Personal digital assistant

Product introduction

PDAs are generally not equipped with a keyboard, and use handwriting input or voice input. The operating systems used by PDAs mainly include PalmOS, WindowsCE and EPOC. The origin of PDA can be traced back to the NewtonMessagePad launched by Apple in 1993. Soon after that, some manufacturers launched similar products.

PDA can be divided into four categories: electronic dictionary, palmtop computer, handheld computer equipment and personal communication assistant. Due to the development of technology and market, the latter two have gradually merged together.

Classified by use, it is divided into industrial grade PDA and consumer PDA. Industrial-grade PDAs are mainly used in the industrial field. Common barcode scanners, RFID readers, POS machines, etc. can all be called PDAs; consumer PDAs include more, smart phones, tablet computers, handheld game consoles, etc. PDA allows users to send and receive data wirelessly. As many application software are now available, PDA is not only a mobile electronic secretary, but also a stock advisor and a gateway to the global information banking and communication electronic highway. Although PDA is usually regarded as a palmtop computer, PDA is not a computer in the true sense of the term. A more realistic explanation is that consumers may be looking for desktop computing power in palmtops or PDAs. At the same time, PDA is also used as a portable mobile personal information device that can provide two-way information exchange.

Product branch

1. Pen-type handheld computer

Pen-type handheld computer is The most classic type of PDA. PDA is a brand-new information device with completely different user objects from microcomputers. This idea has been intensively embodied in pen-type handheld computers. The main feature of the pen-type handheld computer is to emphasize the application of the pen. Therefore, it generally does not have a keyboard, and the pen is its only input method. In order to support pen input, pen-type handheld computers are equipped with handwriting recognition software with good performance. Typical pen-type handheld computers include Apple’s NewtonMessagePad, NewtonMessagePad100, NewtonMes-sagePad110, NewtonMessagePad120, NewtonMessagePad2000, and Tandy and Casio’s Zoomer (Tandy’s called ZPDA, and Casio’s called Z-7000). NewtonMessagePad2000 is the latest PDA from Apple. It has strong Internet functions and has built-in word processing and spreadsheet software.

It is worth mentioning that Apple has adopted a completely open strategy for Newton's structure, encouraging other manufacturers to make Newton compatible products. At present, many manufacturers have obtained licenses to produce products based on the Newton structure. These companies include: CirusLogic, Matsushita, Siemens, Motorola, Sharp, Toshiba, American Telecom, Holland Telecom, etc. Because these companies introduced technology from Apple, their products are basically the same as Apple's Newton, such as Sharp's ExpertPadPI-7000. Except for adding a protective plate to the display surface, other main features are exactly the same as NewtonMessagePad.

2. Palmtop PCs

The developers of handheld PCs (Hand-HeldPC or PalmtopsPC) are mostly manufacturers that traditionally produce large, small or micro computer systems. To a certain extent, the handheld PC is a miniature product of the portable computer, and its characteristic is to pay attention to the compatibility of the PDA and the microcomputer. Many of the characteristics of PCs can be found in handheld PCs. For example, handheld PCs mostly use DOS as the operating system and the keyboard as the main input method. Typical handheld PCs include HP's 100LX and 200LX, IBM's ThinkPad710, Fujitsu's 325Point, and Acer's AcerPad100. Among them, HP100LX and 200LX are the most representative. Its operating system is DOS5.0, CPU is 80C186, and the display is compatible with CGA. It is equipped with a batch of application software such as MailMobile, LapLinkRemote, Lotus1-2-3 and PocketQuicken. The user can quickly grasp its use method. A variety of new types of handheld PCs appeared at the Comdex’96 autumn exhibition held in Las Vegas last year. These handheld PCs all use WindowsCE (Consultor Electronics) newly developed by Microsoft as the operating system. WindowsCE is a pocket version of Windows, on which applications such as Word and Excel can be run.

3. Personal Communications Machines

The developers of personal communications machines (PersonalCom-municators) are mostly manufacturers that traditionally produce communications products. The main feature of the personal communicator is to focus on the communication capabilities of the PDA. All PDAs that can be called personal communicators are equipped with modems and powerful communication software, which can send or receive E-mail and Fax via wired and wireless networks. Personal communication devices do not have very high requirements for input methods, and a considerable number of personal communication devices do not have the ability to recognize handwritten characters. In addition, because the personal communication machine introduces a large number of communication components, its price is generally higher. Typical personal communication devices include AT&T's EO440 and EO880, Motorola's Envoy and Marco, Sony's MagicLink, and BellsouthMobility's Simon. EO440 and EO880 were launched in March 1993 and were one of the first PDAs to come out.

