Plessey Epic PS25003 User manual

PS25003 EPIC development kit user guide
Demonstration Kit Standard Components
PS25003
•Control and interface box (CIB).
•Control and interface box software (download from website).
•USB cable.
•2xPS25013 connector cables.
•Flying lead (2m long), 4mm plug to crocodile clip.
•Conductive sheet.
Demonstration Kit Sensor Options
The PS250003 is supplied with a choice of one of the following options:
•2x PS25101 sensors, or
•2x PS25102 sensors, or
•2x Single channel demonstration boards with EPIC sensors*, or
•1x Dual channel demonstration board with two EPIC sensors*
* Various EPIC sensors are available on these demonstrator boards.

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User Guide Contents
1.0 Introduction. Page 2
2.0 The EPIC sensors. 2
3.0 The Control and Interface Box. 5
4.0 The Control and Interface Box Software. 7
4.1 System Requirements 7
4.2 Software Installation 7
4.3 Software Use 7
4.4 Software Shutdown 14
5.0 Example applications. 15
5.1 Obtaining an electrocardiogram (ECG) signal 15
5.2 Obtaining other physiological signals 16
5.3 Non-contact ECG 17
TERMS and CONDITIONS 20
Introduction
The EPIC technology provides active electric potential sensors that may be used in a range
of applications.
This demonstration unit comprises a pair of EPIC active sensors and a Control and Interface
box (CIB). It is a flexible system that may be used to explore a range of applications from
electrophysiological signal detection such as ECG (EKG) and EEG through to local electric
field detection for applications such as motion sensing.
2.0 The EPIC sensors
The demonstration sets are supplied with either:

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•2x PS25101 sensors, or
•2x PS25102 sensors, or
•2x Single channel demonstration boards with EPIC sensors*, or
•1x Dual channel demonstration board with two EPIC sensors*
* Various EPIC sensors are available on these demonstrator boards
PS25101 and PS25102: These are metal body sensors. Each is terminated by a 1.5m cable
and a four pin DIN plug. The DIN plug attaches directly to the inputs of the PS25003
Control/Interface box. This sensor style is depicted below:
PS25101 or PS25102 Metal Body Sensor Showing Front and Back, Cable and Plug
The alternative sensor type to the metal body sensor is the so called ‘Compact Sensor’. An
example is shown in the images below:

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PS25201B Compact Sensor Showing Front and Back
These compact sensors are intended for surface mount in a finished system. This style of
sensor is not directly suitable for connection to the Control/Interface Box and so these
sensors are supplied on small demonstration boards that are terminated by a robust socket.
Single channel and dual channel boards are available. The image below shows examples
of these two board types:
Single Channel Demonstration Board Carrying a Compact Sensor
Dual Channel Demonstration Board Carrying Two Compact Sensors
The demonstration boards are connected to the Control/Interface Box by two PS25013
cables (supplied). These are terminated by a four pin DIN plug that attaches directly to the
inputs of the PS25003 Control/Interface box.
The details of the sensors and demonstration boards is summarised in the table below:

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Supplied
Sensor
Supplied
Quantity
Channels
Body
Style
Mounted
sensor
Sensor
Type
Freq. Range (-3dB)
Voltage
Gain
Termination
Supplementary
Component
Lower
Upper
PS25101
2
Single
Metal
N/A
Contact /
non-
contact
200mH
z
10kHz
50
Cable +
DIN
PS25102
2
Single
Metal
N/A
Contact /
non-
contact
200mH
z
20kHz
10
Cable
+DIN
PS25012A
1
2
Single
Demo
board
PS2520
1B
Contact /
non-
contact
200mH
z
10kHz
50
Socket
PS25013
cables
(supplied)
PS25012B
1
1
Dual
Demo
board
PS2520
1B
Contact /
non-
contact
200mH
z
10kHz
50
Socket
2x PS25013
cables(supplied
)
PS25012A
3
2
Single
Demo
board
PS2520
3B
Contact /
non-
contact
200mH
z
20kHz
10
Socket
PS25013
cables
(supplied)
PS25012B
3
1
Dual
Demo
board
PS2520
3B
Contact /
non-
contact
200mH
z
20kHz
10
Socket
2x PS25013
cables(supplied
)
PS25014A
1
2
Single
Demo
board
PS2540
1B
Non-
contact
200mH
z
20kHz
50
Socket
PS25013
cables
(supplied)
PS25014
B1
1
Dual
Demo
board
PS2540
1B
Non-
contact
200mH
z
20kHz
50
Socket
2x PS25013
cables(supplied
)

