Calculate the highest modulating frequency for following data:
Case: Alternate black and white dots for equal vertical and horizontal resolution.The no. of scanning lines are 250.Interlace ratio is 1:1 picture repetition rate is 50/second aspect ratio 12:9.Vertical retrace time 10% of frame delay.Horizontal retrace period is 20% of line period.Resolution factor is 80%.
Above question asked by my professor.I solved it.
resolution factor=80%=o.8=kell factor
Hr=Na*k*aspect ratio =250*0.8*(12/9) =266.66 pixels or line equivalent 267 pixels
There is 250 lines/frame there is 50 frames/second
So, 250*50=12,500 total lines
So time required is,
1/12,500=80 micro second
Retrace period is 20% of total time,
So, 80 micro second*20% =16 micro second
So,trace time = 80-16=64 micro second
1 horizontal line=267 pixel 2 pixel=1 cycle
1 cycle=267/2=133.5=133 cycle (equivalent)
For 133 cycle required 64 micro second,So for 1 cycle
=64*10^-6/133 =0.48 micro second
fmax=1/Tmin=10/0.48 micro second=2.08 mhz
But sir told me there is some small mistake in my solution but I didn't get whats wrong in above solution.
So is there anybody who can help me with this ?