{
freq[1].freq = wantedcurrentfrequency
freq[1].set =gettimeofdaynow()
setfrequency(freq[1])
waituntillplllocked()
freq[1].ready=gettimeofdaynow()

addtocollection(freq[1])
//do stuff

freq[1].invalidate=freq[2].set =gettimeofdaynow()
freq[1].freq = wantednextfrequency
setfrequency(freq[2])
waituntillplllocked()
freq[2].ready=gettimeofdaynow()
addtocollection(freq[2])
}

{
getframebuffers(frame1,frame2,....)

field1_start = field1.time
field1_end=field1.time+fieldduration

forall(i in fields, j in freqs)
{
field[i].valid=false
if(field[i].start >freq[j].ready && field[i].end <freq[j].invalidate)
	field[i].freq=freq[j].freq
        field[i].valid=true
if(field[i].start <lowest_field_start)
	lowest_field_start=field[i].start
}

forall (j in freqs)
{
if(freq[j].end)<lowest_field_start)
      removefromcollection(freqs,freq[j]) //increase startpointer for freqs ??
}

}