1575[dxatlas] Re: Timing Question
- Nov 17, 2009Dave,
With so much Internet access variability across the world, there will never be a single Internet source that will give a good result for all - that is why there are hundreds of NTP time servers across the Internet - spread all around the world. With a large population of Time Servers there will always be a few time servers accessible anywhere.
The question is still, can you get to the Internet in an adequate form to retrieve time that meets the needs of Faros. Only you can answer that question, by testing your connection. But, we can help you do the tests to find out.
The best approach is to divide your problem up. Lets work on one thing at a time - forget the beacons for the moment. First - the Internet connection.
What type of Internet connection do you have?
How fast is it?
Is it connected all the time?
--- In email@example.com, "Dave" <dave@...> wrote:
> Hi to you too Peter! Nice hearing from you again. Yep, Faros is a good
> program but *somehow* timing has to be addressed. I'll look at the
> references in your email but I hope Alex can help some too. I can't believe
> I only 'see' one beacon a few times a day back-to-back time slots.
> Timing is the issue I think -and my Faros also hears but does not record
> loud signals- with Faros and solving it will add a lot to the system
> overall. I was wondering if we all sync to a single source if it would
> help... Then again the transmitters all have their own timing patterns, so
> unless we ALL go onto one single time server we'll all be different. Gotta
> be a GPS solution here somewhere.
> Good stuff at Dave Taylor's site.
> Let's keep this thread going... Good stuff here.
> DM78qg // KA0SWT
> -----Original Message-----
> From: firstname.lastname@example.org [mailto:email@example.com]
> On Behalf Of vk4iu
> Sent: Tuesday, November 17, 2009 15:53
> To: firstname.lastname@example.org
> Subject: [dxatlas] Re: Timing Question
> G'Day Dave,
> I like your web site. I have a similar goal in mind - all of which came to
> a halt when I realised I was getting useless observations because of the
> problem of delivering stable time data to Faros. I hope you don't mind if I
> have a look at the Java on your pages.
> What are the problems caused by the ISP?
> For my journey through "time", I used the the usual ntpd NTP Time Server
> software and drivers on both Ubuntu Linux 9.04 Desktop and 8.10 Server,
> installing from the standard "package management" using Synaptic. On
> Windows XP, I used a port of the same software from Meinberg -
> http://www.meinberg.de/english/sw/ntp.htm - and Meinberg's NTP Time Server
> Monitor to observe and plot the statistics from all the ntpd servers.
> I used many, and varied Internet time servers, and also connected my Garmin
> eTrex Vista GPS via a serial port to the Meinberg software on Windows, using
> the NMEA data strings only - the eTrex has no PPS output.
> It was all a very good learning experience, but with a lot of frustrations -
> all with "the time", and my Internet connection. The actual software
> installations were relatively simple and straight forward. One could
> describe the experience like big game hunting - hours and hours of
> observation and "taking aim", with the actual result occuring in just a
> minute or two. It is the sort of thing one has to do, to really understand
> what is happening with time and how it affects the Faros observations.
> I went through the usual careful steps - got the radio-PC connection to work
> with OmniRig, checked for reasonable signals from all the beacons one could
> expect, then I simply fired up Faros. Initially, I selected a few time
> servers from the list and observed what happened over a day or so. The
> "dots" on the detail page were all over the place, and the UTC Clock
> accuracy "red line" went all over the place. Next I updated the
> TimeServer.lst with the usual "pool" of servers for Australia - see
> www.pool.ntp.org. For the UK they would be things like 0.uk.pool.ntp.org.
> I got the same result - dots all over the place.
> That's when I implemented my own time servers.
> That gave me a reasonably straight line for the red "Faros time" in UTC
> Clock Info, Clock Accuracy. But the Faros observations on the Details panel
> went on a "roller coaster ride" day after day - the line of "dots" for
> beacon observations varying by 80-90ms over the day. The coloured blocks on
> the History page looked wonderful, but the data behind them was rubbish. I
> sat and watched the Monitor page for hours - time and again I watched Faros
> totally ignore nice strong beacon signals. Faros ended up following my time
> servers, which in turn followed the Internet time. Faros followed my
> servers because they were the fastest in terms of packet delay, and time
> variation. But, over many hours my time servers followed a large sine
> curve, with the 15 minute panel in the Clock Accuracy looking very flat.
> A last act, which has proven reasonably successful so far, was to
> decommission my time servers, but trawl through their logs and find the
> servers that were used for long periods of time as the reference. I then
> did ping tests, and trace routes on them, to find the closest and fastest 10
> servers. I now have reasonable, straight lines of dots on the Details
> panel, and good SP/LP observations with no "missed" observations by Faros.
> But ... I really don't expect it to last, and I certainly expect it to vary
> somewhat. I think it is good enough for casual use, but not enough for
> propagation studies, or good radio contest planning.
> The observations from the Garmin eTrex NEMA strings were useless - most of
> the Internet servers had less variation in time.
> In summary, my conclusions.
> My "broadband wireless" Internet connection is far too variable in terms of
> "packet delay" for good time keeping at the precision needed by Faros. Its
> nice and fast under normal use, but not good enough for time keeping, at the
> accuracy we need for Faros. The packet delay is mostly in the "wireless
> link", but add that variability to the variability of the Internet as a
> whole, the Internet time server load and subsequent variability, and
> finally, the use of the connection by other people and devices in my
> household - and Faros cannot "keep time" well enough.
> A NEMA strings based "consumer" GPS is not good enough - much too variable
> for the accuracy we need for Faros. I will report whether a "good" GPS can
> do it - see below.
> A "wired" ADSL or cable Internet connection may be good enough, provided the
> connection is stable in packet delay - that is, not overloaded by other uses
> in your household, or the network between you and the time servers. Only
> good time server selection, and rigorous observation over time will show
> whether or not the connection is adequate for serious use with Faros.
> My current plan.
> I initially dismissed creating a stratum 0 reference time server - the
> Meinberg PCI card is priced at $3500 in Australia. But ...
> Alex VE3NEA alerted me to the following web site http://time.qnan.org I
> have ordered a Garmin 18x LVS, $100 n Australia, and I will proceed to
> integrate it into my Linux server. On that site there is a reference to
> http://www.satsignal.eu/ntp/index.html which is a fantastic source of
> information relevant to getting Faros a good time signal. I have high hopes
> of having a fantastic Faros installation for propagation study, site and
> antenna comparisons.
> Peter VK4IU
> --- In email@example.com, "Dave Baxter" <dave@> wrote:
> > Hi...
> > I'm the guy who created the IC-PCR1000 "helper" app, so it can be used
> > with Faros/Omni-Rig. I did test it here before letting Dave M have a
> > copy, and AFIK no timing issues, but I stand to be corrected on that
> > if any are found directly attributed to that program of mine.
> > I do agree with Peter, try things with a rig that is directly
> > supported by Omni-Rig first, just in case.
> > Question for Peter. What software, program, tool, etc, did you try when
> > you tried a local GPS driven NTP server of your own? Did the
> > GPS/Server use a 1PPS signal, or just the NMEA data from the GPS?
> > Curious....
> > Regards to All.
> > Dave G0WBX.
> > PS: My Faros status page, all working from an old Icom IC-R70, and
> > another of my own programs to glue it all toghether.
> > http://g8kbv.homeip.net:8008/
> > Yes, I too have some NTP issues, but caused by my ISP.
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