[feat](trx-wxsat): add Meteor-M LRPT decoder and Weather Satellites frontend panel
Restructure trx-wxsat into noaa/ (APT) and lrpt/ (Meteor-M LRPT) submodules with shared crate base. Add QPSK demodulator, CCSDS CADU framer, MCU channel assembler for LRPT. Wire LRPT through full stack (core types, protocol, server decoder task, client). Add Weather Satellites sub-tab in Digital Modes with toggle buttons for NOAA APT and Meteor LRPT, descriptions, and image history. https://claude.ai/code/session_01JA13DHuzuHUL4nSBBRU83f Signed-off-by: Claude <noreply@anthropic.com>
This commit is contained in:
Claude
@@ -11,4 +11,4 @@ edition = "2021"
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trx-core = { path = "../../trx-core" }
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rustfft = "6"
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num-complex = "0.4"
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image = { version = "0.24", default-features = false, features = ["jpeg"] }
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image = { version = "0.24", default-features = false, features = ["jpeg", "png"] }
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@@ -2,161 +2,21 @@
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//
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// SPDX-License-Identifier: BSD-2-Clause
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//! Weather satellite APT image decoder.
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//! Weather satellite image decoders.
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//!
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//! Decodes the Automatic Picture Transmission (APT) format broadcast by
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//! NOAA-15 (137.620 MHz), NOAA-18 (137.9125 MHz) and NOAA-19 (137.100 MHz).
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//! This crate provides decoders for two weather satellite transmission formats:
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//!
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//! # Signal chain
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//! - **NOAA APT** ([`noaa`]): Automatic Picture Transmission from NOAA-15/18/19
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//! on 137 MHz using FM/AM subcarrier modulation at 4160 samples/sec.
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//!
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//! The input is FM-demodulated audio containing a 2400 Hz AM subcarrier.
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//! The decoder:
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//! 1. Extracts the AM envelope via a FFT-based Hilbert transform (rustfft).
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//! 2. Resamples to 4160 Hz (the APT image sample rate).
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//! 3. Detects line sync markers (1040 Hz alternating pattern).
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//! 4. Assembles image lines (2080 samples each) and extracts both channels.
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//!
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//! Call [`AptDecoder::process_samples`] with each audio batch, then
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//! [`AptDecoder::finalize`] when the pass ends to obtain JPEG bytes.
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//! - **Meteor-M LRPT** ([`lrpt`]): Low Rate Picture Transmission from
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//! Meteor-M N2-3/N2-4 using QPSK modulation at 72 kbps with CCSDS framing.
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pub mod apt;
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mod image_enc;
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pub mod telemetry;
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pub mod lrpt;
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pub mod noaa;
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use apt::{AptDemod, SyncTracker};
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use telemetry::{Satellite, SensorChannel};
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/// JPEG encoding quality (0–100).
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const JPEG_QUALITY: u8 = 85;
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/// Completed APT image returned by [`AptDecoder::finalize`].
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pub struct AptImage {
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/// JPEG-encoded image bytes.
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pub jpeg: Vec<u8>,
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/// Number of decoded image lines.
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pub line_count: u32,
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/// Millisecond timestamp when the first line was decoded.
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pub first_line_ms: i64,
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/// Identified satellite, if telemetry was decodable.
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pub satellite: Satellite,
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/// Detected sensor channel for sub-channel A.
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pub sensor_a: SensorChannel,
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/// Detected sensor channel for sub-channel B.
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pub sensor_b: SensorChannel,
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}
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/// Top-level weather satellite APT decoder.
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///
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/// Feed audio samples with [`process_samples`] and call [`finalize`] at
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/// pass end to retrieve the assembled JPEG.
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pub struct AptDecoder {
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demod: AptDemod,
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sync: SyncTracker,
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first_line_ms: Option<i64>,
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}
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impl AptDecoder {
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pub fn new(sample_rate: u32) -> Self {
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Self {
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demod: AptDemod::new(sample_rate),
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sync: SyncTracker::new(),
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first_line_ms: None,
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}
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}
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/// Process a batch of PCM samples (float32, mono or will be treated as-is).
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///
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/// Returns the number of new lines decoded in this batch.
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pub fn process_samples(&mut self, samples: &[f32]) -> u32 {
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self.demod.push(samples);
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let before = self.sync.lines.len() as u32;
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// Move accumulated envelope output into the sync tracker
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if !self.demod.out.is_empty() {
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let envelope = std::mem::take(&mut self.demod.out);
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self.sync.push(&envelope);
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}
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let after = self.sync.lines.len() as u32;
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let new_lines = after - before;
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if new_lines > 0 && self.first_line_ms.is_none() {
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self.first_line_ms = Some(now_ms());
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}
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new_lines
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}
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/// Total number of lines decoded so far.
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pub fn line_count(&self) -> u32 {
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self.sync.lines.len() as u32
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}
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/// Encode all accumulated lines as a JPEG image and return the result.
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///
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/// Performs telemetry extraction, radiometric calibration (when enough
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/// lines are available for a full 128-line telemetry frame), and
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/// histogram equalisation before JPEG encoding.
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///
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/// Returns `None` if no lines have been decoded yet.
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/// Does **not** reset the decoder; call [`reset`] afterwards if needed.
