With the rapid growth in research activity on future wireless networking applications and protocols, experimental study and validation is becoming an increasingly important tool to obtain realistic results that may not be possible under the constrained environment of network simulators. However, experimental results must be reproducible and repeatable for them to be used to compare proposed systems and to build prototypes. In this paper, we address the issue of repeatability in wireless experiments in the Open Access Research Testbed for Next-Generation Wireless Networks (ORBIT) testbed and propose a mechanism to promote reproducible experiments using periodic calibration of the equipment. Several experimental results that capture repeatability in time and space using our initial testbed setup are also provided.