RX888 MkII with OnAir: USB 3 setup

An experimental native driver that talks to the radio over USB itself.

New in 0.2.6 (beta pre-releases), not in 0.2.5.

Still being hardened. The driver was written from the open SDDC protocol and tested against a simulated FX3; the MkII on real hardware is still being hardened. Please report what you see.

What it does#

OnAir talks to the radio over USB itself (no vendor library). HF (direct sampling, 64 or 128 Msps ADC clock) and VHF / UHF (R828D tuner, up to about 1.75 GHz) are covered; the sample rate list is 0.25 to 64 Msps.

Windows quick start#

In Zadig turn on List All Devices.
Install WinUSB for 04B4:00F3 and again for 04B4:00F1 (RX888mk2).
Unplug and replug the cable on a USB 3 port.
Press refresh in OnAir's radio list.

If the Cypress driver from the official RX-888 / HDSDR installer still owns the device, repeat Zadig on 00F1 and replug. A LimeSDR-USB shares 04b4:00f1; OnAir tells them apart by the product name.

Firmware#

The radio has no program of its own: the FX3 needs SDDC_FX3.img. Official OnAir packages ship it in the codecs folder (on Linux in lib/onair/). OnAir loads it into the radio's RAM when needed; nothing is flashed. A hand-built copy may need the file from the SDDC_Driver releases page, or the environment variable ONAIR_RX888_FIRMWARE pointing at it.

Requirements and settings#

It must be on a USB 3 port: the stream is up to 256 MB/s. On Linux a udev rule for 04b4:00f1 / 00f3 is needed.
Settings: ADC clock (auto, 64, 128 MHz or exact), input (auto, HF, VHF), HF attenuator, dither, randomiser, PGA, bias tee.