21 May 2009

Netbook (eeepc), FT817, digital modes

Our Summer holidays will take place on the same location of last year, just one week later. I already know the lodging, surroundings and somewhat, propagation too. Last year I did only CW QRP with a total of 56 contacts. The most limiting factor was operator's conditions, that became a lousy CW'er when tired. So this year I will (might) try digital modes.

I borrowed a netbook computer (eee PC, if you prefer) to check how it would perform. It is an Asus machine with 8.9" 1024x768 display On WinXP I installed Digipan, MultiPSK and WSPR as a starting point.

First test was with WSPR after syncing the clock (Dimension4). This netbook has enough computing power to keep up with the DSP/FFT analysis of WSPR slots (2 minutes). It takes 1'35" to digest two minutes of capture (one WSPR cycle), so the CPU runs at full steam 75% of time.

Then I tried to play with PSK31. I looked at MultiPSK because it supports several modes, but I was scared by the plethora of configuration options and the buttons density on the small 8.9" display. I tried a transmission test in my headphones but the signal was distorted. Discarded.

I moved on to DigiPan. I had used it in the past, so I am slightly familiar with its user interface. I love the multichannel reception capability. It sounds good without clicks or hum. CPU load is not excessive even with the multichannel scroll.

The keyboard of these netbooks is small. You need small fingers and a bit of practice to type fast without errors, so better plan good macros in advance.

This 6-cell battery (660mAh) lasts longer than I can afford to stay on the air, so the setup is probably valid for portable, exclusively battery powered, operations.

The same netbook also has Ubuntu 9.04 installed. I added HAM radio packages through the graphical interface and they load fine. Unfortunately fldigi transmitted signal sounds very bad and I could not understand how good the CPU usage is. I think I will stay with WinXP.

By the way, I used a fully isolated audio interface between the FT-817 and netbook. Since netbook has no serial/parallel port I kept my RTX in USB mode and used the VOX function. All signals picked on the FT-817 side Mic/Ear sockets.