Portsdown 4 Pluto

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Introduction

Evariste, F5OEO has produced firmware for the Pluto SDR which enables it to be a very capable DATV modulator. This firmware has 2 modes.

  • RTMP stream Input
  • Webpage Control with UDP stream input.

The Webpage control mode is ideal for desktop computers and is continually being developed. It is not suitable for use with the Portsdown. The RTMP stream input mode is very suitable for use in small systems and this is what is used by the Portsdown.

Mode of Operation

The existing Portsdown software has had additional commands added to enable it to generate an RTMP stream (using ffmpeg) and send it to the Pluto. RTMP will only handle H264 encoding, so MPEG-2 modes are not available.

Suitable Pluto Firmware

All testing has been done using F5OEO's "for the brave" Pluto firmware (FIRM2101RC of 5 February 2020). Extract the firmware from this zip file File:FIRM2101RC.zip and follow the instructions on this web page VERY CAREFULLY Analog Devices Firmware Upgrade Instructions. The Pluto must already have been modified for extended frequency range, and it is worth enabling the second processor.

Powering the Pluto

The Raspberry Pi 4 has increased power capabilities on its USB ports, and the Pluto does not work well with USB Hubs, so it is recommended that you connect the Pluto directly to a USB3 port (the blue ones) on the Raspberry Pi 4. Do not use a USB hub or power the Pluto from its USB power port.

Current Functionality

  • H264 only. No MPEG-2 or H265
  • 4:3 SD, 16:9 or 720p. No 1080p
  • You can set and store (for each band) Pluto relative power on a range of 0 to -71. This approximates to dBm, but is plus or minus 10 dB.
  • Maximum frequency 4.1 GHz (so no 6 cm band).
  • I have seen it work well on symbol rates between 125 and 1000 kS.
  • DVB-S or DVB-S2
  • DVB-T from 150 kHz to 1 MHz bandwidth
  • Video source Pi Cam (must have USB audio dongle connected as well), Comp Video, old-style C920, Test card, Contest or LKV373A HDMI.
  • Pluto and RPi GPIO PTT switching implemented, but the test card mode overuns after deselection of transmission
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