Portsdown 4

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The Portsdown 4 transceiver software has been specifically designed to be used with the Raspberry Pi 4 and the official Raspberry Pi 7 inch touchscreen. It will drive a Pluto SDR or the LimeSDR.

Portsdown 4 is the simplest and easiest to construct, with a barebones system consisting of:

  • Raspberry Pi4 2GB model
  • 7" touch screen
  • 8, 16 or 32 GB SD card
  • Adalm Pluto or Lime SDRmini SDR hardware

This will give you a DVB-S2 and DVB-T DATV transmit system from 30 to 3500 MHz when using a Lime SDR and 50MHz to 4100 MHz with the Pluto.

With the addition of a MiniTiouner USB receiver [[1]], you will have a full spec DVB-S/S2 DATV transceiver.

With the addition of the Knucker USB tuner you will also have DVB-T receive capabilities.

Building a Portsdown 4

Dave G8GKQ published this step by step guide to building a Portsdown 4 in CQ-TV 271:

media:Getting Started With Portsdown 4.pdf

Capabilities

Portsdown 4 transmit capabilities:

  • DVB-S, DVB-S2 and DVB-T (H264 only) transmissions from a Pluto SDR connected by USB
  • DVB-S, DVB-S2 and DVB-T (MPEG-2 and H264) transmissions from a LimeSDR Mini or LimeSDR USB using stock LimeSDR firmware
  • DVB-S and DVB-S2 (MPEG-2 and H264) transmissions from a LimeSDR Mini using "LimeDVB" firmware
  • 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 as a source

Portsdown 4 receive capabilities:

When the Portsdown 4 is connected to the internet:

  • Display of streams from the BATC Streamer

When a MiniTiouner USB receiver is connected via USB:

When a BATC Knucker USB tuner is connected by USB:

  • Reception and display of DVB-T and DVB-T2 (MPEG-2, H264 and H265) signals

Portsdown test and alignment aids

  • Basic spectrum display of band occupancy using the "Portsdown Band Viewer" - note this requires a LimeSDR Mini to be connected.

Hardware

Portsdown 4 Block.PNG

No other models of Raspberry Pi or touchscreen are planned to be supported in the near future.

Portsdown 4 GPIO connections

Due to a reassignment of the GPIO pins on Raspberry Pi4, 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.

Portsdown hardware

Full details of the Portsdown hardware are available here.

Software

The Portsdown 4 software is available on a pre-programmed SD card which you can buy 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

Langstone Narrow band 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.

Note: the Langstone software needs a Pluto SDR to be connected by USB, and a compatible USB Audio dongle.

Pluto Capabilities

The Portsdown 4 support for the Pluto SDR is still under development and there are some limitations on 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
  • I have built my Portsdown 4 but the screen is upside down. How can I get it the right way up?
Menu 3, System Config, Invert 7 inch

More information

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

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