An unattended ground sensor system design (1)

1 design tasks and devices

1.1 design tasks

(1) to design the miniaturization of ground sensor systems, in a certain range to identify personnel, wheeled and tracked vehicles, and send the recognition results to the receiving display subsystem.

Detection range 200-400 m.

(2) technical parameters: rated input voltage DC 12V, 5V DC 78M05 conversion out of voltage for DSP systems, wireless transceiver modules and asynchronous serial port to use.

(3) have the system post and accurately shows the recognition result.

1.2 devices

Use TMS320VC5509A digital signal processing chip as ground sensor system's main control chip.

TMS320VC5509A is a high-performance 16-bit fixed-point digital signal processor, the resource can accomplish vibration and acoustic signal sampling and target identification function. Sensor conditioner and amplifier main device was United States TI company OPA4336. Other major components are as follows:

SDRAM(HY57V64 1 620ETP)、FLASH(Am29LV8OOD)、CPLD(EPM570T100C5N)、TL16C550C 。

2 system hardware design

Ground sensor system is mainly composed of DSP small systems, sensor conditioner and amplifier, asynchronous serial port communications circuits, wireless transceiver modules of four parts.

This system through the vibration and sound sensors gathering ground moving target signals from sensors to adjust and make amplification circuit into the DSP features analysis and recognition, recognition of the results through asynchronous serial port to a wireless transceiver module back to the command post. System hardware frameworks such as Figure 1 figure 1 hardware frame

2.1 sensor selection

2.1.1 vibration sensor.

Selection of miniature DX20 lap Magnetoelectric sensor as ground motion signal sensor.

2.1.2 sound sensor

Choose the type of sound sensor 733A01 as sound-signal sensor.

2.2 DSP small system

DSP power for small systems with DC 5V and TLV1117-3.3 and TLV1117-ADJ voltage chip provides 3.3V and 1.6V two voltages, and JTAG port hardware emulation and download program, SDRAM for dynamic storage collected data, FLASH save program, DSP run reset reloaded DSP internal RAM running, CPLD is responsible for the selection of peripheral devices.

DSP through 16 root data bus and 14 root address bus through the CPLD and SDRAM and FLASH, serial port for communication. DSP core for systems of zuo, complete data acquisition, analysis, or short-term energy analysis, dynamic time warping algorithm (DTW), etc.

2.3 sensor conditioner and amplifier

Ground motion sensor should be able to detect the movement of vehicles within 200m and 20m signal within personnel footsteps, sound sensor you can feel the noise of vehicles within 600m.

So far, the sensor detects the target signal is very weak, usually only mV-level. So small signal must first undergo pre-amplification and preprocessing in order to carry out collection and processing. In addition, because the requirements miniaturization, signal amplification processing circuit power consumption should be small. Design a low-power, low noise, high gain amplifier, is the key technology of the system. Taking into account the frequency of seismic signal is below 150 Hz, vehicle noise frequency during exercise in about, so in 250Hz amplifier to add a low-pass filter (such as diagrams C28, C38) to further environmental noise suppression.

OPA4336 provides four independent amplifier.

System amplifier circuit consists of two levels: the two symmetric phase amplifier U6A and constitutes the first level, U6C U6B for second-level differential amplifier, U6D is sound amplifier. Sensor conditioner and amplifier as shown in Figure 2.

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