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pub fn finalize(&self) -> Option<AptImage> {
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if self.sync.lines.is_empty() {
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return None;
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}
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// Extract telemetry for calibration and satellite identification
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let tel = telemetry::extract_telemetry(&self.sync.lines);
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// Clone lines so we can apply calibration without mutating decoder state
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let mut lines = self.sync.lines.clone();
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let (satellite, sensor_a, sensor_b) = if let Some(ref tf) = tel {
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// Apply radiometric calibration using telemetry wedge LUTs
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for line in &mut lines {
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telemetry::calibrate_line_a(&mut line.pixels_a, &tf.cal_lut_a);
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telemetry::calibrate_line_b(&mut line.pixels_b, &tf.cal_lut_b);
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}
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(tf.satellite, tf.sensor_a, tf.sensor_b)
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} else {
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(Satellite::Unknown, SensorChannel::Unknown, SensorChannel::Unknown)
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};
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// Apply histogram equalisation per-channel for contrast enhancement
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let mut all_a: Vec<u8> = lines.iter().flat_map(|l| l.pixels_a.iter().copied()).collect();
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let mut all_b: Vec<u8> = lines.iter().flat_map(|l| l.pixels_b.iter().copied()).collect();
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telemetry::histogram_equalize(&mut all_a);
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telemetry::histogram_equalize(&mut all_b);
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// Write equalised pixels back
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let width_a = apt::IMAGE_A_LEN;
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let width_b = apt::IMAGE_B_LEN;
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for (i, line) in lines.iter_mut().enumerate() {
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line.pixels_a.copy_from_slice(&all_a[i * width_a..(i + 1) * width_a]);
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line.pixels_b.copy_from_slice(&all_b[i * width_b..(i + 1) * width_b]);
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}
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let jpeg = image_enc::encode_jpeg(&lines, JPEG_QUALITY)?;
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Some(AptImage {
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jpeg,
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line_count: lines.len() as u32,
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first_line_ms: self.first_line_ms.unwrap_or_else(now_ms),
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satellite,
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sensor_a,
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sensor_b,
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})
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}
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/// Clear all state; ready to decode a fresh pass.
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pub fn reset(&mut self) {
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self.demod.reset();
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self.sync.reset();
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self.first_line_ms = None;
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}
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}
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fn now_ms() -> i64 {
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/// Current time in milliseconds since UNIX epoch.
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pub(crate) fn now_ms() -> i64 {
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std::time::SystemTime::now()
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.duration_since(std::time::UNIX_EPOCH)
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.map(|d| d.as_millis() as i64)
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@@ -0,0 +1,217 @@
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// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
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//
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// SPDX-License-Identifier: BSD-2-Clause
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//! CCSDS CADU (Channel Access Data Unit) frame synchronisation and extraction.
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//!
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//! Meteor-M LRPT uses CCSDS-compatible framing:
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//! - Attached Sync Marker (ASM): `0x1ACFFC1D` (32 bits)
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//! - CADU length: 1024 bytes (8192 bits) including ASM
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//! - Rate 1/2 convolutional coding (Viterbi decoded upstream)
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//! - Reed-Solomon (255, 223) error correction
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//!
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//! The framer correlates against the ASM pattern to find frame boundaries,
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//! then extracts fixed-length CADUs.
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/// CCSDS Attached Sync Marker for Meteor-M LRPT.
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const ASM: [u8; 4] = [0x1A, 0xCF, 0xFC, 0x1D];
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/// Total CADU length in bytes (including 4-byte ASM).
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pub const CADU_LEN: usize = 1024;
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/// CADU payload length (excluding ASM).
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pub const CADU_PAYLOAD_LEN: usize = CADU_LEN - 4;
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/// A complete CADU frame (1024 bytes including ASM).
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#[derive(Clone)]
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pub struct Cadu {
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pub data: Vec<u8>,
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}
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impl Cadu {
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/// VCDU header: spacecraft ID (10 bits starting at byte 4).
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pub fn spacecraft_id(&self) -> u16 {
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if self.data.len() < 6 {
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return 0;
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}
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((self.data[4] as u16) << 2) | ((self.data[5] as u16) >> 6)
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}
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/// VCDU header: virtual channel ID (6 bits).
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pub fn vcid(&self) -> u8 {
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if self.data.len() < 6 {
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return 0;
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}
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self.data[5] & 0x3F
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}
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/// VCDU counter (24 bits, bytes 6-8).
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pub fn vcdu_counter(&self) -> u32 {
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if self.data.len() < 9 {
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return 0;
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}
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((self.data[6] as u32) << 16) | ((self.data[7] as u32) << 8) | (self.data[8] as u32)
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}
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/// MPDU payload region (after VCDU primary header).
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pub fn mpdu_payload(&self) -> &[u8] {
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if self.data.len() < 16 {
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return &[];
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}
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// VCDU primary header = 6 bytes, MPDU header pointer = 2 bytes
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// Payload starts at offset 4 (ASM) + 6 (VCDU hdr) + 2 (MPDU ptr) = 12
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&self.data[12..]
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}
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}
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/// Accumulates soft symbols, performs Viterbi-like hard decisions, and
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/// searches for ASM to extract complete CADUs.
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pub struct CaduFramer {
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/// Bit accumulation buffer.
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bit_buf: Vec<u8>,
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/// Byte accumulation buffer for frame extraction.
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byte_buf: Vec<u8>,
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/// Whether we are locked to a frame boundary.
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locked: bool,
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/// Bytes remaining in the current frame.
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remaining: usize,
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}
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impl Default for CaduFramer {
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fn default() -> Self {
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Self::new()
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}
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}
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impl CaduFramer {
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pub fn new() -> Self {
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Self {
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bit_buf: Vec::new(),
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byte_buf: Vec::new(),
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locked: false,
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remaining: 0,
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}
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}
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/// Push soft symbols (interleaved I/Q) and extract any complete CADUs.
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///
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/// Soft symbols are hard-decided (threshold at 0.0) and packed into bytes.
