Gigabit optical link test system for RPC muon trigger in the CMS experiment

High-energy experiments like Atlas, Alice, CMS or LHCb at the LHC accelerator at CERN will be performed in very harsh conditions for electronic equipment. High radiation level in the experimental halls causes that commonly available electronic devices do not work properly. A specialized optical transmitter - GOL (gigabit optical link) has been designed at CERN to meet the radiation environment requirements. The design goal was to supply device resistant to high radiation, fast, and being able to transmit data through optical links. Transmitter was designed considering two important characteristics of its work environment: high radiation level and gigabit transmission speed. Proper internal structure of GOL chip allows to minimize single event upsets (SEU) caused by ionizing radiation. Unfortunately, the design does not eliminate SEU completely. This paper presents testing system for the GOL. Its main purpose is testing new prototypes of optical fibre gigabit transmission systems using GOL transmitter and commercial receiver components. The system will be implemented in the CMS experiment for control purposes. It will monitor optical link and transmission quality in the RPC detector. System consists of hardware layer and software layer. Hardware layer, based on Altera FPGA programmable devices. Software has been developed using C++ environment integrated with VME controller hardware.