In this contribution Time-Hopping (TH) codes are developed based upon the theory of congruences. These codes can be used for coherent multiuser asynchronous spread spectrum communication systems. They represent a compromise between Costas codes, which have nearly ideal auto-ambiguity properties, and congruential codes presenting nearly ideal cross-properties. The presented code applied not in ranging applications but communications system presents good performance in terms of Bit Error Rate (BER) for UltraWide Band Impulse Radio (UWB-IR) systems. Examples of typical auto- and cross-ambiguity functions are given to illustrate the performance of the presented codes jointly with BER evaluation.