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Going SOTA /P with WSJT-X


#61

Hi Tom,
You could run Dimension 4 in the background and have it resync your clock every 15 minutes or so. Note that the latest version of D4 has been sexed up by some dopey programmer who thought it would be cool to have you sync from a different time source each time. Bad idea. When setting up override this and select a local source.

BTW a recent test using my Club’s call VK3APC/P showed about half of the initial replies included the /P. I presume this is due to the stations running different versions of the software. See partial screen capture.
image

Have fun.

73
Ron
VK3AFW


#62

What makes you think it is a bad idea?


#63

Doesn’t Dimension 4 require an Internet connection? That puts undesirable demands (charge, Bluetooth, data etc) on my aging phone. I can set the time manually to within 0.5 seconds as and when required, and that is sufficient for successful FT8 ops.


#64

Just wondering, if the tablet had its own connection (sim card, account, phone number, bill etc) could you rely on that to align the time to the telco reference time? And, next, would that be accurate enough?

My cheap Lenovo tablet is a wifi only version, but if aligning to network time was important for digi mode users, perhaps that would drive the next tablet purchase. it would also then have access to sotawatch, etc, but all that falls down if there is no local phone network coverage.

Andrew VK1DA/VK2UH


#65

Just use a GPS. Dont need WiFi, network connection etc etc.
Compton


#66

Hi Compton,
do you mean taking the time from a GPS device and resetting the time on the tablet to agree with GPS time? Wouldn’t that would mean it would be offset from UTC?


#67

Yes, It works on my laptop.

I’ve tried no time synch during an activation, just synched it before I left home for the 3 hourt drive to Mt Bindo and it worked. Time synch with Dimension 4 (or similar) with a connetion to the 3/4G smart phone and it worked and synching with a GPS connected to the laptop and it worked.

So there are lots of ways to do it and they can all be made to work.
Compton


#68

“GPS time” is currently 18 seconds fast relative to UTC, but every GPS device I have ever encountered automatically subtracts this offset before presenting the time on its display or external interface. In effect, a GPS device gives you UTC.

Martyn


#69

I’ve really settled on the “less is more” approach for the time being. My tablet has just the single micro USB socket for a connection to anything - including charging. Providing I charge it up before going out, it will do a couple of hours FT8 on a hill, so that’s OK, as I use that socket to connect to the MiniProSC interface.

I had previously used my smartphone as a WiFi hotspot and had the tablet syncing with internet time servers, but that was fiddly - and took longer to do than just setting the clock manually while looking at my 60kHz clock!

In order to take the GPS approach, I would need to buy a GPS device that could connect to my tablet via Bluetooth and get that configured. I really do think I’ll just keep adjusting the tablet clock manually at the start of each FT8 activation! Simple, fast, and free!


#70

An interesting set of links about time systems and how the link to each other. Sadly it’s an old page and some links have suffered from age related bit-rot and don’t work anymore whilst others have bad certificates etc. Still you can “do the needful” as my colleagues in the VU-land office would say.

http://leapsecond.com/java/gpsclock.htm


#71

Hi Tom,
Less is better, no doubt. Sometimes the extra stuff is worth the operating convenience, albeit at the expense of battery power.

The VLF time reference transmissions are not strong enough here to activate a locked watch or clock. Even WWV/JJY on HF is not audible for much of the day. And my super precise sundial loses lock in fog. GPS time is accessible on all summits and can be used to manually set time if your device allows that. Any GPS hand held mapper will give accurate time.

The old WSJT software had a clock adjust facility.

Anyway you know when you are off time by looking at the FT8 decoded signal screen.

Have fun.

73
Ron
VK3AFW


#72

Hi Andy,

Nothing “makes” me think that. I know it is bad having had problems with big (several seconds) jumps in “corrected” time until I found what the newer versions of D4 were up to. I know there are claims the system allow for two way time latency and the drift rate of the local clock. But it doesn’t work as advertised.

There are several people on the FT8 developers discussion group who have had 200 seconds change in their computer clock by time sync apps. Yes it gets fixed on the next check, but for 15 minutes or whatever reset time you have programmed you are up the creek unless you see the problem and manually intervene. My errors were often large although usually less than 5 seconds until I found the problem. I do think that’s bad. Really bad. Yuuuge errors. Not funky or cool. Not enough dispersed Beta testing.

With a local source fixed as the reference D4 goes OK with some manual intervention. Like a young puppy you can’t leave it to it’s own devices without regular checks. D4 may not dig up your daffodils but it sure as heck can bury your FT8 ops.

73
Ron
VK3AFW


#73

A 200sec jumps says the SNTP server selected was broken not the protocol.


#74

I have always found Meinberg NTP better and more stable than Dimension 4 … but that’s just me.

https://www.meinbergglobal.com/english/sw/ntp.htm

However, Tom’s manual method of setting his tablet time by reference to a radio-synchronised watch (Anthorn or Mainflingen) is generally perfectly adequate for FT8 purposes.

73,
Walt (G3NYY)


#75

No, it’s not “just you” - the two programs work in very different ways and are suitable for different circumstances.

Dimension 4 is a pretty simple application which just does a periodic clock synchronisation to a time server. It delivers a quick fix based on the assumption that the network time is always better than the local clock. However this makes it very intolerant of a time server that gives the wrong answer, or if the synchronisation is disturbed by long or asymmetric network latency.

The Meinberg program works very differently. It is a port of the original NTP daemon that the NTP protocol was designed to support. It is a long running process which aims to establish a mesh of timeservers which reach a consensus. It aims to transfer not only the time, but to establish error bounds on it. It peers with multiple servers in parallel and there is code to disregard servers that are clearly outliers (so-called falsetickers). When setting the machine’s local clock, it is explicitly designed to avoid sudden jumps - instead it adjusts the rate at which the local clock ticks to bring it gradually into line. It can even carry on doing this in the absence of network connectivity, based on the last known measurement of the native local clock rate.

It follows from this that the Meinberg program is superior for a long running machine. For a server running 24x7 it wins hands down. It works pretty well on a home workstation which may run for several hours at a time.

It is less useful for something like a tablet that frequently goes to sleep and runs very intermittently to minimise battery use. The algorithms rely on the process being scheduled to run regularly. It quite deliberately works rather slowly, so it is not going to solve the problem of taking a tablet out of a bag on a summit and getting on the air straight away with the time spot on.

Martyn M1MAJ


#76

BKT TimeSynch is another, http://www.maniaradio.it/en/bkttimesync.html. This one allows you to connect a GPS to it and then either use a timeserver via the web or the GPS. I have used it sucessfully both ways.

Compton


#77

I have fairly recently changed from using the Meinberg program to using http://www.timesynctool.com/ which I find better on my Shack PC.


Stewart G0LGS


#78

FT8-CALL

Could this be the answer for SOTA working on FT8?

73,
Walt (G3NYY)


#79

I’m already working FT8 on SOTAwith all required info exchanged (including SOTA ref and /P). No answer required.