PSK with ATS3A, success on the air


Hi gang.


In my previous posting, I described my first tests of BPSK31 signal and ATS3A.



During the last weekends, I extended PocketDigi to modulate BPSK31, BPSK63 and QPSK31 on ATS3A. The interface and protocol is described in my previous posting.


I tested it on the table first. The signal is not as clean as if it would be generated by a SSB transceiver, but I found worse signals on the air. Most of the commonly used PSK software received that non ideal BPSK31 and BPSK63 signal without any problems. The exception is QPSK31, which was decoded only by MixW, but nobody is using QPSK31 on the air anyway.


I had a first chance to try it on the air this weekend. My PSK31 setup is very portable now, but I aim to make it even smaller.

- Stock ATS3A with a modified firmware

- FSK Bell 202 decoder (receiving part of BayCom modem, half the size of Altoids tin, see my previous post)

- 2xLiPol 1800mAh battery

- Z-match

- iPaq 3630 Pocket PC computer

- foldable infrared keyboard

- LW antenna


I made about 10 QSOs on 40 and 80m, most of the QSOs on the first call. I did not receive any complaints about signal quality, I suppose that the sidelobes are below noise if using QRP levels. I checked temperature of the finals after each longer QSO and the finals were only warm.


Wow! The first PSK31 transceiver in Altoids tin, giving 2 watts with 80% efficiency on two LiPols. Anyone wants to experiment?


The next steps will be RTTY and other MFSK modes (MFSK16, Olivia, Contestia) and simplification of the interface board. I hope to replace the external FSK decoder by a single Op Amp and firmware extensions. I hope to fit the interface board in the main Altoids tin one day.


73, Vojtech OK1IAK