General |
|
4-ch EEG monitor and
neurofeedback with integrated Binaural Beat generator, flashing
LED glasses and binocular rivalry monitor |
EEG |
Channels |
4 x monopolar +
reference + neutral, or 2 x bipolar + neutral (strappable) |
|
A->D Sampling Rate |
8.196mSec (~122.07 Hz) |
|
A->D Resolution |
10-bit precision,
accuracy 9-bits or better |
|
Anti-aliasing filter |
Switched capacitor 8th
order elliptic (r=1.2) LPF each channel, fc=programmable |
|
3dB bandwidth |
0.5 – 35/40/44Hz (60Hz
countries) selectable |
|
CMRR |
>95dB |
|
Channel gain |
V/V: fixed 20k, or
independently Ch1/2, Ch3/4 10k-40k in 64 steps under ALC (+-20%*
absolute, +-2% ch to ch)
(+- 2% absolute to order); * digital potentiometer spec
|
|
Driven Right Leg |
Sum of ch common mode,
mains hum suppression, current limited to IEC 60601 |
|
Probe health measure |
Measure of 2nd
stage dc offset compensation, each channel separately |
|
Electrodes |
6 x 80-160u" silver
plated casings surrounding saline impregnated sponge
Expected life: >3 months usage
|
|
Connector |
8-way Modular |
Binaural Beat
Generator |
General |
2048 16-bit unsigned
cosine lookup table with interpolation
9 preset, 1 user programmable carrier frequencies, 10 preset
volume settings (L & R)
9 preset, 1 user programmable beat frequencies
monaural pink masking noise, 10 preset volume settings
all in up to 8 sequences, each up to 9 minutes in 1 minute
increments, or loop forever
|
|
Programmable Carrier
Frequency Range |
0.0 – 999.9Hz, 0.1Hz
precision, 0.125Hz accuracy |
|
Programmable Beat
Frequency Range |
0.0 – 99.9Hz, 0.1Hz
precision, 0.125Hz accuracy |
|
Preset Carrier Freqs |
65.8, 73.6, 165, 197,
246, 393, 440, 492, 526 Hz |
|
Preset Beat Freqs |
0, 1.2, 4.4, 6.6, 9.9,
13.2, 19.8, 26.3, 39.5 Hz |
|
Pink Noise algorithm |
Pinkish filter –
3dB/octave on white noise (summation of staggered 1st
order filters (also 4 octave Voss-McCartney to order) |
|
White Noise algorithm |
Linear congruential
(seed=16457), (15-bit linear feedback shift register to order) |
|
D->A Sampling Rate |
3.90625kHz |
|
D->A Resolution |
8-bit |
|
D->A filtering |
Switched capacitor 8th
order elliptic (r=1.2) LPF each channel, fc=1670Hz |
|
Audio 3dB Bandwidth |
80 – 1670 Hz |
|
Headset impedance |
> 30 ohms |
|
Audio connector |
3.5mm stereo |
Light glasses |
LEDs |
2 x 4 high intensity
blue |
|
Modes |
Left eye – right eye,
or Left field of vision – right fov (selectable on glasses)
Sync flash – alternate L & R flash (selectable on unit)
|
|
Connector |
4-way modular/3.5mm
stereo (I); 8-way modular (II) |
Binocular Rivalry |
Abh II Display |
Left ocular field –
vertical lines moving left
Right ocular field – horizontal lines moving down
|
|
Abh I Display |
Necker Cube |
|
L-R Discriminator |
Converging tubes 40mm
dia, 33cm long |
|
Eye Alternation Rate |
0.0 – 2.9 Hz, 0.1 Hz
resolution |