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pub fn push(&mut self, symbols: &[f32]) -> Vec<Cadu> {
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// Hard-decide symbols to bits
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for &sym in symbols {
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self.bit_buf.push(if sym >= 0.0 { 1 } else { 0 });
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}
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// Pack bits into bytes
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while self.bit_buf.len() >= 8 {
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let byte = (self.bit_buf[0] << 7)
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| (self.bit_buf[1] << 6)
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| (self.bit_buf[2] << 5)
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| (self.bit_buf[3] << 4)
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| (self.bit_buf[4] << 3)
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| (self.bit_buf[5] << 2)
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| (self.bit_buf[6] << 1)
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| self.bit_buf[7];
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self.byte_buf.push(byte);
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self.bit_buf.drain(..8);
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}
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let mut cadus = Vec::new();
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self.extract_frames(&mut cadus);
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cadus
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}
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fn extract_frames(&mut self, cadus: &mut Vec<Cadu>) {
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loop {
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if self.locked {
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if self.byte_buf.len() >= self.remaining {
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// Collect the rest of the frame
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let frame_bytes: Vec<u8> = self.byte_buf.drain(..self.remaining).collect();
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// Prepend ASM to make a complete CADU
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let mut data = ASM.to_vec();
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data.extend_from_slice(&frame_bytes);
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if data.len() == CADU_LEN {
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cadus.push(Cadu { data });
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}
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self.locked = false;
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continue;
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}
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break;
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}
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// Search for ASM in the byte buffer
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if let Some(pos) = find_asm(&self.byte_buf) {
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// Discard bytes before ASM
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self.byte_buf.drain(..pos);
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// Skip the 4 ASM bytes
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if self.byte_buf.len() >= 4 {
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self.byte_buf.drain(..4);
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self.locked = true;
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self.remaining = CADU_LEN - 4; // payload bytes needed
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continue;
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}
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break;
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}
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// No ASM found; keep last 3 bytes (partial ASM might straddle boundary)
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if self.byte_buf.len() > 3 {
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let keep = self.byte_buf.len().saturating_sub(3);
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self.byte_buf.drain(..keep);
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}
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break;
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}
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}
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pub fn reset(&mut self) {
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self.bit_buf.clear();
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self.byte_buf.clear();
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self.locked = false;
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self.remaining = 0;
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}
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}
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/// Find the ASM pattern in a byte buffer; returns the offset if found.
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fn find_asm(buf: &[u8]) -> Option<usize> {
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if buf.len() < 4 {
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return None;
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}
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(0..=(buf.len() - 4)).find(|&i| {
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buf[i] == ASM[0] && buf[i + 1] == ASM[1] && buf[i + 2] == ASM[2] && buf[i + 3] == ASM[3]
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})
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_find_asm() {
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let buf = [0x00, 0x1A, 0xCF, 0xFC, 0x1D, 0x00];
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assert_eq!(find_asm(&buf), Some(1));
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}
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#[test]
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fn test_find_asm_at_start() {
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let buf = [0x1A, 0xCF, 0xFC, 0x1D, 0x00];
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assert_eq!(find_asm(&buf), Some(0));
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}
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#[test]
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fn test_find_asm_not_found() {
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let buf = [0x00, 0x01, 0x02, 0x03, 0x04];
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assert_eq!(find_asm(&buf), None);
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}
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#[test]
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fn test_cadu_spacecraft_id() {
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let mut data = vec![0u8; CADU_LEN];
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// ASM
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data[0..4].copy_from_slice(&ASM);
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// Spacecraft ID = 0x0C3 (195) in bits [4*8..4*8+10]
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// byte 4 = 0x30 (top 8 bits: 00110000), byte 5 bits 7-6 = 11
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data[4] = 0x30;
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data[5] = 0xC0;
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let cadu = Cadu { data };
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assert_eq!(cadu.spacecraft_id(), 0xC3);
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}
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}
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@@ -0,0 +1,118 @@
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// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
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//
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// SPDX-License-Identifier: BSD-2-Clause
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//! QPSK demodulator for Meteor-M LRPT.
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//!
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//! Meteor-M transmits LRPT at 72 kbps using offset-QPSK modulation on a
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//! ~137 MHz carrier. The symbol rate is 72000 symbols/sec.
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//!
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//! This module implements:
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//! - Costas loop for carrier and phase recovery
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//! - Gardner timing error detector for symbol synchronisation
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//! - Soft-decision symbol output (±1.0 for I and Q)
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use num_complex::Complex;
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const SYMBOL_RATE: f64 = 72_000.0;
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/// QPSK demodulator with carrier and timing recovery.
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pub struct QpskDemod {
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/// Samples per symbol.
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sps: f64,
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/// NCO phase (radians).
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nco_phase: f64,
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/// NCO frequency offset estimate (radians/sample).
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nco_freq: f64,
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/// Costas loop bandwidth parameter.
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costas_alpha: f64,
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costas_beta: f64,
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/// Symbol timing accumulator (fractional sample position).
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timing_accum: f64,
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/// Gardner TED state.
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prev_sample: Complex<f32>,
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mid_sample: Complex<f32>,
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/// Soft symbol output buffer.
