subject: Wireless Sensor Networks Transmission Circuit Design [print this page] 0 Introduction Wireless Sensor Network is a RGS system (remote ground sensor system), it is a use of multiple sensors as an integrated component of information gathering, data fusion, coding processing, sent to the command center to handle after reduction in the monitoring platform demonstrated by the detection system. It combines sensor technology, image detection technology, vibration detection technology, voice detection technology, wireless Communicate Technology, digital coding technology, information fusion technology and computer technology as a whole, is a combination of high integration and comprehensive technology. Wireless multi sensor network system consists of the following components:
(1) System front-end sensors and GPS modules?? Signal acquisition part: mainly by images, sound, vibration and infrared sensors to detect cell and GPS modules, responsible for monitoring battlefield information to complete the task.
(2) information transmission parts: the main responsible for the information collected for remote coding and wireless transmission.
(3) command center control platform for the parts: the main unit to complete the monitoring and remote control signal reception task, and all information collected fusion analysis. Will address the results to the command center personnel to enable them to timely and accurately grasp the battlefield situation, and make the appropriate decisions.
This article is a wireless sensor network image transmission system hardware design and software programming ideas.
1 transmitter modem hardware circuit design and working principle
Modem hardware launch, and the recipient, as required for different tasks, it is not the same. Launch party modem circuit schematic shown in Figure 1.
System uses the +5 V Power supply By the radio station Battery Transformed supply. MSM7512 B 3.579 545MHz using the special crystal, due to its internal ground Capacitance Without external compensation components; single chip using a frequency of 11.059 2MHz crystal, mainly to set the baud rate, you can get accurate baud rate, the effective work of the timer to avoid the accumulation of errors, external compensation components are the two 30pF capacitors. MCU is running in order to prevent the misuse, should microcontroller EA / VPP terminal (31 feet) set high to ensure that access to the internal microcontroller program memory. As modem Chip MSM7512B and SCM W77E58 support TTL level, so the first single chip USART TXD, RXD and MSM75125B directly connected to the XD and RD; MCU P1.0, P1.1 are connected: MSM7512B of MOD2 and MOD1, according to communication requirements of transition between the transceiver to control the modem chip, the work of the state; P1.4 controls the radio transmit / receive status of the conversion (PTT). MSM75125B the AO and AI, respectively through the interface circuit and radio transmission / Receiver Connected. External monitor as the system all by the light-emitting diode display circuit and the resistance, including one red light-emitting diode D1 to supply instructions, Leung said the system initialization process correctly; yellow light-emitting diode D2 to send the correct instructions, the system each time the data correctly send a task, it should flash once; D3 instructions for the carrier detection, if the detected light indicates the modem to the effective channel carrier signal; D4 for the data transfer instructions, the system sends the data it flashes until the data transmission is completed. If the front transmission sensor data needs to produce a falling edge pulse, external interrupt trigger SCM INTO (P3.2), microcontroller interrupt response, it will forward to the 8-bit parallel data from the P2 port (P2.0 ~ P2. 5) read as P2 port internal pull-up resistor, so as an input when the TTL or MOS circuits can be driven, rather than external pull-up resistor. W77E58 serial communication port 2 can be reserved for system expansion port backup.
