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Robin Getz
409e1f1a00
The ui object is created during MeshcoreDemodGUI and MeshtasticDemodGUI construction and remains valid for the lifetime of the widget. Remove the unnecessary null check to avoid misleading static analysis tools into assuming ui can be null. This resolves a Coverity false positive where the later call to updateDechirpModeUI() was reported as a possible null dereference in both places. Signed-off-by: Robin Getz <rgetz503@gmail.com>
MeshCore demodulator plugin
Introduction
This plugin demodulates and decodes incoming MeshCore wire packets. It is the
RX counterpart of the MeshCore modulator plugin (channeltx/modmeshcore)
and the standalone lora_trx headless transceiver in gr4-lora.
The decode pipeline is derived from the Meshtastic demodulator (LoRa-SDR-based, configurable BW/SF/CR/sync). MeshCore EU defaults are baked in: 869.618 MHz / 62.5 kHz / SF 8 / CR 4/8, sync word 0x12.
Status
Functional surfaces:
- LoRa PHY decode covering MeshCore EU radio params (preamble, sync,
CFO, soft demod), with the following adjustments:
m_nbSymbolsMaxdefault raised to 1023 (256 symbols are needed for a 120-byte ADVERT at SF=8 / CR=4/8; the prior default of 255 clipped this); channel filter cutoff widened to BW/1.25; interpolator upsample regime infeed();m_chirpinitialization aligned to the standard LoRa upchirp. Packet::decodeFrame(inmodemmeshcore) for ADVERT / TXT_MSG / GRP_TXT / ANON_REQ / ACK / PATH / CTRL packets.- ADVERT signature verification (Ed25519 via vendored Monocypher).
- Auto-augmented PSK for public channels.
- Optional UDP JSON sink (
sendJsonViaUDP) for off-process observation. - Radio parameters (BW, SF, CR, preamble length, frequency offset)
exposed via combo controls. BW combo includes 62500 / 125000 /
250000 Hz — the bandwidths used by the MeshCore firmware CLI's
set radio freq_MHz,bw_kHz,sf,crcommand. - Preset combo populated with the well-known MeshCore regional
defaults (EU_NARROW, EU_LONG_RANGE, EU_MEDIUM_RANGE, AU,
AU_VICTORIA, CZ_NARROW, EU_433_LONG_RANGE, NZ, NZ_NARROW, PT_433,
PT_868, CH, USA, VN, USER). Default is
EU_NARROW(869.618 MHz / SF 8 / BW 62.5 kHz / CR 4/8). Selecting a preset applies its freq/BW/SF/CR viamodemmeshcore::command::applyMeshcorePreset. - The Region and Channel controls are hidden: region is implicit in the preset frequency, and group channels are managed via the keys dialog rather than a numbered Channel selector.
Outstanding:
- WebAPI schema now uses dedicated
SWGMeshcoreDemodSettings/SWGMeshcoreDemodReportschemas (no longer a placeholder).
References
- MeshCore protocol: https://github.com/meshcore-dev/MeshCore
- gr4-lora python decoder:
scripts/src/lora/decoders/meshcore.py - gr4-lora python crypto:
scripts/src/lora/core/meshcore_crypto.py - Vendored Monocypher: https://monocypher.org (BSD-2-Clause OR CC0-1.0)
- Vendored tiny-AES-c: https://github.com/kokke/tiny-AES-c (public domain)