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Digitrax Radio Throttle Problems at Big Shows

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Hi.  We have just done Warley with our layout, Solent Summit, which is rather big at 65’ by 26’.  We use Digitrax as our DCC system and because of the size and we walk with the trains, we use Duplex Radio throttles.  The D402DCE, lots of them.  The layout has four UR92 receivers, three on poles around the layout and one in the main command station.  Normal this system is solid, never gives us a problem.  But a Warley, the radio simply could not work.  At 9.am it was perfect but once the public came in it started to get bad and by 9:30 failed.  The throttles reverted to infer red but even that was poor by 10am.  Once the show closed, it all worked perfectly again. Talking to Sunningwell Command Control at the show, DCC specialist, they said we were not alone, and the issue was with the hundreds, if not thousands of WIFI signals from smartphones hot spotting etc.  We used an app to see how many Wi-Fi signals where available and there were tonnes.  We tried changing the system channel, but it had no effect.  We already have our own group system name.

 

Has anybody had this also, or any advice?

 

Cheers,

 

James

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We suffered the same problem with Digitrax Duplex throttles on 82G at Peterborough a while back.

Digitrax seems particularly susceptible to these issues.

Suggest you look at connecting to JMRI and using smartphone throttles connected to your own dedicated router.

Best

John K

 

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Hello John

 

I also use Digitrax hand throttles and have all sorts of issues which I don't understand as I am not a DCC expert/enthusiast. So have nothing to add other than I will follow this thread with interest.

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It may simply be necessary to use wired handsets as the public is not going to stop using smartphones and I suspect that most people wouldn’t know whether they have a live hotspot or not.

 

what I did notice from the other reports of issues is that most people were having issues with 2.4Ghz radio and yet when using 5Ghz connections the problems were greatly reduced.

 

this would make sense as 5Ghz is newer and devices that support this standard have better components and up to date firmware and software - but whilst 5Ghz might work now that will change as more and more devices use 5Ghz and you will be back to wired handsets.

 

upping the power to ‘drown out’ other signals won’t help either as other exhibitors will simply do the same and once more you are back at the same place.

 

temporary solutions include changing the channel to a less congested channel either manually, or by using a decent router which has automatic channel optimisation m, ideally with beam forming technology. You can get these from Hauwei and TP Link at reasonable cost.

Edited by WIMorrison

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We had our WiFi-Multimaus throttles incapacitated from 1:30 on Saturday and I’d gone to Sunningwell to get an extra long wander lead made and we were looking at the scan which was showing hundreds of phone hotspots making the top of the screen a mush of colour it was so dense. Once they lost contact they just couldn’t see the Z21 to connect due to the power of the signals. Our mobiles and tablets continued to work without issue and could find the Z21 and connect. I suspect the lower power of the multimaus meant it was ‘drowned out’ by the power of the phones. 

On Sunday we watched the same scanner and the dense mush of phones was much much lower and we could see the Barrowmore group, NER Autocar and the US electric layout next to us as the only three up at that level. We had no problem with the Multimaus connecting on Sunday. 

I suspect many either don’t know how to switch off their hotspot or can’t be bothered but we could see them come and go at max strength as people walked by popping on and off the list and all were xxxxx’s Phone!

 

We aren’t going to stop that as they will just ignore announcements to switch off hotspots and ramping up the power of our routers is just going to wipe out other layouts around us. A friend in the business has suggested some kit he uses in these multi shared offices in London so we will see how that goes and if successful I’ll report back. Basically it scans for the less used channels but I’m not sure if the Multimaus etc are compatible until we look into it more. 

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When setting up the Digitrax radio system on a club layout we came across the document at the following URL

 

https://nrmrc.org/sites/default/files/publications/setup_and_train_operations_with_digitrax_duplex_throttles_and_radio.pdf

 

This gives details of the problems they have experienced, and recommends the use of 4 channels least used by normal wifi.

The UK situation may be different however.

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As I understand it , Digitrak is using a duplex radio on 2,4Ghz , but its not Wifi .  The fact is today , designing in such a radio is a waste of time as the spectrum is so crowded , you get drowned out by Wifi .  ( I see its actually 802.15.4 )

 

Good choice a few years ago , bad choice today 

 

If you are using a Wifi based system , you have a better fighting chance , but the issue is all these seperate islands of Wifi and the devices cant negotiate a clear channel , its made worse by modern 2,4Ghz protocols like "802.11n"  which swamp the spectrum 

 

expecting to use Wifi  ( or any 2.4Ghz protocol ) in a semi-realtime control requirement is unfortunately a fools errand ( and we have a Z21 ) especially in large public gatherings 

Edited by Junctionmad
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51 minutes ago, Junctionmad said:

 

expecting to use Wifi  ( or any 2.4Ghz protocol ) in a semi-realtime control requirement is unfortunately a fools errand ( and we have a Z21 ) especially in large public gatherings 

 

Well it swamped the Multimice but didn’t stop the phones using the app so not a fools errand but something to be aware of as I doubt any show is going to surpass Warley for personal hotspots in a small area. 

