Dear Jacques, Very interesting your studio work and experiences. I bought a year ago a couple of second hand GPS receivers and Leitch clocks belonging to TV studios and radio stations so I can imagine a little bit of what you are talking about.
I am interested in sharing the experiences with Beagle Bone. I got one recently. I would like to use Linux instead of FreeBSD. If you wish we could correspond over the email to do some tests and try to get two versions of the micro NTP box. What do you think about it? Regards, Edgardo Molina Dirección IPTEL www.iptel.net.mx T : 55 55 55202444 M : 04455 20501854 Piensa en Bits SA de CV Información anexa: CONFIDENCIALIDAD DE INFORMACION Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente mediante un correo electrónico y que borre el presente mensaje y sus anexos de su computadora sin retener una copia de los mismos. Queda estrictamente prohibido copiar este mensaje o hacer usode el para cualquier propósito o divulgar su en forma parcial o total su contenido. Gracias. NON-DISCLOSURE OF INFORMATION This email is strictly confidential and may also be privileged. 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On Oct 25, 2012, at 4:17 AM, Jacques Tiete <[email protected]> wrote: > Hello Magnus, > > I know what you're talking about, I'm working for a company specialized in > broadcasting (from studio's to stations to satellites...) and in this world > correct > timing is paramount, we live by the 1/25 second rythm and even less if you > have to sync on a line in the image ;-). > Some time ago we were instaling a complete TV station and had huge problems > with image stability and also especially the correct starting time of a clip > or transmission. > Nobody wants to start his newsreel at eg. 20:00:05;23... it must be > 20:00:00;00 > We were looking into this and noticed that the customers servers (Win!) where > synced by SNTP, this is plain c..p! > Have a look @ http://technet.microsoft.com/en-us/library/cc773013(WS.10).aspx > Especially where it says: > "Important > The W32Time service is not a full-featured NTP solution that meets > time-sensitive > application needs and is NOT SUPPORTED by Microsoft as such. For more > information, > see Microsoft Knowledge Base article 939322, Support boundary to configure > the > Windows Time service for high-accuracy environments." > > Also have a look @ http://support.microsoft.com/kb/939322 > It says: > "We do not guarantee and we do not support the accuracy of the W32Time > service > between nodes on a network. The W32Time service is not a full-featured NTP > solution > that meets time-sensitive application needs. The W32Time service is > primarily > designed to do the following: > Make the Kerberos version 5 authentication protocol work. > Provide loose sync time for client computers. > The W32Time service cannot reliably maintain sync time to the range of 1 to 2 > seconds. > Such tolerances are outside the design specification of the W32Time service." > > So it is... 1 to 2 seconds....!!!!!!!! > > Our video playout servers are decent super stable units that use heaps of > Xilinx FPGA's > for coding/decoding videostreams supervised by a mil-spec VXworks OS, it uses > the > so-called LTC for synchronising the playout, implemented mostly in hardware so > I did not suspect our machines. I did install a new TCG (TimeCode Generator) > where > I also had heaps of problems with, I did debug the stuff together with the > manufacturer's > R&D and finally got a perfectly synced station AND a Stratum-1 NTP > (everything in > double with automatic failover, a requirement for a TV-station). (Thanks to > lurking for > years as a genetically predispositioned Time-Nut, my father was a > watchmaker...So I > knew more or less what a was talking about and could prove things thanks to > my TBolt etc.) > Then I did install Meinberg NTP-client on every Win machine and all was > suddenly > perfectly running, everybody happy! > This also solved some frequent file versioning problems for storing different > versions of > videoclips especially in a mixed Win/Lin environment where Linux proved to be > the > more logical/strict way of implementation. > > Another thing, being considered as the local video timenut a colleague called > me from > Saudi Arabia where he was having timing problems on two locations spaced > 700km. apart > where he had funny image jumps at the exact same time, both stations were > synced by > each the same TCG with GPS option (same as above), could the americans jam > the GPS > signals over there, somebody heard about this? It could be a real problem for > us, we > may need to use another method for station timing (Rb maybe, with some > regular syncing > etc.) > > Sorry for my long message but I don't often send timenut mail and this is a > good example > of some real-life timenutting ;-) > > I also have here a nice BeagleBone mini Linux board resting, where I would > want to install > a FreeBSD image on and implement a NTP with a promising GPS board from > Adafruit, > something for the long and cosy winter evenings... :-) > > > Best regards, > > Jacques Tiete > > > > > From: Magnus Danielson <[email protected]> > To: Time-Nuts <[email protected]> > Subject: [time-nuts] Timing performance of servers > Message-ID: <[email protected]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Fellow time-nuts, > > When spending time on a conference last week, I heard one interesting > comment that they lost data due to bad timing on their Windows servers. > > Now, I know that the standard Windows uses SNTP in order to achieve the > goal of having the timing of the machines sufficiently aligned to allow > Kerberos authentication. SNTP suffice for that, as it needs to be a > handful of minutes in line. > > If you need better performance than that, you should use NTP (and then > download and install Meinbergs Windows-client for NTP). > > Then again, I would point out that for this type of data, it would most > probably be better served on a Linux box. > > What should be a nice wake-up call for them would be a summation of how > different strategies would give them clock precision of sufficient > grade. So, does anyone know of such measurements presented anywhere? > > There are bits and pieces, but the ideal for this case would be if they > where collected in one page/paper. > > This is an awareness thing, so that people can do a little more > well-informed choices. > > Cheers, > Magnus > > > > ------------------------------ > > Message: 6 > Date: Wed, 24 Oct 2012 19:04:50 -0500 > From: Edgardo Molina <[email protected]> > To: Discussion of precise time and frequency measurement > <[email protected]> > Subject: Re: [time-nuts] Timing performance of servers > Message-ID: <[email protected]> > Content-Type: text/plain; charset=iso-8859-1 > > Dear Mangus, > > I will allow myself to share a comment on your thread. > > Timing on windows servers is not one of their plausible strengths. It was > clearly pointed out during the SIM conference last week at CENAM. In fact > there was an interesting discussion about the drawbacks when using NTP > Windows based servers and all kind of NTP appliances compared to full size > Linux based NTP servers. The example of what NIST is using nationwide for > their servers set an example of good server hardware and linux to provide the > nation's NTP pulse. > > I haven't done any experiments with Windows for NTP services, still it could > be interesting as to set a benchmark while comparing it to the Linux boxes. > > I am currently trying out the Domain Time II NTP client from Symmetricom for > the thesis. I have to come back to Symmetricom's Miguel Garc?a to decide on > purchasing a Domain Time II NTP client kit. How is the Mainberg NTP client > different from the Symmetricom version? Have you tried both? If not I will be > more than glad to help comparing both if you can help me pointing out the > source for a demo version of Mainberg's software. Maybe then an objective > review of both clients will be in order, I will be more than glad to do it or > to test them against Windows NTP services, appliances and/or Linux NTP boxes. > I have at least an example of those at the office. > > -13 > Just my 2x10 cents. > > > Regards to you and the group, > > > > Edgardo Molina > Direcci?n IPTEL > > www.iptel.net.mx > > T : 55 55 55202444 > M : 04455 20501854 > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