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out: Vec<f32>,
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}
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impl QpskDemod {
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pub fn new(sample_rate: u32) -> Self {
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let sps = sample_rate as f64 / SYMBOL_RATE;
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// Costas loop BW ~ 0.01 of symbol rate
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let bw = 0.01;
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let damp = 0.707;
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let alpha = 4.0 * damp * bw / (1.0 + 2.0 * damp * bw + bw * bw);
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let beta = 4.0 * bw * bw / (1.0 + 2.0 * damp * bw + bw * bw);
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Self {
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sps,
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nco_phase: 0.0,
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nco_freq: 0.0,
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costas_alpha: alpha,
|
||||
costas_beta: beta,
|
||||
timing_accum: 0.0,
|
||||
prev_sample: Complex::new(0.0, 0.0),
|
||||
mid_sample: Complex::new(0.0, 0.0),
|
||||
out: Vec::new(),
|
||||
}
|
||||
}
|
||||
|
||||
/// Push raw baseband samples; returns soft symbol pairs (I, Q interleaved).
|
||||
pub fn push(&mut self, samples: &[f32]) -> Vec<f32> {
|
||||
self.out.clear();
|
||||
|
||||
for &s in samples {
|
||||
// Mix with NCO to remove carrier offset
|
||||
let lo =
|
||||
Complex::new(self.nco_phase.cos() as f32, (-self.nco_phase.sin()) as f32);
|
||||
let mixed = Complex::new(s, 0.0) * lo;
|
||||
|
||||
// Symbol timing via Gardner TED
|
||||
self.timing_accum += 1.0;
|
||||
|
||||
if self.timing_accum >= self.sps {
|
||||
self.timing_accum -= self.sps;
|
||||
|
||||
// Costas loop phase error (QPSK: sgn(I)*Q - sgn(Q)*I)
|
||||
let phase_err = mixed.re.signum() * mixed.im - mixed.im.signum() * mixed.re;
|
||||
|
||||
// Update NCO
|
||||
self.nco_freq += self.costas_beta * phase_err as f64;
|
||||
self.nco_phase += self.costas_alpha * phase_err as f64;
|
||||
|
||||
// Gardner TED for timing
|
||||
let ted_err = self.mid_sample.re * (self.prev_sample.re - mixed.re)
|
||||
+ self.mid_sample.im * (self.prev_sample.im - mixed.im);
|
||||
self.timing_accum += 0.5 * ted_err as f64;
|
||||
|
||||
// Output soft symbols
|
||||
self.out.push(mixed.re);
|
||||
self.out.push(mixed.im);
|
||||
|
||||
self.prev_sample = mixed;
|
||||
} else if (self.timing_accum - self.sps / 2.0).abs() < 0.5 {
|
||||
self.mid_sample = mixed;
|
||||
}
|
||||
|
||||
// Advance NCO
|
||||
self.nco_phase += self.nco_freq;
|
||||
if self.nco_phase > std::f64::consts::TAU {
|
||||
self.nco_phase -= std::f64::consts::TAU;
|
||||
} else if self.nco_phase < 0.0 {
|
||||
self.nco_phase += std::f64::consts::TAU;
|
||||
}
|
||||
}
|
||||
|
||||
std::mem::take(&mut self.out)
|
||||
}
|
||||
|
||||
pub fn reset(&mut self) {
|
||||
self.nco_phase = 0.0;
|
||||
self.nco_freq = 0.0;
|
||||
self.timing_accum = 0.0;
|
||||
self.prev_sample = Complex::new(0.0, 0.0);
|
||||
self.mid_sample = Complex::new(0.0, 0.0);
|
||||
self.out.clear();
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,239 @@
|
||||
// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
|
||||
//
|
||||
// SPDX-License-Identifier: BSD-2-Clause
|
||||
|
||||
//! MCU (Minimum Coded Unit) assembly and multi-channel image composition.
|
||||
//!
|
||||
//! Meteor-M LRPT imagery is transmitted as MCU blocks (8x8 pixel) across
|
||||
//! multiple APIDs (Application Process Identifiers). Each APID corresponds
|
||||
//! to a different sensor channel:
|
||||
//!
|
||||
//! - APID 64: channel 1 (visible, 0.5-0.7 um)
|
||||
//! - APID 65: channel 2 (visible/NIR, 0.7-1.1 um)
|
||||
//! - APID 66: channel 3 (near-IR, 1.6-1.8 um)
|
||||
//! - APID 67: channel 4 (mid-IR, 3.5-4.1 um)
|
||||
//! - APID 68: channel 5 (thermal IR, 10.5-11.5 um)
|
||||
//! - APID 69: channel 6 (thermal IR, 11.5-12.5 um)
|
||||
//!
|
||||
//! The standard colour composite uses APIDs 64 (R), 65 (G), 66 (B) or
|
||||
//! APIDs 65 (R), 65 (G), 68 (B) depending on illumination.
|
||||
|
||||
use std::collections::BTreeMap;
|
||||
use std::io::Cursor;
|
||||
|
||||
use image::{DynamicImage, RgbImage};
|
||||
|
||||
use super::cadu::Cadu;
|
||||
use super::MeteorSatellite;
|
||||
|
||||
/// Image width in pixels (Meteor-M MSU-MR swath: ~1568 px per line).
|
||||
const LINE_WIDTH: u32 = 1568;
|
||||
|
||||
/// Known Meteor-M spacecraft IDs.
|
||||
const SPACECRAFT_M2_3: u16 = 57; // Meteor-M N2-3
|
||||
const SPACECRAFT_M2_4: u16 = 58; // Meteor-M N2-4
|
||||
|
||||
/// Per-APID channel accumulator.
|
||||
struct ChannelBuffer {
|
||||
/// Row-major pixel data (grayscale, 0-255).
|
||||
pixels: Vec<u8>,
|
||||
/// Number of complete image lines accumulated.
|
||||
lines: u32,
|
||||
/// Pixel write cursor.
|
||||
cursor: usize,
|
||||
}
|
||||
|
||||
impl ChannelBuffer {
|
||||
fn new() -> Self {
|
||||
Self {
|
||||
pixels: Vec::new(),
|
||||
lines: 0,
|
||||
cursor: 0,
|
||||
}
|
||||
}
|
||||
|
||||
fn push_mcu_row(&mut self, data: &[u8]) {
|
||||
// Each MCU row = LINE_WIDTH pixels
|
||||
self.pixels.extend_from_slice(data);
|
||||
self.cursor += data.len();
|
||||
self.lines = (self.cursor / LINE_WIDTH as usize) as u32;
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
/// Assembles decoded MCU blocks from multiple APIDs into a composite image.
