Abstract: Tracking down
radiated and conducted immunity problems in electronic equipment can be
difficult. Since the official standards based tests illuminate the
whole system, information about the exact cause of the problem can be
impossible to determine from test results in many cases. Direct injection of an RF signal into a circuit
can narrow down the problem, often in minutes, to the root cause. A
video presentation of the principle is offered including using the
technique on an operating PCB.
Figure 1 shows the test setup to demonstrate the principle. My
March-April 2014 Technical Tidbit
describes the method, but the video shown in Figure 2 includes applying
the method to an operating circuit. The applied stress in the video simulates fields
of ~100 V/m, far higher than commercial circuits need to withstand (and
in this case a protoboard, for which there is no requirement), but is
useful in illustrating application of this method.
Details of the
methodology, including signal levels, strategy, and other details are
not covered in this video and are included in my seminars. They may be
the subject of a future Technical Tidbit. These details and care may be
needed with this method so as not to spend time chasing problems that
don't exist in the circuit.
Figure 2. Application of Direct RF Injection Video
You are welcome to copy this video, use it in training, or distribute it as long as it is unedited and shown it its entirety.
Summary: Direct
injection of RF energy can be useful in tracking down radiated and
conducted immunity problems. The video presented shows both the
principle and its use demonstrated on a live circuit. Details of the
methodology, including signal levels, strategy, and other details are
not covered in this video and are included in my seminars and may be the
subject of a future Technical Tidbit.
Technical Tidbit on this site related to this article:
Equipment used in this Technical Tidbit:
