An infrared single target tracking and burglar alarm system design (1)

0 introduction

As the era of continuous improvement, people on their environment place high demands, particularly in terms of safety in the home, had always kept the uninvited guests.

Many communities have intelligent alarm system that greatly improves the safety of the community, effectively ensure the residents of personal and property safety. Because infrared is not visible, has a strong anonymity and confidentiality, security, surveillance and other security equipment has been widely used.

Domestic currently use various anti-theft, security alarm Basic are based on ultrasound, active infrared emitting/receiving and microwave technology.

The current widely based on infrared target tracking and anti-theft system mainly has two categories: active infrared tracking system and passive infrared tracking alarm system. The former is mainly used for video conferencing, Office personnel tracking or hospital patient tracking, active infrared tracking system its advantage is that targeted, false alarm rate is low, but has not yet been applied to the security area. The latter is mainly applied to certain civil or commercial alarm system, due to the person of a certain wavelength, infrared radiation, infrared detector detects infrared chopper arising from changes in the signal to trigger the alarm circuit, its sensitivity is high, suitable for detection of moving targets. Use it to make the alarm and the current market sales of many security alarm equipment, has the following characteristics: no need to use infrared or magnetic waves and other emission sources; high sensitivity, wide control range; good for hiding, mobile installation.

For some large warehouse or confidentiality higher places, usually want staff to enter its behavior tracking without warning; and on non-system internal staff in a burglar alarm at the same time, and keep track of the video.

The demand for this application, this article presents a new and active and passive infrared alarm in one target tracking and alerting system design, gives a schematic diagram, on the basis of this analysis system workflow. Particular system of passive infrared tracking alarm function is for some incidents subsequent investigation provides reliable evidence.

1 system structure

System as shown in Figure 1.

Which IR receiver IR2638, STC89C53RC microprocessor, motor control circuits A3977, cameras, infrared active tracking module; Pyroelectric infrared sensor KP506B, microprocessor STC89C53RC, motor control circuits A3977, camera, alarm, passive tracking alarm module.

Proactive tracking module is used to track into the detection range of portable infrared transmitter of a known target module infrared receiver that receives from a known target specific frequency infrared signals, and the infrared signal conversion to electrical signals output to the microprocessor, MPU on signal conditioning, and according to the field of positioning algorithm get target location, and then through the motor to turn the head to achieve the goal of tracking camera on, finish proactively track the target function.

Passive tracking alarm module is used to track into the system does not carry the infrared transmitter of unknown destination, module Pyroelectric sensor infrared is used to detect human radiation infrared signals and convert them into electrical signal output to the microprocessor, MPU and then get the signal and the target location after output alarm signal alarm; at the same time output tracking signal through the motor head towards the camera on the target trace, complete passive tracking goals and alarm functions.

2 system modular

2.1 active tracking module

This module is mainly done on target identification and tracking of the initiative.

Mainly includes infrared sensor accept circuit, infrared vision neural conditioning circuit and the camera servo circuit. Modules as shown in Figure 2.

(1) target: this refers to the ability to emit infrared receiver receiving specific frequency section of infrared signals of the IR emitter.

(2) infrared receiver: components adopts major integrated infrared sensor (IR2638).

Infrared remote control signal is a series of intensity modulation of binary pulses, in order to make it in the wireless transfer process from other infrared signal interference, are usually first modulation carrier frequency in specific, and then by infrared emission diode launch out. Therefore requires infrared receivers to filter out other carrier, only to receive the signal of that particular frequency and restore it to binary pulse code, demodulation. Integrated infrared sensor-infrared electric diode, amplifier low noise level, and limiter, filter bandpass, modem and shaping driver circuits, integrated, small size, high sensitivity.

(3) infrared vision neural conditioning circuit: infrared integration of sensors and frequency channel.

Integration of the sensor signal to accept to be a time frequency, output frequency modulated signal that, due to the integration of the sensor itself determines the output frequency response characteristics of low-frequency modulation is the interval in the form of pulse train, so you need to again demodulation. The objective characteristics of the signals sent one secondary frequency circuit, through the level circuit output level to determine whether the input signal is the established objectives of signature. Here LM567 selection frequency channel of the main components, because of its good noise reduction capabilities and center frequency stability and is widely used in various communication devices to decode and AM, FM signal demodulation circuit.

(4) servo circuit: mainly include microprocessors and secondary circuit, motor driver circuit for complete rotation of the camera to keep track of goals.

Microprocessor based sensor circuit and signal conditioning channel logic output to determine target relative to the center axis of the lens, and the issue of control signal to drive the motor to hosted video cameraAdjust the infrared plaque to receive screen Center to target tracking and always lock the field Center. Here, SCM STC89C53RC chosen as its central microprocessor, the system adopts the most A3977 stepping motor driver circuit, A3977 is a specialized for bipolar stepper motor micro stepping motor IC driven, its internal integrated stepper and direct decoding interfaces, reverse control circuit, dual h-bridge driver, current output 2.5 A, maximum output power can be nearly 90 W. A3977 motor driver circuit shown in Figure 3.

2.2 passive infrared detection alarm module

This module is mainly done on non-portable infrared transmitter General fever objects target detection and tracking, including Pyroelectric infrared sensor circuits, signal conditioning circuits, alarm circuit and the camera servo circuit.

Circuit shown in Figure 4.

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