scope:

Introduction

Electromagnetic interference (EMI) may be any signal or electromagnetic noise generated by electrical machinery or equipment, or present as a result of wanted signal transmissions at other frequencies. It may be electromagnetic noise (EMN) from pulse generators used for digital transmissions or in computers, or it may be narrow band signals from transmissions or harmonics of transmissions, including radar. In some radar equipment the EMN generated by the modulator is a function of the radar's pulse repetition frequency and may cover a wide band of frequencies will below the fundamental carrier frequency. Many sources of signal noise and EMN found in and around aircraft are discussed in Appendix B.