@Thanasis ...if you want to keep 20Mhz try to change

if pulse(x)>=2 and pulse(x)<=4 then p(x)=0 'if pulsewidth between 20 and 40uS then read as '0'
if pulse(x)>=6 and pulse(x)<=8 then p(x)=1 'if pulsewidth between 60 and 80uS then read as '1'

to this one

if pulse(x)>=9 and pulse(x)<=21 then p(x)=0 'if pulsewidth between 20 and 40uS then read as '0'
if pulse(x)>=29 and pulse(x)<=41 then p(x)=1 'if pulsewidth between 60 and 80uS then read as '1'

and let me know