During the RF Back to Basics : Part 1 – Signal Analysis Webcast, hosted by Agilent Technologies, on 25 January 2012, we received a great number of real-time questions from a broad audience.
If one person asks - someone else will want to know the answer too - so we have captured various questions and answers and are posting them individually here, in this Forum, for your future reference and immediate enjoyment!
Answer: The name “video filter” is based on historical terminology dating back to the earliest days of spectrum analyzer technology. Since this low-pass is positioned after the envelope detector, there is no RF or IF frequency present at that point in the signal path. In early analog SA designs, the output of this filter was the baseband video signal that drove the vertical plates on the CRT display. Of course, with today’s digital IF circuits and digital LCD displays, the term may seem quaint, but the concept is still the same.