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A quick look at another forum shows this has been a big problem reported since at least 2014. Digitrax seem to be most affected but we also had failures there in 2017 and also at Peterborough using Lenz via their older interfaces.  Since then we have stuck to wired throttles.

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I hope my decision to use a 5g router and private network with Android controllers works out......

 

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Do you mean 5Ghz rather that 5g - they are not the same thing? ;)

 

Plus there is no point in having 5Ghz if you controller only works with 2.4Ghz.

 

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25 minutes ago, WIMorrison said:

Do you mean 5Ghz rather that 5g - they are not the same thing? https://www.rmweb.co.uk/community/uploads/emoticons/default_wink3.gif

 

Plus there is no point in having 5Ghz if you controller only works with 2.4Ghz.

 

No - I do mean 5Ghz using Android and NetGear router  rather than 5th gen phone.

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The problem with hotspots is not helped by them being defaulted to on (like Bluetooth) for most phones, because the manufacturers and OS developers want to track 'you' all the time wherever you are to feed you adverts...

 

I have enough problems with 2.4GHz WiFi channel contention at home, let alone in a busy public place.

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I'm not shocked that the 2.4GHz arena that Digitrax are forced to use is rather...overpopulated.  Best alternatives might be to use the IR option instead, or tethered.  I'd suggest that tethered is about 99.95% reliable, and the IR will have some serious issues with some types of lighting based on experience with the Lego implementation of it.  I have a UR-92 at home, but use tethered op's instead. 

 

Other suggestions are to use more than one receiver on Digitrax layouts- one at each end might be helpful as power is a ^4 function, and the handholds don't have a huge amount to spare.  New 9V batteries would also likely help a little bit.

 

 

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When I took my old layout 'Galatia' to Warley a couple of years back we had to give up on the JMRI / Sprog / Digitrax wireless system we were trying to use the volume of traffic. Admittedly my wireless router wasnt the best but I'm not sure it would work any better given an upgrade.

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4 hours ago, peach james said:

 IR will have some serious issues with some types of lighting based on experience with the Lego implementation of it. 

 

This problem is reducing significantly as more lights move from incandescent/flourescent to LED/SMD as LED/SMD emit on specific frequencies well away form IR rather than all the stray radiation from older lights.

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13 hours ago, Ian J. said:

The problem with hotspots is not helped by them being defaulted to on (like Bluetooth) for most phones,

 

I've never come across an Android 'phone where bluetooth or hotspot were on by default. Maybe some dodgy app is turning them on.

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There are other unlicensed bands that can be used for radio but they would require more of a home-brew solution. As soon as word get out the same problem could/would occur.

 

This problem was predicted when DCC radio throttles first appeared but most users seemed to bury their heads in the sand and assume only a relatively few exhibition layouts would use them.

 

It's like the old R/C flying systems with the little coloured pennant on the aerial to show what frequency you were using. Once all the colours were used up... The difference being that, to get the data rate up, more recent WiFi spreads the signal across multiple channels so there are fewer channels than would seem on the face of it.

 

One worrying take away from my day job was that factory automation suppliers are pushing WiFi (probably because they can), claiming to have cracked the real-time and security issues.

 

I wonder if there would be a way to setup VPNs for each layout using common infrastructure in the exhibition venue, rather than each layout having it's own access point?

 

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Thanks for all the comments guys, its interesting reading.  We did end up using 'tethered' at 3 points on the layout, but with 155 foot of mainline, that was a real pain.  As the majority of our trains have sound and other fun functions its great to walk around with the trains to drive them like trains.  Ir seemed to be week as well.  We had three masts with UR92s on but we found you had to be so close due to the light in the hall.  We will need to think about this for big shows. 

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8 minutes ago, Crosland said:

 

I wonder if there would be a way to setup VPNs for each layout using common infrastructure in the exhibition venue, rather than each layout having it's own access point?

 

An interesting concept. With a decent router (or mesh installation) and an ethernet connection to each layout's JMRI (or other interface to their DCC), a communal throttle wifi could work. It isn't as if there is a lot of bandwidth needed for the app. A VPN on each controlling interface would keep the operators of layout A out of layout B's system, etc. Something worth proposing to a smaller exhibition as a prototype experiment. The sticking point would be Z21 and DR5000 based layouts that have their own built in Wifi and protocol. They are also very channel, power, and performance limited. 

 

At the last Freemo meet that I supplied power and control for, the reliability in the school hall where there was loads of interference was 

1: wifi on 5ghz. no issues

2: wifi on 2.4 some connection problems, ssid showed every channel with multiple strong access points, not just phone ones. 

