ST's STA2056 to a high level of integration programs provide a very good cost-effectiveness. STA2056 GPS receiver will be in the framework of RF and base-band together so that developers will be able to save energy and cut the time required for school, to market faster. STA2056 part of the base-band using ARM7 TDMI as the core, the frequency of up to 66 MHz; part of the initiative RF antenna system also includes a passive antenna connection with the interface. In addition to the advantages of low power consumption, STA2056 built-in ROM and SRAM, therefore it only needs to use a small number of external components. STA2056 a small QFN-68 package, can effectively reduce the overall material (BOM) cost and product size, design products so that more low-cost short and thin.

              Figure 2  High cost-effective GPS receiver architecture (STA2056 for example)

If the base-band radio and separation, will increase the difficulty of design, but will also increase flexibility. Baseband module can be embedded Flash memory and supports more extensive bus interface. ST's STA2058 is using this framework, very applicable to the vehicle application. Its integrated 32-bit MCU (ARM7TDMI) and embedded flash memory module, GPS systems and other support RTCA-SC159/WAAS/EGNOS. STA2058EX also broad support for CAN, SPI, UART, I2C, USB interface, and so on, with an external memory interface, can be used for long-distance information processing services platform that allows for bonding logic (Glueless) with external devices (such as: GSM / GPRS module, Chip cards, audio DSP) connected.

              Figure 3 High flexible discrete GPS receiver architecture (STA2058 for example)

Power consumption and noise are the often two problems. To GPS receiver, the lower power consumption, noise and interference suppression are the keys for system design.

Noise generated mainly by high-frequency transfer from the process of a low-frequency, noise suppression mechanism must be implemented in this aspect. For example, use the appropriate allocation between the front-end RF and correlator to minimize the harmonic signals of SAMP CLK, to avoid mixing in the intermediate frequency (IF) link, to achieve the objective of noise suppression. In addition, the layout and wires of unit on the circuit also need for proper planning, because these factors will also affect the status of interference.

The main source of power is the operation of correlator, so reducing power consumption can control each channel; that is, when all channels need not start, the system can be adjusted only start for the relevant channels. Moreover, the use of backup battery power supply voltage can be reduced, and also helps save power.

GPS antenna technical requirements
GPS system performance and is closely related to the antenna. Satellite signal for the general background noise -136 dBW, in order to avoid interference, the international telecommunications regulations in the satellite transmission of the signal should be no larger than -154 dBW. So weak GPS signal antenna requirements must be very high sensitivity.