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BT48i Heart Rate Sensor User’s Guide
Short description
The Heart rate sensor BT48i provides a simple way to study the heart's function.
Unlike an electrocardiograph (EKG), which monitors the electrical signal of the
heart, this sensor monitors the flow of blood through the veins.
The cardio clip consists of a small infrared LED, which illuminates the tissue and a
light sensitive detector, which detects the amount of light transmitted from the
tissue.
As the heart forces blood through the blood
vessels, the amount of blood changes with time.
The sensor measures the light level transmitted
through the vascular tissue and the corresponding
variations in light intensities that occur as the
blood volume changes in the tissue. The
measured signal is amplified, inverted and
filtered. The sensor is equipped with an
amplification knob that allows amplifying the signal when it is too weak.
The Heart rate sensor can be directly connected to analog BT inputs of CMA
interfaces. The sensor cable BT - IEEE1394 needed to connect the sensor to an
interface is not supplied with the sensor and has to be purchased separately (Order
Code BTsc_1).
Measurement procedure
•
Insert the jack plug from the cardio clip into the jack socket at the side of the
sensor box.
•
Attach the clip to either the fingertip or to the ear lobe. You can also place the
clip on the web of skin between the thumb and index finger.
•
Check if the recorded signal is strong enough. If this is not the case you may use
the amplification knob to amplify the signal.
•
Stay still as any muscle movements will influence the signal.
•
Wait until the signal stabilizes and start recording data.
The recorded pulse waves
show details of the pumping
action of the heart. Example of
a measurement is shown in the
figure. The blood flowing
through the earlobe rises at
the start of the heartbeat. This
is caused by the contraction of
the ventricles forcing blood
into the arteries. In the Coach
program you can determine