DTAC denies its mobile signals interfere with BTS skytrain's traffic control system

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DTAC denies its mobile signals interfere with BTS skytrain's traffic control system

By The Nation

 

FILE photo//Wikipedia

 

Total Access Communications (DTAC) has denied that its mobile frequency band has interfered with the automatic traffic management system of the BTS skytrain.

 

Prathet Tankuranan, deputy CEO of DTAC, said on Tuesday that TOT telecommunications company licensed the 2,300 MHz bandwidth to DTAC and it did not emit signals beyond the allocated bandwidth.

 

Prathet said DTAC engineers are working closely with Bangkok Transit System (BTSC), the operator of the skytrain, to try to isolate the radio frequency interference.

 

Prathet made his comments after Anat Arbhabhirama, director and adviser of BTSC, said on Monday that a problem has been caused on the skytrain by radio frequency interference, especially at the busy Siam station.

 

A Chulalongkorn University engineering lecturer has hinted that the inference might be caused by the 2,300 MHz bandwidth mobile signal because skytrains use 2.4 GHz and 5 GHz radio signals for WiFi communications in the automatic traffic management system.

 

Source: http://www.nationmultimedia.com/detail/national/30348630

 

-- © Copyright The Nation 2018-06-26

[sungod]

Messed up again this morning as I stand on the train, not as bad as yesterday thankfully.

[Crossy]

Interference with CBTC (Communications Based Train Control) systems is a global and rapidly growing problem. Try a Google search. 

 

Mostly it stems from the fact that (incredibly) there's no licensable frequency band allocated for CBTC, it has to use the unlicensed 2.4 and 5GHz bands as used by WiFi. Yup, your home router has the potential to stop the BTS! Unlikely, but Shenzhen metro has had issues linked to Wifi usage on the trains.

 

The suggestion that the (newly operating at 2.3GHz) DTAC tower is, at least part of the problem, is reasonable. Anyone who's used CB or amateur radio knows about intermodulation between adjacent channels and 2.3GHz isn't that far from 2.4GHz, cell towers have pretty potent transmitters up there.

 

[robblok]

12 minutes ago, Crossy said:

Interference with CBTC (Communications Based Train Control) systems is a global and rapidly growing problem. Try a Google search. 

 

Mostly it stems from the fact that (incredibly) there's no licensable frequency band allocated for CBTC, it has to use the unlicensed 2.4 and 5GHz bands as used by WiFi. Yup, your home router has the potential to stop the BTS! Unlikely, but Shenzhen metro has had issues linked to Wifi usage on the trains.

 

The suggestion that the (newly operating at 2.3GHz) DTAC tower is, at least part of the problem, is reasonable. Anyone who's used CB or amateur radio knows about intermodulation between adjacent channels and 2.3GHz isn't that far from 2.4GHz, cell towers have pretty potent transmitters up there.

 

Crossy, even if its reasonable DTAC paid for this frequency and as you said the BTS had no license for its signal and uses a commonly used frequency. I would say that the BTS should adapt and find a solution. They make tons of money don't buy rolling stock so let them invest something in their cash cow.

[mtls2005]

Hopefully, the signaling system is at least "secure", the last thing I want to see is some young hacker on the BTS "drivin' that train" on his mobile - and turning his train into an "Express". 

 

 

Maybe the BTS is using free WiFi hotspots, and those are overburdened with folks - not the drivers - torrenting, or playing "Subway Surfers"?

 

 

Edited June 26, 2018 by mtls2005

[mercman24]

same old Thailand, blame someone else, for your problems

[Crossy]

23 minutes ago, mercman24 said:

same old Thailand, blame someone else, for your problems

I place the blame squarely with the CBTC manufacturers for not lobbying harder for a licensable band dedicated to train control. Of course it's cheaper to do nothing.

 

Also, whilst DTAC did pay for their 2.3GHz allocation it's the duty of any operator of transmitting equipment to minimise interference with other legitimate users.

 

A solution will be found, it must be, but in the current licencing climate only a move to 5GHz is practical, and that band is becoming increasingly cluttered.

 

 

[sungod]

25 minutes ago, mercman24 said:

same old Thailand, blame someone else, for your problems

I think you will find its a world wide practice.

 

[TallGuyJohninBKK]

14 minutes ago, Crossy said:

I place the blame squarely with the CBTC manufacturers for not lobbying harder for a licensable band dedicated to train control. Of course it's cheaper to do nothing.