4. Organizer

The developers of Organizer are mostly manufacturers of traditional home appliances. Its development actually precedes PDA. After the appearance of PDA, some of the newly introduced high-end organizers have similar functions to PDAs, so they are also included in the category of PDAs. However, there are several significant differences between the organizer and other types of PDAs: First, the function is weak. Generally speaking, the organizer does not have an operating system and can only run some fixed application software, such as plan management, scheduling, etc. It also does not have the communication function; second, the price is low, usually the price of the organizer is only about 70% of other types of PDA; third, because of its simple function, the battery life of the organizer is longer, generally up to 70 hours; 4. It is the sales of the organization machine that has formed a certain scale and has a certain user group. Typical organizers are PDA600PenPad from Amstrad, WizardOZ-9600 from Sharp and Boss from Casio. Due to the diversification of PDA systems, the categories given above are only relative. There are some PDAs that are difficult to be classified into. For example, the operating system of Fujitsu’s PoqetPdaPlus is DOS. It seems that it should be called a handheld PC, but it uses a pen as the only input method, so it is very useful. Features of pen-style handheld computers.

Product category

PDA should actually be subdivided into four categories: electronic dictionaries, handheld computers, handheld computer devices, and personal communication assistants. Due to the development of technology and market, the latter two have gradually merged together.

1. Electronic dictionary

pda(3 sheets)

Among all PDA products, this is the simplest one. Its main function is to provide functions such as Chinese and English translation, phone number storage, English word reading, etc. Its characteristic is that all its programs are solidified in the memory, so the storage capacity is limited, the function is relatively single and does not have expansion sex. But these products also have their incomparable advantages. For example, they are more targeted and provide the required functions, such as games, calculations, and notes. In addition, it also has the characteristics of small size and simple operation. Representatives of such electronic dictionaries include Kuaiyitong, celebrities, Wenquxing, etc. Of course, some new electronic dictionaries now also provide communication functions. Through the additional connection kit, you can exchange data with computers and similar products. There are also some electronic notebooks on the market, which focus on notes and daily business management. These products often have a relatively large storage capacity, but their essence is still the same as an electronic dictionary, and their programs are solidified on the memory chip, and they also do not have the ability to expand. The typical representative of this type of product is the familiar business communication.

2. Pocket PC

Usually, the digital world will only call this type of handheld computer a PDA, which also represents The true meaning of PDA. Because it has almost all the functions of a general home computer. The biggest feature of handheld computers is that they have their own operating system, which is generally solidified in ROM. Most of the storage devices used are relatively expensive IC flash memory, and the capacity is generally about 16MB. Palm computers generally do not have a keyboard, and use handwriting and soft keyboard input methods. At the same time, they are equipped with a standard serial port, infrared access method and built-in MODEM to facilitate personal computer connection and Internet access. The biggest difference between the handheld computer and the previous products is the scalability of its applications. Based on their respective operating systems, anyone can use programming languages to develop corresponding applications. You can also install and uninstall arbitrarily on your handheld computer. Because its functions are very complete, it is also more complicated in operation, which is not suitable for junior users who don't know much about computers.

In the handheld computer part, it will be divided into Palm and PocketPC according to the different operating systems. Palm adopts PalmOS system, developed by Palm Company; while PocketPC adopts WinCE series system, developed by Microsoft. Because of the differences in body performance and systems, these two bodies are quite different.

3. Handheld computer equipment

The English name of the handheld computer equipment is HPC, which means HandheldPC. This is a product that lies between a notebook computer and a palmtop computer. why would you said this? Because it has a general operating system for handheld computers, but it is equipped with a small keyboard. And its appearance is similar to a traditional notebook computer. Its function is stronger than that of a handheld computer, but the same volume and weight have to be increased, so it is inferior to the handheld computer in terms of portability.

