Hi all.

I am doing a rather simple (on the surface of it) one off project to make a remote serial display for a ballistic chronograph unit I have.
The serial comms is easy, did that and happy with that and can get the raw timer data and a feet per sec value.

However I found out from a datasheet that if I use raw timer data from the chronograph and ignor it's internal calculated values I can get about 4% better accuracy. Great, except for one catch. This is the equation that PBP needs to run on the incoming value.

VELOCITY = (12 / ( RAW * ( 1 / 12000000 ) ) / 12


Velocity is the data I need to calculate in FPS (feet per second)
RAW is the incoming chronograph data value and can be as high as a 24bit number but I can get away with bounding it to a 16bit number I think.
12 is the distance between the chronograph sensors in inches (perhaps I should use metric units then convert ?)


I'm no math head sadly and get a headache just writing the equation (runs in the family). Can anyone help with using PBP math to crunch this, I'm lost because of the small fraction involve (1/12000000 divide) which if I do the usual decimal point shifting will blow the other values over 32 bit.

Any tips (other than go back to school) welcome.

Martin