From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 7BB813CB37 for ; Sat, 2 Mar 2024 11:03:01 -0500 (EST) Received: by mail-pf1-x431.google.com with SMTP id d2e1a72fcca58-6d9f94b9186so3001903b3a.0 for ; Sat, 02 Mar 2024 08:03:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1709395380; x=1710000180; darn=lists.bufferbloat.net; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=RhrvkLiPfNEMGo29UYadMbB3H0CSCcTRsMseNKICIjs=; b=mJ9Q5GC9vCJJ3gj0SHz2XE1CeTY6Qi+0TSBFswUhbPwvdB1+K4Ot2UY1Gy256Xvdky 614TAbcChRdF1m6mBM2LvdydZsHI2zAEUC+suG40yE6bRcAdzhAJd1KKV4rzPIZWyOKK BBORpk5tqKZ7FCntbWk7zs58mlCxjuLeeBMfzIt3AJkna4ydTa8qNQV9X+85vRQIbZXz CM6nUC/ACNgd5xIp0R5bytB1uprkUwZR3Ih43CFaXFk3mjT7vgINPDgwa+RkSEjHL77H ceynnXAgX1y467Cs5sZvtvXGE0zLDiaLXhHJ9kgshhFnelrgEswJn9Y67Ywt9wWDD3AP gLkQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709395380; x=1710000180; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=RhrvkLiPfNEMGo29UYadMbB3H0CSCcTRsMseNKICIjs=; b=Fw71oTjFhQI/gBTKBAoGbfz5IhjRkQNICSGX1CwBCcEpI4+Ovne/9BW5F0xB0JPTv4 rkHd0k3UEAnTv+RbXAaVhFlLJ85Ou0VrzOnWxI58zUJMmtZkgXen7Y2c3Ea3YiGxWyW1 J6QvpxsnmZI/R8+0JGonqVnxDPlJuh4DIf04/4YyN8iRkEuHXoPe7+2oPWSyfY+Nn1yP fh+9VPTy5TEraEpvedW5Y91HP/iZnBNWHBlnh/fDS2JnkPELfd9Ax1V1/W737FfaUlQ/ cLIcX2XeZQAzlHgCv0rtEhbpVzSMeaWjD683UDnKRMJzL6Gw1mPBUTUW41erMXtoUkl5 TvoQ== X-Gm-Message-State: AOJu0Yy7XU3OL3SDXXJ2FBb+hG+Nb7IxdkhIoMIcuReyti+cuPHpy4l6 SHbs1Kyco6lOYUlMJDvK81cgAvcYWOowx/JUuBXqiBbAHNiB738NX+ZFt0xpxQm2loxPXFf+57u OtDHmoOoCNUI7RhNe3MJ4A3jSU/E= X-Google-Smtp-Source: AGHT+IHMntgrYN4gYohXMSGHSyB4vL+PorGHjNdYPsVSEe1mXvJYpBxyO7QJfmY2P1bLNlvPYkDqP3iBiy9gDpjK+Jk= X-Received: by 2002:a05:6a20:7354:b0:1a1:4a22:59a2 with SMTP id v20-20020a056a20735400b001a14a2259a2mr840962pzc.34.1709395380127; Sat, 02 Mar 2024 08:03:00 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Hesham ElBakoury Date: Sat, 2 Mar 2024 08:02:47 -0800 Message-ID: To: Christian von der Ropp Cc: Hesham ElBakoury via Starlink , Sebastian Moeller Content-Type: multipart/alternative; boundary="00000000000069cf0d0612afa0cd" Subject: Re: [Starlink] Time Synchronization in Satellite Networks X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 02 Mar 2024 16:03:01 -0000 --00000000000069cf0d0612afa0cd Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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. M=C3=A4rz 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 challenge= s: >>> > 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 roug= hly >>> 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 sur= face >>> 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 dri= ft, >>> caused by factors like temperature variations, radiation exposure, and >>> power fluctuations, can lead to inconsistencies in timekeeping across t= he >>> 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 im= pact >>> on other functionalities. >>> > 5. Evolving Technologies: As satellite technologies and applications >>> continue to evolve, new challenges related to synchronization might eme= rge. >>> For example, the integration of constellations with thousands of satell= ites >>> 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. > --00000000000069cf0d0612afa0cd Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi=C2=A0Christian,
How you synchronize t= he time of the satellites in the network? Are you saying each satellite has= a master clock?

Hesham<= /div>

On Sat, Mar 2, 2024, 7:38 AM Christian von der Ropp <cvdr@vdr.net> wrote:
Why not acquire the time directly from by= the satellite terminal and run local NTP servers instead of syncing via th= e Internet? LEO satellite terminals always have onboard GNSS antennas for g= eolocation which is necessary to find the satellites, so integrating a loca= l GNSS-disciplined Stratum-1 NTP server seems trivial to me.


<= div class=3D"gmail_quote">
Am 2. M=C3=A4rz 2024 17:25:59 O= EZ schrieb Hesham ElBakoury via Starlink <starlink@lists.buf= ferbloat.net>:
Hi=C2=A0Sebastian,
Can we still use PTP = and NTP for time synchronization in=C2=A0 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 <moeller0@gmx.de&g= t; 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 signal= s travel through cables at the speed of light,

[SM] The speed of light in your typical glas fibers (and accidentally the i= nformation 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 l= evel is a mere 90 KM/s slower than in vacuum.

> satellite communication involves signals traveling vast distances thro= ugh space. This creates significant delays.

[SM] Sure distances might be larger, but propagation speed is around 100000= Km/s faster... my main point is speed of light is a) dependent on the mediu= m 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. T= his drift, caused by factors like temperature variations, radiation exposur= e, and power fluctuations, can lead to inconsistencies in timekeeping acros= s the network.
> 3. Signal Degradation: As signals travel through space, they can degra= de due to factors like atmospheric interference, ionospheric disturbances, = and solar activity. This degradation can introduce noise and errors, impact= ing the accuracy of time synchronization messages.
> 4. Limited Resources: Satellites have limited power and processing cap= abilities. Implementing complex synchronization protocols can be resource-i= ntensive, requiring careful optimization to minimize their impact on other = functionalities.
> 5. Evolving Technologies: As satellite technologies and applications c= ontinue 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 complex= ity of the network.
> These challenges necessitate the development of robust and efficient t= ime synchronization protocols for satellite networks and an integrated sate= llite and=C2=A0 terrestrial networks
> Are you aware of such time synchronization protocols?
> I would think that using Satellite simulators is the most viable way t= o 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.
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