[ntp:questions] Re: Fingerprinting hosts by clock skew
terje.mathisen at hda.hydro.com
Sat Mar 5 14:24:27 UTC 2005
John Ackermann N8UR wrote:
> I'm guessing Dave was joking in his comments, but the frequency vs. temp
> curve actually can provide a very accurate thermometer. HP manufactured
> one along those lines, with a crystal and oscillator contained in the
> sensor and a frequency meter for the display, that had something like
> 0.001 degree C resolution. And, those of us who play with frequency
I actually did exactly this for my Master's thesis:
A 2-3 m long single-mode optical fiber, with laser mirrors at both ends,
and a single-mode laser source:
The resulting optical oscillator had a temperature sensitivity of about
0.01 degree per resonnance peak.
Using a longer piece of fiber would have increased the resolution linearly.
> standards often see temperature related fluctuations even in units that
> have ovens or double ovens.
> Another example is an antenna that I use to receive Loran-C
> transmissions for frequency monitoring. The antenna is up on my roof
> and contains an FET preamplifier. I've seen an 80 nanosecond diurnal
> phase shift as the antenna warms up and cools down each day.
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"
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