prf::pr::Afsk1200Decoder class final
#include <pr/afsk/decoder.hpp>

Streaming AFSK1200 decoder for PCM16 mono input.

Input samples are consumed incrementally. The decoder:

  • accumulates startup samples to lock symbol phase,
  • performs fixed-point Goertzel tone-energy comparison per recovered symbol,
  • emits raw channel level bits (pre-NRZI, pre-HDLC deframing).

Output bits intentionally preserve modem-level information so higher layers can perform NRZI decode, flag hunting and bit destuffing without re-reading audio.

Constructors, destructors, conversion operators

Afsk1200Decoder()
Construct decoder with default mode (AFSK1200) and 48 kHz setup.

Public functions

auto mode() const -> PacketRadioMode
Return currently configured runtime mode.
auto pending_bits() const -> std::size_t
Return number of queued recovered bits.
auto pop_bit(bool* out_bit) -> bool
Pop one recovered raw channel bit.
void process_block(std::span<const std::int16_t> samples)
Feed a contiguous block of PCM16 samples.
void process_sample(std::int16_t sample)
Feed one PCM16 sample into the streaming decode pipeline.
auto quality_stats() const -> RxQualityStats
Return current RX quality snapshot.
void reset()
Reset all runtime state and clear pending output bits.
auto sample_rate() const -> std::uint32_t
Return currently configured sample rate.
auto set_mode(PacketRadioMode mode) -> bool
Select runtime modem mode.
auto set_sample_rate(std::uint32_t sample_rate_hz) -> bool
Select input sample rate.

Function documentation

bool prf::pr::Afsk1200Decoder::pop_bit(bool* out_bit)

Pop one recovered raw channel bit.

Parameters
out_bit out Destination for popped bit.
Returns true if a bit was available.

void prf::pr::Afsk1200Decoder::reset()

Reset all runtime state and clear pending output bits.

Configuration (selected mode and sample rate) is preserved.

bool prf::pr::Afsk1200Decoder::set_mode(PacketRadioMode mode)

Select runtime modem mode.

Parameters
mode Requested mode.
Returns true if mode is supported by this decoder instance.

Unsupported modes disable decode processing until a supported mode is set.

bool prf::pr::Afsk1200Decoder::set_sample_rate(std::uint32_t sample_rate_hz)

Select input sample rate.

Parameters
sample_rate_hz PCM sample rate in Hz.
Returns true when supported tone coefficients are available.

The decoder currently supports a fixed set of rates with precomputed coefficients for deterministic integer DSP.