Research On The Key Technology Of UWB Position Tag

UWB positioning technology is a new kind of wireless positioning technology, it tranmits information by using nanosecond level even picosecond pulse. In recent years, with the rapid development of wireless short-range communication and the progress of Wireless Local Area Network (WLAN) technology, indoor positioning technology has got a big development. The future trend of wireless location technology is combining the positioning technology of indoor and outdoor to realize seamless and precise positioning. Ultra-wideband has high transmission rate, low power consumption, good resistance to multipath effects, high security and low system complexity, using UWB positioning is well qualified to fill precise positioning. Positioning technology based on UWB stands out in the numerous wireless location technology, becomes a hot spot of current wireless positioning technology research. UWB position tag plays an vital role in the whole system as the front end of the UWB positioning system, this article will study the key technology of UWB tag from the narrow pulse, pulse modulation and pulse frequency spectrum forming three aspects.First, based on the analysis of the UWB pulse generation method and pulse selection, a simple ultra-wideband pulse generator is designed. The pulse generator produces class gaussian narrow pulse using the competition adventure role of logic gate, and then gets a first order gaussian pulse through the first order differential circuit. Testing the actual circuit, a pulse is got with repetition frequency of10MHZ, pulse width of3ns, pulse amplitude of500mv. The circuit is low cost, simple structure, easy to make, and has a strong engineering practicality.Secondly, on the foundation of research on modulation of UWB pulse, the paper presents a design scheme of TH-PPM-UWB signal using PIC single chip microcomputer. To verify the correctness of TH-PPM modulation procedures, PIC MCU development board and online emulator is used. Then joins baseband UWB pulse generating circuit, the TH-PPM-UWB signal is obtained, and further demonstrates the accuracy of this method.Finally, in order to satisfy the FCC requirements of ultra-wideband radiation power spectrum, this paper designs a novel ultra wideband bandpass filter, on the basis of the traditional three coupled resonator, the filter achieves notched performance at a particular frequency band (5.7GHz to5.8GHz) by adding coupling refers, inhibition level of notch band up to-40dB, avoids interference of the narrowband signal. At the same time, due to join the slot conical resonator,the high frequency stopband characteristics of bandpass filter also has further improved, strengthen the characteristics of suppress the harmonic characteristics.