Sampling rate

Product: Muse
Version:
Platform: Android

Description: The EEG samples from the muse have timestamp. I could learn that the samples do have varying intervals. This leads to inconsistent sampling rate.

Expected behaviour: I expect the timestamp intervals to be constant.

Actual behaviour:
1579582684.009970,
1579582684.010292,
1579582684.010433,
1579582684.010561,
1579582684.010677,
1579582684.010797,
1579582684.010938,
1579582684.011135,
1579582684.011277,
1579582684.011405,
1579582684.011525,
1579582684.011639,
1579582684.059801,
1579582684.059941,
1579582684.060054,

Steps to reproduce: The generated muse file do have the timestamps.

I assume your data that you posted is from a .muse file, not Mind Monitor which has a different timestamp. If you examine the CSV data below, which came from a .muse file recorded in Muse Lab, there are a number of entries of the same data type with the very same timestamp. The data values are changing, so it’s not redundant data but the timestamp doesn’t seem to be high enough resolution for the data format. I’ve noticed this in Mind Monitor too (maybe even Muse Direct files (I’d have to double check).

So what I’ve done is I use the sampling rate in the Muse specification for the data analysis and essentially that data is averaged out. Also keep in mind that the way the data is received from the Muse headband is interrupt driven, it’s not polled at a specific sample rate. That alone will likely introduce some possible small differences in the timestamps.

1574651166.360000, /muse/eeg, 846.1539, 850.58606, 847.3626, 848.5714, 884.83514
1574651166.360000, /muse/eeg, 832.4542, 849.7802, 851.39197, 849.7802, 805.8608
1574651166.360000, /muse/eeg, 846.55676, 846.9597, 853.4066, 853.00366, 818.3516
1574651166.360000, /muse/eeg, 869.5238, 846.55676, 856.2271, 856.63007, 869.12085
1574651166.360000, /muse/eeg, 861.06226, 848.5714, 857.8388, 857.4359, 852.6007
1574651166.361000, /muse/eeg, 838.49817, 847.3626, 854.21246, 855.42126, 802.23444
1574651166.367000, /muse/eeg, 842.9304, 846.9597, 854.61536, 856.2271, 814.7253
1574651166.367000, /muse/eeg, 862.27106, 849.7802, 855.0183, 856.63007, 871.53845
1574651166.367000, /muse/eeg, 860.2564, 848.5714, 853.8095, 857.4359, 885.2381
1574651166.368000, /muse/eeg, 836.08057, 845.34796, 852.1978, 853.8095, 826.4103
1574651166.369000, /muse/eeg, 833.663, 848.5714, 847.76556, 848.97437, 807.8755
1574651166.371000, /muse/eeg, 854.61536, 848.97437, 847.76556, 851.79486, 871.53845
1574651166.371000, /muse/gyro, 0.47103882, 0.50094604, 5.15152
1574651166.371000, /muse/gyro, 0.38131714, 0.47851562, 5.33844
1574651166.371000, /muse/gyro, 0.25421143, 0.3439331, 5.33844
1574651166.372000, /muse/acc, -0.24389648, 0.19799805, 0.94488525
1574651166.373000, /muse/acc, -0.2446289, 0.19732666, 0.94317627
1574651166.373000, /muse/acc, -0.24603271, 0.19732666, 0.9423828
1574651166.374000, /muse/eeg, 862.674, 845.7509, 857.03296, 856.2271, 908.60803
1574651166.374000, /muse/elements/touching_forehead, 1
1574651166.374000, /muse/elements/alpha_absolute, 0.22403088, -0.5564282, 0.07889185, 0.36646974
1574651166.375000, /muse/elements/beta_absolute, 0.09028149, -0.25967345, 0.05568538, 0.13859516
1574651166.375000, /muse/elements/delta_absolute, -0.3571756, -0.6499789, -0.4385234, -0.1803911
1574651166.376000, /muse/elements/theta_absolute, -0.15036403, -0.62527907, -0.4659649, -0.21109004
1574651166.376000, /muse/elements/gamma_absolute, -0.46092454, -0.3939347, -0.1920929, -0.43634877
1574651166.376000, /muse/elements/horseshoe, 1.0, 1.0, 1.0, 1.0
1574651166.376000, /muse/eeg, 848.97437, 844.94507, 857.03296, 855.0183, 865.4945
1574651166.376000, /muse/eeg, 838.9011, 843.3333, 849.7802, 849.3773, 811.0989
1574651166.376000, /muse/eeg, 854.61536, 843.73627, 857.03296, 853.00366, 844.5421
1574651166.376000, /muse/eeg, 866.7033, 842.52747, 857.03296, 853.8095, 889.2674
1574651166.376000, /muse/eeg, 851.39197, 840.5128, 849.3773, 850.989, 856.63007
1574651166.377000, /muse/eeg, 836.08057, 846.1539, 853.00366, 858.24176, 806.26373
1574651166.377000, /muse/eeg, 848.5714, 851.39197, 854.61536, 860.65936, 818.7546
1574651166.377000, /muse/eeg, 869.5238, 849.7802, 856.63007, 860.2564, 884.83514
1574651166.377000, /muse/eeg, 860.2564, 844.94507, 853.8095, 857.4359, 883.6264
1574651166.378000, /muse/eeg, 832.8571, 844.1392, 846.55676, 845.34796, 813.1135
1574651166.378000, /muse/eeg, 835.6777, 846.1539, 852.6007, 847.3626, 820.7692
1574651166.378000, /muse/eeg, 855.82416, 844.1392, 858.24176, 857.03296, 865.09155
1574651166.378000, /muse/eeg, 855.82416, 844.1392, 860.65936, 855.42126, 879.59705
1574651166.379000, /muse/eeg, 837.6923, 841.7216, 854.61536, 853.4066, 841.7216
1574651166.379000, /muse/eeg, 834.87177, 843.73627, 851.39197, 857.03296, 807.8755
1574651166.379000, /muse/eeg, 855.0183, 850.989, 856.2271, 859.0476, 856.2271
1574651166.379000, /muse/eeg, 859.45056, 847.3626, 850.58606, 857.03296, 882.4176
1574651166.379000, /muse/eeg, 840.9158, 840.5128, 848.5714, 855.42126, 844.94507