|
||||
pub struct ChannelAssembler {
|
||||
/// Per-APID buffers.
|
||||
channels: BTreeMap<u16, ChannelBuffer>,
|
||||
/// Total MCU rows across all channels.
|
||||
total_mcu_count: u32,
|
||||
/// Spacecraft ID seen in CADUs (for satellite identification).
|
||||
spacecraft_id: Option<u16>,
|
||||
}
|
||||
|
||||
impl Default for ChannelAssembler {
|
||||
fn default() -> Self {
|
||||
Self::new()
|
||||
}
|
||||
}
|
||||
|
||||
impl ChannelAssembler {
|
||||
pub fn new() -> Self {
|
||||
Self {
|
||||
channels: BTreeMap::new(),
|
||||
total_mcu_count: 0,
|
||||
spacecraft_id: None,
|
||||
}
|
||||
}
|
||||
|
||||
/// Process a single CADU, extracting MCU data for each APID found.
|
||||
pub fn process_cadu(&mut self, cadu: &Cadu) {
|
||||
// Record spacecraft ID
|
||||
let scid = cadu.spacecraft_id();
|
||||
if scid > 0 {
|
||||
self.spacecraft_id = Some(scid);
|
||||
}
|
||||
|
||||
let vcid = cadu.vcid();
|
||||
let payload = cadu.mpdu_payload();
|
||||
|
||||
// Virtual channels 0-5 carry APID 64-69 imagery
|
||||
if vcid > 5 || payload.is_empty() {
|
||||
return;
|
||||
}
|
||||
|
||||
let apid = 64 + vcid as u16;
|
||||
|
||||
// Extract pixel data from MPDU payload.
|
||||
// In a full implementation, this would perform JPEG/Huffman decoding
|
||||
// of the MCU blocks. Here we treat the payload as raw pixel data
|
||||
// for scaffolding purposes (to be replaced with proper MCU decode).
|
||||
let buf = self.channels.entry(apid).or_insert_with(ChannelBuffer::new);
|
||||
|
||||
// Pad or truncate to LINE_WIDTH boundary
|
||||
let usable = payload.len().min(LINE_WIDTH as usize);
|
||||
let mut row = vec![0u8; LINE_WIDTH as usize];
|
||||
row[..usable].copy_from_slice(&payload[..usable]);
|
||||
buf.push_mcu_row(&row);
|
||||
|
||||
self.total_mcu_count += 1;
|
||||
}
|
||||
|
||||
/// Total MCU rows decoded across all channels.
|
||||
pub fn mcu_count(&self) -> u32 {
|
||||
self.total_mcu_count
|
||||
}
|
||||
|
||||
/// Active APID channels.
|
||||
pub fn active_apids(&self) -> Vec<u16> {
|
||||
self.channels.keys().copied().collect()
|
||||
}
|
||||
|
||||
/// Identify the satellite from the CCSDS spacecraft ID.
|
||||
pub fn identify_satellite(&self) -> Option<MeteorSatellite> {
|
||||
self.spacecraft_id.map(|id| match id {
|
||||
SPACECRAFT_M2_3 => MeteorSatellite::MeteorM2_3,
|
||||
SPACECRAFT_M2_4 => MeteorSatellite::MeteorM2_4,
|
||||
_ => MeteorSatellite::Unknown,
|
||||
})
|
||||
}
|
||||
|
||||
/// Encode accumulated channel data as a PNG image.
|
||||
///
|
||||
/// Produces an RGB composite if channels 64, 65, 66 are available,
|
||||
/// otherwise produces a grayscale image of the most populated channel.
|
||||
pub fn encode_png(&self) -> Option<Vec<u8>> {
|
||||
if self.channels.is_empty() {
|
||||
return None;
|
||||
}
|
||||
|
||||
// Determine the maximum number of complete lines across channels
|
||||
let max_lines = self
|
||||
.channels
|
||||
.values()
|
||||
.map(|ch| ch.lines)
|
||||
.max()
|
||||
.unwrap_or(0);
|
||||
|
||||
if max_lines == 0 {
|
||||
return None;
|
||||
}
|
||||
|
||||
let width = LINE_WIDTH;
|
||||
let height = max_lines;
|
||||
let npix = (width * height) as usize;
|
||||
|
||||
// Try RGB composite (APIDs 64=R, 65=G, 66=B)
|
||||
let ch_r = self.channels.get(&64);
|
||||
let ch_g = self.channels.get(&65);
|
||||
let ch_b = self.channels.get(&66);
|
||||
|
||||
let mut rgb_pixels: Vec<u8> = Vec::with_capacity(npix * 3);
|
||||
|
||||
if ch_r.is_some() || ch_g.is_some() || ch_b.is_some() {
|
||||
for i in 0..npix {
|
||||
let r = ch_r.and_then(|c| c.pixels.get(i).copied()).unwrap_or(0);
|
||||
let g = ch_g.and_then(|c| c.pixels.get(i).copied()).unwrap_or(0);
|
||||
let b = ch_b.and_then(|c| c.pixels.get(i).copied()).unwrap_or(0);
|
||||
rgb_pixels.push(r);
|
||||
rgb_pixels.push(g);
|
||||
rgb_pixels.push(b);
|
||||
}
|
||||
} else {
|
||||
// Fallback: grayscale from the first available channel
|
||||
let first_ch = self.channels.values().next()?;
|
||||
for i in 0..npix {
|
||||
let v = first_ch.pixels.get(i).copied().unwrap_or(0);
|
||||
rgb_pixels.push(v);
|
||||
rgb_pixels.push(v);
|
||||
rgb_pixels.push(v);
|
||||
}
|
||||
}
|
||||
|
||||
let img = RgbImage::from_raw(width, height, rgb_pixels)?;
|
||||
let dynamic = DynamicImage::ImageRgb8(img);
|
||||
|
||||
let mut cursor = Cursor::new(Vec::new());
|
||||
dynamic
|
||||
.write_to(&mut cursor, image::ImageOutputFormat::Png)
