GPS is the abbreviation of Global Positioning System (GPS). GPS uses navigation satellites for time measurement and ranging to form a global positioning system. It can provide personal positioning, timing and speed measurement functions. This article refers to the address: http:// 1. The basic structure and characteristics of GPS GPS is a sophisticated satellite navigation system. The system consists of 24 satellites orbiting the Earth, and the satellite continuously transmits position and time information. These satellites are evenly distributed over six orbits, each with four satellites. The ground GPS receiver can receive 5 to 12 satellite signals. In order to achieve the ground positioning function, the GPS receiver needs to receive at least 4 satellite signals, 3 of which are used to calculate the latitude, longitude and altitude of the GPS receiver, and the fourth signal provides synchronous time calibration. The GPS system is mainly divided into three parts: first, satellite, providing positioning information in the sky; second, the control system, maintaining the normal operation of the satellite on the ground to ensure the health of the satellite; third, the receiver, used by the general user part. The positioning principle is to divide the earth into 12 cross-sections, each of which has two positioning satellites at an angle of 180 degrees. Therefore, at any point on the earth, there are always 12 positioning satellites on the top of the head. . The distance, coordinates and angle between the satellite and the satellite are known. The distance between the satellite and the human is measurable. According to the geometric principle, the receiver usually determines the two-dimensional coordinates by receiving the information of three satellites. At latitude and longitude, the altitude is obtained by receiving information from four satellites. At present, satellite (up to 27) networks operate in asynchronous, near-Earth orbit and cover the whole world, ensuring the operation of the positioning system. The GPS receiver needs to lock at least 4 stars to provide positioning information. The long series of codes (or combinations of numbers) broadcast or transmitted by these satellites are called pseudo-random codes. The GPS receiver can calculate the transmission time of the satellite by using parameters such as the known satellite pseudo-random code, the speed of light, and the look-up table that maintains the position of the satellite, and then convert the transmission time into a distance. Under the condition of multiple satellites (greater than 4), the position of the GPS receiver can be calculated by solving the trigonometric equation, and the position of the user is also provided. The GPS chip is composed of a radio frequency integrated circuit, a digital signal processing circuit and standard embedded GPS software. The radio frequency integrated circuit is used for detecting and processing GPS radio frequency signals, the digital signal processing circuit is used for processing intermediate frequency signals, the standard embedded GPS software is used for searching and tracking GPS satellite signals, and the user coordinates and speed are solved according to these signals, and the main market is Wireless for devices, cars, portable juice computing devices, and some CPS professional users. FIG. 1 is a schematic block diagram of a handheld GPS system chip structure. 2. Advantages of traditional GPS and new technology GPS solutions So far, traditional GPS, such as the global positioning technology used in mobile devices, has problems such as high price, large power consumption, and large size. Therefore, the development of a pure software GPS receiver, through the software to complete the function of the GPS chip, thereby further reducing costs, and promoting more handheld mobile devices using GPS functions is aimed at the market's main demand for next-generation technology. 2.1 Advantages of the new technology GPS solution It is a significant reduction in system cost, power consumption and size compared to other hardware-based multi-chip solutions. The software solution works in both automatic and auxiliary GPS modes, providing position information for the system (such as car tracking) every second. The algorithm can also be adapted to meet the requirements of walking or indoor applications, providing optimal GPS design for mobile products such as cellular phones, PDAs, digital cameras, MP3 players, laptops, portable DVD players. 