Multi-scale direct sequence ultra wide band (MS/DS-UWB) is a new multiple access technique for UWB communications. It utilizes the dyadic (i.e., with a power of two) scaled orthogonal wavelets spread by direct sequence codes creating dyadic scaled multi-band structure exposing the scalability of the spectrum. Services are assigned to different orthogonal sub-bands with respect to their data rates. Comparing to the conventional DSUWB, increased pulse durations reduce the complexity of the conventional DS-UWB system. We show that the spectral structures of MS/DS-UWB using the four scales of Daubechies-5 and Daubechies-10 wavelets fit in to the FCC UWB mask. In terms of the probability of error performance over an asynchronous awgn channel, the proposed design promises better performances compared to a single band UWB design when multi-rate services are available.