How long is a hz?

Sean Bruno sbruno at miralink.com
Mon Jan 28 10:53:25 PST 2008


Jason Slagle wrote:
> On Mon, 28 Jan 2008, Sean Bruno wrote:
>
>> I couldn't quite find the definition for "hz" in sys/ this morning.  
>> What is it's value and where is it defined?
>
> From http://en.wikipedia.org/wiki/Hertz
>
>    The hertz (symbol: Hz) is the International System of Units (SI) base
>    unit of frequency. Its base unit is cycle/s or s^-1 (also called
>    inverse seconds, reciprocal seconds). In English, hertz is used as 
> both
>    singular and plural. As any SI unit, Hz can be prefixed; commonly used
>    multiples are kHz (kilohertz, 10^3 Hz), MHz (megahertz, 10^6 Hz), GHz
>    (gigahertz, 10^9 Hz) and THz (terahertz, 10^12 Hz).
>
>    One hertz simply means one cycle per second (typically that which is
>    being counted is a complete cycle); 100 Hz means one hundred cycles 
> per
>    second, and so on. The unit may be applied to any periodic event--for
>    example, a clock might be said to tick at 1 Hz, or a human heart might
>    be said to beat at 1.2 Hz. The frequencies of aperiodic events, 
> such as
>    radioactive decay, are expressed in becquerels.
>
>
But more importantly, where is "hz" defined in the kernel tree?

Sean


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