4. Personal communication assistant machine

Personal communication assistant machine is the most fashionable one among so many kinds of products. Its concept is to combine some of the functions of handheld computers with mobile phones and pagers. The biggest feature of this product is that it abandons the general telephone line and adopts the wireless data receiving method, which makes the product more adaptable. Although if it is singular, the early products are designed based on mobile phones, and their business functions are significantly inferior to ordinary handheld computers, and are only equivalent to the functions of ordinary electronic notebooks. They are currently developed based on the WinCE system and Palm. The products, collectively referred to as SmartPhone, have functions equal to or higher than that of handheld computers, and also have communication functions and wireless data exchange, which represent the future development direction of handheld computers.

5. Special test equipment

EMENU35 universal handheld terminal has a complete power management system, and it is also a solution with abundant peripherals. It perfectly integrates the software and hardware systems, and it can still provide low standby current when supporting heavy load equipment such as CDMA20001x (3G module)/CDMA, GPS, and network ports, which greatly extends the use time and standby time of the equipment. At present, it is widely used in telecommunications testing, transportation, logistics and special testing fields.

Product features:

1. Use low-power ARM microprocessor, main frequency 400MHz, bus frequency 133MHz;

2. Use WINCE5.0 operation The system provides a customized version of the perfect handheld device;

3. High-quality power management: to ensure that the product works more stably and lastingly;

4. Use 3.5-inch 320×240 true color LCD As a display device, the screen has a touch screen and supports handwriting input;

5. Provide 1 power button (press for 5 seconds to turn on/off, press for 2 seconds to sleep/wake up), 7 function buttons;< /p>

6. Built-in CDMA module, support phone dialing and answering, support one-key dial-up Internet access, SMS reception;

7. Built-in GPS module, support various electronic maps, fast hot start Navigation and positioning;

8. Provide a 10/100M adaptive RJ45 network port, and use dynamic loading drive to ensure its low-power power management;

9. Provide master-slave USB interface; support synchronization with PC through Microsoft ActiveSync, which is convenient for file transfer, application update, etc.;

10. Provide TF card socket, support 2GB TF memory card;

11. The customized system supports .NETCompactFramework2.0/3.5, IE6.0/UCWEB browser, WordPad, PPPoe, etc., handwriting input method, provides SDK, which is convenient for users to carry out secondary development.

Basic classification

Industrial PDA

Including barcode scanners, RFID readers, etc. Industrial-grade PDA is characterized by its sturdiness and durability. It can be used in many harsh environments. At the same time, it has been optimized for industrial use characteristics. The catchwell CW30 industrial-grade PDA can support RFID reading and writing and barcode scanning functions at the same time, and it also has the IP54 industrial grade, which is not available in consumer handheld terminals.

Barcode Scanner

Also known as barcode reader, barcode scanner, barcode scanner, barcode scanner and barcode reader. It is a reading device used to read the information contained in the bar code [1]. It uses optical principles to decode the content of the bar code and transmit it to a computer or other device through a data cable or wirelessly. It is widely used in supermarkets, logistics express, libraries, etc. to scan barcodes of commodities and documents.

Scanner (2 photos)

Barcode scanner is usually called barcode scanner/reader, which is used to read the information contained in barcode Equipment, can be divided into oneOne-dimensional, two-dimensional barcode scanner. The structure of a barcode scanner usually consists of the following parts: light source, receiving device, photoelectric conversion component, decoding circuit, and computer interface. The basic working principle of the scanning gun is: the light emitted by the light source irradiates the bar code symbol through the optical system, and the reflected light is imaged on the photoelectric converter through the optical system, and is interpreted as a digital signal that the computer can directly accept by the decoder. . In addition to the classification of one and two-dimensional barcode scanners, it can also be classified into: CCD, full-angle laser and laser handheld barcode scanners.

Radio frequency identification

Radio frequency identification is RFID (RadioFrequencyIDentification) technology, also known as electronic tags, radio frequency identification. It is a communication technology that can identify specific targets and read and write related data through radio signals. There is no need to establish mechanical or optical contact between the recognition system and a specific target. Commonly used are low frequency (125k~134.2K), high frequency (13.56Mhz), ultra high frequency, passive and other technologies. RFID readers are also divided into mobile and fixed. RFID technology is widely used, such as: libraries, access control systems, food safety traceability, etc.

UHF PDA

UHF PDA is used to read RFID tags, which has great advantages in reading UHF tags. UHF electronic tags have great advantages in reading and writing distance.

