This invention relates in general to electrical communications and more particularly to position indication.
When instrumentation computers are used during field test exercises it is customary to use Global Positioning System (GPS) receivers to provide accurate positioning information and synchronizing signals to the computers. Since a GPS receiver can provide an interface with only a single computer, each computer must be provided with its own GPS receiver. This is not practical when a large number of collocated computers are used.
It is therefore an object of this invention to operate several collocated instrumentation computers off a single GPS receiver.
This and other objects of the invention are achieved by an apparatus for providing GPS positioning information to a master computer and a plurality of slave computers from only one GPS receiver. The apparatus includes positioning information providing means adapted to be coupled between the GPS receiver and the computers for providing each computer with a replica of a positioning information signal from the GPS receiver so that each computer receives all of the positioning information it would have received if it had been connected to its own GPS receiver. In addition, the apparatus includes synchronizing means adapted to be coupled between the GPS receiver and the computers for providing each computer with a replica of a synchronizing signal from the GPS receiver so that each computer receives the synchronizing signal it would have received if it had been connected to its own GPS receiver. Further, the apparatus includes means adapted to be coupled between the GPS receiver and the master computer for passing a control signal from the master computer to the GPS receiver to set up and control the state of the GPS receiver.
The apparatus provides GPS positioning information to a plurality of computers through the novel use of a master-slave relationship among the computers. The master computer communicates with the GPS receiver as if the slave computers were not present and sets up and controls the state of the GPS receiver. The slave computers have no control over the GPS receiver and operate in a listen-only mode. The positioning information signal and the synchronizing signal are coupled off, converted to the proper levels, buffered, reconverted, and sent to each of the slave computers. The apparatus provides indicators showing the status of the positioning information signal and the synchronizing signal. This increases user confidence in the status of the apparatus, while enabling quick diagnosis of any problems that may arise.
The apparatus provides significant cost savings by reducing the number of GPS receivers and associated hardware and cabling required in the deployment of test instrumentation during developmental and operational field test exercises. It also saves on manpower because a single GPS is installed rather than multiple units. It increases reliability while reducing the consumption of power by reducing the number of active elements.