Portsdown 4

The Portsdown 4 system has been specifically designed to be used with the Raspberry Pi 4 and the official Raspberry Pi 7 inch touchscreen.

It will drive a LimeSDR (tested with the Mini, but probably Lime SDR USB as well), the DATV Express board (DVB-S only) and, as an experimental capability, the Pluto SDR.

No other models of Raspberry Pi or touchscreen are planned to be supported in the near future so please don't ask!

Capabilities

The Portsdown 4 has the following capabilities:

• DVB-S and DVB-S2 (MPEG-2 and H264) transmissions from a LimeSDR Mini connected by USB
• DVB-S and DVB-S2 (H264 only) transmissions from a Pluto SDR connected by USB
• DVB-S (MPEG-2 and H264) transmissions from a DATV Express Board connected by USB
• Supported transmit video sources include the Raspberry Pi Camera, C920 WebCam or a USB-connected EasyCap composite video capture device
• Streaming to the BATC Streamer using the Raspberry Pi Camera or EasyCap composite video capture device
• Reception and display of DVB-S and DVB-S2 (MPEG-2, H264 and H265) signals received by a BATC MiniTiouner Mk 2 connected by USB.
• Display of streams from the BATC Streamer
• Control of a Pluto, DATV Express, ADF4351 and Elcom Microwave Source using the Portsdown 4 Signal Generator.

The Portsdown 4 does NOT support the BATC Filter-modulator board or Ugly mode.

Currently not everything is working, so please have patience.

Hardware

Portsdown 4 GPIO connections

Due to a reassignment of the GPIO pins on Portsdown 4, the connections are different to previous generations of Portsdown.

The Portsdown 4 GPIO Connections are defined here: Portsdown 4 GPIO Connections.

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.

Software

The Portsdown 4 software is available on a pre-programmed SD card from the BATC shop https://batc.org.uk/shop/portsdown-transmitter-pre-programmed-sd-card/

If you wish to build your own card the build is on GitHub at https://github.com/BritishAmateurTelevisionClub/portsdown4

You MUST start with a fresh build of Raspios Buster (NOT Raspbian) on an SD Card of 8 GB or greater, so you will need to rebuild any previous Langstone or Portsdown A27 card.

Langstone Microwave transceiver

The Portsdown 4 software build is also compatible with the Langstone Microwave transceiver software, which can be loaded from touchscreen selections (menu 2) AFTER the Portsdown software has been installed.

See https://wiki.microwavers.org.uk/Langstone_Project for more details and the full spec of the Langstone.

To operate, the Langstone software needs a Pluto to be connected by USB, and a compatible USB Audio dongle.

Pluto Capabilities

The Portsdown 4 support for the Pluto SDR is experimental at the moment and it has limited functionality as described here Portsdown 4 Pluto.

FAQ

• Is it possible to rotate the PiCam image in software as it is on it's side?

No - you need to do the camera mounting modification which Colin G4KLB described in CQ-TV 267

• Can I upgrade from Langstone or a previous version incluing Portsdown A27?

No - you must start with a clean image on your SD card

• When I try to update I get the error "Unable to contact GitHub for update, Internet connection to Google seems OK". The solution is to log in by ssh and run the following commands:

cd /home/pi
wget https://raw.githubusercontent.com/BritishAmateurTelevisionClub/portsdown4/master/update.sh  -O /home/pi/update.sh
chmod +x /home/pi/update.sh
./update.sh

More information

For more information see https://forum.batc.org.uk/viewtopic.php?f=103&t=6804