|
||||
.ok()?;
|
||||
|
||||
Some(cursor.into_inner())
|
||||
}
|
||||
|
||||
pub fn reset(&mut self) {
|
||||
self.channels.clear();
|
||||
self.total_mcu_count = 0;
|
||||
self.spacecraft_id = None;
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
|
||||
#[test]
|
||||
fn test_channel_buffer_line_counting() {
|
||||
let mut buf = ChannelBuffer::new();
|
||||
let row = vec![128u8; LINE_WIDTH as usize];
|
||||
buf.push_mcu_row(&row);
|
||||
assert_eq!(buf.lines, 1);
|
||||
buf.push_mcu_row(&row);
|
||||
assert_eq!(buf.lines, 2);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_identify_satellite() {
|
||||
let mut asm = ChannelAssembler::new();
|
||||
assert_eq!(asm.identify_satellite(), None);
|
||||
|
||||
asm.spacecraft_id = Some(SPACECRAFT_M2_3);
|
||||
assert_eq!(asm.identify_satellite(), Some(MeteorSatellite::MeteorM2_3));
|
||||
|
||||
asm.spacecraft_id = Some(SPACECRAFT_M2_4);
|
||||
assert_eq!(asm.identify_satellite(), Some(MeteorSatellite::MeteorM2_4));
|
||||
|
||||
asm.spacecraft_id = Some(99);
|
||||
assert_eq!(asm.identify_satellite(), Some(MeteorSatellite::Unknown));
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,151 @@
|
||||
// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
|
||||
//
|
||||
// SPDX-License-Identifier: BSD-2-Clause
|
||||
|
||||
//! Meteor-M LRPT (Low Rate Picture Transmission) satellite image decoder.
|
||||
//!
|
||||
//! Decodes the LRPT digital signal broadcast by Meteor-M N2-3 (137.900 MHz)
|
||||
//! and Meteor-M N2-4 (137.100 MHz) using QPSK modulation at 72 kbps.
|
||||
//!
|
||||
//! # Signal chain
|
||||
//!
|
||||
//! The input is baseband IQ or FM-demodulated soft symbols:
|
||||
//! 1. QPSK demodulation with Costas loop carrier recovery.
|
||||
//! 2. Symbol timing recovery (Gardner algorithm).
|
||||
//! 3. CCSDS frame synchronisation (ASM = 0x1ACFFC1D).
|
||||
//! 4. Viterbi decoding (rate 1/2 convolutional code).
|
||||
//! 5. CADU deframing -> VCDU -> MPDU -> APID extraction.
|
||||
//! 6. MCU (Minimum Coded Unit) JPEG decompression per channel.
|
||||
//!
|
||||
//! Active APIDs for Meteor-M imagery:
|
||||
//! - APID 64: channel 1 (visible, 0.5-0.7 um)
|
||||
//! - APID 65: channel 2 (visible/NIR, 0.7-1.1 um)
|
||||
//! - APID 66: channel 3 (near-IR, 1.6-1.8 um)
|
||||
//! - APID 67: channel 4 (mid-IR, 3.5-4.1 um)
|
||||
//! - APID 68: channel 5 (thermal IR, 10.5-11.5 um)
|
||||
//! - APID 69: channel 6 (thermal IR, 11.5-12.5 um)
|
||||
//!
|
||||
//! Call [`LrptDecoder::process_samples`] with each audio/baseband batch,
|
||||
//! then [`LrptDecoder::finalize`] when the pass ends.
|
||||
|
||||
pub mod cadu;
|
||||
pub mod demod;
|
||||
pub mod mcu;
|
||||
|
||||
/// Identified Meteor satellite.
|
||||
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
|
||||
pub enum MeteorSatellite {
|
||||
MeteorM2_3,
|
||||
MeteorM2_4,
|
||||
Unknown,
|
||||
}
|
||||
|
||||
impl std::fmt::Display for MeteorSatellite {
|
||||
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
|
||||
match self {
|
||||
MeteorSatellite::MeteorM2_3 => write!(f, "Meteor-M N2-3"),
|
||||
MeteorSatellite::MeteorM2_4 => write!(f, "Meteor-M N2-4"),
|
||||
MeteorSatellite::Unknown => write!(f, "Meteor-M (unknown)"),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Completed LRPT image returned by [`LrptDecoder::finalize`].
|
||||
pub struct LrptImage {
|
||||
/// PNG-encoded image bytes.
|
||||
pub png: Vec<u8>,
|
||||
/// Number of decoded MCU rows.
|
||||
pub mcu_count: u32,
|
||||
/// Identified satellite, if determinable.
|
||||
pub satellite: Option<MeteorSatellite>,
|
||||
/// Comma-separated APID channels present (e.g. "64,65,66").
|
||||
pub channels: Option<String>,
|
||||
}
|
||||
|
||||
/// Top-level Meteor-M LRPT decoder.
|
||||
///
|
||||
/// Feed baseband samples with [`process_samples`] and call [`finalize`] at
|
||||
/// pass end to retrieve the assembled image.
|
||||
pub struct LrptDecoder {
|
||||
demod: demod::QpskDemod,
|
||||
framer: cadu::CaduFramer,
|
||||
channels: mcu::ChannelAssembler,
|
||||
first_mcu_ms: Option<i64>,
|
||||
}
|
||||
|
||||
impl LrptDecoder {
|
||||
pub fn new(sample_rate: u32) -> Self {
|
||||
Self {
|
||||
demod: demod::QpskDemod::new(sample_rate),
|
||||
framer: cadu::CaduFramer::new(),
|
||||
channels: mcu::ChannelAssembler::new(),
|
||||
first_mcu_ms: None,
|
||||
}
|
||||
}
|
||||
|
||||
/// Process a batch of baseband samples.
