Beat Between Sound Carrier and Color Signal Components in a Television Receiver

In the course of color television field tests, it has been found that receivers need about 50 db of sound attenuation in the i-f channel in order to prevent beat between the sound carrier and the color carrier components from appearing in the receiver. It was of some interest to determine whether this high requirement was justified in an ideal receiver or was only the result of defects in a practical receiver. A study of this indicated that this much sound rejection is generally required in an ideal receiver having the standard selectivity curve. The calculated value of attenuation is 44db, which, because of transmission vagaries and other variations, points to the use of at least a 50 db sound trap.