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Sensor options
3.0 The Control and Interface Box (CIB)
Control and Interface box
The Control and Interface box (CIB) provides an easy interface for the evaluation of EPIC
sensors with both analog outputs and also digitised output (USB) using the internal data
acquisition (DAQ) card. The front and back panels are detailed below:

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FRONT
Control and Interface box front panel
•Power and signal socket for two sensors (channel A and B).
•Switchable gain of x1 and x10.
•Switchable low pass filtering
•Switchable notch filtering, used in conjunction with,
oNotch filter frequency selector, 50 or 60Hz
•Analogue outputs for each sensor (channel A and B)
•Analogue difference output for the two sensors (channel A - channel B)
REAR
Control and Interface box rear panel
•Earth terminal
•Driven Right Leg (DRL) circuit
oPhase selector
oGain control, x1 to x100
o4mm output socket
•A USB 2.0 interface
LOW PASS -
OUT
IN
GAIN -
X1
X10
NOTCH -
IN
OUT
POWER -
A B DIFFERENTIAL
50Hz
60Hz
OFF
ON
INPUTS
A B
OUTPUTS
LOW PASS -
OUT
IN
GAIN -
X1
X10
NOTCH -
IN
OUT
POWER -
A B DIFFERENTIAL
50Hz
60Hz
OFF
ON
INPUTS
A B
OUTPUTS
USB
EARTH
INV
NON-INV
PS25003
x1 x100
DRL Out USB
EARTH
USB
EARTH
INV
NON-INV
PS25003
x1 x100
DRL Out

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A short specification of the control and interface box is:
Parameter
min
typ
max
Units
Notes
Supply voltage –USB 2.0
5.0
V
Low pass filter
30
Hz
Notch filter frequency
50/60
Hz
attenuation
30
dB
Q
4
Analogue output impedance
10

Data acq’n resolution
12
bit
Sampling rate
10
kS/s
Output rate
150
Hz
The power for the internal electronics of the box is provided by the data acquisition card.
This is a National Instruments card, USB-6008. The internal electronics can onlybe powered
by connection of the USB port to a computer with the driver for the DAQ installed.
4.0 The Control and Interface Box (CIB) Software
The CIB requires a connection to a laptop with the associated CIB software installed. The
protocols provided by the software enable the internal data acquisition card within the CIB
and this, in turn, provides power to the other electronics within the box.
The enabled USB connection is also required if the analogue output signals from the box are
to be sent to an oscilloscope since the acquisition card is the only method of applying power
to the CIB electronics.
The CIB software provides a rolling oscillogram and a chart recorder capability.
4.1 System Requirements
The system requirements for a Windows/PC system are:
Processor
Pentium III/Celeron 866 MHz or equivalent
RAM
256 MB
Screen Resolution
1024 x 768 pixels
Operating System
Windows 7/Vista/XP/Windows Server 2003 R2 (32-
bit)/Windows Server 2008 R2 (64-bit)

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4.2 Software Installation
The software can be downloaded from the customer portal found on the internet at:
http://www.plesseysemiconductors.com/
Download and install the software before connection of the CIB to the computer.
Follow the on-screen installation instructions.
After installation has been performed a reboot of the system is required to complete the
installation process.
4.3 Software Use
Once the software is installed the CIB may be connected to a USB socket. The CIB will be
automatically detected and the driver loaded.
The software may now be started. Provided the CIB is connected and the drivers loaded
then the software will display the box:
Confirmation CIB is connected correctly - Click “OK”.

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The soft oscilloscope and data logger will now be displayed:
Start-up Screen with CIB switched off –CIB data acquisition card is active.
The CIB can now be switched on using the power switch on the CIB front panel. The red
power LED should light.
After settling an oscillogram should be generated. The example below shows a typical
difference trace (A-B) that will be obtained from a sensor held in each hand:

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Initial Signal (ECG type) generated by two EPIC sensors, left and right hand.
The software has the following controls:
•Voltage Scale
•Time Base
•Offset
and the following features:
•Data Logging
•Select Signal
•Filter Control
Time Base
This may be adjusted to increase or decrease the time (x) axis of the oscillogram:

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Voltage Scale
This may be adjusted to increase or decrease the voltage (y) axis of the oscillogram:
Offset
This may be adjusted to apply an offset to the voltage (y) axis of the oscillogram:

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Select Signals
The Select Signals check boxes allow the displayed signals to be selected. The signal
options are:
•A-B This is a difference signal between the two sensors, A and B.
•A This is sensor A signal.
•B This is sensor B signal.
None, one, two or all may be selected.
Filter Control
The Filter Control check boxes allow the following digital filters to be applied and modified:
•High Pass (HP) filter
•Comb filter
•Low Pass filter
The effect of these filters may be further modified or adjusted using the Advanced Filter
options tab at the top of the screen:

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These filters are applied to the digitised signal by the local processing of the signals in the
PC. These controls do not adjust or override the internal filtering options of the CIB.
Data Logging
The data logging controls on the soft front panel of the oscilloscope allow the start, stop,
save and clear functions of the data recorder. Further, the Logging Options tab at the top of
the screen provides additional control over the data logging function.

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The data can be saved as a text file that is either comma or tab delimited. The data is
tabulated in the form
0.000 0.008346 -0.008809 -0.018999
0.001 0.009432 -0.008183 -0.019048
0.002 0.010199 -0.007738 -0.018926
0.003 0.010598 -0.007477 -0.018621
0.004 0.010596 -0.007394 -0.018130
The columns represent for following:
Time (s) A-B (V) A (V) B(V)
The data may be opened with a text editor and may be readily processed in a spread sheet.
Below are example graphs made in a spread sheet.

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4.4 Software Shutdown
The CIB software is closed by use of the EXIT button. Once the software is closed the CIB
may be switched off and then the USB connection may be broken.
It is inadvisable to disconnect the USB connection while the CIB software is running.
5.0 Example Applications
5.1 Obtaining an electrocardiogram (ECG) signal:
Start by setting:
•Gain to “x10”
•Low pass “IN”
•Notch filter“IN”
Signal Voltage versus Time
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 1 2 3 4 5 6 7 8
Time /s
Voltage /V
A-B
A
B

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Oscilloscope:
If using an oscilloscope connect the control and interface box differential output to an
oscilloscope using a standard BNC cable, set the time base to 0.5secs/cm and Y gain to
0.5Volts/cm dc coupled.
Virtual instrument:
If using the soft virtual instrument then drag the voltage setting to about 1.5, select
“Differential A-B” from the channel selection and click on the “Start” button, the time axis
should start to scroll.
Switch on the module power and hold one sensor in each hand (hands should be clean and
dry) with the tips of the thumbs resting lightly (do not squeeze) on the contact surface of the
sensor. It is important that both the violet coloured electrode face and outer metal case of
the sensor contact the skin. After a few seconds settling time your ECG should be displayed
by the oscilloscope/PC centred on 0 volts. Everyone’s ECG is different so you may need to
adjust the scope setting/voltage scale for an optimal display; if the ECG appears inverted
swap the sensors over to opposite hands. If you now squeeze the sensor between your
thumb and forefinger you should still see your ECG but the level of baseline noise will
increase noticeably; this is an electromyogram (EMG) signal caused by nerve impulses to
the muscles in the forearm. The EMG signal can also be seen more clearly by placing both
sensors next to each other on one forearm and then clenching the fist; no ECG signal should
be present and the EMG signal level should increase the harder you clench your fist.
It is also possible to detect the ECG signal through clothing if the subject is wearing a shirt
that is predominantly made of a natural fibre such as cotton. An ECG can be obtained by
holding one sensor over the mid sternum and the other on the left hand side of the chest.
The shape of the signal may be different to the finger tip ECG and will change depending on
the relative positions of the sensors.
It is possible but not recommended to connect the sensors directly to your own equipment.
5.2 Obtaining other physiological signals:
Start by setting:
•Gain to “x10”
•Low pass “IN”