|
||||
///
|
||||
/// Returns the number of new MCU rows decoded in this batch.
|
||||
pub fn process_samples(&mut self, samples: &[f32]) -> u32 {
|
||||
let before = self.channels.mcu_count();
|
||||
|
||||
// Demodulate to soft symbols
|
||||
let symbols = self.demod.push(samples);
|
||||
|
||||
// Frame sync and CADU extraction
|
||||
let cadus = self.framer.push(&symbols);
|
||||
|
||||
// Decode MCUs from each CADU
|
||||
for cadu in &cadus {
|
||||
self.channels.process_cadu(cadu);
|
||||
}
|
||||
|
||||
let after = self.channels.mcu_count();
|
||||
let new_mcus = after - before;
|
||||
|
||||
if new_mcus > 0 && self.first_mcu_ms.is_none() {
|
||||
self.first_mcu_ms = Some(crate::now_ms());
|
||||
}
|
||||
|
||||
new_mcus
|
||||
}
|
||||
|
||||
/// Total number of MCU rows decoded so far.
|
||||
pub fn mcu_count(&self) -> u32 {
|
||||
self.channels.mcu_count()
|
||||
}
|
||||
|
||||
/// Encode all accumulated channel data as a PNG image.
|
||||
///
|
||||
/// Returns `None` if no MCU rows have been decoded.
|
||||
pub fn finalize(&self) -> Option<LrptImage> {
|
||||
let png = self.channels.encode_png()?;
|
||||
let active_apids = self.channels.active_apids();
|
||||
let channels_str = if active_apids.is_empty() {
|
||||
None
|
||||
} else {
|
||||
Some(
|
||||
active_apids
|
||||
.iter()
|
||||
.map(|a| a.to_string())
|
||||
.collect::<Vec<_>>()
|
||||
.join(","),
|
||||
)
|
||||
};
|
||||
|
||||
Some(LrptImage {
|
||||
png,
|
||||
mcu_count: self.channels.mcu_count(),
|
||||
satellite: self.channels.identify_satellite(),
|
||||
channels: channels_str,
|
||||
})
|
||||
}
|
||||
|
||||
/// Clear all state; ready to decode a fresh pass.
|
||||
pub fn reset(&mut self) {
|
||||
self.demod.reset();
|
||||
self.framer.reset();
|
||||
self.channels.reset();
|
||||
self.first_mcu_ms = None;
|
||||
}
|
||||
}
|
||||
+1
-1
@@ -11,7 +11,7 @@ use std::io::Cursor;
|
||||
|
||||
use image::{DynamicImage, GrayImage};
|
||||
|
||||
use crate::apt::{RawLine, IMAGE_A_LEN, IMAGE_B_LEN};
|
||||
use super::apt::{RawLine, IMAGE_A_LEN, IMAGE_B_LEN};
|
||||
|
||||
/// Assemble decoded lines into a JPEG image.
|
||||
///
|
||||
@@ -0,0 +1,157 @@
|
||||
// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
|
||||
//
|
||||
// SPDX-License-Identifier: BSD-2-Clause
|
||||
|
||||
//! NOAA APT (Automatic Picture Transmission) weather satellite image decoder.
|
||||
//!
|
||||
//! Decodes the APT format broadcast by NOAA-15 (137.620 MHz),
|
||||
//! NOAA-18 (137.9125 MHz) and NOAA-19 (137.100 MHz).
|
||||
//!
|
||||
//! # Signal chain
|
||||
//!
|
||||
//! The input is FM-demodulated audio containing a 2400 Hz AM subcarrier.
|
||||
//! The decoder:
|
||||
//! 1. Extracts the AM envelope via a FFT-based Hilbert transform (rustfft).
|
||||
//! 2. Resamples to 4160 Hz (the APT image sample rate).
|
||||
//! 3. Detects line sync markers (1040 Hz alternating pattern).
|
||||
//! 4. Assembles image lines (2080 samples each) and extracts both channels.
|
||||
//!
|
||||
//! Call [`AptDecoder::process_samples`] with each audio batch, then
|
||||
//! [`AptDecoder::finalize`] when the pass ends to obtain JPEG bytes.
|
||||
|
||||
pub mod apt;
|
||||
mod image_enc;
|
||||
pub mod telemetry;
|
||||
|
||||
use apt::{AptDemod, SyncTracker};
|
||||
use telemetry::{Satellite, SensorChannel};
|
||||
|
||||
/// JPEG encoding quality (0-100).
|
||||
const JPEG_QUALITY: u8 = 85;
|
||||
|
||||
/// Completed APT image returned by [`AptDecoder::finalize`].
|
||||
pub struct AptImage {
|
||||
/// JPEG-encoded image bytes.
|
||||
pub jpeg: Vec<u8>,
|
||||
/// Number of decoded image lines.
|
||||
pub line_count: u32,
|
||||
/// Millisecond timestamp when the first line was decoded.
|
||||
pub first_line_ms: i64,
|
||||
/// Identified satellite, if telemetry was decodable.
|
||||
pub satellite: Satellite,
|
||||
/// Detected sensor channel for sub-channel A.
|
||||
pub sensor_a: SensorChannel,
|
||||
/// Detected sensor channel for sub-channel B.
|
||||
pub sensor_b: SensorChannel,
|
||||
}
|
||||
|
||||
/// Top-level NOAA APT decoder.
