The digital tv programs (HD5, dig5, dig8 plus digCNA) are transmitted through UHF chan 38. Yes, all four squeezed into one channel. This was the channel used for City and Sports chans many years ago (can any one remember?)
Hmm, doubt they are all squeezed into UHF 38...
According to these links at the right-hand side under "Terrestrial" section:
MediaCorp HD5 - Wikipedia, the free encyclopedia
MediaCorp Channel 5 - Wikipedia, the free encyclopedia
MediaCorp Channel 8 - Wikipedia, the free encyclopedia
MediaCorp Channel U - Wikipedia, the free encyclopedia
Channel NewsAsia - Wikipedia, the free encyclopedia
Only HD5 is UHF 38, while the rest are UHF 29 "multiplex carrying Mediacorp channels digitally".