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Suitable Data Format
The circuit of the TSOP17.. is designed in that way that
unexpected output pulses due to noise or disturbance
signals are avoided. A bandpassfilter, an integrator
stage and an automatic gain control are used to
suppress such disturbances.
The distinguishing mark between data signal and
disturbance signal are carrier frequency, burst length
and duty cycle.
The data signal should fullfill the following condition:
Â• Carrier frequency should be close to center
frequency of the bandpass (e.g. 38kHz).
Â• Burst length should be 10 cycles/burst or longer.
Â• After each burst which is between 10 cycles and 70
cycles a gap time of at least 14 cycles is neccessary.
Â• For each burst which is longer than 1.8ms a
corresponding gap time is necessary at some time in
the data stream. This gap time should have at least
same length as the burst.
Â• Up to 1400 short bursts per second can be received
Some examples for suitable data format are:
NEC Code, Toshiba Micom Format, Sharp Code, RC5
Code, RC6 Code, RÂ–2000 Code, Sony Format
When a disturbance signal is applied to the TSOP17..
it can still receive the data signal. However the
sensitivity is reduced to that level that no unexpected
pulses will occure.
Some examples for such disturbance signals which
are suppressed by the TSOP17.. are:
Â• DC light (e.g. from tungsten bulb or sunlight)
Â• Continuous signal at 38kHz or at any other
Â• Signals from fluorescent lamps with electronic
ballast (an example of the signal modulation is in the
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18.03.2006, 15:54 Uhr
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