[time-nuts] 10MHz standard for comms receivers

jimlux jimlux at earthlink.net
Mon Oct 1 16:54:43 EDT 2018


On 10/1/18 10:44 AM, Dana Whitlow wrote:
> Isn't it the case that computer clocks these days are subject to two
> influences that make them worthless for timing?
> 
> 1. Deliberate random FM to spectrally spread RFI leakage.
> 
> and
> 
> 2, Wild variations of clock speed according to usage needs of the moment,
>      in order to reduce average power consumption and thermal loading.
> 


yes and no..

microcontrollers and things with microcontrollers do use spectrum 
dithering, it's less common in a PC.

While the "instruction rate" might vary with the needs of the moment and 
die temperature, there's usually some clock and corresponding counter 
that runs at a relatively constant rate so the CPU knows what time it is.

That said, a 10 ppm (or even 50 ppm) oscillator in a PC would be "high 
performance"

My macbook air shows 56.652 in ntp.drift




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