LibreSDR and the Portsdown 4

The Portsdown 4 supports transmission using the LibreSDR with the firmware supplied by DL1JM and PA2JSA. It has been tested with firmware versions 0226 and 0326 (builds 1.20 and 1.21).

Initial Set-up

The link to the firmware is available from PA2JSA. Contact via the e-mail address on his qrz.com page

Download the firmware and unzip to get a .img file. Using software such as Win32 Disk Imager, write this image file to an SD Card. Firmware versions 0226 and 0326 (builds 1.20 and 1.21) have been tested so far.

Insert the SD Card into the LibreSDR, connect it to the LAN, and apply power to the LibreSDR through the "OTG" slot. The power can be derived from one of the the Raspberry Pi USB sockets, but note that no data is passed over this connection.

After it has booted up, you should be able to "ping libre" from the command line of any Windows or Linux PC on the network. This will display the IP address of the LibreSDR, which you can then enter into a browser to read the documentation. However, this step is not necessary for use with Portsdown.

Use with the LibreSDR and Portsdown connected to a LAN

To use with the Portsdown, simply update the Portsdown to the latest development version (you may need to do a normal update to the latest production version before this option becomes available), and then select "Output to" on Menu 1. If the Portsdown can see the LibreSDR on the network, the LibreSDR button will be blue. If it is grey, it means that the Portsdown cannot see the LibreSDR on the network and some investigation will be required.

It is possible to set a specific IP address on the Portsdown for the LibreSDR. To do this, go to "Menu 3", select "Pluto and Libre Config", and then "Set LibreSDR IP Address". The default value is dhcp, which looks for the LibreSDR on its default name of libre, however a network address can be inserted here instead.

It is not possible to use a USB connection between the LibreSDR and the Portsdown - only LAN connection is supported.

Select Libre SDR as the Output device on Menu 1. Operation is very similar to the Pluto. Only H264 video encoding is supported and the frequency limits are from 70 MHz to 6 GHz. Power can be adjusted from the LibreSDR power button on Menu 1, in the range 0 to -30 (approximately dBs). Power selections below -30 do not seem to result in reliable transmission. The stored power setting is also used for Pluto transmissions.

Portable use without a LAN or Router - Not Released Yet

Portsdown software version 202603090 (?) introduced the capability to directly connect the LibreSDR to the Portsdown using a single network lead, with no need for a local network or router. Power still needs to be supplied to the LibreSDR OTG port through a USB lead (possibly from the Raspberry Pi). This configuration is ideal for portable operation. To set up this configuration, follow these steps:

• Go to "Menu 3", "Pluto and Libre Config", and touch the button "DHCP Disabled for LibreSDR".
• Select "Yes" if you wish to proceed. The Portsdown will reconfigure and reboot.
• If connected to a network, unplug the network lead straight away. THIS IS VERY IMPORTANT OTHERWISE YOU WILL CAUSE CHAOS ON YOUR NETWORK.
• Disconnect Power from your LibreSDR so that it forgets its previous IP address.
• Connect the LibreSDR directly to the Portsdown using a network cable (it does not need to be a cross-over cable).
• Once the Portsdown has rebooted (it will hang for about 30 seconds during the reboot as it tries to find a local network), reconnect power to the LibreSDR. Wait 30 seconds for the LibreSDR to start up.
• On Menu 1, "Output to LibreSDR" will be greyed out. Touch the button and then touch the "LibreSDR" on the bottom row.
• If all is well, the "Output to LibreSDR" button on Menu 1 will have turned green. If not you will get a "No LibreSDR Detected" message asking you to recheck connections and power.
• You can then use the LibreSDR for transmit as usual. Also, BandViewer is available after you set the "Pluto" IP address - see below.

On return to your shack, BEFORE CONNECTING TO YOUR NETWORK:

• Power up the Portsdown
• Go to "Menu 3", "Pluto and Libre Config", and touch the red button "DHCP Enabled for LibreSDR".
• Select "Yes" if you wish to proceed. The Portsdown will reconfigure and reboot.
• You can now connect to your network.
• On Menu 1, "Output to LibreSDR" will again be greyed out. Touch the button and then touch the "LibreSDR" on the bottom row.
• If you have the LibreSDR connected to the network, the "Output to LibreSDR" button on Menu 1 will have turned green.
• You can now use your Portsdown as usual. Remember to reset the "Pluto" IP address if you have been using BandViewer in the directly connected configuration.

Notes:

• In DHCP enabled mode, the Portsdown IP address is 192.168.10.50. It will normally allocate the address 192.168.10.51 to the LibreSDR. You can check this from "Menu 2", "File Menu", "List Network Devices".

Using the LibreSDR with BandViewer

Because the LibreSDR is very similar to the Pluto, it can be used with the "Pluto BandViewer" application. However, before this will work, the IP address for the LibreSDR needs entering using the "Set Pluto Address for Portsdown" button accessed from the "Pluto and Libre Config" menu (accessed from Menu 3). There is one limitation: the 50 MHz span does not seem to work. The 2, 5 , 10 and 20 MHz spans all work normally.

Thanks to DL1JM and PA2JSA for this excellent firmware.