Again very unlikely to be an Avus as they use Voigtlanders own lenses, and it's not like any Ihagee I've adverts for in the 1930's. That rimset shutter gives a rough idea of the date as does the lens serial number which is 1929-31. I've a 1929 Almanac on it's way in the post at the moment I'll see what possiblities there are - no of roughly similar cameras.
It could possibly be a "Beier of Freisen" manufacture, but the "DF" or is it "FD" logo may prove elsewise.. The labeling on the shutter is who made the shutter, and the model.
The FD is the shutter manufacturer F.Deckel.
I had a good look through my BJP Almanacs and in 1929 Xenars aren't listed on cameras from any manufactuer however some smaller companies aren't advertising. There's no Xenars on any rebranded cameras either. They appear on Nagel cameras not long after and then on Kodak cameras after they bought the Nagel company however this camera isn't like any of the Nagel/Kodak Six-16 cameras.