The problem of anchor nodes placement in indoor positioning systems is labor intensive and time consuming process. A self-calibrating scheme is proposed to determine the position of the anchor nodes using Ultra-Wide band impulse radio (UWB-IR). These positions can be further used to determine the position of the target nodes. The time difference of arrival measurement technique is employed to self-calibrate the anchor nodes. The proposed scheme is verified with the simulation results, as well as with an in house designed sensor nodes experimental setup.