PSK31In the HamQSO filter: Digital
PSK31: what it is and where to find it on the bands
PSK31: a narrow keyboard-to-keyboard digital mode for real conversations at low power.
PSK31 sends text at typing speed in a signal only 31 Hz wide, so dozens of conversations fit in the space of one voice channel.
Unlike FT8 it is a free-form chat: you type, the other station reads it as you go.
Activity has moved largely to FT8, but the PSK frequencies are still worth a look for a real QSO.