3: Z21 on 2.4 Wanmaus or Z21 app. very limited range, loads of disconnection/reconnection issues.

4: Digitrax duplex radio. Loads of connection problems and an almost hourly reboot of the receiver and slot purge in JMRI was needed as it kept filling slots every time a loco was selected. (ie loco 2356, would take 5 slots, 2,3,5,6,2356) 

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I doubt this will be a problem at most shows as there won't be thousands of people around the immediate area and it was ok again on sunday for our Z21 even at Warley. We experienced the wifi issues at Freemo meets but it was the number of throttles trying to connect exceeding the recommended number or like mentioned above JMRI needing the list clearing out. I have no idea what a VPN would entail but you'd be relying on each organisation having someone who understood it and could coordinate it with everyones DCC systems, that sounds like a headache in itself.

You could still see a lot of personal phones on sunday but overall the traffic was at a lower level and I was checking it every hour to see if we were approaching the same levels as Saturday.

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37 minutes ago, Jamestrainparts said:

Thanks for all the comments guys, its interesting reading.  We did end up using 'tethered' at 3 points on the layout, but with 155 foot of mainline, that was a real pain.  As the majority of our trains have sound and other fun functions its great to walk around with the trains to drive them like trains.  Ir seemed to be week as well.  We had three masts with UR92s on but we found you had to be so close due to the light in the hall.  We will need to think about this for big shows. 

 

The Digitrax system, in common with most others, will allow for unplugging and walking, whilst the train continues to run.  The issue is the need to re-plug, with an adequate number of sockets available, and whilst unplugged the loco is not under direct control.  (But its not under control if the Radio or IR fails ).    

 

The communal "big WiFi" could work in theory, but I can't see how a complex exhibition like Warley could make it work with the diverse nature of exhibitors, many of whom don't understand technical issues.    It has a better chance at more closed events, like a Fremo big module build in a sports hall, where there already has to be a certain amount of technical coordination to make the giant modular layout actually work.     And as discussed above, there are lots of products with their own constraints making coordination harder.    Yes, short term, WiFi (mostly phone) based throttles on 5Ghz is likely to work, until lots of people start getting devices which automatically make use of the 5Ghz space.   Probably got five years, maybe a little more, on that stategy, as many a "lets get our own access point" model railway solution will be re-using old stuff and unlikely to have 5Ghz on an old domestic unit.  

 

 

 

 

 

 

 

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Due to the extra long time before Digitrax released their Duplex throttles in the UK we went down the road using JMRI through a router and Wi Throttle apps. Most of the time it has worked well but the first issue came up a few years ago when we kept losing wifi connection. It turned out to be when a large layout powered up it knocked out our connection. Our router was (by default) set to auto channel but since then we have it to a set channel and generally works OK even at larger shows although these days most of our current operators prefer to use the Digitrax tethered throttles. 

Regarding visitors mobiles being set to wifi and Bluetooth on, its probably more likely that people forget to switch these options off. I sometimes forget but normally do switch them off to conserve battery and better security.

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On 25/11/2019 at 13:12, WIMorrison said:

It may simply be necessary to use wired handsets as the public is not going to stop using smartphones and I suspect that most people wouldn’t know whether they have a live hotspot or not.

 

what I did notice from the other reports of issues is that most people were having issues with 2.4Ghz radio and yet when using 5Ghz connections the problems were greatly reduced.

 

this would make sense as 5Ghz is newer and devices that support this standard have better components and up to date firmware and software - but whilst 5Ghz might work now that will change as more and more devices use 5Ghz and you will be back to wired handsets.

 

upping the power to ‘drown out’ other signals won’t help either as other exhibitors will simply do the same and once more you are back at the same place.

 

temporary solutions include changing the channel to a less congested channel either manually, or by using a decent router which has automatic channel optimisation m, ideally with beam forming technology. You can get these from Hauwei and TP Link at reasonable cost.

I fear you may have misunderstood.

If you take your own router which is password protected and not connected to the internet, it matters not a jot how many thousands of people are using phones around you.

I have twice operated at Warley successfully with JMRI and smartphones with no interference fro any other systems.

Digitrax duplex is a waste of space in a busy environment.

John K

 

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@John K I can assure you that I have not misunderstood anything, I have designed, built, managed and maintained wired, WiFi and satellite based networks that have had many tens of thousands of users.  I fully understand the operation of TCP/IP (plus other protocols) and the various transport mechanisms that are involved in LAN, WAN and RAN.

 

It might help you to read up on 802.11 and whilst there look into adjacent and co-channel interference and how they impact congestion - or even easier just google WiFi congestion and read some of the learned articles that you be offered, especially the ones for IEEE ;)

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