Hi Hesham,
caveat, this is far from my area of expertise, but I would simply try to get
GPS/Glonass/Galileo antennas into the birds and have each sync their clock
individually from such a source, which would remove the necessity for time
synchronisation protocols. That said, I see neither PTP not NTP as suited, as
both presumably assume that server and clients do not move to fast in relation
to each other, while arbitrary members of a LEO constellation might have quite
large relative speds, no?
Regards
Sebastian
> On 2. Mar 2024, at 16:25, Hesham ElBakoury <helbako...@gmail.com> wrote:
>
> Hi Sebastian,
> Can we still use PTP and NTP for time synchronization in Satellite networks
> or we need new protocols? If we need new protocols, do such protocols exist?
>
> Thanks
> Hesham
>
> On Sat, Mar 2, 2024, 7:18 AM Sebastian Moeller <moell...@gmx.de> wrote:
> Hi Hesham
>
> > On 2. Mar 2024, at 16:03, Hesham ElBakoury via Starlink
> > <starlink@lists.bufferbloat.net> wrote:
> >
> > Time synchronization, for satellite networks, faces several challenges:
> > 1. Signal Propagation Delays: Unlike terrestrial networks where signals
> > travel through cables at the speed of light,
>
> [SM] The speed of light in your typical glas fibers (and accidentally the
> information propagation speed in metallic conductors) comes in roughly at 2/3
> of the speed of light in vacuum, while the speed of light in air at see level
> is a mere 90 KM/s slower than in vacuum.
>
> > satellite communication involves signals traveling vast distances through
> > space. This creates significant delays.
>
> [SM] Sure distances might be larger, but propagation speed is around
> 100000Km/s faster... my main point is speed of light is a) dependent on the
> medium b) not the things that differentiates space from the earth's surface
> here, but mere geometry and larger distances on larger spheres...
>
> > 2. Clock Drift: Even highly precise atomic clocks, used in satellites, are
> > susceptible to "drift" - gradually losing or gaining time. This drift,
> > caused by factors like temperature variations, radiation exposure, and
> > power fluctuations, can lead to inconsistencies in timekeeping across the
> > network.
> > 3. Signal Degradation: As signals travel through space, they can degrade
> > due to factors like atmospheric interference, ionospheric disturbances, and
> > solar activity. This degradation can introduce noise and errors, impacting
> > the accuracy of time synchronization messages.
> > 4. Limited Resources: Satellites have limited power and processing
> > capabilities. Implementing complex synchronization protocols can be
> > resource-intensive, requiring careful optimization to minimize their impact
> > on other functionalities.
> > 5. Evolving Technologies: As satellite technologies and applications
> > continue to evolve, new challenges related to synchronization might emerge.
> > For example, the integration of constellations with thousands of satellites
> > poses unique synchronization challenges due to the sheer scale and
> > complexity of the network.
> > These challenges necessitate the development of robust and efficient time
> > synchronization protocols for satellite networks and an integrated
> > satellite and terrestrial networks
> > Are you aware of such time synchronization protocols?
> > I would think that using Satellite simulators is the most viable way to
> > develop and test these protocols given that using satellites is not that
> > easy.
> > Thanks
> > Hesham
> >
> >
> >
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