A Base Transceiver Station (BTS) has four main blocks or logical entities: radio frequency (RF) block, baseband block, control and clocking block, and transport block. The radio frequency module (RFM) receives signals from portable devices (via the air interface) and converts them to digital data. The baseband block processes the encoded signal and brings it back to baseband before relaying it to the terrestrial network via the transport block. Coordination between these three functions is maintained by a control block.
The OBSAI specification seeks to meet its goal for an open market for BTS globe valve components by defining interfaces between the four blocks and external interfaces between the