Firstly, each of them is high-pass filtered to remove the static or slowly varying gravitation signal. The filter is implemented by a computation- ally efficient autoregressive filter of the first degree. Effectively the filter subtracts from the input an inte- grated value of the output. A gain coefficient of 1/8 is inserted in the loop to adjust the response time and frequency response. The -3 dB cutoff frequency is approximately 1/53 of the sampling rate. The transfer function of the filter is: