Hi Christian, How you synchronize the time of the satellites in the network? Are you saying each satellite has a master clock? Hesham On Sat, Mar 2, 2024, 7:38 AM Christian von der Ropp wrote: > 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. > > > Am 2. März 2024 17:25:59 OEZ schrieb Hesham ElBakoury via Starlink < > starlink@lists.bufferbloat.net>: > >> 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 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 >>> > >>> > >>> > >>> > _______________________________________________ >>> > Starlink mailing list >>> > Starlink@lists.bufferbloat.net >>> > https://lists.bufferbloat.net/listinfo/starlink >>> >>> -- > Diese Nachricht wurde von meinem Android-Mobiltelefon mit K-9 Mail > gesendet. >