Howard F. Fortescue Ltd. is registered in England and Wales; Company No. 6237839.

HFF has more than 25 years experience in the Optical Disc Industry.

Programme Time & Radius

Calculator

t = P x (R² – r²) / (TP x LV)

t     = Duration (seconds)

R   = End Radius (mm)

R   = Start Radius (mm)

LV = Linear Velocity (m/s)

TP = Track Pitch (micron)

It is important to get the Units right. Strictly these should be in SI units (MKS: metres, kg, seconds) but the numbers are a bit silly so I’ve used mm as the basis instead of metres. LV and TP are 1000x bigger and 1000x smaller, respectively, than mm, so the 1000s cancel out.

You can try this in Excel;  (Note: With a Browser other than Internet Explorer 7 (or above) you may have to do some formatting in Excel. If it doesn't work easily please Contact Us.)

just cut and paste the text below into the top left (A1 to A5) of a new spreadsheet and then cut and paste the formula into cell B5.

A1 - Start Radius (mm)

A2 - End Radius (mm)

A3 - Linear Velocity (m/s)

A4 - Track Pitch (micron)

A5 - Duration (seconds)

=PI()*(B2^2-B1^2)/(B3*B4)

Put your values in column B next to the appropriate text.

Here are some sample figures you can paste into B1 to B4.

25

58

1.5

1.2

You should get the answer 4780.46 seconds which is pretty much the longest “legal” CD you can make. (79min, 40sec, 34frames).

Of course if you make any parameter on the specification limit then 50% of the product will be out of specification.