How to modulate PSK63 with liquiddsp?
Posting a standard is actually a good point.
After reading several definitions i've figured out that i have to keep the symbol (and thus the phase) if I want to transmit 1 and reverse it if i want to transmit zero.
(see: http://www.arrl.org/psk31-spec, PSK-63 has just higher speed, about 63 baud.)
if(ctr==(11025/63)){
    ctr=0;
    c=message[subsym]-'0';
    subsym++;
    if(subsym&gt;=strlen(message)){
        subsym=0;
    }
    if(!c) // here instead of just assigning bit=symbol
    sym_in = !sym_in;
}