BIOSIGNAL MEASUREMENT SYSTEM
An embodiment is a biosignal measurement system including a plurality of electrode devices, each including an electrode, an amplifier circuit configured to amplify a biopotential measured via the electrode, a quantization circuit configured to convert the biopotential amplified by the amplifier into digital data to generate biopotential information, a transmitter configured to transmit the biopotential information, and a receiver configured to receive reference potential information of the amplifier, and a biosignal generation device including a wireless receiver configured to receive the biopotential information transmitted from the plurality of electrode devices, an arithmetic circuit configured to generate a biosignal waveform and the reference potential information using the biopotential information in at least two of the plurality of electrode devices, and a transmitter configured to transmit the reference potential information to the plurality of electrode devices, where the amplifier of each of the plurality of electrode devices is configured to amplify the biopotential using reference potential information received from the biosignal generation device.
1 - 8 . (canceled)
9 . A biosignal measurement system comprising:
a plurality of electrode devices, each including an electrode, an amplifier circuit configured to amplify a biopotential measured via the electrode, a quantization circuit configured to convert the biopotential amplified by the amplifier into digital data to generate biopotential information, a transmitter configured to transmit the biopotential information, and a receiver configured to receive reference potential information of the amplifier; and
a biosignal generation device including a wireless receiver configured to receive the biopotential information transmitted from the plurality of electrode devices, an arithmetic circuit configured to generate a biosignal waveform and the reference potential information using the biopotential information in at least two of the plurality of electrode devices, and a transmitter configured to transmit the reference potential information to the plurality of electrode devices, wherein
the amplifier of each of the plurality of electrode devices is configured to amplify the biopotential using reference potential information received from the biosignal generation device.
10 . The biosignal measurement system according to claim 9 , wherein
the plurality of electrode devices include a master electrode device which is one of the plurality of electrode devices and a slave electrode device which is the electrode device other than the master electrode device,
the biosignal generation device is implemented in the master electrode device, wherein
the arithmetic circuit implemented in the master electrode device is configured to generate the biosignal waveform and the reference potential information using the biopotential information obtained in the master electrode device and the biopotential information obtained in the slave electrode device.
11 . The biosignal measurement system according to claim 9 , wherein each of the plurality of electrode devices includes a reference potential correction circuit configured to correct a phase variation of the reference potential information caused by a propagation delay with respect to the biosignal generation device, wherein the amplifier is configured to amplify the biopotential using the reference potential information corrected in the reference potential correction circuit.
12 . The biosignal measurement system according to claim 11 , wherein the reference potential correction circuit is configured to estimate a lag in data of the reference potential information using a correlation value calculated using data of a plurality of pieces of the reference potential information, and is configured to correct the phase variation of the reference potential information on a basis of the estimated lag.
13 . The biosignal measurement system according to claim 11 , wherein
the reference potential correction circuit includes a phase comparator configured to perform phase-comparison between a signal of the biopotential and a signal of a reference potential obtained from the reference potential information, a low-pass filter configured to output a direct-current component of an output of the phase comparator, an oscillator configured to output a signal of a frequency corresponding to an output of the low-pass filter, a modulator configured to amplitude-modulate the reference potential information using an output of the oscillator, an all-pass filter configured to input an output signal of the modulator, and a demodulator configured to demodulate an output signal of the all-pass filter as the corrected reference potential.
14 . The biosignal measurement system according to claim 9 , wherein each of the plurality of electrode devices further includes a reference potential correction circuit configured to interpolate a reference potential changing stepwise according to a sampling rate of the electrode device by estimating a periodic signal included in a signal of the reference potential in the amplifier circuit, wherein the amplifier is configured to amplify the biopotential using the reference potential interpolated in the reference potential correction circuit.
15 . The biosignal measurement system according to claim 14 , wherein the reference potential correction circuit is configured to interpolate the reference potential using an AR model.
16 . The biosignal measurement system according to claim 15 , wherein the reference potential correction circuit is configured to interpolate the reference potential information changing stepwise using an AR coefficient calculated by the biosignal generation device.
17 . The biosignal measurement system according to claim 10 , wherein each of the plurality of electrode devices includes a reference potential correction circuit configured to correct a phase variation of the reference potential information caused by a propagation delay with respect to the biosignal generation device, wherein the amplifier is configured to amplify the biopotential using the reference potential information corrected in the reference potential correction circuit.
