Re: [Starlink] Fwd: Microstate Accounting and the Nyquist problem

[Karl Auerbach <karl@cavebear.com>]

Measuring things across network is indeed made a lot easier if we have a 
solid, precise, synchronized clock at the end points.

(I would have thought that Starlink would have had a built-in clock 
based on the resonance of the heavy isotope of Elonmuskium.)

HP once upon a time had a patent on using GPS to get that time sync for 
doing network measurements.  But that was in the 1980's. One hopes that 
that patent has long since faded into dust.

(Not long ago I wrote a fairly simple tool that runs on Linux on cheap 
hardware, I call it "C-Clamp" that wraps around a device or network 
(such as a satellite uplink and downlink) and sends packets to itself 
and collects numbers so it can generate statistics about the amount of 
delay, its stability (are there bursts, and if so, how big and how 
often), losses, etc etc.  Since it has a single clock it can get some 
fairly high precision time measurements.)  I thought it would be fun to 
slap one of these around two Starlink dishes located at the same 
location (or within a distance I could cross with a single Ethernet cable.)

I've long been intrigued by all the interesting stuff that astronomers 
derive by watching deviations of periodic or predictable events.  
There's an astrophysicist at UC Santa Cruz who apparently is interested, 
as am I, whether we can apply those techniques to measuring paths on 
networks.

For one project I was going to buy a big bag of ESP32s (fun little 
systems-on-a-chip) and use them as network pulsars that would emit a 
predictable pattern of packets of various size, times (and intervals, 
sometimes bunched together sometimes widely separated.)  A receiver 
could lock onto the pattern and from the dissonance between the emission 
times and the reception times could intuit things about the path.

I understand that RIPE has done something like this.

     --karl--