studied non-line-of-sight recognition based on the UWB positioning system in tunnels by analyzing channel propagation parameters. The application of UWB positioning technology in tunnel personnel positioning also faces many challenges, such as signal acquisition in real environment, multiuser mutual interference, multipath effect, and non-line-of-sight propagation. Since then, UWB technology has become a hot spot in current wireless communication research. This landmark paper opened the first step in systematic research on UWB theory. In the 1990s, SCHOLTZ RA first proposed the use of impulse pulses for time-hopping modulation in multiple-access communication systems. These advantages make UWB positioning technology a better choice for high-precision wireless positioning of tunnels. Communication with nanosecond narrow pulses does not require carrier signal modulation, and its positioning accuracy can reach centimeter level. It has strong anti-interference ability, high transmission rate, high security, strong penetrating ability, high multipath resolution, and relatively simple system structure.
![wavelet denoising easyhdr wavelet denoising easyhdr](https://www.mathworks.com/help/examples/wavelet/win64/CompareDenoisedSignalsExample_05.png)
UWB positioning technology has advantages that other positioning technologies cannot match. Ultrawideband transmission power of −41.3 dBm/MHz and the frequency range of 3.1 to 10.6 GHz were established by the Federal Communications Commission (FCC) in the United States. UWB technology first appeared in the 1960s, and its initial application was limited to military, disaster rescue search, radar positioning, and ranging. The precise positioning of the tunnel cannot be ignored.Īt present, the technologies commonly used for personnel positioning under tunnels include Radio Frequency Identification (RFID) positioning technology, Zigbee positioning technology, Wi-Fi positioning technology, and UWB positioning technology. Therefore, real-time safety monitoring of the tunnel construction site and obtaining specific location information of each construction person are of great significance for reducing accident losses. In the event of a landslide or other security incident, due to the existing communication conditions inside and outside the tunnel and the limitations of the communication mechanism, it is difficult to grasp the distribution of personnel under the tunnel during rescue, resulting in low efficiency of rescue and difficulties in search and rescue. In the process of tunnel construction, there are some problems due to the strong sealing, inconvenient communication, and bad environment. The safety of tunnel construction has become a hot issue. Therefore, tunnel construction of roads, railways, and subways is an important component of the transportation network. Building a modern transportation network is an inevitable requirement of economic construction and social development. In recent years, with the continuous development of the economy, more urgent requirements have been put forward on the transportation network. The wavelet threshold denoising method can weaken the influence of outliers in the motion positioning of UWB personnel and improve the positioning accuracy.
WAVELET DENOISING EASYHDR VERIFICATION
The verification by the positioning experiment shows that the method is suitable for tunnel personnel positioning. According to the denoising effect, the db5 wavelet 5-layer decomposition, under the heuristic threshold estimation criterion, the soft threshold function denoising is the best denoising method. The soft threshold function and the hard threshold function are, respectively, selected to perform wavelet threshold denoising on the motion positioning result in the tunnel. The wavelet analysis is used to decompose the motion signal of the personnel in the tunnel, and the low frequency coefficient and high frequency coefficient of the signal are decomposed to determine the influence of the motion noise of the personnel on the UWB positioning.
![wavelet denoising easyhdr wavelet denoising easyhdr](https://image.slidesharecdn.com/aqr-150214071917-conversion-gate01/95/image-denoising-using-wavelet-14-638.jpg)
![wavelet denoising easyhdr wavelet denoising easyhdr](http://intelligentonlinetools.com/blog/wp-content/uploads/2018/12/figure1.png)
The positioning algorithm of the method adopts a three-sided positioning algorithm based on symmetric double-sided two-way ranging. A wavelet threshold denoising method for motion positioning of people in tunnels is proposed. A special environment for tunnel personnel positioning and the ultrawideband (UWB) positioning system are affected by personnel movement, which leads to the problem of lowering positioning accuracy. Therefore, personnel positioning technology has important application value in tunnel safety construction. In the process of tunnel construction, the problems of strong sealing, inconvenient communication, and harsh environment pose a serious threat to the personal safety of construction workers.