FSK modem: bit/timing recovery

Hello Glen

> Well, the easiest way is that floating point should be
> used for quantities that have a relative uncertainty, and fixed
> point for ones that have an absolute uncertainty.
>
> Many physical measurements have a relative uncertainty, that is
> the uncertainty in measuring increases as the quantity increases,
> or at least that is all that is needed.  This is often true of
> length and time measurements over many orders of magnitude.
>
> For others the uncertainty stays constant, or only varies over
> a small number of orders of magnitude.  This is usually true
> for money.  I expect my checking account balance to the cent,
> even if I have tens of thousands of dollars.  It does surprise
> me sometimes to see a house priced at $499,999, where $500,000
> is only 0.0002% more, though they could do $499,999.99.

Sadly, against my recommendations over more than twenty years, I know of 
many financial applications that use IEEE floats to represent money, and of 
course to this day I repeatedly spend hours each year explaining rounding 
errors away.

> Baud rate generation is usually done by taking a crystal oscillator
> and dividing it down using a programmable counter.

But that assumes your timebase is going to be able derive the precise baud 
rate from integral division. Sometimes that's not the case.

Certainly I'd agree it's the preferred scenario to be able to use an 
integral division.

Cheers, Howard