Decode KAPP with an SDR

Group

KA family (own modes)

In the mode list

KAPP, 100 kHz packets

What KAPP is

KAPP: the packet mode of the KAAL family, 100 kHz wide (80 ksym/s, BPSK to 1024-QAM with LDPC, bursts with selective repeat). Receive lists the messages that arrive whole with the profile, SNR, counts and a constellation; it only listens and sends no acknowledgement. Transmit sends a text or a file one-way, repeated, to a radio or an IQ file.

Frequencies and settings

OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is KAPP, 100 kHz packets.

What OnAir shows

KAPP: the packet mode of the KAAL family, 100 kHz wide (80 ksym/s, BPSK to 1024-QAM with LDPC, bursts with selective repeat). Receive lists the messages that arrive whole with the profile, SNR, counts and a constellation; it only listens and sends no acknowledgement. Transmit sends a text or a file one-way, repeated, to a radio or an IQ file.

Limits and what it was checked with

Checked with generated signals and impairments; recordings of real signals welcome.

Which radio you need

This is a shortwave mode, so the radio has to tune HF. An SDRplay, Airspy HF+ or an RTL-SDR in direct-sampling mode do that directly; with a HackRF an HF upconverter or a direct-sampling receiver is the usual route. A long wire or loop antenna matters more than the radio.

Receiving and the law

Questions about KAPP

More in KA family (own modes)