LakeShark: a LoRa chip turned handheld radio scanner on the LilyGO T-Display P4

LakeShark by SAMS0N1TE turns the LilyGO T-Display P4 into an open-source handheld radio multitool. The trick behind it is the companion LR2021-SDR project: an undocumented command in the Semtech LR2021's ROM hands over raw 16-bit I/Q samples instead of demodulated LoRa packets, so a LoRa chip becomes a software-defined radio. On one LR2021 board the author measured reception from 100 MHz to 2.74 GHz, well past the datasheet bands, at up to 250,000 samples per second over plain SPI, tested on LR2021 ROM 1.24. On the LR2021 version of the LilyGO T-Display P4, LakeShark decodes P25 Phase I voice, FM/AM, POCSAG pagers and 1090 MHz ADS-B aircraft with no external SDR, and also runs MeshCore messaging, LoRa tools, live waterfalls, Sub-GHz capture with Flipper-style .sub export, offline maps with GPS, and a compass. The SX1262 version keeps MeshCore, LoRa and POCSAG; add an RTL-SDR dongle (RTL-SDR Blog V3/V4) over USB for FM, P25 and ADS-B. HackRF One support is experimental. Note this is an LR2021 trick: it does not turn the SX1262 in common Meshtastic boards into an SDR, and LakeShark's mesh app speaks MeshCore, not Meshtastic. You install it from Chrome or Edge with the project's browser installer over a USB data cable, then update over Wi-Fi from the UPDATE app; a microSD card holds maps, captures and recordings. You can also build it with ESP-IDF 5.5.4 plus the patches in the repo. Several features are marked experimental (P25 Phase II, LR2021 I/Q transmit and replay, HackRF), and the README reminds you that radio reception and transmission are subject to local laws. On October 22, 2026 the LilyGO store listed the T-Display P4 TFT 830-945 MHz LR2021 version at $100.39 (in stock) and the AMOLED LR2021 versions at $124.31 (sold out). The README's LR2021 build target uses the AMOLED board defaults, so check the installer supports the TFT LR2021 board before you buy it.