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ROTEX XT: Service & Maintenance Manual - rev. 1.0
11. APPENDIX
11.1. TECHNICAL NOTES ON CARDIO RECEIVERS
The receiver shown in the figure below is equipped with:
• an antenna a, designated the "coil", which receives the signal from the transmitter strap worn by
the user.
• an integrated circuit b, designated the ASIC, which has the function of filtering the analog signal
and generating a pulse train corresponding to the received heart rate.
• two contacts c parallel to the coil, on which a 15 k Ohm resistor is sometimes mounted.
The following paragraphs contain various suggestions regarding the cardio receivers, which may be
useful for improving the reception of the cardio signal.
11.1.1.
ASIC
TYPE OF
The cardio receivers can be equipped with 3 different types of ASIC models, identifiable by the code
marked on the component: MAS, FTC or HRRE. These ASICs are characterized by different
reception ranges and different levels of immunity to noise. Tests have determined that the maximum
reception distances are as follows:
As regards sensitivity to noise, the best ASIC is the HRRE model. This ASIC is also the one
recommended by the manufacturer.
Figure 11.1-1
ASIC
DISTANCE
(cm)
MAS
90
FTC
100
HRRE
85
Page 11.1
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