Relationship between global positioning system and PMP

Global Positioning System (GPS) is a new generation of satellite navigation and positioning system, which was developed by the United States in 1970s. It took 20 years and cost 20 billion dollars. 1994 is fully built, and it has all-round real-time three-dimensional navigation and positioning capabilities by land, sea and air. After nearly 10 years of application in China's surveying and mapping departments, it shows that GPS has won the trust of the majority of surveying and mapping workers with its remarkable characteristics of all-weather, high precision, automation and high efficiency, and has been successfully applied to geodesy, engineering survey, aerial photogrammetry, vehicle navigation and control, crustal movement monitoring, engineering deformation monitoring, resource investigation, geodynamics and other disciplines, bringing a profound technological revolution to the field of surveying and mapping.

Global Positioning System (GPS) is the second generation satellite navigation system in the United States. It is developed on the basis of meridian satellite navigation system and absorbs the successful experience of meridian system. Like meridian system, GPS consists of three parts: space part, ground monitoring part and user receiver.

The space part of GPS uses 24 satellites with a height of about 20,200 kilometers to form a satellite constellation. 2 1+3 satellites all have nearly circular orbits, with an operating period of about 1 1 hour 58 minutes, distributed on six orbital planes (four satellites in each orbital plane), and the orbital inclination angle is 55 degrees. The distribution of satellites makes it possible to observe more than four satellites anywhere in the world at any time, and maintain the geometric figure (DOP) with good positioning accuracy. This provides a global navigation capability that is continuous in time.

Global positioning system has the characteristics of good performance, high precision and wide application, and it is the best navigation and positioning system so far. With the continuous improvement of the software and hardware of GPS, the application fields have been continuously explored, which have spread all over the national economy and gradually penetrated into people's daily lives.

Explore the mystery of PMP application

The PMP market has experienced three years of development and evolution since ARCHOS Company of France launched the first real PMP in 2002. PMP has developed from a single multimedia player to a multifunctional personal digital media center. In this paper, I want to know about the functional evolution of PMP, and share the application prospect of PMP with readers, in order to draw lessons from the subsequent PMP designers and manufacturers.

I. Scheme selection

Many companies choose their schemes carefully when launching PMP, which directly determines the market positioning and functional application of future products. Here I still review the mainstream PMP solutions in the market.

1, a high-end PMP solution advocated by TI, AMD and INTEL.

Most of these schemes are soft decoding, and a large number of software codecs are advocated to support new image file formats on the market. The main frequency of CPU is high, and the whole hardware interface has rich functions. It can support many high-end applications, such as GPS, HDTV, DV and PDA. The disadvantages of the scheme are obvious, such as high cost, high design threshold, strong software ability and various licenses, which are enough to make you want to stop. It is precisely because of the rich functions of this scheme that our system design becomes more and more complicated, and the software architecture becomes more and more complicated, and the cycle of making prototypes and debugging templates is also quite long. Except for a few powerful design companies and manufacturers who launched the product PMP, they were forced to give up R&D halfway. In the use of LCD, most of them use 3.5-7 inch screens, some products use windows CE operating system, and the design uses touch screen.

2. Midrange PMP solutions represented by SIGMADESIGNS and FREESCALE.

The codec of SIGMDESIGNS uses hardware. Typical EM85 1 1S supports the most popular MPEG4 4 encoding formats, such as DIVX and XVID, but does not support RM and WMV9. If you want to support these image formats, you can only hope for newer chips. Fortunately, this scheme supports hard disk and HDTV output, and Freescale's IMAX2 1 processor supports RM and other movie formats. The cost of this scheme is moderate enough to meet the design requirements of ordinary portable multimedia players. At present, many companies can provide such solutions, so the threshold is not high. Basically, the license of 1K is prepaid, and it can be imported into production. Unconsciously, it has become the most mainstream PMP scheme in the market. And this scheme, the most mainstream is the 3.5-inch and 4-inch design, and some companies use the 2.5-inch card reading scheme, which is the best in the industry and has found another way.

3. Low-end PMP scheme represented by Lingyang and Zhuoran.

Some readers may think that this scheme is not a PMP scheme, and prefer it as a high-end MP3 scheme, because it hardly supports any mainstream MPEG-4 format. Most image files must be converted by their own conversion software before the CPU can decode them. The image quality is also very general, probably because it is used for DV, and it is easier and cheaper than other schemes in supporting camera functions. Many companies and manufacturers who were not optimistic about such products at that time suffered a lot. They all build their own platforms by means of built-in Flash+SD card, and the cost is even lower than the price of well-known domestic brand MP3, so they seize a large number of customers. In order to consider the cost, most of the early 2.5-inch analog screen design was adopted, which was very low in cost and won the majority of consumers.

