基于電力線載波技術(shù)的醫(yī)療病房呼叫系統(tǒng)的設(shè)計外文翻譯

1、外文資料原文Design Of Medical Ward Call System Based On Power Line Carrier TechnologyI. INTRODUCTIONThe medical ward call system is a kind of call tools when the patient needs access to care or diagnosis, patient's req

2、uest can be quickly transmitted to doctors or nurses on duty. It is one of the necessary equipment to improve the level of hospital care. Currently, there are many medical ward call systems with different types and diffe

3、rent function on the market, they are divided into two categories: the cable-type and wireless-type[1]. Traditional cable-type medical ward call systems tend to use a centralized call system structure, power lines, data

4、communication lines, voice communication lines transmit separated, has Line with the laying of more, high cost, installation difficulties, poor real-time, high failure rate and other shortcomings.Wireless-type medical wa

5、rd call systems do not lay the line, but its reliability is poor, and radio waves can interfere with other medical instruments and equipment, most hospital do not use such wireless call system.With the development of com

6、munication technology, people have done a lot of research work for power line carrie communication technology. Power line carrier communications technology refers to a means of communication which uses power lines to

7、transfer data and media signal. It loads high-frequency contains information on current, then use current transmission,then use the adapter which receives information to separate high-frequency from the current, and tran

8、sferred to a computer or telephone in order to achieve information transmission. Electricity supply network is the most popular network in the world, low voltage power lines connect to thousands of families, it can be us

9、ed for data communication and information transmission without laying dedicated communication line and occupying the wireless channel resources[2]. Therefore, it has become possible that using low voltage power lines a

10、s the transmission medium, and using spread spectrum, digital encoding, single-chip control technology to achieve ward calls.In this study, the power line carrier communication technology has been applied to ward call sy

11、stem. The entire system requires only a two-core shielded cable, through the power cord that the host provides to each extension realize two-way data communication.With low cost, simple installation, extensive t

12、ransmission lines, etc, the hospital ward has a good application prospect in practice.II. SYSTEM STRUCTURE AND WORKING PRINCIPLEThe call system mainly consists of the host, extensions and power line carrier circuits, t

13、he host is installed on the ward nurse duty room, extensions were installed in the ward, a host can control multiple extensions，一 220V civil power lines is as a transmission channel, in order to achieve two- way communic

14、ation between the host and the extension. The structure of system is shown in Fig. 1.The system uses a centralized power supply, supplies work power to ward extension through the two-core cable by the communicating hosts

15、. The signal of the host to each extension through the power line carrier circuit, after 一 220 V commercial power line transmission, achieves the half- duplex data communication between the host and t

16、he extension. A line to both ends at D1, Clamped by D1, the starting level of the signal is at a fixed value, and to prevent excessive inrush current. C2, C3 and L2 constitute a parallel resonant circuit whose resonant f

17、requency is 120 kHz. The 120 kHz signal in the input weak signal is selected frequency and amplified in order to improve the sensitivity of the received signal. It is sent to the SIGin port of chip PL2102, the carrier si

18、gnal received by PL2102 demodulates the data bit information after being treatment in-house, the data bit information is output to the host and extension control chip by RXD TXD port, meanwhile, HEAD sync

19、 outputs low level.Signal transmitting circuit: It includes the power amplifier, the filter shaping circuit and the composite pipe complementary symmetry power amplifier circuit comprised of V1, V2, V3, and V4. It

20、 amplifies the power of the carrier modulation signal outputted by PL2102's PSK OUT port. It is added to the coupling coil after filtering integer by C1 and L1, and is fed into the power line through the coupling coi

21、l. The carrier modulation signal outputted by PL2102 is amplified through the power amplifier circuit, filter out signal noise and false signal. Capacitor C1, inductor L1 (18uH/200mA) of the integral filter circuit are u

22、sed to adjust the emission current and waveform, reducing C1 and increasing L1 will reduce the emission current and improve the waveform. Conversely, it will increase the emission current and waveform distortion. As the

23、coil load capacity is a fixed value, adjusting C1 and L1 will affect the transmission power and their power of the coil. Meanwhile, the emission voltage VHH affects size of the transmitted power, following the launch vol

24、tage drop, transmit power has declined, the higher the voltage is, the greater the transistors own power consumption is. This emission voltage is typically chosen between lOV 一18V [6].C.Design of the extension circuitThe

25、 extension includes MCU AT89C52, power line modulation chip PL2102 and some peripheral circuits. Schematic is shown in Fig. 3. Eight request button switches are connected to the port PO of the MCU AT89C52, when a butt

26、on is pressed, the input state of the port PO corresponding to this button is 0. When the MCU confirms that the host calls its address, it will scan 8-bit I /O port status of port P0, once a key is pressed, the request i

27、nformation corresponding to this button will immediately send to the host, and wait for the host to confirm. When the correct information is returned, the host drives the corresponding LED indicators display via P2 port

28、to indicate that a request signal sent successfully. Eight button switches for request are numbered, each switch represents a kind of information for request, which can be defined by users [7].P1.0 and RESET port of the

29、MCU AT89C52 connect the backup power and power-down protection circuit in order to ensure that the system can work properly when power failure occurs. If the system has detected “an imminent loss of power“ signal, the si

30、gnal through an external interrupt INTO requests interrupt to the host. The host responses to an interrupt and sends the relevant data into the RAM to store, then write “0“ into P1.0, the low level on P1.0 pin triggers 5

31、55 timer,the 555 timer output pulse depends on R, C and VCC. If the timer 555 end timer, VCC is still normal, this shows that the “imminent loss of power“ signal is the wrong alarm signal, the 555 output pulse is added t

32、o RESET and the host re-operation after reset. If the 555 timer end timing,VCC is really lower, the 555 timer outputs high level triggered by the P1.0 low level, and adds to RESET for standby power until VCC has return

33、ed to normal, then keep a positive pulse width time determined by the R, C. The appropriate R, C value Should be selected in order to have enough power on reset time after the main power supply VCC Returns to normal, the

34、n make the host resume normal operation after reliable reset. The AT89C52 clock uses on- chip clock oscillator mode, the quartz crystal (9.6MHz) and oscillation capacitor are external connected between XTAL1 and XTAL2 pi