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What is the reason why the treasure detector cannot normally report to the police and false alarm?


Release time:

2022-02-03

The normal operation of the treasure detector does not mean that it can alarm normally, but it can maintain good detection sensitivity and low false alarm rate in various environments. False alarm refers to the alarm output when the detector is in use. In the general observation of the human eye, we may not see any interference source, only to see no one passing by, no object to disturb us and other macro information.

What is the reason why the treasure detector cannot normally report to the police and false alarm?

The normal operation of the treasure detector does not mean that it can alarm normally, but it can maintain good detection sensitivity and low false alarm rate in various environments. False alarm refers to the alarm output when the detector is in use. In the general observation of the human eye, we may not see any interference source, only to see no one passing by, no object to disturb us and other macro information. In fact, the cause of false alarm of treasure detector is often non macro information, that is to say, it is often interference information that can not be observed by human eyes, such as radio frequency interference, sound from various sound sources, etc. It will interfere with the ultrasonic detector and cause false alarms; various heat sources, even sunlight, will cause large temperature changes in a seemingly calm environment, causing false alarms from the thermal detector. In this way, it is understood that the false alarm does not occur out of thin air, but there is a certain external stimulus. External interference causes the data of the internal circuit of the treasure detector to change, and when the defined value of the alarm is reached, a false alarm will occur.

Most of the traditional treasure detectors use analog circuits, and the sensor part of the detector receives the detection signal is often very weak, so it needs a large multiple of the amplification circuit, often need frequency discrimination circuit, comparison circuit and so on. These analog circuits tend to drift when the ambient temperature and humidity change, thereby changing the amplification factor. The signal-to-noise ratio of the weak signal to be amplified is limited, and various background noise signals will be superimposed on the useful detection signal. Improper amplification of background noise caused by drift can lead to false positives. In addition, the analysis method of the treasure detector signal will also affect the detection results; simple amplification of the analog circuit analysis signal, simple frequency comparison and other methods will make the analysis results uncertain, thus misjudged as false alarm.

Underreporting may also be due to technical limitations. In the manufacturing process of components, the whole treasure detector and PCB board welding assembly process will appear poor contact, flux corrosion and other reasons. After using for a period of time, tiny sparks will be generated, noise will increase, and redundant signals will appear when the circuit is introduced, resulting in frequent false alarms. The transmission rate and detection range of the conveyor belt in the industrial production line will also affect the sensitivity of the detector, which requires the operator to limit the transmission rate of the conveyor belt within a range, and the distance between the metal detector and the detected metal object should also be appropriately selected.

The accuracy and reliability of the handheld treasure detector depends on the stability of the electromagnetic emission frequency, and the working frequency of 80~800 kHz is generally used. The lower the operating frequency, the better the iron detection performance. The higher the working frequency, the better the detection performance of high carbon steel. The sensitivity of the detector decreases with the increase of the detection range, and the magnitude of the induced signal depends on the size and conductivity of the metal particles.

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