Vincotech offers "Extended Ephemeris" data for its portfolio of A1084 and A1035-H SiRFstarIII modules. This was enabled as a result of close cooperation with SiRF, now the GPS entity of CSR. This way, GPS modules and GPS antenna modules can calculate a first position after long breaks even under bad conditions quickly.
Most GPS applications ask for a short TTFF (time to first fix) after the GPS receiver is switched on.
The structural conditions of the GPS system require a new download of the orbital data (Ephemeris) of the satellites in case the receiver was switched off for more than four hours and is switched on again. The time needed to do so is between 18 and 36 seconds under good conditions. Therefore the calculation of a first position takes typically 27 or 28 seconds. The currently available Ephemeris data have a validity of two to four hours only, thus causing the the same problem with the next longer off/on cycle . To overcome a new load of the data every time such a cycle has passed, "Extended Ephemeris" models have been introduced. In principal, these models include an extrapolation of the currently valid Ephemeris data based on mathematical methods taking the ellipsoid orbits of the satellites and gravitational effects into account. The validity is extended to several days, the calculation itself is done on separate servers.
With the support of SiRF (CSR), the company can now offer the data for its current SiRFstarIII based GPS modules, A1084-A/B (GPS receiver module) and A1035-H (GPS antenna module). The company provides these data on its server for its customers. The customer may access these data once a day and use them for his applications. A typical example is telematics units, devices mainly based on GSM/GPRS and GPS. They are often used in applications such as fleet management or stolen vehicle recovery. The company's customer (in this case a service provider) transmits the data then to the units in the field. There, a few commands are enough to feed the data into the receiver and store them. If sent to a low power mode, where only the RTC keeps running and SRAM is maintained and powered on again afterwards, the real data becomes invalid (e.g. after a switch off over night). However, the data can still be used. No new loading is necessary and a first position can be calculated quickly. As long as the data are available irrespective of real or "artificial" ones, the GPS receiver can work with lower signal strength. Therefore, a position can be calculated in positions even, where it would not be possible without the data. This is important for units inside a vehicle or generally covered installations. The company enables the use of the data on its own A1074 telematics box.
