a During the experiment, the resonant accelerometer was installed on a rotary table to sense the acceleration change, while the reading resonator was statically arranged. The sensing resonator and the reading resonator were synchronized through the unidirectional electrical coupling method. b The spectrum response of the reading resonator when the external acceleration changed. Each vertical slice in the figure represents a 10 s average of the spectrum response. An obvious synchronization range can be observed in the middle of the graph, where all other sidelobes vanish. When entering and leaving the synchronization range, the system plunges into chaos, and all the resonant peaks are very disordered. c The synchronization range determines the measurement range of the synchronized resonant accelerometer, which is linearly dependent on the perturbation intensity. The blue area in the graph indicates the proportion of the synchronization range to the whole measurement range of ±1 g. Increasing the voltage of the synchronizing signal is an effective way to expand the synchronization range; however, an overlarge perturbation intensity (red region) might destroy the oscillation rhythm of the reading resonator and even threaten its integrity. When the system is out of the synchronization range (points A and C), the synchronized resonant accelerometer operates as two independent oscillators. d Resolution test of the synchronized resonant accelerometer. As the external acceleration changes, the reading oscillator shifts stepwise with the sensing oscillator. According to the calculation of the Allan deviation, the stability of the reading oscillator after synchronization was enhanced from 90.8 to 19.4 ppb, which was an improvement of 5–6 times, while that of the sensing oscillator remained 181.4 ppb. The calculated resolution of the original resonant accelerometer is ~17.3 μg. However, with the help of the synchronization enhancement, the resolution of the synchronized resonant accelerometer is increased ninefold to 1.91 μg.