some simple calculation 48 Mb/34 channels = 1.41 Mb/channel. Now they convert into 8psk hence increase in bandwidth, i.e. Near about 18 Mb/1.41 ~ 12 channels.
But for in future they are use to add some data channels so we can expect 3 to 5 more channels on this tp means gssran and shubham bro are very correct.