2.2 The characteristics of the new technology GPS program Combining proprietary RF IC design technology with new software GPS technology, it has developed a solution that fully meets the demanding requirements of mobile and portable products, such as Maxim's RF IC design technology combined with Philips' innovative software GPS technology. Wu is a typical representative. This can be specified from the following two points. a About the initial design. The first based on this new technology GPS solution is a reference design optimized for laptop USB accessories. This design enables low cost/high performance GPS add-ons. The simplest form can be a GPS strip that turns a laptop into a large screen navigation device. Another application is a USB GPS accessory for connecting to a smartphone with USB OTG. In addition, this small, low-power design can be combined with other devices such as USB memory drives or USB MP3 to implement GPS functionality in these devices. b Hardware/software integration. The entire reference design is based on a GPS receiver front end, such as the Maxim-based MAX2741 GPS receiver front end, with its MAX2741 built-in LNA, adaptive AGC, and VCO. In addition, the MAX2741 integrates a 1, 2 or 3 bit to support a reference frequency from 2MHz to 26MHz and operates from a 2.7V to 3.0V supply. Software (such as Philips' Spot software) is 600Kb code written in ANSI C that can be loaded and run on a variety of standard processors such as ARM, Intel Xscale or TI-OMAP. The software obtains the GPS front-end receiver output and satellite positioning information, and then downloads the satellite ephemeris, uses new technology for signal processing, extracts satellite signals, and generates effective positioning information. 3. Example application of new technology GPS solution 3.1 Application of the existing application processor in the infotainment system to complete the GPS/Galileo function A unique software-based GPS solution that completes GPS/GalileoGa upgrades without changing hardware. Similar to the Global Positioning System (GPS), Galileo is the European navigation system Galileo being developed by the European Space Agency. It is expected to be fully operational within a few years. Adding a Galileo navigation system to a GPS satellite system will greatly improve performance compared to systems with only GPS. Due to the long design cycle in the automotive market, today's manufacturers are actively preparing for the application of this new technology. GPS/Galileo (GNSS) technology utilizes the system's main processor to perform the required GNSS positioning calculations without the need for expensive and bulky baseband ICs. So the entire hardware bill of materials for GNSS is reduced to just the RF front-end circuitry. The new technology delivers performance comparable to traditional hardware-connected multi-chip GPS solutions, but at the lowest cost in the industry and the smallest in size. The GNSS solution provides unparalleled flexibility for infotainment systems. The software offers stand-alone mode and assistance mode and can be optimized to meet your car navigation needs. Figure 2 is a schematic block diagram of a conventional GPS solution and a new software-based GPS solution. figure 2 3.2 Turning a UMPC or laptop into a fully functional GPS navigation system Unique software GPS, cost and size reduction of 50%. Global Positioning System (GPS) technology utilizes the system's main processor to perform the required GPS calculations without the need for expensive and bulky GPS baseband ICs. In addition, highly integrated and extremely flexible RFICs (such as the MAX2741) maximize the reuse of other system resources such as the reference clock. Moreover, this software-based GPS requires only a small number of BOMs, further reducing the size and cost of the GPS solution. The GPS solution offers unparalleled flexibility to extend location-based applications in ultra-mobile PCs (UMPCs), laptops, PDAs and smartphones. Independent and Assisted GPS modes and different sized software are available and can be optimized for different applications such as car navigation, personal navigation or single point position correction applications. The schematic diagram is the same as that of FIG. 2. 