When mobile phones first entered cars, their uses were limited to telephony via a hands-free setup. Now, these devices are increasingly being used to access the Internet on the road to contact local services or augment satellite-based navigation. A significant and increasingly important function is navigation responding to the momentary traffic situation. It determines how many mobile phone subscribers are logged into a cell and at what speed they are moving. The more such subscribers present in a cell and the slower they are moving, the denser the traffic or else a traffic jam has built up.
Another combined option for satellite-based navigation and mobile phones is offered by emergency call systems--such as eCall--that are used in the event of an accident or breakdown. This intelligent emergency call system determines the position of the vehicle via satellite and sets up a data and voice link to an emergency call center via the mobile communications network. Vehicle fleet management and the German toll system, for example, also operate with satellite-based navigation and mobile communications technology. The frequency ranges they use depend on the regions in which they operate.
An extensive range of AEC-Q200-qualified EPCOS SAW filters (single and diplexer) is also available in package sizes of 3.0 × 3.0 mm² down to 1.4 × 1.1 mm² with various center frequencies, insertion losses and useful bandwidths for the typical frequency bands. A selection from the current product range is shown in Table 2.
Table 2: AEC-Q200-qualified EPCOS SAW filters for mobile-communications-based applications. For full resolution click here.
All the listed RX filters and 2in1 components have unbalanced inputs of 50 Ω and balanced outputs of 150 Ω. All listed TX and RX diversity filters have unbalanced inputs and outputs of 50 Ω.