Testing a HamTV Receiver using the Portsdown

The Portsdown 4 system can be set to transmit a near-HamTV specification signal from a Pluto SDR on boot-up.

Equipment Required

• Raspberry Pi 4 with 1, 2 or 4 GB of memory. Not any other Raspberry Pi version.
• A power supply for the Raspberry Pi.
• A fast MicroSD Card of 8 GB or more capacity. SanDisk Ultra UHS-1 card recommended (the red one).
• A genuine Analog Devices Pluto SDR with USB lead.
• A PC for use during the set-up phase, with a MicroSD card reader and a network and internet connection.
• A wired network connection for the Raspberry Pi during setup.

Setup Activities

1. Configure the Pluto
2. Load the operating system on the SD Card
3. Run the automated build script on the SD Card
4. Use a web browser to configure the Portsdown software to the correct settings

After these steps, the Pluto will start transmitting a 2 MS DVB-S signal on 2395 MHz every time the system is started up.

Configuring the Pluto

The Pluto needs to have the frequency range extending (even though we are oeprating inside the designed frequency range), AND it needs special firmware to be loaded.

Connect to Pluto in SSH at the IP address: 192.168.2.1 (Bitwise software under windows and Pluto connected by USB).

user: root password: analog For more details on the connection to Pluto see the article: https://f1atb.fr/sdr-adalm-pluto-setup/

To extend the frequency, just define environment variables. Before modification, a first visualization of these variables is possible with the command: fw_printenv

Then to modify the frequency band type the 3 commands below:

1. fw_setenv attr_name compatible
2. fw_setenv attr_val “ad9364”
3. reboot

The special firmware is 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.

Note that the more recent Revision C (outside label) (marked as Revision D on the PCB) Plutos need an extra environment variable setting for the frequency extension. In addition to the other commands, at the command line of the Pluto enter

fw_setenv compatible ad9364

You can check that you have the correct Firmware loaded from the "Pluto Configuration Menu" (reached from Menu 3). It should report Firmware version v0.31-4-g9ceb-dirty.