UHF radio frequency tags are referred to as microwave radio frequency tags. UHF and microwave frequency RFID generally adopt the principle of electromagnetic emission. Working frequency:

Ultra high frequency (902MHz～928MHz)

: EPCC1G2 (ISO18000-6C)

Available data area: 240-bit EPC code

Tag identifier: (TID)

64-bit working mode: readable Write

Consumer PDA

Consumer handheld terminals mainly refer to smart phones, handheld computers, tablet computers, etc.

Software and hardware technology

The six features mentioned in the previous introduction of PDA are mainly the results obtained by observing the PDA from the user's point of view, and the structure and composition of its software and hardware systems can better reflect the nature of the PDA. The software and hardware technical fields most closely related to PDA and the most important for PDA are: operating system, CPU chip, communication, application software development environment and programming language, pen input, PC card, FlashRAM, battery and LCD.

Operating system

There are two types of operating systems used by PDAs: the first type is the operating system of the desktop PC or compatible with it; the second type is for the PDA Operating system written by features. The former includes DOS, WinPDA and WindowsCE. Among them, WinPDA is a PDA variant of MSWindows. Microsoft has terminated the development of WinPDA in 1994. The latter include Apple’s NewtonIntelligence, Geowork’s GEOS, GeneralMagic’s MagicCap and Co’s PenPoint.

Personal digital assistant

The use of an operating system compatible with PC reflects the idea that PDA is a companion of PC. The advantage of this approach is that it is compatible with desktop PCs to a certain extent, and enables users who are familiar with PCs to quickly master the use of PDAs. However, because PDA and PC are very different in many aspects, the same operating system alone does not make the software on the PC run directly on the PDA. Therefore, it is not necessarily a good idea to use the PC operating system on the PDA. Microsoft's unsuccessful attempts to implement WinPDA on PDAs illustrate this problem to a certain extent. The operating system specially developed for PDA has two notable features:

(1) The file system usually adopts an object-oriented organizational structure. NewtonIntelligence's file system is a typical example. Like OLE and OpenDoc, it changes the structure of the file system from operation-centric to data-centric. The data managed by the NewtonIntelligence system is stored in a frame (Frame), and each frame is composed of multiple slots (Slots). The content contained in each slot can be data, commands to manipulate data, or other structures.

(2) Compared with other kinds of operating systems, the degree of modularity is higher. A typical example is GEOS. It separates the basic core from the user interface and supports two interfaces. One is a general interface, which is shared by all GEOS applications; the other is a dedicated interface, which is set by the developer. The separation and transmission of information between these two interfaces is implemented by an intermediate abstraction layer.

CPU chip

The CPU chip of PDA can be divided into three generations. The first-generation chips were used in the earliest PDAs. They include ARM610 from ARM and Hobbit92010 from AT&T. ARM610 is used in Apple's "NewtonMessagePad". Hobbit92010 is used in EO EO440 and EO880. Both of them are 32-bit chips with RISC structure. The second-generation chips include Hitachi’s SH700 series, NEC’s V800 series, Intel’s and VLSI’s Polar series, Motorola’s 68349 and AMD’s AM386SC. Hobbit92020 launched by AT&T after Hobbit92010 and ARM710 from ARM also belong to this generation. SH700, V800 and Polar are 32-bit RISC chips, 68349 and AM386SC are CISC chips. The chips introduced after 1995 are the third-generation chips. This generation of chips mainly includes PowerPC602 and PowerPC603e from IBM and Motorola, and StrongARM from DEC and ARM. They all use RISC structure.

No matter which generation the CPU chip of PDA belongs to, it is obviously different from the CPU chip of microcomputer. Its features include:

Low price: The price is generally between 25 and 50 dollars, unlike the Pentium chip that requires hundreds of dollars. For example, despite the high level of integration of AM386SC, its price is only $50 (quotation in 1994).

Small size: The diearea size is generally 50-100 square millimeters. For example, the chip size of ARM610 is 71 square millimeters, Hobbit 92010 is 92 square millimeters, and 68349 is 100 square millimeters. The Pentium's chip size is 294 square millimeters.

The working voltage is low: the working voltage is mostly 3.3 volts. There are a few chips whose working voltage is lower, such as V810 which is 2.7 volts.

