| 摘要 |
A burst demodulator prevents transmission efficiency from being lowered, and a dynamic range of an input strength from being narrowed, by providing a stable frame signal even if the reaction is rapid against the input and the input strength is low. A logarithm amplifier outputs an electric power strength of a modulated input signal as a logarithm value, and an integrator smooths the output of the logarithm amplifier and outputs the smoothed output as an RSSI. The comparator compares the RSSI with the appropriate reference value REF while including some margin within the noise level, and outputs the frame signal of an 'LO' state when the RSSI is lower than the REF, that is, during the non-signal zone, of an 'HI' state when the RSSI is higher than the REF, that is, during the signal zone. The period of the comparator output continuously remaining in the 'LO' state cannot exceed one clock period even if the comparator output flutters within one time slot. When the comparator output is fixed to the 'LO' state and the CLK is input by two clocks, the output of the counter becomes the 'HI' state, whereby the output of the counter and the OR computing element mask the CLK, which fixes the counter output to the 'HI' state until the comparator output becomes the 'HI' state again.
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