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

Peter Gottlieb nerd at verizon.net
Sat Mar 2 16:10:03 EST 2013

I had one for work a while back and asked the IT security guys about it and was 
told that the change was on a fixed schedule but of course each fob was a little 
different due to temperature, over time, etc and that the system automatically 
"learned" the fobs and opened or tightened its tolerance for when the fobs 
updated.  So if you had a slow one the system would adapt over time and just 
learn to expect that but if the timing got too far off they would replace the 
fob.  I suppose if you kept messing with the timing by leaving in the sun or 
freezer eventually you would get rejected logins and your IT people would want 
to replace it, unless they manually really loosened up the timing windows.  The 
people I asked didn't mind my inquiries and seemed eager to chat but some places 
might be a bit more paranoid.

On 3/2/2013 3:57 PM, Jim Lux wrote:
> On 3/2/13 12:30 PM, lists at lazygranch.com wrote:
>> My fob only outputs a code on demand, that is after I push the button.
>> Any of the motion detection programs that use webcams would detect the change 
>> in display, but with a multiplexed  display, I'm not sure how well.
> Interesting point.. mine only has the 6 digit (7-segment) display, but I'm 
> sure it's multiplexed (digit/segment)..
> But, the mux rate is fairly high, compared to the "transition time" for the 
> segments.  So maybe I can average over some (short) time...
> What I want to do is see what the temperature dependence is. (prompted by 
> leaving the fob in the sun, and having the code rejected, presumably because 
> it was "slightly ahead")
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