Answer to Question #172229 in Physics for amit

Question

Explain the image frequency and double spotting phenomena in case of AM receivers. How can they be overcome?

Answer 1

Double spotting means the same stations gets picked up at two different nearby points, on the receiver dial. It is due to poor front end selectivity i.e. inadequate image frequency rejection. Double spotting is harmful because a weak station may be masked by the reception of a strong station at same point, on the dial.

Double spotting can be reduced by increasing the front end selectivity of the receiver. RF amplifier stage will help in avoiding double spotting. Double spotting can be used to calculate the intermediate frequency (IF) practically.