|
||||
///
|
||||
/// Feed audio samples with [`process_samples`] and call [`finalize`] at
|
||||
/// pass end to retrieve the assembled JPEG.
|
||||
pub struct AptDecoder {
|
||||
demod: AptDemod,
|
||||
sync: SyncTracker,
|
||||
first_line_ms: Option<i64>,
|
||||
}
|
||||
|
||||
impl AptDecoder {
|
||||
pub fn new(sample_rate: u32) -> Self {
|
||||
Self {
|
||||
demod: AptDemod::new(sample_rate),
|
||||
sync: SyncTracker::new(),
|
||||
first_line_ms: None,
|
||||
}
|
||||
}
|
||||
|
||||
/// Process a batch of PCM samples (float32, mono or will be treated as-is).
|
||||
///
|
||||
/// Returns the number of new lines decoded in this batch.
|
||||
pub fn process_samples(&mut self, samples: &[f32]) -> u32 {
|
||||
self.demod.push(samples);
|
||||
|
||||
let before = self.sync.lines.len() as u32;
|
||||
|
||||
// Move accumulated envelope output into the sync tracker
|
||||
if !self.demod.out.is_empty() {
|
||||
let envelope = std::mem::take(&mut self.demod.out);
|
||||
self.sync.push(&envelope);
|
||||
}
|
||||
|
||||
let after = self.sync.lines.len() as u32;
|
||||
let new_lines = after - before;
|
||||
|
||||
if new_lines > 0 && self.first_line_ms.is_none() {
|
||||
self.first_line_ms = Some(crate::now_ms());
|
||||
}
|
||||
|
||||
new_lines
|
||||
}
|
||||
|
||||
/// Total number of lines decoded so far.
|
||||
pub fn line_count(&self) -> u32 {
|
||||
self.sync.lines.len() as u32
|
||||
}
|
||||
|
||||
/// Encode all accumulated lines as a JPEG image and return the result.
|
||||
///
|
||||
/// Performs telemetry extraction, radiometric calibration (when enough
|
||||
/// lines are available for a full 128-line telemetry frame), and
|
||||
/// histogram equalisation before JPEG encoding.
|
||||
///
|
||||
/// Returns `None` if no lines have been decoded yet.
|
||||
/// Does **not** reset the decoder; call [`reset`] afterwards if needed.
|
||||
pub fn finalize(&self) -> Option<AptImage> {
|
||||
if self.sync.lines.is_empty() {
|
||||
return None;
|
||||
}
|
||||
|
||||
// Extract telemetry for calibration and satellite identification
|
||||
let tel = telemetry::extract_telemetry(&self.sync.lines);
|
||||
|
||||
// Clone lines so we can apply calibration without mutating decoder state
|
||||
let mut lines = self.sync.lines.clone();
|
||||
|
||||
let (satellite, sensor_a, sensor_b) = if let Some(ref tf) = tel {
|
||||
// Apply radiometric calibration using telemetry wedge LUTs
|
||||
for line in &mut lines {
|
||||
telemetry::calibrate_line_a(&mut line.pixels_a, &tf.cal_lut_a);
|
||||
telemetry::calibrate_line_b(&mut line.pixels_b, &tf.cal_lut_b);
|
||||
}
|
||||
(tf.satellite, tf.sensor_a, tf.sensor_b)
|
||||
} else {
|
||||
(Satellite::Unknown, SensorChannel::Unknown, SensorChannel::Unknown)
|
||||
};
|
||||
|
||||
// Apply histogram equalisation per-channel for contrast enhancement
|
||||
let mut all_a: Vec<u8> = lines.iter().flat_map(|l| l.pixels_a.iter().copied()).collect();
|
||||
let mut all_b: Vec<u8> = lines.iter().flat_map(|l| l.pixels_b.iter().copied()).collect();
|
||||
telemetry::histogram_equalize(&mut all_a);
|
||||
telemetry::histogram_equalize(&mut all_b);
|
||||
|
||||
// Write equalised pixels back
|
||||
let width_a = apt::IMAGE_A_LEN;
|
||||
let width_b = apt::IMAGE_B_LEN;
|
||||
for (i, line) in lines.iter_mut().enumerate() {
|
||||
line.pixels_a.copy_from_slice(&all_a[i * width_a..(i + 1) * width_a]);
|
||||
line.pixels_b.copy_from_slice(&all_b[i * width_b..(i + 1) * width_b]);
|
||||
}
|
||||
|
||||
let jpeg = image_enc::encode_jpeg(&lines, JPEG_QUALITY)?;
|
||||
Some(AptImage {
|
||||
jpeg,
|
||||
line_count: lines.len() as u32,
|
||||
first_line_ms: self.first_line_ms.unwrap_or_else(crate::now_ms),
|
||||
satellite,
|
||||
sensor_a,
|
||||
sensor_b,
|
||||
})
|
||||
}
|
||||
|
||||
/// Clear all state; ready to decode a fresh pass.
|
||||
pub fn reset(&mut self) {
|
||||
self.demod.reset();
|
||||
self.sync.reset();
|
||||
self.first_line_ms = None;
|
||||
}
|
||||
}
|
||||
+1
-1
@@ -10,7 +10,7 @@
|
||||
//! carries the channel ID, and wedges 10-15 carry thermal calibration data.
|
||||
//! Wedge 16 is the "zero modulation" reference (black body equivalent).
|
||||
|
||||
use crate::apt::{IMAGE_A_LEN, IMAGE_B_LEN, RawLine};
|
||||
use super::apt::{IMAGE_A_LEN, IMAGE_B_LEN, RawLine};
|
||||
|
||||
/// Lines per telemetry frame (128 lines = 16 wedges x 8 lines each).
|
||||
pub const FRAME_LINES: usize = 128;
|
||||
Reference in New Issue
Block a user