FT8 Skimmer

NB. The descriptions below and the associated software require the 2020-06-28 release (or later) of Pavel Demin’s software for the Red Pitaya 125-14 and 122.88-16.

Red Pitaya as FT8 skimmer for RBN

Pavel Demin’s FT8 receiver for the Red Pitaya only reports its decodes to pskreporter.info

Using the instructions below you can upgrade an installation of Demin’s FT8 receiver to not only upload spotted callsigns to RBN (via RBN Aggregator) but for the 125-14 also apply a 24h cycle for which frequency bands to skim (similar to RBN Aggregator’s ini-file cycling for CW Skimmer Server). 

Demin’s software for the 122.88-16 covers 16 bands and thus covers not only the “regular” FT8 subbands but also a handful of popular F/H subbands.

Please note that, due to sheer volume, FT8 spots are treated differently on RBN and are not directly visible on the web site. Also, not all retail cluster nodes carry them. Examples of cluster nodes that do are W9PA-5 (telnet: dxc.w9pa.net:7374) and VE7CC (telnet: dxc.ve7cc.net:23 using the SET/FT8 command).

Don’t be alarmed by the bursty nature of the decoder. Since it does a bulk decoding of all signals received once every 60 seconds, there can be hundreds of decodes. The decodes are however effectively throttled by RBN Aggregator that prevents calls from being spotted more than once per ten minute period. This means that, apart from the very first minute of operation, only a few dozen of the spots will actually be uploaded to RBN in each batch. However, due to sheer traffic volume, the spot count per hour is much higher than for CW or RTTY.

Before you start, make sure the Red Pitaya and the computer running RBN Aggregator are on the same LAN and subnet. If they are not, the UDP broadcast transfer will not work. Also decide on which port RBN Aggregator will be using for receiving the FT8 spots from the Red Pitaya. (2238 may be a good choice if you are already uploading spots from WSJT-X via port 2237.) Make sure you activate this port number for listening on the FT8 tab in RBN Aggregator. 

The instructions below will create a dedicated FT8 skimmer SD card. If you plan to run other applications on your Red Pitaya from time to time, such as a spectrum analyzer, use a separate SD card for this installation. However, if you want to use other of Demin’s applications (they are all included in the same SD Card image) you can either comment out the line copying start.sh to /media/mmcblk0p1 in install.sh and start the application manually or use the stop.sh and start.sh shell scripts found in the ~/apps folders. 

Be aware that the Red Pitaya can only run one radio application at the time.


Red Pitaya 125-14 

Installation

Follow the below instructions literally. Do not take shortcuts or try to customize the installation until you have it working.  

Download Pavel Demin’s SD-card image zip-file for your Red Pitaya 125-14 and unpack the content onto a clean, FAT32-formatted SD card. You can do this on a Windows PC.

SSH (using e.g. Putty on a Windows computer) to the Red Pitaya. Default user name is “root”, default password is “changeme”.

Semioptionally – change the password to something more secure.

# passwd 

Optionally – modify the welcome message to include the identity of the Red Pitaya (e.g. “my FT8 skimmer”).

# nano /etc/motd 

Install git

# apk update
# apk add git 

Fetch the installation package

# git clone https://github.com/bjornekelund/upload-ft8-to-rbn
# cd upload-ft8-to-rbn

Install the utilities for configuration cycling and RBN upload

# ./install.sh

Configure your skimmer. In total there are (unfortunately) five files to edit. Add grid, call, antenna information (for pskreporter), and broadcast IP port as required. For twilight duration, empirical studies suggest that two hours is a good number. Should you live closer to the equator you may want to use a shorter number, such as 1.5. Setting it to zero disables the use of the twilight configuration file write-c2-files-gray.cfg. Enter your device’s calibration factor in ppm (with one decimal using period as decimal separator!) in each of the three configuration files. If you do not know your calibration factor, leave it at 0.0. More information on calibration can be found on the calibration page. You may also want to modify the band selection for the three daylight periods. This is done by commenting/uncommenting the corresponding lines. If you do this, make sure you activate maximum eight bands and also keep an eye on the commas for correct syntax. The number after “chan =”  is the antenna input used for that frequency. The receiver supports the use of two different antennas. Exit the editor for each of the five files with Ctrl-S Ctrl-X. Let the script run to the end. Do not exit prematurely with e.g. Ctrl-C. 

