measuring pellet speed w/o a chrony using www.audacity.com

There was an app a few years ago that used the microphone in your phone to measure the speed of your pellets by sound alone. I tried it and it did actually work but was a real pain setting up a room perfectly to do it in. Everything had to be precisely measured and positioned. Not worth doing at all when you can just pick up a real chonograph on sale for $75 or one of the aliexpress tiny units for $25.
 
According to the information that I just looked up the F1 chronograph will see speeds from 30 fps to 7000 FPS. I got mine from walmart through the internet it was only 99.99 with lights. I bought this about 2 years ago.

The pics & videos I see of the F1 chrony shows a digital readout with three positions left of the decimal point. I don't understand how it can see speeds over 999.9 fps. Am I wrong?