Caldwell has yet to feature for the Latics so far this season after undergoing a hip operation over the summer.
The defender has been making positive progress in his recovery and could be in line for his comeback in the Premier League before the end of the month.
"I've been training with the lads for the past week doing football stuff day in and day out," Caldwell told the club's official website.
"That's pretty good progress, but I'm still not up to full speed for where I would like to be so I'm probably still a couple of weeks away from actually playing in games.
"I'm well ahead of schedule in terms of where I thought I would be at this time, but although I'm back training I'm still a way off being able to play in games.
"There's stiffness and the mobility is still not quite there, but still well ahead of schedule and still working hard to try and get back to playing games."