# ./config.sh

Check that we are in business by tailing the log file and watch it build up. (Don’t worry if you get an error message that the file does not exist at first, just wait and it will appear.) Once started, you will see lines added to the log file a few times per minute. The first upload to RBN will happen 2-3 minutes after boot and then once every minute. This is due to the pipelined nature of the processing. You should also see the periodic bursts of spots on RBN Aggregator’s FT8 tab. 

# tail -F /dev/shm/decode-ft8.log

when you are done, hit Ctrl-C. After having letting the decoder run for a few minutes, check the temperature of the main system chip. if you are above 70 degrees C, you probably need a fan. 

# ./temp.sh

Finally log off and leave the Red Pitaya alone.

# exit

If you want to understand/modify/build the radioday  and upload-to-rbn utilities, you can find their source code and Makefiles on GitHub. They can both be git cloned to the Red Pitaya and built there. 

Update

If you want to update your installation to the latest version you simply do:

# cd ~/upload-ft8-to-rbn
# git pull
# ./install.sh

Re-enter your configuration data. The application will automatically restart.

# ./config.sh

Deinstallation

Should you ever want to disable the functionality and return to only reporting spots to pskreporter, run the deinstall script. 

# cd ~/upload-ft8-to-rbn
# ./deinstall.sh

The application will automatically restart.


Red Pitaya 122.88-16 

Installation

Follow the below instructions literally. Do not do take other steps suggested on Pavel’s web site, such as copying start.sh to the root of the SD card. 

Download Pavel Demin’s SD-card image zip-file for your Red Pitaya 122.88-16 and unpack the content onto a clean, FAT32-formatted SD card. Although the image is Linux, it is OK to do this on a Windows PC.

SSH (using e.g. Putty on a Windows computer) to the Red Pitaya. Default user name is “root”, default password is “changeme”.

Semioptionally – change the password to something more secure.

# passwd

Optionally – modify the welcome message to include the identity of the Red Pitaya (e.g. “my FT8 skimmer”).

# nano /etc/motd

Install git

# apk update
# apk add git

Fetch the installation package

# git clone https://github.com/bjornekelund/upload-ft8-to-rbn-2
# cd upload-ft8-to-rbn-2

Install the utilities for RBN upload

# ./install.sh

The next step is to configure the skimmer. In total there are three files to edit. Add grid, call, antenna information (for pskreporter), and broadcast IP port as required. (The script will determine the broadcast IP address automatically.) Enter your device’s calibration factor in ppm with decimal format. If you do not know your calibration factor, leave it at 0.0. More information on calibration can be found on the calibration page. You may also want to modify the band selection to include popular DX Fox/Hound base frequencies such as 7056, 10131, and 14090kHz. (Keep in mind that the frequency in the configuration file is the band center, i.e. 1500Hz above the base frequency.) This is done by adding/commenting/uncommenting the corresponding lines. If you do this, make sure you do not exceed 16 active frequency entries and also keep an eye on the commas for correct syntax. The “chan = 1” for each frequency is for input selection. The receiver supports using two different antennas, with individual band selection. Exit the editor for each of the three files with Ctrl-S Ctrl-X. Run the script to the end. Do not exit prematurely with e.g. Ctrl-C. The application will automatically start when the configuration is completed. You may see an error message about the device ‘mvl0’ not existing but this is expected and harmless.

# ./config.sh

Check that we are in business by tailing the log file and watch it build up. (Don’t worry if you get an error message that the file does not exist at first, just wait and it will appear.) Once started, you will see lines added to the log file a few times per minute. The first upload to RBN will happen 2-3 minutes after boot and then once every minute. This is due to the pipelined nature of the processing. You should also see the periodic bursts of spots on RBN Aggregator’s FT8 tab. 

# tail -F /dev/shm/decode-ft8.log

When you are done, hit Ctrl-C. After having letting the decoder run for a few minutes, check the temperature of the main system chip. if you are above 70 degrees C, you probably need a fan. 

# ./temp.sh

Then log off and leave the Red Pitaya alone.

# exit

If you want to understand/modify/build the upload-to-rbn utility, you can find the source code and Makefiles on GitHub. It can be git cloned to the Red Pitaya and built there. 

Update

If you want to update your installation to the latest version you simply do:

# cd ~/upload-ft8-to-rbn-2
# git pull
# ./install.sh

Re-enter your configuration data.

# ./config.sh

The application will automatically restart

Deinstallation

Should you ever want to disable the functionality and return to only reporting spots to PSK Reporter, run the deinstall script. 

# cd ~/upload-ft8-to-rbn-2
# ./deinstall.sh