openwrt-one-sdr v0.2.0

Turns an OpenWrt One into a wideband, receive-only SDR: the MT7981 Wi-Fi radio
captures 14-bit IQ at 40 Msps on 2.4 and 5 GHz, streams it as VITA 49 over the
2.5 GbE port, and a Linux host shows it as a live spectrum and waterfall.

New in v0.2.0

• 40 MHz channel width on both bands. The radio now comes up HE40 (2.4 GHz
  in monitor mode to keep the full 40 MHz), so the 40 Msps capture fills the
  window instead of ~20 MHz. Confirmed on both bands in bounded on-hardware
  tests with zero counted drops.
• Correct per-band native sample lanes in the driver and capture helper (a
  previous stride mismatch mis-reported 2.4 GHz timing), tune reports the
  verified HE40 block centre, and the default setup brings up a 40 MHz block.

Get going

1. Flash openwrt-one-sdr-v0.2.0-squashfs-sysupgrade.itb to the board (a
   normal OpenWrt sysupgrade). It boots to its LAN at 192.168.1.1.
2. Set up from your host — unpack openwrt-one-sdr-v0.2.0-sdr-tools.tar.gz
   and run ./setup.sh <board-lan-ip> (needs only ssh/scp and Python 3),
   then reboot the board.
3. View — build the host viewer/bridge and open the browser UI, as in the
   project README "Getting started".

Prefer to build it all yourself? Follow README path B (docs/reproduce.md +
init/deploy.sh).

About the firmware

No MediaTek firmware is distributed here. The image carries the stock blob
exactly as OpenWrt ships it; setup.sh patches a copy of your board's own
stock firmware locally (toolchain-free, via apply-producer.py) into the SDR
firmware, which never leaves your machine. See release/README.md.

Assets

• openwrt-one-sdr-v0.2.0-squashfs-sysupgrade.itb — flashable image (stock fw + SDR driver)
• openwrt-one-sdr-v0.2.0-sdr-tools.tar.gz — host bring-up bundle (no toolchains)
• SHA256SUMS

Known limits

40 Msps; Wi-Fi channel-grid tuning (snap to nearest HE40 block centre); 5 GHz
limited to U-NII-1; ~25 s retune; residual overruns under sustained capture.
Calibrated passband flatness and indefinite gap-free operation remain unproven;
80 Msps is not a validated 80 MHz receiver. Details in the README "Design
approach and limitations".