Low power consumption: It is mostly made of CMOS and other low-power materials, so the power consumption is very low. For example, the power consumption of the V810 is 100 milliwatts, and the power consumption of 68349 is 300 milliwatts. The Pentium consumes nearly 20 watts of power. In addition, the CPU chip of the PDA generally has a power management unit, which can adjust the use of electrical energy according to work needs. For example, the power of the monitor and some external devices can be turned off at a certain time.

High integration: the chip generally contains a variety of functional components. Some CPU chips even only need to add ROM and RAM to form a complete PDA system. For example, the content integrated on the Polar chip includes CPU, graphics processing components, power management components, storage control components, and LCD interfaces.

EIP (ExecuteInPlace) function: When the clock is stopped and restarted, the original state will not be lost, and the code in ROM can be run directly without being loaded into RAM.

Communication

Currently, PDA's support for communication functions is limited to sending E-mail and Fax through wireless communication networks. Due to the transmission speed of wireless communication networks and software functions, it is necessary to The goal of the next step is to directly access the data files in the remote host. The factors affecting the communication function of PDA mainly come from three aspects: wireless communication network, communication components and communication software. In the United States, there are currently 4 different wireless communication networks available, namely:

cellular phone network.

The CDPD (CellularDigitalPacketData) network is developed by companies such as AT&T, Motorola, BellAllanticMobileSystem, Ngnex, GTE, SouthwesternBell, McCawCellular and Sprint.
RAM network is developed by companies such as BellsouthMobileSystem and RAMBroadcasling.
Ardis network was developed by Motorola and IBM.

In addition, PCS (Personal Communication System) has developed rapidly recently, and it may replace the existing cellular telephone network in the future. There is fierce competition regarding PCS standards, and Japan, the United States, and Europe have their own plans. Japan hopes to adopt their PHS (Personal HandyPhones) as the standard; Europe pushes DECT (DigitalEuropean Cordless Telephone); the United States hopes to adopt WACS (Wireless Access Communication System) as the standard.

PC card/slot has brought good news to communication components. All communication components, such as a modem card, can be made into a PC card. The user only needs to insert such a PC card into the PDA to connect to the communication network. However, PDA puts forward higher technical requirements for modem cards, and most of the original modem cards are not suitable for working in a mobile environment. When transmitting voice, a slight interruption is not a big problem, and when transmitting E-mail, Fax or data files, even an extremely short transmission interruption cannot be tolerated.

Compared with communication hardware, the development level of communication software lags behind. Currently, software developers have to develop different application software for different modems. In order to improve the efficiency of communication software development, existing companies have introduced some communication-oriented operating systems and programming languages for the development of communication software. The representative of the former is GeneralMagic's MagicCap, and the representative of the latter is the company's Telescript language.

Application software development environment and programming language

Maybe because PDA application software is generally completed by its manufacturer and a third party, the current publicly launched PDA application software development Environment and programming language are less. The MagicCap operating system and Telescript language mentioned above are one of them. Another typical example is the NTK (NewtonToolKit) environment and NewtonScript language developed by Apple for NewtonMessagePad. The NTK environment is composed of two parts, one part runs on the Mac microcomputer, the other part runs on the NewtonMessagePad, and the two parts are connected through a serial port. NTK is a graphical environment, it provides buttons, menus and other visual components (View), application developers can use these visual components and direct manipulation methods to generate NewtonMessagePad applications.

Pen input

Pen and mouse are different input technologies. The mouse is a pointer pointing device, which always corresponds to the position pointed by the cursor on the display screen, while the pen does not correspond to a certain position on the screen. The content input by the user through the pen can be divided into two types: handwriting and Gesture. The handwriting corresponds to a character string or an image, the character string is usually recognized as the corresponding ASCⅡ code, and the mark represents the command issued by the user. For example, drawing √ on an object means it is selected, and drawing × means deleting the object. In order to avoid the trouble of recognizing handwritten characters, some PDAs introduced a new data type DataInk. In many cases, the handwriting input by the user can be stored as DataInk type data, and it is not necessary to convert them into text characters. In the DataInk type variable, in addition to the bitmap information of the handwriting, some additional information such as the writing time, the pressure of the pen on the screen when writing, and the angle of the pen are also stored. In order to promote the development of pen input technology, relevant people have proposed an industry standard Jot specifically used to describe handwriting.

