We’ve been discussing signals from the perspective of their bandwidth relative to the bandwidth of the receptor and have not considered them from the EMC point of view. RF signal energy can get from the emitter to the receptor by conduction or by radiation. We’ll discuss that later. Regardless of the energy transfer process, using the FCC classification scheme we … [Read more...]
Abracadabra the Broadband Signals Disappeared
Almost all EMC engineers these days are familiar with MIL-STD-461 and its various revisions because it has influenced the procedures in virtually all present day EMC standards. The original document and the A, B and C revisions all had requirements for measuring both broadband (BB) and narrowband (NB) emissions. When MIL-STD-461 was first released (July 31, 1967), the … [Read more...]
Random or Coherent Signals
In the previous post, I indicated that coupled Broadband energy levels are determined by whether the signals are random or coherent. Random/non-coherent signals originate from sources that are not time related. A couple of good examples would be receiver thermal noise and DC motor brush noise. Another would be the RF environment taken as a whole. Because the individual energy … [Read more...]
Narrowband and Broadband Signals
As I indicated in the previous post, this discussion begins examining signal characteristics from an electromagnetic compatibility (EMC) perspective. But first, a few words to describe EMC. This is a relationship issue. We want all the equipment items to get along in peace and in harmony, but if one of them is a big source and the other is a wimpy receiver, they may not play … [Read more...]
