Active stylus and touch input system

A touch input system, comprising:

• an active stylus, configured to periodically transmit a downlink beacon signal and a plurality of downlink signals;
• and
• a touch panel, configured to receive the downlink beacon signal and the plurality of downlink signals so as to synchronize timing with the active stylus and analyze information transmitted by the active stylus, comprising:
• a memory;
• a receiving module;
• and
• a touch panel controller, coupled to the memory and the receiving module;
• wherein the touch panel controller controls the receiving module to receiving the downlink beacon signal and the plurality of downlink signals, and the downlink beacon signal is composed of a plurality of bit data and comprises:
• a preamble, stored in the memory, for synchronizing the timing;
• a digital data, for transmitting information from the active stylus to the touch panel;
• and
• a cyclic redundancy check, for executing an error check or an error correction for data;
• wherein the touch panel is an in-cell/on-cell organic light-emitting diode (OLED) touch screen or an in-cell/on-cell liquid-crystal display (LCD) touch screen;
• wherein the plurality of bit data of the downlink beacon signal are modulated into a plurality of symbols to be transmitted by a direct-sequence spread spectrum (DSSS) technology with a plurality of pseudo noise code (PN code).