PC card

PC card is also called PCMCIA card. PCMCIA is a standard established by the Personal Computer Memory Card International Association (Personal Computer Memory Card International Association). It specifies the connection method between the PC card and the PC card slot. In addition to supporting RAM cards and ROM cards, the PCMCIA standard also supports modem cards, network cards and I/O interface cards. According to the regulations of the International Standards Association for Personal Computer Memory Cards, there are three different types of PC cards. The length of these three PC cards is 85.6mm, the width is 54mm, and there are 68 jacks. The difference between the three is their thickness and the size of the corresponding slot. The thickness of type 1 PC card is 3.3mm, RAM card and ROM card are usually type 1 card; type 2 is 5.5mm, modem card and I/O interface card are usually type 2 card; type 3 is 10.5mm, some special PC cards are usually type 3 cards. PC card slots are also divided into three types. Type 1 PC card slot supports Type 1 PC card; Type 2 PC card slot supports Type 1 and Type 2 PC cards; Type 3 PC card slot supports Type 1, Type 2, and Type 3 PC cards.

FlashRAM

FlashRAM is one of the most promising mass storage devices widely used on PDAs. it One-dimensional, two-dimensional barcode scanner. The structure of a barcode scanner usually consists of the following parts: light source, receiving device, photoelectric conversion component, decoding circuit, and computer interface. The basic working principle of the scanning gun is: the light emitted by the light source irradiates the bar code symbol through the optical system, and the reflected light is imaged on the photoelectric converter through the optical system, and is interpreted as a digital signal that the computer can directly accept by the decoder. . In addition to the classification of one and two-dimensional barcode scanners, it can also be classified into: CCD, full-angle laser and laser handheld barcode scanners.

Radio frequency identification

UHF PDA

UHF PDA is used to read RFID tags, which has great advantages in reading UHF tags. UHF electronic tags have great advantages in reading and writing distance.

UHF radio frequency tags are referred to as microwave radio frequency tags. UHF and microwave frequency RFID generally adopt the principle of electromagnetic emission. Working frequency:

Ultra high frequency (902MHz～928MHz)

: EPCC1G2 (ISO18000-6C)

Available data area: 240-bit EPC code

Tag identifier: (TID)

64-bit working mode: readable Write

Consumer PDA

Consumer handheld terminals mainly refer to smart phones, handheld computers, tablet computers, etc.

Software and hardware technology

Operating system

CPU chip

No matter which generation the CPU chip of PDA belongs to, it is obviously different from the CPU chip of microcomputer. Its features include:

The working voltage is low: the working voltage is mostly 3.3 volts. There are a few chips whose working voltage is lower, such as V810 which is 2.7 volts.

EIP (ExecuteInPlace) function: When the clock is stopped and restarted, the original state will not be lost, and the code in ROM can be run directly without being loaded into RAM.

Communication

cellular phone network.

The CDPD (CellularDigitalPacketData) network is developed by companies such as AT&T, Motorola, BellAllanticMobileSystem, Ngnex, GTE, SouthwesternBell, McCawCellular and Sprint.
RAM network is developed by companies such as BellsouthMobileSystem and RAMBroadcasling.
Ardis network was developed by Motorola and IBM.

Application software development environment and programming language

Pen input

PC card

FlashRAM

FlashRAM is one of the most promising mass storage devices widely used on PDAs. it, There are also certain requirements for the location of the equipment, the transmission line is difficult to organize, inconvenient to carry, and unsightly. Through the wireless network constructed by Bluetooth, the connection between PDA and computer can be made more convenient, or for Web browsing, or downloading software, so that users can conveniently and timely exchange data and information no matter when and where.

Multiple functions

PDA is moving towards the trend of multi-functional integration of computing, communication, network, storage, entertainment, e-commerce, and professional applications. In particular, PDA mobile phones with a combination of PDA and mobile phone functions are favored by more and more high-end users, and are gradually becoming a new trend and mainstream force in the international mobile terminal market, and are gradually moving towards socialization and standardization.

China Internet of Things School-Enterprise AllianceI believe: The PDA market contains unlimited business opportunities and potential, and all major companies and company groups in the world are striving PDA is developing in the direction that it wants. In the Mainland, the mobile phone market is basically dominated by overseas Motorola, Nokia, Ericsson and other companies, while the PDA market is dominated by domestic manufacturers. Therefore, our country needs to seize the opportunity and strive for a place in this competition.