1、附录 B：外文文献及译文 Visual Round wireless doorbell in the voice communications system design and implementation First:Introduction Microelectronics technology, wireless technology and network technology for the development of modern people living environment of security, facilitate the provision of a stron
2、g technical support， This presents a smart area for the safety of the new wireless doorbell system visualization Round, On the systems overall structure and working principle and the key technology full-duplex digital voice communications for the design and realization of， Analysis of the digital tr
3、ansmission of voice processing, a frame structure on the design and realization of the CPLD in a wireless doorbell system visualization Round-frame synchronization . Finally, the prototype system by the field test, stable performance, reliable, clear voice, has good practical value. The development
4、of electronic, wireless and networktechnologyprovides the strongtechnical support for security and convenience of modern residential quarters. In this paper, weintroduce a new style wireless visual inter-conversation doorbell system, which is used in theintelligent residential quarters. Then explain
5、s the structure of this system, andits full-duplexdigital voice communication is designed and implemented. We emphasize the digital voice processin transmission, and discuss the design of the structure of frame, and the framesynchronizationrealized in CPLD. Finally, the test result shows a stable an
6、d reliable quality, clear voice andfairly practical value. Second:Features At present domestic doorbell has been a lot of visualization products, mainstream product is wired, one-way voice and Simulation. Visual Round wireless doorbell system combines computer technology, wireless communications and
7、 digital signal processing technology used in high-frequency wireless transmitter receiver, installation without cabling, would not undermine the effectiveness decoration. Visual Round wireless doorbell system is the next generation of electronic security systems, modern gardens, Villa, Villa ideal
8、security device. Family in the living room, through the screen to see images, voice speaking, remote understanding of the situation outside, accurate judgement visit in the capacity of the reception to decide whether to open the door to protect the familys personal and property safety. The system us
9、es modular hybrid technology, digital voice, video simulation, the future is all-digital wireless doorbell system visualization talk of a transition, the systems main features are: (1)2.4 GHz, 900MHz high-frequency signal transmission. (2)In the 60 m clearly within the scope of stable transmission a
10、udio and video signals at a barrier such as distance is 30m. (3)If on the doorbell, Ding Dong Sound hints open automatically monitor screen (4)Wireless unlock, and control of the electric door lock control. (5)Indoor Wireless proactively monitor. (6)Delay shut down automatically monitoring system. (
11、7)Wireless transmission, the receiver can easily be placed, easy installation. (8)Wireless full-duplex voice communication. The system is composed of two parts: part of indoor and outdoor part. Visual Round wireless doorbell system uses full-duplex digital wireless voice programmes, indoor and outdo
12、or machines are corresponding to the four basic modules, including A / D / A modules from voice codec chip MC145481 completed, the speech signal processing module from the CPLD digital voice signals as well as a package of reconciliation package synchronization, thereby enhancing anti-jamming capabi
13、lity. wireless transmit / receive modules to deal with the digital signal modulation and demodulation, it suitable for wireless channel transmission. Third:Voice transmission processing Although voice processing digital signal transmission than analog signals have great advantages, but digital signa
14、l analog signal difficult than receiving, processing requirements more stringent than the analog signal,with the development of society, wireless communication equipment widely used, resulting in increased electromagnetic interference, and advances in technology enabling wireless receiver continuous
15、ly improve receiver sensitivity, wireless receiver in the corresponding sent equipment will not be there when the output data demodulation. Wireless communications must be according to data frame transmission of data packet, and must be adopted and reliable way to ensure the frame synchronization of
16、 data from the chaos of the data frame will be legitimate identified. Frame synchronization can be used in synchronous or synchronous code. Synchronization of the relatively high hardware requirements to achieve more difficult, it seldom use more than a code synchronization. Synchronous Code should
17、ensure that the choice of code and data re-synchronization code probability as low as possible, so as to the general application of the HS .That the need for re-design code to escape if a frame set up between the timer and overtime provisions of the transfer agreement in the data frame length, frame
18、 synchronization code can be arbitrary choice, the general choice 0xAA, 0x55, such as 0 - 1 uniform Distribution of data, and in order to improve reliability, often the choice of multi-byte frame synchronization code, such as 0xAA 0xBB (2-byte frame synchronization code). To establish stable communi
19、cation, a standard wireless data transmission frame should include at least the following parts: (1) Jumping code: in the receiving establishment phase, providing reception threshold level, its length and hardware relevant data, wireless doorbell system visualization Talkback used in the x99 is 0. (
20、2) redundant code: According to experience, usually adopts a 0xff or 0xff, 0x66 results were relatively good, and the establishment of communication to correct errors arising from the phase-out-of-step serial receiver, in the slow speed (19200 bps), the two often use L-redundant code is not adopted
21、in the design. (3)Synchronous Code: used for frame synchronization, data transfer and use of relatively low-bit-rate code word, and in order to improve reliability, and a 2-byte or 2 bytes above synchronous code words such as 0xaa 0xbb. Visual Round wireless doorbell system is used in the 0xCCCCCC.
22、(4)Data: users want to transfer data to improve the reliability of communications, the proposed Manchester encoding the data or using DPCM send, and data validation. Manchester encoding or used in the DPCM transmitted, the length of the data generally should not exceed 256 bytes； on the contrary, sh
23、ould not exceed 64 bytes. But speaking in the wireless doorbell visual system, digital voice wireless transmitter module maximum data transmission rate of 76.8 kbps, but the voice from the A / D chip from 64 kbps data there, as affected by the CPLD antenna bandwidth capacity and launch two factors c
24、onstraints, we do not have to deal with complicated coding. 0 x99 precursor for which code for the initial bit synchronization and receive state machine reset, 0xCCCCCC data frame synchronization code, frame synchronization for eight yards behind-control code. Visual Round wireless doorbell system i
25、n the control code number of small, indoor to outdoor is three, has taken the initiative to monitor the lock, removable hang up. Outdoor to indoor control signal only a call button, we will design the frame synchronization byte code for the control signal transmission in the back to keep up with the
26、 control signal in bytes of voice and data units. Software using top-down design methodology, a total of five documents: the top-level documents were, transmit modules accept modules, digital phase-locked loop and frame state machine. Top-level document for the system clock with a 2048 kHzvoice code
27、c interface chip MC145481, including sending and receiving of two functional modules L module which is sent to send data in the original data before adding header, voice communications frame 0x99 first, 0xCC, 0xCC, 0xCC, followed by the control signal byte, in bytes of voice and data units for L rec
28、eiver module is to detect and control the speech signal, the relatively complex, including digital phase-locked loop and frame status two-state, if detected 0xCC, 0 from the state into a state if a byte is 0xCC from a state into two states, or else to return to state 0； If the first three bytes or 0
29、xCC from entering the state 2 3 state into synchronous state, or to return to state 0 which DPLL is a bit synchronization. As voice signals are relatively weak in general, according to Mu/A code of law, may be even longer, 1, so that the receiver can not extract the correct information in sync, so we carried out a simple voice and data handling, even if 1 is greater than the number eight, an eighth reverse, namely, 1 to 0. As one of the quantitative data
