What you need is a External Time Vector Modifier/Analyzer. It slows down time to whatever speed you set it to. You slow time down on the piece of gear you want to test, until you can count the pulses. From there you can multiply the pulses you count per second by the factor you slowed time down to and get your frequency. I saw one on eBay a few months ago for under $1000. Good for lots of stuff, not just manually counting frequency.