Spectrum that overlaps in time, geography and frequency is allocated to more than one radio network. The ancillary information includes metadata information and audio information. The blocks in each second sequence of blocks are encrypted using a cipher in block chaining mode, initialized with a respective initialization vector for each second sequence of blocks. The parallel linkage system also facilitates adjustment of the integrated tailgate work surface to convenient working heights. The damper is connected to a grounding pole of a driving circuit for quickly removing the charge so as to achieve damping effect and minify or even eliminate the vibration and noise caused by AC electric field.