 

Also, whilst DTAC did pay for their 2.3GHz allocation it's the duty of any operator of transmitting equipment to minimise interference with other legitimate users.

 

A solution will be found, it must be, but in the current licencing climate only a move to 5GHz is practical, and that band is becoming increasingly cluttered.

 

 

As you alluded earlier, one might think and expect that public mass transit train control systems would operate on their own specifically licensed dedicated bands/frequencies -- instead of sharing the airwaves on the same bands as every Tom, Dick and Somchai in Bangkok.   But, but, but...

 

 

[Lupatria]

We all know what it means here when a sentence starts with ...denies.

[robblok]

2 hours ago, Crossy said:

I place the blame squarely with the CBTC manufacturers for not lobbying harder for a licensable band dedicated to train control. Of course it's cheaper to do nothing.

 

Also, whilst DTAC did pay for their 2.3GHz allocation it's the duty of any operator of transmitting equipment to minimise interference with other legitimate users.

 

A solution will be found, it must be, but in the current licencing climate only a move to 5GHz is practical, and that band is becoming increasingly cluttered.

 

 

If Dtac is responsible maybe a short term solution can be arranged, but long term should be done by investments and changes by the BTS maybe getting their own frequency.  Something should be done to solve this problem ASAP of course. 

[bluesofa]

3 hours ago, Crossy said:

I place the blame squarely with the CBTC manufacturers for not lobbying harder for a licensable band dedicated to train control. Of course it's cheaper to do nothing.

 

Also, whilst DTAC did pay for their 2.3GHz allocation it's the duty of any operator of transmitting equipment to minimise interference with other legitimate users.

 

A solution will be found, it must be, but in the current licencing climate only a move to 5GHz is practical, and that band is becoming increasingly cluttered.

 

 

I remember the 2.4GHz band, but what's the 5GHz band used for - is that open to all as well?

 

[Crossy]

10 minutes ago, bluesofa said:

I remember the 2.4GHz band, but what's the 5GHz band used for - is that open to all as well?

 

Yeah, 5GHz is the "other" WiFi band (most modern WiFi kit does both), licence free and increasingly busy.

[Muhendis]

I am amazed that any mass transit system uses a relatively easily accessible wireless network to control it's systems. Thinking about terrorist activities, it must surely be more sensible to use fibre optics which are prone to neither hacking nor random stray interference.

[humbug]

i can believe telecom operators can do this as i am pretty sure(no hard evidence, or experience in telecoms)

That they try to block their competitors signals

 

I will never use true but if i go near the true office on ratchada or the cp group(own true) on silom i always have zero to neglible internet coverage on my phone

 

 

[observer90210]

5 hours ago, Crossy said:

Interference with CBTC (Communications Based Train Control) systems is a global and rapidly growing problem. Try a Google search. 

 

Mostly it stems from the fact that (incredibly) there's no licensable frequency band allocated for CBTC, it has to use the unlicensed 2.4 and 5GHz bands as used by WiFi. Yup, your home router has the potential to stop the BTS! Unlikely, but Shenzhen metro has had issues linked to Wifi usage on the trains.

 

The suggestion that the (newly operating at 2.3GHz) DTAC tower is, at least part of the problem, is reasonable. Anyone who's used CB or amateur radio knows about intermodulation between adjacent channels and 2.3GHz isn't that far from 2.4GHz, cell towers have pretty potent transmitters up there.

 

Very true. I also was wondering what if some pranksters started using GSM signal blockers (that are sold freely all over the web) ? It could be very easy to jam the transport grid with little or no technical know how ?

Edited June 26, 2018 by observer90210

[Muhendis]

1 minute ago, humbug said:

i can believe telecom operators can do this as i am pretty sure(no hard evidence, or experience in telecoms)

That they try to block their competitors signals

 

I will never use true but if i go near the true office on ratchada or the cp group(own true) on silom i always have zero to neglible internet coverage on my phone

 

 

I've noticed this sort of effect too. Going into various pubs in the UK, as has been known, virtually kills any mobile phone activity but in the case of the OP lack of communications isn't the problem. It is as Crossy said probably co-channel interference.

[thedemon]

Since the trains are necessarily connected to the grid to get the electricity to run their trains you would think that utilizing that for communication might be a better long term solution than going against an ever decreasing availability of radio bandwidth.

[Bangkok Barry]

5 hours ago, sungod said:

I think you will find its a world wide practice.

