By The Nation
A huge number of train commuters were stranded for four hours during rush hours on Monday and Tuesday, prompting a public outcry for the operator to fix the chronic problem.
The train operator, Bangkok Mass Transit System Public Company (BTSC), said its signalling system malfunctioned due to radio frequency jamming, as its 2400MHz spectrum experienced interference. The watchdog called in representatives of BTSC, Total Access Communication (DTAC) and TOT yesterday to seek ways to tackle the radio frequency interference problem that has hit the Skytrain service.
NBTC secretary-general Takorn Tantasith said after the meeting that the problem was caused by the jam between the 2,300MHz spectrum band and the 2,400MHz band.
TOT has granted the 2310MHz-2370MHz range band to DTAC under partnership deals to provide broadband wireless service, while BTS has utilised the 2,400MHz band to manage its train operation. Though the gap between the TOT band and that of BTS is 30MHz, jams can sometimes occur.
The NBTC has recommended that BTS train system shift to use the 2480MHz-2495MHz frequency in order to solve the problem in the long run and that TOT switch off a number of the 2300MHz cellular base stations along the Skytrain routes on a temporary basis until BTS finishes implementing the change, Takorn added.
Surapong Laoha-Unya, executive director of BTS Group Holdings, said that BTS planned to finish installing related signal-receiving equipment and signal filters and move to the new band tomorrow. He believes that the BTS will be able to offer normal service as usual from Saturday. A TOT representative said that TOT would work with BTS to solve this problem.
Narupon Rattanasamaharn, DTAC’s senior vice president, Head of Regulatory Division, said he believes that DTAC’s existing 2300MHz customers would not be affected by the temporary shutdown of the 2300MHz base stations, as their cellphone devices would automatically switch to the company’s 1800MHz and 2100MHz |frequencies during the period.