Presets |
|
11 (I): setupEEG, focus,
relax, release, intuit, sleep, theWorks, external, user defined (3
off); +2 (II): setup Probes, setup SigGen |
Modes |
Binaural Beat |
Probes & feedback
tones off |
|
EEG |
Binaural Beat off,
chimes or chords feedback tones |
|
EEG+Binaural Beat |
Chimes reward only,
superimposed on Binaural Beat tones |
|
EEG+Beat+Sweep |
Binaural Beat frequency
sweeps between peak EEG and target brainwave frequency,
L/R chosen dynamically based on lower instantaneous threshold
value
|
Displays |
General |
64x128 pixel
chip-on-glass graphic display, menu controlled contrast adjustment |
|
Menus |
Rolling and scrolling
menus and submenus |
|
Probes Display |
Time domain Ch 1&2
or Ch 3&4, uVolt readout, auto scaling analog gain/digital
gain w. readout; linear Y axis, Ch 1&2 or Ch 3&4 Probes
d.c. offset readout |
|
Frequency Display |
Frequency Domain 0 –
60Hz , 1/f compensated, Ch 1&2 or Ch 3&4, log Y axis, auto
scaling analog gain/digital gain w. readout, probes status |
|
Mirror Display |
Left/Right Hemisphere
Brain Mirror Ch ½ or ¾, Bands: delta, theta1, theta2, alpha,
beta1, beta2, gamma, pseudo log Y axis, R/S ratio values, probes
status |
|
Coherency Display |
Phase space display of
peak reinforce & suppress band for previous ~120 FFTs Ch
1&2 or Ch 3&4, R/S ratio values, probes status |
|
Centricity Display |
Spatial mean for Ch1
Reinforce band applied to Ch 1/2/3/4, maker size reflects R/S
ratio amplitude for each channel, R/S ratio values, probes status |
|
Halleys Display |
Bat length is determined
by R/S ratio for Ch 1/2/3/4 (left top, left bottom, right top,
right bottom resp., counts success in deflecting ball, R/S ratio
values, probes status |
|
Binaural Beat Display |
Sequence number, left
frequency, right frequency, beat frequency, left volume right
volume, pink noise level, time remaining, R/S ratio values |
|
EEG Log Display |
Previous 64 smoothed R/S
values sampled each ~30sec, or
Previous 32 logged R/S values Ch 1&2 or Ch 3&4
|
|
Synchrony Display |
Instantaneous &
smoothed values of complex cross-correlation of FFT phasors in Ch1
reinforce band reflected over Ch1<>2, 2<>4,1<>3,
& 3<>4, Range –1.0 to 1.0 |
|
Samadhi Display |
Eyelids response to
reinforce band amplitude and R/S ratio resp, Ch 1&2 or
3&4, R/S ratio values, probes status |
|
Synchrony Log Display |
Previous 64 smoothed
Xcorel. Values sampled each ~30sec, or
Previous 32 logged Xcorel. Values, Ch F&B or Ch L&R
|
|
Eye Rivalry Display |
Left ocular field –
vertical lines moving left
Right ocular field – horizontal lines moving down
Left-right dominance % readout, eye switching rate readout Hz,
auto boost flag
|
|
Eye Rivalry Log |
Previous 64 smoothed
dominance & sw rate values sampled each ~30sec, or
Previous 32 logged dominance & sw. rate values
|
|
Impedance (AbhayamudraII
only) |
Measurement of a.c.
