and DMR, or 25 kHz for marine VHF.

sample_rate in band_defaults.<name>

Type
number or null
Default
null
Limits
above 0

SDR sample rate in Hz. Must be high enough to cover the whole band plus margins, for example 2 MHz for the 188 kHz PMR446 band.

channel_width in band_defaults.<name>

Type
number or null
Default
null
Limits
above 0

Occupied bandwidth of each radio channel, in Hz. When null, the scanner uses 84% of channel_spacing, which leaves guard bands between radio channels.

modulation in band_defaults.<name>

Type
string or null
Default
null

Modulation the scanner demodulates for recording: NFM, AM, USB, or LSB, in any letter case. USB and LSB are for HF voice: amateur convention is LSB below 10 MHz and USB above, and HFGCS, VOLMET, and marine HF use USB.

recording_enabled in band_defaults.<name>

Type
boolean or null
Default
null

Whether bands of this type record audio from detected transmissions. When null, each band decides from its reception_class.

reception_class in band_defaults.<name>

Type
string or null
Default
null
Limits
one of general, not_general, unsettled

How UK law treats listening to bands of this type. general is what Ofcom calls general reception, which anyone may receive: licensed broadcasting, amateur and CB radio, and weather and navigation transmissions. not_general is a service outside general reception, such as PMR446, business radio, marine, military airband, and emergency services, which Ofcom says it is illegal to listen to. unsettled is for bands where the position is unclear, such as civil airband. A band that does not set recording_enabled records only when it is general. This describes UK law and is not legal advice: the law where you are decides what you may receive and record.

snr_threshold_db in band_defaults.<name>

Type
number or null
Default
null

Signal-to-noise ratio in dB at which a radio channel counts as active. Lower values detect weaker signals and trigger more often on noise.

sdr_gain_db in band_defaults.<name>

Type
number or string or null
Default
auto

SDR gain in dB, or auto for automatic gain control. Higher gain is more sensitive, and also amplifies noise and can cause clipping. A band's sdr_gain_db describes what auto does on each receiver, and what a number does on a HackRF One.