RE: Doppler software to measure speed
I figure it's closer to 190 mph..
I measured the speed using Creative Wave Studio after setting my Creative Surround Mixer to the "What U Hear" record mode. Once I had recorded the sound in Wave Studio, I selected the area I wanted to measure and zoomed in until I could see the pulses. For this plane, I could see them best at the 1:2 setting. For other planes, it'll depend on the rpm of the engine. To make the measurement, I click and hold on the pulse closest to the right side of the screen, drag the mouse to the left until I get to the pulse nearest the left side on the screen, and then let go. There's a box in the lower right corner of Wave Studio that tells you the length of time that you just highlighted. I counted the pulses starting with the second one and ending with the last one. I divided the number of pulses by the amount of time which gave me the frequency. On the approach side, I measured 28 pulses in 0.043 seconds and for the departure, I measured 17 pulses in 0.043 seconds. The corresponding frequencies are 651 Hz and 395 Hz. According to the spreadsheet published by Harry Lagman, that gives an actual engine rpm of 29,500 and a ground speed of 189 mph.
I've attached a screen capture of measuring the frequency in Wave Studio.
Lynn