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This paper introduced a system based on wireless network technology, which achieved node-to-node data collection and transmission. The ZigBee-based wireless network of the system adopted the chip CC2530 of TI company. The system developed applications based on Z-STACK for data collection and wireless transmission, it used VC++ to make a PC software for real-time monitoring of temperature and humidity. The research results show the feasibility of the system, and it would be widely used in the measure field of agriculture.

The study proposes a novel time-frequency analysis technique, titled time-frequency synchroextracting transform which enhances the accuracy of synchroextracting transform. The synchroextracting transform is a powerful postprocessing method that sharpens the energy distribution of spectrogram. However, its limitation is the sole use of time or frequency factors that cannot accurately portray signals containing both 'slowvarying' and 'fast-changing' components. The proposed method applies the synchroextracting procedure in both time and frequency dimensions to improve the energy concentration. A fast Fourier transform--based algorithm is also provided for efficient implementation. The proposed method is validated via numerical and empirical data. Compared with advanced methods including synchrosqueezing transform and synchroextracting transform, the proposed method is suitable to analyse wider range of signals and has better noise robustness than the original synchroextracting transform.

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