I'll give you a table here, and you can make a horizontal comparison intuitively:

Intel sigma Design Freescale Lingyang zoran

Operating system Linux wince

The video format divx/xvid/mpeg1/2/4h.264/wmv9divx/xvid/mpeg1/2/4h.263/wmv9divx/xvid/mpeg1/2/4wmv9divx/xv is supported.

Support the camera. Yes, yes, yes, yes, yes.

Support card reading all all All All All All SD SD

Strong support Yes Yes No No No No.

Mainstream LCD 3.5~7 Touch Screen 3.5~7 Touch Screen 3.5~7 Touch Screen 3.5~4 2.5~4 2.5 2.5

The cost is high, about 220 dollars high, about 2 10 dollars high, about 230 dollars, about 190 dollars low, about 120 dollars low, about 60 dollars low, about 70 dollars.

Second, the exploration of application

In addition to watching movies, playing music, browsing pictures, reading words, listening to FM and other basic functions, in recent years, many PMPs have added functions such as digital companion, video recorder, GPS, DVB-T, PDA and network. Now let's introduce these functions one by one.

1. Digital Companion

Digital companion is basically realized by OTG function. With the help of a large-capacity hard disk, digital photos and short films can be easily backed up. In 2003 and 2004, the digital companion market on the market was very good and sold very well. At first, it was a flash card digital camera companion, and later it evolved into the form of OTG. Ali is one of the most compatible chips. M5637 can support mass storage devices, such as ordinary flash drives, mobile hard disks, MP3 players, digital cameras and digital video cameras. In particular, it supports the PTP format protocol adopted by Canon and Sony, the mainstream digital cameras. At present, the speed of storage and backup is about 1.5MB/S, and a 256MB card can be backed up in less than 3 minutes. Because it is an OTG chip, it can also be used as a USB 2.0 device to exchange files with computers. The overall cost increases by about $3, which is acceptable to most manufacturers. The only regret is that you can't choose a single file backup, and you can't complete the analysis of usb devices. At present, most products can only be completely copied. I think IC manufacturers can do this when integrating with PMP solutions. In this case, many usb applications will be more, such as TV tuner connected to usb and so on. At this time, we can choose OTG products from Philips, Oxford and Cypress.

2. Imaging record

Unfortunately, MP4, a large-capacity hard disk, does not use the video recording function. Video recording functions range from home MPEG-2 CD-ROM video recorder to MPEG-2 hard disk video recorder, and then to MPEG-4 hard disk video recorder. Video recording quality and storage capacity are optimized to the greatest extent. For software codec, such as TI, this function is easy to realize, but for MPEG-4 encoder, more optimization is needed. You can consider buying mature encoders designed by other companies and then transplanting them to DSP. Hardware codecs, such as sigmadesigns, generally need to add an MPEG-4 encoder, such as GO7007SB of WIS, but often the cost of such a system will increase by $20. At this time, a large number of consumers may not have to pay the bill.

3. Personal digital assistant

PDA is similar to digital companion. This product has been hard to find in the market and has been replaced by other products. The solutions of Intel and AMD support WINCE platform, and the old embedded microprocessors such as PXA27X and AU 1200 are experienced in supporting windows platform. With the player based on WINCE platform, consumers can operate their own PMP like using windows, cooperate with touch screen operation and handwriting function, open word and excel to handle daily files and business notes, and use their own powerpoint software to output training introduction documents to the projector through ordinary AV signals, thus becoming a portable computer, and business applications are incisive. Of course, using WINCE platform, according to different authorization modes, you need to pay different authorization fees.

4. Digital camera

And the lower-end Sunplus solution, they can support 2 million and 3 million cmos cameras, clearly capture the interesting things in life and do whatever they want. At present, the mainstream manufacturers of CMOS sensors are ominivision, micron and pixelplus, and the prices continue to fall, so adding this function is very popular among consumers. Compared with the camera function of mobile phones, the usage rate is much higher, because most mobile phones with 300,000 1.3 million cameras do not support card expansion, and the memory is generally only 1m ~ 2m, which cannot meet the long-term shooting needs, so the camera function of mobile phones has long been a decoration and slogan. MP4 has built-in large-capacity FLASH and supports 1GB SD card, which undoubtedly makes this function popular, while the cost and technical difficulty of other solutions to do this function will increase a lot.

5. Global Positioning System (GPS)

When GPS was added to PMP, I think many automobile equipment manufacturers, especially automobile DVD manufacturers, have been snooping for a long time. As a high-end application, it is mainly made on AMD and INTEL platforms based on WINCE. Touch screen has basically become a standard configuration, but it is generally more than 4 inches, so the cost of the whole system is very high. More and more design companies introduce GPS into PMP. At present, many GPS receiver manufacturers are trying to reduce power consumption. The itrx 100 introduced by Fastrax, Finland, consumes only 120mW and its volume is only 16.2 x 18.8 x 3(mm), which greatly saves the poor battery playing time of PMP.