Configuration¶

Merged receiver mode runs when datalink starts without a bearer subcommand:

datalink --config datalink.toml

The file is TOML with [output], one or more [[sources]], and optional [[sources.receivers]] for I/Q sources.

Sample rate values¶

The sample rate basically determines the bandwidth and the number of channels you can listen to.

Any reasonable sample rate value should work with datalink you may prefer:

• a multiple of 12.5 kHz for classic VHF ACARS
• a multiple of 105 kHz for VDL2

Complete example¶

[output]
jsonl = "-"
redis_url = "redis://localhost:6379"

[[sources]]
id = "wideband-vhf-vdl2"
name = "8 MHz VHF/VDL2 capture"
file = "~/captures/gqrx_20260603_083011_134000000_8400000_fc.raw"
format = "cf32"
center_freq = 134_000_000
sample_rate = 8_400_000

[[sources.receivers]]
bearer = "vhf"
channels = [131_525_000, 131_725_000, 131_825_000]

[[sources.receivers]]
bearer = "vdl2"
channels = [136_675_000, 136_775_000, 136_875_000, 136_975_000]

[[sources]]
id = "airframes-live"
name = "Airframes.io live feed"
websocket = "airframes://"

Output¶

Sources¶

I/Q sources can be files, stdin, or SDR devices. They need a center frequency and sample rate unless these can be inferred.

[[sources]]
id = "hackrf-vhf-vdl2"
name = "HackRF wideband"
hackrf = { device = 0 }
center_freq = 133_062_500
sample_rate = 8_400_000
rf_gain = true
lna_gain = 24
vga_gain = 26

Event sources currently use websocket and do not contain receiver blocks.

Receivers¶

Receivers attach protocol-specific demodulators to an I/Q source.

[[sources.receivers]]
bearer = "hfdl"
channels = [8_912_000, 10_081_000, 11_387_000]

Valid I/Q receiver bearers are vhf, vdl2, and hfdl.

If channels are omitted, datalink selects known channels that fit inside the configured source bandwidth.

Validation notes¶

• Source ids must be unique and non-empty.
• I/Q sources must have at least one receiver.
• Event sources must not have receiver blocks.
• Explicit channels are checked against source bandwidth when center_freq, sample_rate, and channels are all provided.
• Use explicit format, center_freq, and sample_rate for raw captures when filename inference is not reliable.