Portsdown 4

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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 Block.PNG

Portsdown 4 GPIO connections

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

There are 2 GPIO pins that have changed for the RPi 4. One drives the ADF4351 (was on 27, now pin 33) which you will not be using, the other is the Band LSB (or D0) this has moved from pin 28 to pin 32.

Pin 32 is available on the GPIO breakout board as the "I" pin which is pin 2 on J03. More details here: https://wiki.batc.org.uk/images/2/27/PO ... CE_SCH.pdf


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

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