The problem seems to be CPU load, Some of that may come from the DRMTST back-end program which performs the decode, some from the TCL front end which uses Expect to parse the status information that it outputs at quite a high rate, some from the filesystem and IO writing the file. I didn’t have the sound output wired up to test this. TRXAMADRM does support the EasyPAL BSR mechanism to request retries. Despite the promising results shown, I was not able to receive a whole image without asking EasyPAL to make multiple transmission attempts. The picture in the image was provided with the software. First Run Running TRXAMADRM on the Raspberry Pi I installed Audacity and used its input level meter and a short test recording to check that the input level was correct. If anything the screen shot shows an input that is too loud, but not so loud that the reception fails.

When the level is correct for receiving data, you should be able to see the four pilot signals as solid lines in the waterfall with the data as a nicely contained grey texture around it. The transmit data is louder than the waterfall text data, so waterfall text is not a good way of setting levels. I connected directly into the Signalink’s “Speaker” input from the headphone output of my netbook running EasyPAL and played waterfall texts until my callsign appeared clearly in the waterfall display.

Using alsamixer I was able to find that my Signalink USB adapter was card 1. The sound device is selected by card number. The Raspberry Pi has limited USB output current. I don’t know how much current the Signalink draws. I have a Signalink USB connected via a powered USB hub. This produced the separate receive and transmit applications and a waterfall window. The one that seems to work is startdrmtrx.sh. The build took quite a while, and left me with ARM binaries for the Raspberry Pi.

I installed the following packages on the Pi: I then checked the code into Git so that I can keep track of any changes. I downloaded Version 3.1 and removed the Windows version and the pre-compiled binaries for X86. I thought I’d see if it would run on a Raspberry Pi. PA0MBO has a DRM transceiver for Linux, TRXAMADRM. A limitation with this so far is that EasyPAL is only available for Windows. RAYNET in my area use EasyPAL to transmit images and other data.

Easypal software