impedance of individual electrode-scalp impedances at 30Hz. Range:
0..125Kohm ± 2K ohm. Auto calibration
feature. |
|
Signal Generator
(AbhayamudraII only)
|
2-tone mode: F1 &
F2: 0.0..49.9Hz, 0.0..39.9uVpp*, individually settable
Sweep mode: Flo & Fhi: 0.0..49.9Hz, 0.0..39.8uVpp*, rate
0..59 seconds
|
Protocol |
General |
Select reinforce &
suppress band for each of 4 channels. R&S can be any of delta,
theta1, theta2, alpha, beta1, beta2, beta3, or gamma. R/S calc
based on digital filters (~65mSec response), X-correlation calcs
& displays based on FFT (130+mSec response) |
|
Artefact Suppression |
Delta change in Spectral
energy measured & compared with threshold -> inhibit reward |
Digital Filters |
General |
Elliptic 4th
order BPF, 2nd order Direct Form II cascade
implementation with Q15 format coefficients, 10-bit data |
|
Delta 3dB Bandwidth |
0.6 – 3.0 Hz, pass
0.7dB, reject 48dB |
|
Theta 1 3dB BW |
3.5 – 4.8 Hz, pass
0.1dB, reject 49dB |
|
Theta 2 3dB BW |
5.7 – 7.6 Hz, pass
0.1dB, reject 48dB |
|
Alpha BW |
8.5 – 10.7dB, pass
0.1dB, reject 48.5dB |
|
Beta 1 BW |
11.8 – 15.0 Hz, pass
0.1dB, reject 48dB |
|
Beta 2 BW |
17.2 – 21.5 Hz, pass
0.1dB, reject 48dB |
|
Beta 3 BW |
24.5 – 34.0 Hz, pass
0.1dB, reject 44dB (53dB @ 50Hz) |
|
Gamma BW |
38.0 – 43.0 Hz, pass
0.1dB, reject 44dB (60dB @ 50Hz) |
FFT |
General |
1:N input overlapped,
raised-cosine windowed, scaling 8-bit Radix2 (8 – 256 points),
2-ch (Ch A real, Ch B imaginary), in-place, complex FFT |
|
Overlap |
4:1 |
|
Points |
64 |
|
Window |
Pseudo Hamming raised
cosine |
|
Lookup table |
64 point signed 8-bit
cosine table |
|
Power Spectrum |
Pseudo power spectrum
using coeff magnitude as proxy |
Aural Reward |
Dynamic threshold |
Reward triggered by
fuzzy logic inference engine – inputs are current R/S ratio, R/S
ratio history, time duration to previous reward hit. No manual
setup required. |
|
(i) Chords |
2048 16-bit unsigned
cosine lookup table, monaural, Base=440Hz, 3rd=550Hz, 5th=
660Hz, 7th=825Hz; ADSR=50/150/600/200mSec resp (not
available in Bbeat mode) |
|
Algorithm (menu
selectable) |
Chord: any 1
R/S->chord 1,any 2->chd 1+2,any 3->chd 1+2+3,all 4->chd
1+2+3+4
ChordSync: any 1 Xcorel->chord 1 etc
|
|
(ii) Chimes |
.wav files for lo,
lo-med, med, med-hi, & hi |
|
Algorithm (menu
selectable) |
R/S LF OR LB(L)/RF OR
RB(R), LF AND LB(L)/RF AND RB(R)
Sync: LFLB Xcorel.-> chime1(L),RFRB->chime2(R), LFRF->chime3(L+R),
LBRB->chime4(L+R)
|
|
(iii) Continuously
variable pitch |
Pitch varies in
accordance with R/S |
|
Algorithm |
Left channel: Ch1 or C3;
Right channel: Ch2 or Ch4
Sync: Left channel: Ch LF-RF or Ch LF-LB, Right channel: LB-RB
or RF-RB
|
Electrode Impedance
Meter
(Abh II)
|
Measurement technique |
Inserts 30.5Hz signal
into Neutral electrode and measures individual signals on other
five electrodes. Current is limited to IEC 60601 values plus
margin. Measurement is sequenced through five electrodes with four
cycles of 30.5Hz for each measurement -> ~0.625 sec for each
pass. Two measurement points allows discrimination of Neutral
& other electrode impedance. |
|
Measurement range |
Sum of each of
electrodes in series with Neutral electrode < 256K W
in 1K W steps. (eg if Neutral electrode
is 50K W , maximum measurement for
other electrodes is 205K W ) |
|
Accuracy: Reference
electrode |
Uncal: ±
3K W ; Cal: ±
1K W |
|
Accuracy: Ch1..4
electrodes |
Uncal: ±
4K W ; Cal: ±
2K W |
|
Accuracy: Neutral
electrode |
Uncalibrated:
unspecified; Calibrated: ± 10K W |
|
Calibration |
Utilizes external eeg
cable termination (supplied) |