4. The core chip is a key part of the GPS system - The advantages and disadvantages of the core chip largely determine the performance difference of different GPS products. The chip technology is directly related to the technical indicators and future development of GPS products. The GPS chip consists of a radio frequency integrated circuit, a digital signal processing circuit and standard embedded GPS software. The radio frequency integrated circuit is used to detect and process GPS radio frequency signals, the digital signal processing circuit is used to process intermediate frequency signals, and the standard embedded GPS software is used. Search and track GPS satellite signals and solve user coordinates and speeds based on these signals. The main market is wireless devices, cars, portable juice computing devices and some CPS professional users. This can be seen from the core technology of the embedded CPS navigation system. Take the 16/32-bit RISC processor S3C2410A chip in the Samsung ARM9 series as an example. The chip's powerful real-time processing capability and rich peripheral interface are very suitable for embedded systems. Development. The system is designed based on these characteristics of the chip. The system is based on the SC2410A microprocessor, and is integrated into two 32M SDRAMs (HY57V561620CT) and 64M NANDFlash (K9F1208UOB) as the smallest system. In addition, a GPS module for GPS signals can be installed outside the system. , the LCD panel for display, and the voice chip system of the LJDAl341TS. ST also offers complete GPS solutions, including GPS baseband controllers and RF receivers. ST's STA2051 uses the ARM7TDMI core, adding a dedicated APB and 12-channel GPS correlator, internal B256K+16K FLASH memory and 6K SRAM, as well as all peripheral resources of the standard STR710. ST cooperates with STA2051 to release a complete software runtime implementation based on ST's proprietary embedded operating system OS. It realizes a complete GPS solution and provides open ARM and peripheral resources to users, which has advantages in power consumption and cost. The STA2051 product family includes the TQFP64's automotive-grade STA201 and consumer-grade STA2051GO, as well as the TQFPl44's more I/O resources for the STA2051E. STA2051 main features: 0.18um process, 3.3V single-supply operation, low power consumption; ARM 7TDMI, 32-bit RISC engine, Debug interface, JTAG; embedded 256k bytes + 16k bytes FLASH, 64k bytes SRAM; EMI (External Memory Interface) (TQFPl44 only), divided into 4 zones, up to 64M bytes; 12-channel GPS hardware correlator (STMicroelectronics IP); independent RTC (Real-Time-Clock) with wake-up function; CAN Controller (CAN Protocol rev.2.0partA and B) up to 1 Mbit/s; four 16-bit multifunction timers (capture, compare, count, PWM); four UARTS, dual SPI, dual I2C and USB (only 144 PIN) and other serial communication; smart card (1S0 7816-3 incl.Clock generation); watchdog and wake-up control (RTC or external trigger); HDLC control (incl.NRZI, FM0 and Manchester encoder); 4-channel 12-bit ADC Converter (Sigma-Delta); on-chip voltage regulator for CPU and core logic; operating temperature: -40 ° C ~ +85 ° C. The 50-channel LEA-5 GPS module delivers speed, sensitivity and ease of integration beyond current levels. The LEA-5GPS module series has the fastest first positioning time in the GPS market. These stand-alone multi-purpose GPS receivers use u-blox 5 GPS and GALILEO chips, which not only have rich functions and flexible connection capabilities, but also are easy to integrate applications, so that the volume and cost are strictly limited by automotive electronics, consumer and industrial. Applications can be launched quickly. U-blox5 provides ultra-fast first-time positioning. It uses a GPS architecture that not only has 50 channels, but also provides more than 1 million correlators and independent positioning and search engines for large-scale parallel search. With the help of u-blox' AssistNow A-GPS service, the u-blox5 chip and module can acquire satellite signals and complete the first positioning in less than one second. These LEA-5 modules are not only the fastest and most sensitive GPS modules on the market, but also small in size and low in cost, making them ideal for mass-market GPS consumer devices. The LEA-5HGPS module includes flash memory, which simplifies carcass upgrades and system setpoint storage; the ROM-based LEA-5S further reduces costs. Both modules offer u-blox's OMASUPL-compatible A-GPS interface and support AssistNow online and AssistNow offlineA-GPS services. The LEA-5 GPS module is a chip from u-blox (Switzerland). It has the following five distinctive features: a parallel channel with an equivalent of more than 1 000 000 correlators, and the sensitivity is improved from the original -l 5 8d bm to no Less than -160dbm; power consumption is less than 50mW; support both GPS and Galileo positioning platforms; cold start time is shortened from the original 34s to cold start 29s, plus A-GPS assisted positioning technology, outdoor cold start can be in ls The number of GPS channels is increased from 16 channels of the fourth generation to 50 channels of the fifth generation. U-blox-g5 can be applied to mobile products such as mobile phones and PDAs, greatly expanding the market for mobile phones. 