[time-nuts] webcam app to watch for and time stamp changes

Peter Gottlieb nerd at verizon.net
Sun Mar 3 12:06:47 EST 2013


Don't get hung up on the display EMI (for it is indeed very very tiny), look for 
any steady emission.  Yes, the amount is small, yes it can be shielded a bit, 
but yes it is certainly possible to pick up.  As I mentioned in my original 
post, you may very well need to shield out external noise to see it clearly.  
And with a not-so-sensitive analyzer, you'll need a pre-amp.  Everything 
electronic emits and is detectable unless it is shielded eight ways to Sunday.

Peter


On 3/3/2013 7:11 AM, Magnus Danielson wrote:
> On 03/03/2013 10:00 AM, Poul-Henning Kamp wrote:
>> Content-Type: text/plain; charset=ISO-8859-1
>> --------
>> In message<657D7F7CC03849419A2A90752E6A60A6 at pc52>, "Tom Van Baak" writes:
>>
>>> When playing with watches a while ago I tried to pick up any 32
>>> kHz signal but failed. Those with 1 Hz stepper motors were easy,
>>> but LED or LCD displays were too electro/magnetic/acoustic quiet
>>> for me to ever detect anything.
>>
>> Most LCD and LED clocks have a shielding metal-coating on the front
>> glass, exactly to eliminate all EMI/EMC issues.
>>
>
> Darn. I should have guessed.
>
> Cheers,
> Magnus
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