hi zammer, First of all u

[khushi]

hi zammer,

 

First of all u need one X-or gate for comaring Frequency with reference i/p frequency.

 

See below i have drawn block diagram

 

wysiwyg_imageupload:12111:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

if any more doubt please feel to ask.