 

 

I think you will find that no Thai ever admits to anything and blames anyone/anything else. At least, that has been my experience in 26 years here. Where I come from, people usually own up and takes responsibility for something and that way it gets investigated if necessary and fixe.

[sungod]

12 minutes ago, Bangkok Barry said:

 

I think you will find that no Thai ever admits to anything and blames anyone/anything else. At least, that has been my experience in 26 years here. Where I come from, people usually own up and takes responsibility for something and that way it gets investigated if necessary and fixe.

26 years ago  (where ever you come from) I bet you used to leave your doors unlocked whilst popping around the neighbors house for a cup of sugar.

 

I dont think the Thais have a monopoly on the behavior you describe even if it is true.Happens many places these days, but hey, lets bash them anyway 'cause its not like back at home.'

 

[hansnl]

2 hours ago, Muhendis said:

I am amazed that any mass transit system uses a relatively easily accessible wireless network to control it's systems. Thinking about terrorist activities, it must surely be more sensible to use fibre optics which are prone to neither hacking nor random stray interference.

Yes, that would be wise.

But costs money.

 

[Muhendis]

9 minutes ago, hansnl said:

Yes, that would be wise.

But costs money.

 

Well yes of course it costs money but in the grand scheme of the billions spent and made on the overall train system it's cost would barely get a mention. I think the wireless gimmick probably caught the attention of some  technologically dumb bureaucrat and so it came to pass.............and now we have trains that enjoy unscheduled failures.

[Crossy]

2 hours ago, Muhendis said:

I am amazed that any mass transit system uses a relatively easily accessible wireless network to control it's systems. Thinking about terrorist activities, it must surely be more sensible to use fibre optics which are prone to neither hacking nor random stray interference.

I too was flabbergasted to discover the use of the regular 2.4GHz band (I'm not a signalling chap).

 

Sadly, fibre tends not to work very well for moving vehicles, radio comms is a must.

 

I also discover that the train radio system (by Bombardier) can't do 5GHz ?

 

[Muhendis]

16 minutes ago, Crossy said:

I too was flabbergasted to discover the use of the regular 2.4GHz band (I'm not a signalling chap).

 

Sadly, fibre tends not to work very well for moving vehicles, radio comms is a must.

 

I also discover that the train radio system (by Bombardier) can't do 5GHz ?

 

Ah yes possibly true. I was thinking of station to station/control room rather that talking to the driver. As far as telemetry from the moving vehicle is concerned that need only be a pickup loop at intervals along the line using short distance coupling. I was involved in the laser coms video link on the Lantau/mainland railway some years ago so optical communication is not unfeasible. 

[Crossy]

3 minutes ago, Muhendis said:

Ah yes possibly true. I was thinking of station to station/control room rather that talking to the driver. As far as telemetry from the moving vehicle is concerned that need only be a pickup loop at intervals along the line using short distance coupling. I was involved in the laser coms video link on the Lantau/mainland railway some years ago so optical communication is not unfeasible. 

Fibre between stations is, of course, a given.

 

Lantau and Airport railway was nigh on 20 years ago (I worked on it too when I was with Cubic), at the time the airport trains were the world's fasted 1,500V DC trains at 135kph but not ATO IIRC.

 

CBTC is the latest (and greatest?) incarnation of ATO, it works very well for the short headways required of metro operation, provided the communication (the "C") is reliable.

 

[lvr181]

3 hours ago, Muhendis said:

I am amazed that any mass transit system uses a relatively easily accessible wireless network to control it's systems. Thinking about terrorist activities, it must surely be more sensible to use fibre optics which are prone to neither hacking nor random stray interference.

Agreed. They only need to attach cabling to their track infrastructure. Seems relatively simple to me (and Muhendis) or have I missed something? 

[Crossy]

12 minutes ago, lvr181 said:

Seems relatively simple to me (and Muhendis) or have I missed something? 

Trains tend to move.

[lvr181]

Just now, Crossy said:

Trains tend to move.

 Damn - I thought it was for the signalling system. 

[Crossy]

1 minute ago, lvr181 said:

 Damn - I thought it was for the signalling system. 

And the trains are controlled by the signalling system, fully automatic, no line side coloured lights (check next time you ride the BTS).

[lvr181]

4 minutes ago, Crossy said:

And the trains are controlled by the signalling system, fully automatic, no line side coloured lights (check next time you ride the BTS).

Never noticed 

 

Has to be a better and more secure system, with less or nil interference in the future, than what's currently used. Will leave it up to the 'experts' if the BTS or Government wants to import some to help.