MIL-STD-461 Testing Advantages Using Time Domain Scan EMI Receivers

Even when using various time-saving procedures, Electromagnetic Interference (EMI) measurement times are still very long –typically several hours for radiated emissions measurements. The introduction of spectrum measurements based on Fast Fourier Transform (FFT)  also known as a time domain scan – allows a significant reduction in measurement times and improves the Probability of Intercept (POI) without affecting accuracy. EMI FFT based receivers can significantly reduce test times, in some cases by a factor of up to almost 2000, using time-domain methods to identify the disturbance spectrum. While many test engineers are following MIL-STD-461, some may not be familiar with the specifics of time domain scan in version MIL-STD-461G.

Taking the R&S EMI test receiver as an example, this white paper compares the measurement speed and level measurement accuracy of a conventional swept frequency spectrum analyzer against the speed and accuracy of advanced time domain scanning. It also contains guidance on making optimum use of time domain scans, plus their advantages in capturing intermittent signals with an improved POI. For those unfamiliar with FFT based receivers, it starts with an overview of the technology that makes them work.