5, GPS chip application - build GPS receiver with MAX2742 The receiver is an important part of GPS (Global Positioning System). For users, the GPS receiver is increasingly used. It is necessary to analyze the GPS receiver architecture first. 5.1 GPS receiver basic architecture A typical GPS receiver includes a functional block as shown in Figure 3, which includes a radio frequency portion (GPS-RF front end), a GPS signal processor, and a main processor. image 3 The RF part includes: GPS antenna, RF filter and GPS RF front end. The RF part receives the satellite signal, separates the pseudo-random code from the carrier frequency, and sends it to the GPS signal processor. In most existing receivers, the RF front-end part plus the GPS signal processor can process 4 to 12 simultaneously. Satellite signal. This parallel processing capability provides higher positioning accuracy and reduced time to output data. The main processor provides data to the user, ie the data can be provided to the user via a GUI (image user interface), display screen, or other operating system approach (as shown on the left side of Figure 4), as to what approach depends on the actual Application requirements. Synchronization and timing are important features of GPS receivers. For this purpose, the digitally controlled temperature-compensated crystal oscillator TCXO (such as DS4000) is used for synchronization and timing. In the block diagram of Figure 3, there are two sources of oscillation, including a REF (reference) crystal (or oscillator) and an RTC (real time clock) crystal. The REF crystal or oscillator can be quite accurate or inaccurate, depending on the receiver used. Typical ranges are between 13MHz and 30MHz, depending on the manufacturer. In applications that use GPS receivers as a precision time reference, the REF oscillator can be a source, an OCXO, or even a TCXO. In this case, the main processor will correct any timing slip between the satellite and the receiver. The RTC crystal provides real-time clock information for the GPS receiver's signal acquisition process to capture different satellites in 27 satellite constellations. Through a lookup table on satellite position information, the RTC helps provide a starting point for locking all visible satellites. 5.2 Building a GPS Receiver with the MAX2742 With the integrated CMOS RF front-end GPS receiver MAX2742 (shown in Figure 2), and with very few external components, a complete GPS solution can be constructed. The MAX2742 is a CMOS, single-chip, GPS front-end downconverter. This high-performance device consumes very low power (32mW, 2.4V) and does not require expensive IF SAW filters and bulky discrete IF SAW filters. The MAX2742 integrates a low noise amplifier (LNA), mixer, BPF, automatic gain control amplifier (AGC), local oscillator synthesizer, clock buffer, and internal digital sampler on-chip. The device interfaces with many commercial GPS baseband ICs for a variety of applications including: car navigation, telematics, automatic security monitoring, asset tracking, location services (LBS) and other consumer electronics. Using the MAX2742 to form a complete GPS RF solution requires only a small number of external components. The MAX2742 operates from an 18.414MHz crystal or TXCO and provides a differential or single-ended IF output (1.023MHz). The total signal conversion gain is 120dB and the noise figure is 4.5dB. The IF signal is sampled at a reference clock frequency of 18.414 MHz. New GPS technology solutions. Automotive electronics, laptops, PDAs, cell phones, digital cameras, portable DVD players, asset management. It can be seen that the GPS chip is developing with high sensitivity, low power consumption, multi-mode (compatible with galileo or other navigation systems), and A-GPS. When developing GPS products, it should focus on various IT devices integrating GPS in the future. For example, mobile phones, digital cameras, PDAs, and notebook computers, as embedded solutions, secondly, we must solve the problem of high sensitivity and low power consumption, apply the most advanced chips, and develop algorithms and hardware for weak signal acquisition and tracking. Huaian Yile excellent product technology Co., LTD , https://www.weibaoxd.com
GPS has been widely used in aerospace, aviation, navigation, transportation, measurement, exploration and many other fields. With the development of digital LSI and the positioning function requirements, GPS has begun to be more embedded in mobile handheld devices and consumer electronics. To this end, this paper will analyze and explain the new GPS technology solutions and chips and their applications. First of all, you should understand the composition and characteristics of GPS. 
6, the conclusion