frames Packet Radio frames at 1200 Baud are much better in MS than CW or SSB To take full advantage of the method, PSK modulation is strongly recommended. An analogic Costa's Loop is the best. Beware of digital Costa's Loop demodulator ( Ham Radio February 1987): it needs strong signals to work We use here a Japanese design PSK modem with few improvements. It uses just LM324 and few others components. It decodes perfectly with S0 signals