Muxwright: a broadcast station for a desk, out of a software defined...

Most people will never own a transmitter. Muxwright turns a cheap software defined radio into a broadcast station small enough for a desk. The radio is an ADALM-Pluto, the board engineering students already use for spectrum work. One browser window drives it.

DAB+, FM with RDS, DVB-T and T2, DVB-C, DVB-S and S2, ATSC, ISDB-T, DTMB, and analog PAL and NTSC all come out of the same interface. Each standard carries its own chain. The DVB-S2 and ATSC stages are bit-identical to the output of gr-dtv, which is the reference implementation everyone else checks against, and the DVB-T2 stage was verified against two independent receivers.

The analog mode is the one that will surprise people. It produces PAL B/G, D/K, I, M and N plus NTSC-M/J with FM sound, negative AM and vestigial sideband, on channels E2 to E12 and K21 to K69. Feed it a test card, an image, a video file or a YouTube link and it adds a clock overlay. A television from 1985 tunes it the way it tuned broadcasts in 1985.

Setting up a single standard normally means a rack of instruments and a week with the specification. Here the dashboard walks through the device and firmware checks, rates the machine, then installs the encoder components from their official sources. The firmware flasher tests its image in RAM before committing and backs up whatever was running. The whole thing runs offline. No cloud account, no telemetry, and the Windows installer does not ask for administrator rights.

What makes it a lab instrument is the loop back. The Pluto's own receive input decodes what it just sent: sync, SNR, service list, text. Every configuration gets rendered and then decoded, and any deviation lands in a report line by line. Print the measurement log with its timestamp and the parameters, and you have something to hand a certification body.

The limits are written down. DVB-C J.83 B and C, ATSC, ISDB-T and DTMB are beta releases that have not been tested against real televisions. Amateur mode requires a licence, and the application enforces the band plan, the call sign inside the programme name, and a filter and amplifier per band. The QO-100 wideband uplink sits at 2401.5 to 2409.5 MHz.

Muxwright is at https://muxwright.com/ . Buy the Pluto, install the package, and a standards-compliant signal is a double click away.

■ Filed from Aeray: the Birds, Air wing of the city.