def test_get_exg_ch(self):
self.assertEqual(get_exg_ch(EChannelType.EXG_ADS1292R_1_CH1_24BIT),
(0, 0))
self.assertEqual(get_exg_ch(EChannelType.EXG_ADS1292R_1_CH2_24BIT),
(0, 1))
self.assertEqual(get_exg_ch(EChannelType.EXG_ADS1292R_2_CH1_24BIT),
(1, 0))
self.assertEqual(get_exg_ch(EChannelType.EXG_ADS1292R_2_CH2_24BIT),
(1, 1))
def _process_exg_signal(self, ch_type: EChannelType, y: np.ndarray) -> np.ndarray:
chip_id, ch_id = get_exg_ch(ch_type)
exg_reg = self.get_exg_reg(chip_id)
gain = exg_reg.get_ch_gain(ch_id)
ch_dtype = ChDataTypeAssignment[ch_type]
resolution = 8 * ch_dtype.size
sensitivity = EXG_ADC_REF_VOLT / (2 ** (resolution - 1) - 1)
# According to formula in Shimmer ECG User Guide
y_volt = (y - EXG_ADC_OFFSET) * sensitivity / gain
return y_volt
def test_post_process_exg_signal(self):
exg_reg1 = ExGRegister(b'\x03\x80\x10\x40\x40\x00\x00\x00\x02\x01')
exg1_gain = 4
exg_reg2 = ExGRegister(b'\x03\x80\x10\x20\x20\x00\x00\x00\x02\x01')
exg2_gain = 2
chip_gain = {
0: exg1_gain,
1: exg2_gain,
}
samples = {
EChannelType.EXG_ADS1292R_1_CH1_24BIT: np.random.randn(1000),
EChannelType.EXG_ADS1292R_2_CH2_24BIT: np.random.randn(1000),
EChannelType.EXG_ADS1292R_1_CH1_16BIT: np.random.randn(1000),
EChannelType.EXG_ADS1292R_2_CH2_16BIT: np.random.randn(1000),
}
samples_w_ts = {**samples, EChannelType.TIMESTAMP: np.arange(1000)}
m_br = Mock(spec=ShimmerBinaryReader)
m_br.get_exg_reg.side_effect = lambda x: exg_reg1 if x == 0 else exg_reg2
m_br.read_data.side_effect = lambda: (dict(samples_w_ts), ((), ()))
type(m_br).sample_rate = PropertyMock(return_value=1)
type(m_br).enabled_sensors = PropertyMock(return_value=[])
type(m_br).has_sync = PropertyMock(return_value=False)
type(m_br).has_global_clock = PropertyMock(return_value=False)
type(m_br).start_timestamp = PropertyMock(return_value=0)
type(m_br).exg_reg1 = PropertyMock(return_value=exg_reg1)
type(m_br).exg_reg2 = PropertyMock(return_value=exg_reg2)
reader = ShimmerReader(bin_reader=m_br, post_process=False)
reader.load_file_data()
for ch_type in samples:
np.testing.assert_equal(samples[ch_type], reader[ch_type])
reader = ShimmerReader(bin_reader=m_br, post_process=True)
reader.load_file_data()
for ch in samples:
bit = 16 if '16' in ch.name else 24
gain = chip_gain[get_exg_ch(ch)[0]]
expected = (samples[ch] - 0) * 2.420 / (2**(bit - 1) - 1) / gain
actual = reader[ch]
np.testing.assert_almost_equal(actual, expected)