A new approach to derive emission requirements on APD in order to protect digital communication systems

Amplitude probability distribution (APD) has been proposed within CISPR as a measure of the emitted electromagnetic energy from electrical equipment. APD describes the envelope statistics of a disturbance from the IF filter of the measurement receiver and is in many ways a suitable model of nonGaussian noise, when determining its impact on a digital communication system. In an earlier paper, the connection between the APD of a disturbance and its effect on a digital receiver was presented. However, to derive a maximum allowed APD out of a maximum allowed bit error probability is a non-trivial problem. Unfortunately, this is exactly the issue when emission requirements should be related to the APD. This paper presents a possible way to put requirements on the APD in order to protect digital communication systems. By letting a measured APD of a disturbance lay below the requirements, the impact on a variety of receivers are guaranteed to not exceed the maximum bit error probability