DAB over here is in perfect sync with AM. I will check it against FM because I’m curious but I think it will be quite accurate. In terms of talkback radio, it is often the case that contractual obligation demand that certain things be transmitted at certain time, no prevarication.
For example, commercials are broadcast every 15 minutes or so on commercial stations. Although with the exception of top-of-the-hour breaks, which take place roughly three minutes to the hour, then they often take Sky News live feed, which demands that, come what may, the news is broadcast precisely starting at the top of the hour. The BBC’s Greenwich Time Signal is, as I recently discovered, generated by the World Atomic Clock, which is accurate to less than 100 Nanoseconds. It may be that overseas broadcasters don’t have the same strict contractual obligations. And it is true to say that I’ve heard one or two digital stations which take a pre-recorded Sky News feed, created at the top of every hour, then rebroadcast shortly thereafter. This inherently means that they cannot start the news broadcast until three minutes past the hour, which is when the Sky news feed ends. Sky News streams this feed via the same satellite that they use for public broadcasts. It’s just a separate transponder which isn’t tuneable, as far as I know. On the Sky+HD and Sky Q boxes, it’s possible to rearrange the channel numbers if you know how to do it. For example, in my own box, I have a number of local radio services which are not local to me, stored on some unused channels. Unfortunately, that does not solve my one biggest headache, which is listening to my favourite team’s BBC commentary. I can’t find a way to do that. BBC Radio seems to be far more encrypted than some commercial services are. Anyway, I digress. Over here, when the BBC Radio 4 digital feed hits the double-length “Beep” which occurs at the top of the hour on the atomic clock, then that “Beep” is also broadcast precisely at the top of the hour. I believe that, on DAB+, there’s a considerable delay between the analogue and digital signals. That is only hearsay, so if I’m wrong about that, please don’t shoot the messenger. Possibly the delay, if there is one, is caused by the superior codecs which DAB+ utilises. Or, maybe there’s some other technical reason why it occurs. But I’m amazed to hear that talkback radio is allowed to miss the top of the hour by seconds or minutes. On 27 Aug 2018, at 22:19, Dane Trethowan <grtd...@internode.on.net> wrote: I’ve ever ever taken any notice of a time signal broadcast from an Internet Radio stream or DAB stream if it comes to that,, I’m a halfwit I know but not quite as bad as all that yet <smile>. Regarding delayed time signals? I agree with you, you either transmit them on time at the top of the hour or you don’t transmit them at all. Having said all that there may be cases where the time signal can’t help but be delayed, suppose you’re listening to radio 2GB in Sydney which is a Talkback station. 2GB uses a 10 second delay and - though I’ve not done any testing - I’m willing to bet that because of the delay used for talkback purposes the time signal probably gets delayed too if the delay is still functioning when the time signal sounds. Since we’re talking about time signals its appropriate to mention that you can call WWV or WWVH on your telephone. As Gordon mentioned there will be a delay but if you’re calling from the US then that delay shouldn’t be any more then 250 milliseconds if that. WWV +13034997111 WWVH +18083354363 > On 28 Aug 2018, at 3:40 am, Gordon Smith <gor...@mac-access.net > <mailto:gor...@mac-access.net>> wrote: > > The atomic clock is used by most commercial and broadcast services over here. > One of the frequencies is, as I said earlier, 10.0 MHz, but it does sometimes > drift a few HTz for whatever reason. It is, however, reliable in the extreme. > > As I said earlier, there are some extremely accurate methods of time > synchronisation these days. They include GPS (where available) and > Internet-based time synchronisation using any of a range of NTP services. > > Until recently, I had my own NTP server hardware. But, for whatever reason, > it won’t boot any more. I suspect it’s the power supply. I had to mount a GPS > receiver module outside on the wall just below my guttering because the > stupid little internal USB antenna which came with the system just wouldn’t > work indoors, as I would have expected. > > The external box, however, produced a 100% reliable signal, and the server > was accurate within 1 Micro-second. > > There are lots of network time server systems available now, and they all > synchronise via the atomic clock. That service will *NEVER* go away, as it’s > used all over the world by governments and commercial, entities, not to > mention scientific organisations, including NASA. > > To be honest, I am quite surprised by what you say about time synchronisation > being out of sync. What’s the point transmitting a signal which is supposed > to provide accurate top-of-the-hour spot if it’s not accurate? > > Oh yes, and just for the record, don’t be deceived by BBC Radio 4 and its > time signals. I guess the obvious reason for that is the Internet. If you’re > listening online, there’s always going to be a certain amount of time lag. > And I’ll tell you something else which I found out today by accident, as this > thread got me curious. I tuned to BBC Radio Four on digital satellite. I > discovered that there is about a 3 second delay on both FM and DAB signals. > So even the terrestrial signals may not be as accurate as we think. The Sky > Satellite signal was always ahead of the terrestrial ones by about 2 to 3 > seconds. The DAB and Analogue FM signals are in perfect sync with each other, > whilst the free-to-air digital TV signal corresponds perfectly with the Sky > Satellite signal. > > On 27 Aug 2018, at 09:58, Dane Trethowan <grtd...