18 . The biosignal measurement system according to claim 10 , wherein each of the plurality of electrode devices further includes a reference potential correction circuit configured to interpolate a reference potential changing stepwise according to a sampling rate of the electrode device by estimating a periodic signal included in a signal of the reference potential in the amplifier circuit, wherein the amplifier is configured to amplify the biopotential using the reference potential interpolated in the reference potential correction circuit.
19 . An electrode device comprising:
an electrode;
an amplifier circuit configured to amplify a biopotential measured via the electrode;
a quantization circuit configured to convert the biopotential amplified by the amplifier into digital data to generate biopotential information;
a transmitter configured to transmit the biopotential information, and a receiver configured to receive reference potential information of the amplifier;
a wireless receiver configured to receive the biopotential information transmitted from another electrode device;
an arithmetic circuit configured to generate a biosignal waveform and the reference potential information using the biopotential information in at least two of the plurality of electrode devices; and
a transmitter configured to transmit the reference potential information to the plurality of electrode devices; wherein
the amplifier is configured to amplify the biopotential using the reference potential information.
20 . The electrode device according to claim 19 , further comprising:
a reference potential correction circuit configured to correct a phase variation of the reference potential information caused by a propagation delay with respect to the biosignal generation device, wherein the amplifier is configured to amplify the biopotential using the reference potential information corrected in the reference potential correction circuit.
21 . The electrode device according to claim 20 , wherein
the reference potential correction circuit estimates a lag in data of the reference potential information using a correlation value calculated using data of a plurality of pieces of the reference potential information, and corrects the phase variation of the reference potential information on a basis of the estimated lag.
22 . The electrode device according to claim 20 , wherein the reference potential correction circuit includes:
a phase comparator configured to perform phase-comparison between a signal of the biopotential and a signal of a reference potential obtained from the reference potential information;
a low-pass filter configured to output a direct-current component of an output of the phase comparator;
an oscillator configured to output a signal of a frequency corresponding to an output of the low-pass filter;
a modulator configured to amplitude-modulate the reference potential information using an output of the oscillator;
an all-pass filter configured to input an output signal of the modulator; and
a demodulator configured to demodulate an output signal of the all-pass filter as the corrected reference potential.
23 . The electrode device according to claim 19 , further comprising:
a reference potential correction circuit configured to interpolate a reference potential changing stepwise according to a sampling rate of the electrode device by estimating a periodic signal included in a signal of the reference potential in the amplifier circuit, wherein the amplifier is configured to amplify the biopotential using the reference potential interpolated in the reference potential correction circuit.
24 . The electrode device according to claim 23 , wherein the reference potential correction circuit is configured to interpolate the reference potential using an AR model.
25 . The electrode device according to claim 24 , wherein the reference potential correction circuit is configured to interpolate the reference potential information changing stepwise using an AR coefficient calculated by the biosignal generation device.
26 . A method of measuring a biosignal, the method comprising:
measuring a biopotential via electrodes of a plurality of electrode devices;
amplifying the measured biopotential in each of the plurality of electrode devices using an amplifier circuit;
converting the amplified biopotential into digital data to generate biopotential information using a quantization circuit in each of the plurality of electrode devices;
transmitting the biopotential information from each of the plurality of electrode devices to a biosignal generation device;
generating, by the biosignal generation device, a biosignal waveform and reference potential information using the biopotential information from at least two of the plurality of electrode devices;
transmitting the reference potential information from the biosignal generation device to the plurality of electrode devices; and
amplifying the biopotential in each of the plurality of electrode devices using the reference potential information received from the biosignal generation device.
27 . The method according to claim 26 , further comprising:
implementing the biosignal generation device in one of the plurality of electrode devices as a master electrode device; and
generating the biosignal waveform and the reference potential information using biopotential information obtained in the master electrode device and biopotential information obtained in at least one other electrode device.
28 . The method according to claim 26 , further comprising:
correcting, in each of the plurality of electrode devices, a phase variation of the reference potential information caused by a propagation delay with respect to the biosignal generation device; and
amplifying the biopotential using the corrected reference potential information.