USER MANUAL SAGA
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Bipolar input channels
The bipolar inputs of SAGA are designed to measure electrophysiological
parameters such as ECG, EMG or EOG, using two electrode connections per bipolar
input. The inputs are configured as a differential amplifier with as output the potential
difference between the two electrodes. Also, here, the amplifier is characterized by
low noise, high common mode rejection and high resolution.
Each input is shielded with the mean of the two input signals. When one of the inputs
falls of, the channel goes in overflow and will show a flat line signal.
Auxiliary input channels
The auxiliary inputs of SAGA are designed to measure physiological parameters that
(may) require a transducer, such as pressure, angle, acceleration, temperature or
skin conductance. The auxiliary inputs are configured as amplifiers with wide input
voltage range to capture the output voltage of the transducers incorporated into
sensor accessories. Additionally, the connectors contain power supply, for
transducers that require electric energy for their operation.
Each auxiliary input connector contains three such amplifiers to accept sensor
accessories with up to three separate transducers, or e.g. a single 3D-
accelerometer. Each connector also contains a sensor identification feature. After
plugging the connector into the SAGA Data Recorder, sensor identification data, and
where appropriate transducer conversion information and calibration data is read out
and made available to the application software. Please refer to the datasheet of your
sensor to see what data is provided to the software.
Tips for obtaining optimal quality data
Placement of device
Mains interference (50/60 Hz) is coming from external sources. This can be many
things. It is a common mistake to state that battery powered devices are not
susceptible to mains interference and devices powered from mains are. Mains
interference can get into your measurement system via multiple ways, for example
if you place your device on a metal table with other electrical equipment on it.
Optimal placement of systems will increase the quality of the acquired data. The
ideal measurement setup is on a non-conducting (wood) or well-earthed table. Mains
cables and power adapters should be placed on the floor or at least not on the same
table as the measurement system.
Patient Ground connection
From all electrodes that are connected for a measurement, the Patient Ground
electrode is the most important one. TMSi recommends to use a (wetted) wristband,
or to clean/prepare the skin as good as possible for optimal skin contact to e.g.
electrode patches. Higher Patient Ground electrode impedance may cause more
mains interference in all of the measurement electrodes.
