In this paper, we present two differential trellis coded space-time modulation schemes when the channel state information is not available at the transmitter and at the receiver. First, we extend the design of super-orthogonal space-time trellis codes to improve their performance. Then, based on these extended super-orthogonal codes, we propose the first differential scheme. Compared with the trellis coded differential unitary space-time modulation scheme, not only does the proposed differential scheme achieve full diversity, but also it provides identical or higher coding gain and much lower decoding complexity. In order to achieve further improved coding gain in addition to full diversity for more than two transmit antennas, we propose a second differential scheme which is based on super-quasi-orthogonal codes. Such a differential scheme outperforms the differential modulation scheme based on super-orthogonal codes with simpler decoding. Simulation results demonstrate the good performance of our schemes