<html><head></head><body><div dir="auto">Why not acquire the time directly from by the satellite terminal and run local NTP servers instead of syncing via the Internet? LEO satellite terminals always have onboard GNSS antennas for geolocation which is necessary to find the satellites, so integrating a local GNSS-disciplined Stratum-1 NTP server seems trivial to me.</div><br><br><div class="gmail_quote"><div dir="auto">Am 2. März 2024 17:25:59 OEZ schrieb Hesham ElBakoury via Starlink <starlink@lists.bufferbloat.net>:</div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div dir="auto">Hi Sebastian,<div dir="auto">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?</div><div dir="auto"><br></div><div dir="auto">Thanks</div><div dir="auto">Hesham</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Mar 2, 2024, 7:18 AM Sebastian Moeller <<a href="mailto:moeller0@gmx.de">moeller0@gmx.de</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Hesham<br>
<br>
> On 2. Mar 2024, at 16:03, Hesham ElBakoury via Starlink <<a href="mailto:starlink@lists.bufferbloat.net" target="_blank" rel="noreferrer">starlink@lists.bufferbloat.net</a>> wrote:<br>
> <br>
> Time synchronization, for satellite networks, faces several challenges:<br>
> 1. Signal Propagation Delays: Unlike terrestrial networks where signals travel through cables at the speed of light,<br>
<br>
[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. <br>
<br>
> satellite communication involves signals traveling vast distances through space. This creates significant delays.<br>
<br>
[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...<br>
<br>
> 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.<br>
> 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. <br>
> 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.<br>
> 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.<br>
> These challenges necessitate the development of robust and efficient time synchronization protocols for satellite networks and an integrated satellite and terrestrial networks<br>
> Are you aware of such time synchronization protocols?<br>
> 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.<br>
> Thanks<br>
> Hesham<br>
> <br>
> <br>
> <br>
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</blockquote></div>
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