Here's a simplification of Neil's formula for stop frequency.
Length is in meters or in feet, velocity factor is a decimal number such as 0.66, result is in mhz.
fmhz = 38376*vf/feet
fmhz = 11697*vf/meters
From Neil's example where he somewhat arbitrarily increased the scan beyond 50 feet
by a factor of 100ns/77ns:
feet = 50*100/77
vf = 0.66
fmhz = 38376*vf/feet
That gives a result of 390.05 MHz, which agrees with Neil's example.
I haven't looked into it yet, but I assume John's "Transform, Low Pass Step"
involves a Fourier Transform or similar, and thus some rather nasty math.
So exactly how this works and where Neil's magic value of 39 comes from
may never be terribly obvious for most of us.
Jerry, KE7ER
