GPS over Fiber System

Distribution of the GPS signal over long distance

Rosenberger presents a new and innovative GPS over Fiber system for applications where coax cannot be used to route the GPS signal to base stations. With more centralized RAN and large-scale DAS applications, there are many cases where the GPS antennas are located too far from the base stations for coaxial losses to be acceptable.

To overcome this issue, the GPS over Fiber system converts the RF signal to light, transmits it over the fiber, and then restores the light to the original RF signal. Working in contrast to the many systems that employ a bulky remote unit – which requires power and separate mounting space – as well as a large master unit encompassing an active GPS splitter, Rosenberger has rethought the process and designed a fiber-optic replacement for the coaxial cable. Instead of a master unit and a remote unit, the system uses an electrooptical converter (E/O converter) at the antenna and an opto-electrical converter (O/E converter) near the base station. By employing this method, the E/O converter becomes a small, compact unit that connects directly to the GPS antenna. The unit is so small that it can even fit within a 1 ½ inch pipe of the kind often used to mount GPS antennas.

The O/E converter handles all alarms and is a compact unit. It can be used to power the E/O converter and can be connected to standard GPS splitters with full support for their redundancy functionality. This means that the GPS over Fiber system fully emulates the behavior of a passive copper cable and GPS antenna, allowing any device that is normally connected to the GPS antenna to maintain proper operation when connected to an O/E converter. Interconnecting the two units i.e. E/O converter to the O/E converter is a thin hybrid cable comprised of fiber and power, which means no power source is required at the GPS antenna.

The individual link support for each GPS antenna allows for the flexibility of using a normal coaxial configuration and simply replacing each coax cable from a GPS antenna with an E/O converter, an O/E converter, and a hybrid cable. With a maximum hybrid cable length of 1.9 miles (3 km), this system can meet the demands of almost any installation