Time Travel - How We Keep Time Across The Modern World (IET Ireland Local Network). 7257

Time Travel - How We Keep Time Across The Modern World (IET Ireland Local Network).

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Dr Jacquline walker, provided an insightful account of how time keeping began, and how over the decades, measurements and observations of time have progressed, from movement of the sun around objects, through to the use of atomic clocks, and now why GPS still remains the choice of satellite coordination.

It really comes down to the different methods of measuring the passing of a day. Not only sundials, we've had water clocks (passing of time through water), candles, and by the 2oth we moved to quartz clocks - whose higher frequency gave a better oscillation for accuracy. But time keeping is regional dependent and that now all systems use leap second, for example international atomic time does not use it, since it's introduction, there are 18 second leap differences between GPS and UTC time. 

She spoke about how the characteristics of time keeping play a key role when determining frequency transfer of local clock synchronisation, such as considering channel delay for remote clock synchronisation and how the position of a transponder can determine how UTC links can even cancel transmission delay. 

Using redundant cocks and internal oscillators is a prime set up to bring about GPS spoofing, when a transmission service operator (TSO)  is unable to synchronise with a GPS, their internal oscillator can be used by the TSO, which introduces a drift, but still allows the TSO to function. If however, the GPS reference time itself is alerted (spoofed) by a slight margin, then then time synchronisation will no longer accurate between the TSO and GPS - this would be a big problem for services that are dependent on an accurate synchronisation. 

This is where a PTP grandmaster can be deployed across the regions acting as a boundary clock providing timing signal to the connected TSO. There are many pros and cons, however at least all nodes remain synchronised, albeit out of synch with UTC for example. With our collective dependency on electronic time keeping, Dr Walker provided a insightful review of the different techniques of time keeping, such as TWSTFT and many more.

The IET Digital Library has many papers available on this topic, click here to see an overview on a PTP Synchronisation for Smart Meter Data paper.
 
Blog The Cyber Lens 31/05/2021 10:28am BST

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