@internode.on.net > <mailto:grtd...@internode.on.net>> wrote: > > As far as time signal services go in Australia we still have the ABC however > this time signal at the top of the hour is not reliable. > Some stations and transmitters in Australia don’t even broadcast the signal > whilst some that do are out of sync due to the fact that the transmitter > takes a direct satellite feed. > In the UK you’re lucky that BBC Radio 4 transmits a time signal at the top of > most hours. > In Australia we have had time signal services on the Shortwave band, the VNG > Standard frequency and time signal service provided by the Australian > Telecommunications Commission on 4.5, 7.5 and 12MHZ was a regular feature up > until 1990 or so. > The service used to broadcast from Linhurst in Victoria. > In 1990 the service was moved to Longana NSW and given a range of new > broadcasting frequencies, 5, 8.638, 9.14 and 16MHZ. > The interesting thing about the reincarnation of VNG was that some of the > frequencies listed above broadcast a voice synthesised talking clock at the > top of each minute whilst others broadcast the current time in morse. > > >> On 27 Aug 2018, at 5:41 pm, Gordon Smith <gor...@mac-access.net >> <mailto:gor...@mac-access.net>> wrote: >> >> In the UK, we’re fortunate to have several of these synchronisation >> stations, based on the Atomic Clock at Greenwich. One of the most widely >> used in terms of analogue signals is the beacon which broadcasts on 10.0 MHz >> using Carrier Wave, (CW) and which has been broadcasting for I don’t know >> how many years. >> >> There are several digital signals as well but they’re all broadcast at UHF >> as far as I know. >> >> But I guess the thinking behind this change is that an ever-increasing >> number of appliances and services now synchronise directly via the atomic >> clocks, or via GPS. In the latter case, they must rely on the Internet being >> available. >> >> I’m not saying I agree with the change. There should have been a much longer >> time frame on this, in order to allow manufacturers to develop products >> which synchronise using different methods. >> >> GPS is only really reliable outdoors, which out of necessity precludes a lot >> of consumer items from the list of possibilities. The Internet, on the other >> hand, would necessitate the presence of broadband or similar. That in itself >> is fraud with difficulties. >> >> However, I can see why the government is trying to do this. It’s obviously >> going to be quite a money saver and that, I am sorry to say, is a governing >> factor the world over. >> >> I am sure this will happen to us at some point as well. I can only hope it’s >> a few years off. >> >> >> On 25 Aug 2018, at 17:38, Dane Trethowan <grtd...@internode.on.net >> <mailto:grtd...@internode.on.net>> wrote: >> >> So what will you do? >> I wonder just how many list members have time pieces that rely on this time >> synchronisation service? >> I don’t think the good folks in Europe or Australia rely on WWVB but >> certainly its big in the US, the digital signal is broadcast on 60KHZ. >> If WWV and WWVH fall silent as well then this will bring some difficulties >> to me too as I have quite a few time pieces here that rely on manual >> synchronisation with a time signal and the only accurate time signal we have >> left now as far as I know is WWV/WWVH on the Shortwave bands - 2.5, 5, 10, >> 15, 20 and 25MHZ -. >> >> >>> https://hackaday.com/2018/08/20/what-will-you-do-if-wwvb-goes-silent/ >>> <https://hackaday.com/2018/08/20/what-will-you-do-if-wwvb-goes-silent/> >> >> ======================================== >> >> My compliments and kindest regards >> Gordon Smith: >> <gor...@mac-access.net <mailto:gor...@mac-access.net>> >> Accessibility & Information Technology Support Specialist.. >> >> This Message Was Created Using 100% Recycled Electrons. If you can avoid >> printing it, please do so. Think of the environment, save a tree! >> >> Contact: >> >> Twitter: @maciosaccess >> >> • UK Free Phone: >> 0800 8620538 >> • UK Geographic / Global: >> +44(0) 1642 688095 >> • UK Mobile/SMS: >> +44 (0) 7804 983849 >> • Vic. Australia: >> +61 38 82059300 >> • US/Canada: >> +1 646 9151493 >> >> ---------------------------------------- >> >> >> > > > ======================================== > > My compliments and kindest regards > Gordon Smith: > <gor...@mac-access.net <mailto:gor...@mac-access.net>> > Accessibility & Information Technology Support Specialist.. > > This Message Was Created Using 100% Recycled Electrons. If you can avoid > printing it, please do so. Think of the environment, save a tree! > > Contact: > > Twitter: @maciosaccess > > • UK Free Phone: > 0800 8620538 > • UK Geographic / Global: > +44(0) 1642 688095 > • UK Mobile/SMS: > +44 (0) 7804 983849 > • Vic. Australia: > +61 38 82059300 > • US/Canada: > +1 646 9151493 > > ---------------------------------------- > > > ======================================== My compliments and kindest regards Gordon Smith: <gor...@mac-access.net> Accessibility & Information Technology Support Specialist.. This Message Was Created Using 100% Recycled Electrons. If you can avoid printing it, please do so. Think of the environment, save a tree! Contact: Twitter: @maciosaccess • UK Free Phone: 0800 8620538 • UK Geographic / Global: +44(0) 1642 688095 • UK Mobile/SMS: +44 (0) 7804 983849 • Vic. Australia: +61 38 82059300 • US/Canada: +1 646 9151493 ----------------------------------------
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