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•Notch filter“IN”
Oscilloscope:
If using an oscilloscope connect the module’s differential output to an oscilloscope using a
standard BNC cable, set the timebase to 0.5secs/cm and Y gain to 0.5Volts/cm dc coupled.
Virtual instrument:
If using the soft virtual instrument then drag the voltage setting to about 1.5 select “Differential
A-B” from the channel selection and click on the “Start” button, the time axis should start to
scroll.
Switch on the module power:
An electrooculogram (EOG) signal can be seen by placing a sensor on each temple, look
straight ahead and wait for the output to stabilise then by looking left then right you should see
a step response as the eyeball moves. Placing the sensors above and below one eye should
enable you to see up and down movement of the eye and also blinking.
It is also possible to detect electroencephalogram (EEG) signals from the head. As these
signals are very small, additional amplification and filtering may be needed. By using
spectrum analysis in conjunction with the EPS system it has been possible to detect alpha
waves within the EEG signal.
It is possible but not recommended to connect the sensors directly to your own equipment.
5.3 Non-Contact ECG on a chair
(extract from Plessey Application Note # 291566)
Start by setting:
•Gain to “x1” (for PS25101 or PS25201/401 sensors) or
•Gain to “x10” (for PS25102 or PS25203 sensors)
•Low pass “IN”
•Notch filter “IN”
•Phase switch“INV” (for all the above sensors)
Connect the DRL output signal to the conductive fabric on the seat of the chair using the
flying lead provided.

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Place the two sensors on the seat back approximately to the left and right of the spine and
mid back.
Virtual instrument:
If using the soft virtual instrument then:
•Select “Differential A-B” from the channel selection.
•Set filters
•High Pass “IN” 8.0 Hz
•Comb “IN” 6 –25 Hz
•Low Pass “IN” 40.0 Hz
•Voltage scale: 10mV or 50mV
•Time base: 0.5s/div
Start the oscillogram. Adjust the gain of the DRL circuit using the gain control on the back
plane of the Control/Interface box. If the gain is too low the ECG signal is lost in the common
mode signal and no net signal can be retrieved. If the gain is too high the system becomes
unstable. There will be an optimum gain when the differential ECG signal is produced. The
soft oscilloscope gain may need to be increased to observe the signal. The position of the
sensors may need to be adjusted to obtain the best signal.
Background
EPIC is a capacitive sensor and so does not rely on ohmic contact to the body for measuring
bio-electrical signals. It therefore has the ability to measure ECG without direct skin contact.
Signals measured on the human body always include a large amount of noise, the major
component of this being 50 or 60 Hz power line noise capacitively coupled to the body from
the mains electricity supply. Measurements such as ECG depend on being able to extract
the small electrophysiological signals from the much larger noise signals.
When using EPIC in “contact mode” for ECG measurement, the subject touches both the
capacitive electrode surface and some metal at the system ground directly with the skin.
This ground reference allows filtering and differential amplification of signals from two
sensors to be effective in removing the mains frequency noise, leaving a high quality ECG
signal.

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Basic configuration for non-contact ECG measurement including capacitively-coupled DRL”
circuit.
In non-contact ECG measurement there is –by definition - no skin contact, and thus no direct
connection can be made between the subject’s body and the system ground. Some other
method of reducing the power line noise is therefore required to enable the ECG signal to be
extracted reliably and accurately. One such method utilises an approach very similar to the
Driven Right Leg (DRL) system that is used for the same purpose in conventional ECG. In
conventional ECG the DRL signal is coupled directly to the patient’s skin; in non-contact
ECG itiscoupledcapacitivelytothe body,throughclothing, via apiece of conductive material
placed –for instance –on the seat or back of a chair. Capacitive coupling of DRL signals is
described by Lim et al 1 and Lee et al2.
1. Settling time –When a subjectfirst sits in the chair and leans againstthe EPIC sensors,
the changes in electric potential will normally send both the sensors and the DRL circuit into
saturation. Because the system contains some large impedances, and hence has some very
long RC time constants, settling times of tens of seconds can be needed before a clean ECG
signal is seen. During this period the signal can either appear very noisy, or be virtually flat,
depending on whether one or both sensors, or the DRL circuit, are “railing”. The subject
should sit still during this time and wait for the circuit to settle, since continually adjusting
position will only make matters worse. Settling times can sometimes be reduced by turning
off the power to the demo box for a few seconds.
2. Clothing –Best results have been obtained when the material between the sensors
and the skin is one or two layers of cotton material. This is therefore recommended as a
starting point for system evaluation. Signals have also been measured successfully through
other materials, including a wool-mix sweater and a polyester fleece in addition to two layers
of cotton material. Examples are shown in figures 6 and 7. If the key parameter of interest
is the “R-R” interval, adjustment of filter settings to reduce or re-centre the signal bandwidth
can give significant improvement in signal quality.
EPIC Sensors in
contact with clothing
Conductive fabric in contact with
clothing, e.g. on chair seat
Output
–
EPIC demo
box