m
Volt Signal Generator
(Abh II)
|
General |
Utilizes external
passive attenuator (supplied)
Frequency range: sine wave, 0.1..49.9 Hz
Frequency accuracy: ± 0.1Hz
Amplitude range: 0.0..39.9 m Voltp-p
Amplitude accuracy (@ 0.0..30.0uV; 1..49Hz): ±
0.5m Voltp-p
(includes coupling capacitor pre-compensation)
Amplitude accuracy @ 0.1Hz: -50%
|
|
Sweep Mode |
Single tone of amplitude
set 0..40m V sweeping between f1 &
f2, each selected in band 0..50Hz, at a selectable sweep period of
0..59 secs. Note some combinations of sweep breadth & sweep
period will be below minimum sweep rate of 0.5Hz/sec causing sweep
to not proceed beyond f1. |
|
Two-tone mode |
Two constant tones each
individually programmed frequency 0..50Hz and amplitude 0..40 m
Voltp-p |
Infrared Link
(Abh II)
|
General |
Frame consists of
sync/data byte + 2/4 channel data bytes (Tx & Rx). 6-bit data
alternates between status & command info. Rx data may add to
or replace locally generated data, 2 x 9-bit samples in burst,
then window to receive burst, if no receive then use local data |
|
Protocol |
Pseudo ping-pong,
peer-to-peer, |
|
Peak wavelength |
870nm |
|
Rx sensitivity |
62.5nA (~40-200nA to
order) |
|
Range |
~50cm |
|
Format |
1 start, 8 data, pseudo
even parity*, 1 stop; *9th bit: no parity error=0,
error=1 |
|
Rate |
38k4 Baud |
|
Synchronisation |
Count 0..3 (prefix of
each sync/data byte at start of frame) |
|
Status Info |
Left/Rigth button,
Ch1/2/3/4 probe status |
|
Commands |
Pause/resume, 2/4 ch,
ALC on/off, EEG local/remote/mix, 8-bit,9-bit(parity) word |
Real Time Clock |
Format |
HH:mm (24 hr) DD:MM,
auto day of month & leap year corrections |
|
Alarm |
Matching HH:mm; if unit
operating-> turn off, if off-> resume at previous settings |
|
Accuracy |
~±
4min/month (~± 30sec/month to order) |
Test Mode |
General |
Menu selection of test
mode, except for strappable selection of left/right earpiece tones
insertion into Ch 1/2 or ¾ for EEG hardware testing |
|
EEG bandwidth |
62.5Hz (to observe
induced mains hum), 1/f compensation removed |
|
Left/Right earpiece |
7.63/3.815 Hz square
wave resp. (to ensure headphones orientation is correct) |
MultiTasking
Dispatcher |
Startup thread |
Power up control |
|
Menu thread |
Controls scrolling of
menus, input of config. commands, execution of commands |
|
Main thread |
Controls main program
loop: fft, dig filters etc, when unit active |
|
Go thread |
Controls inputs when
unit active |
|
COP thread |
Controls servicing of
watchdog timer when unit is active (reset upon software error) |
|
Activity thread |
Controls unit shut down
in absence of regular inputs (power save) |
|
Bitbang thread |
Controls slow serial
port control of peripherals (dig pot) (noise reduction) |
|
Stop thread |
Controls power down of
unit |
Power Managemnt |
Power consumption |
< 100mA @ nom 3.6Vall
times, <100uA in power down |
|
Battery |
3.6V Nicad, 600mAH |
|
On-time |
>5 Hrs continuous,
>1 month in power down (after overnight charge) |
|
Battery life |
~ 1 year, regular use,
regular charging. |
|
Charging |
6-12Vdc >100mA
charger, 20mA trickle (overnight full charge) |
|
Operational measures |
Disable unit upon
charging, "Lo-bat" flash, power down after 5min. idle
timeout when in startup mode, after 2 min in menu mode, after two
hours 15min whilst operating, "place on charger"
warnings |
|
Connector |
1.3mm power jack,
positive centre pin |
Case |
General |
Active components fully
enclosed by case (except connectors) - no exposed metal parts |
|
Material |
ABS GSM UL rated 94 HB
plastic, ~2mm. |