Disturbance Sources Receivers remote control systems must have hi

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Disturbance Sources
Disturbance Sources
Receivers remote control systems must have high sensitivity ready receive signal time. This operating environment also means that they susceptible different kinds disturbance signals. Vishay receivers internal gain optimum sensitivity level such that there unwanted output pulses noise also such that sensitivity high possible data signal. Some commonly found disturbance signals described below. design devices ensure that sensitivity above 1050 drops sharply possible. silicon photo detector therefore receives only limited band from original spectrum "white" light source.
FLUORESCENT LAMPS
spectral emission fluorescent lamps rather complicated. Very little radiation emitted infrared. total spectral emission combination relatively broadband emission from luminescent phosphor spectral peaks emitted from different gaseous components filling tubes. radiation activated luminescent materials mainly visible wavelength band almost light. affect this radiation receivers therefore insignificant. However, direct emission discharge lamp carries modulated signal lamp ballast. portion optical spectrum fluorescent lamp shown expanded figure This part spectrum looks similar typical fluorescent lamps. main disturbing energy Mercury line 1014
LIGHT SOURCES
main light sources found remote control environments sunlight tungsten (incandescent) bulbs. These kind disturbance sources will cause current detector inside module, which turn will produce white noise receiver circuit. negative influence such light reduced optical filtering. Light visible range (400 nm), almost completely removed optical cut-off filter Therefore, only longer wavelength radiation above detected. Special measures were also taken
Radiation emitted typical fluorescent lamp
Normal Irradiation
1000 1050 1100
17058
Wavelength (nm)
Fig. Spectral Emission Fluorescent Lamps
impact light coming from fluorescent lamps receiver very different depending ballast which driving lamp.
Document Number: 80072 Rev. 1.5, 21-Apr-09
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Disturbance Sources
Disturbance Sources
Irradiance
17059
Time (ms)
Fig. Radiated Signal from Fluorescent Lamp with Coil Ballast
signal waveforms four different kinds lamp ballast shown following diagrams. signal shown figure comes from fluorescent lamp with coil ballast, which operated power line frequency. There impact Vishay's receivers ignition pulses. However, some lamps also show higher frequency
components (e.g. figure first power line cycle: kHz). These components interfere with data signal even cause unexpected output pulses with receivers that well designed. different kind disturbance signal caused fluorescent lamps with electronic ballast.
Irradiance
17060
Time (ms)
Fig. Radiated Signal from Fluorescent Lamp with Modulated Electronic Ballast
Typically frequency optical disturbance signal such lamps range between kHz. optical frequency always twice electrical frequency driver circuit lamp ballast. Vishay receiver modules easily suppress disturbance signal shown figure There will unwanted output pulses
such lamps. However, receiver sensitivity will reduced proportion strength disturbance signal. More critical electronic ballasts with higher modulation oscillating amplitude. examples such kind lamps shown figure figure
Irradiance
17061
Time (ms)
Fig. Radiated Signal from Fluorescent Lamp with Strongly Modulated Electronic Ballast power line frequency)
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Document Number: 80072 Rev. 1.5, 21-Apr-09
Disturbance Sources
Disturbance Sources
21494
Irradiance
Time (ms)
Fig. Radiated Signal from Dimmed Backlighting
Such strongly modulated disturbance signals have waveform similar bursts data signal. Hence, almost receivers will produce output pulses these disturbance signals. However, many Vishay receiver modules will suppress even this signal (see table
These receiver modules will evaluate such strongly modulated signals disturbance will reduce internal gain accordingly. They still capable receiving remote control signal lower range than without disturbance signal.
TABLE DISTURBANCE PULSES FLUORESCENT LAMPS OTHER NOISE SOURCES
AGC1 EXAMPLES RECEIVER TYPES TSOP41xx TSOP341xx TSOP581xx TSOP381xx AGC2/8 TSOP12xx TSOP48xx TSOP348xx TSOP362xx AGC3 TSOP343xx TSOP383xx TSOP353xx TSOP753xx noise suppressed noise suppressed disturbance pulses disturbance pulses suppressed most cases noise suppressed noise suppressed noise suppressed AGC4 TSOP24xx TSOP344xx TSOP584xx TSOP854xx
Signal from fluorescent lamp figure suppressed most cases Signal from fluorescent lamp figure Signal from fluorescent lamp figure Signal from fluorescent lamp figure Signal from plasma displays
DISTURBANCE ELECTROMAGNETIC INTERFERENCE
main influence from cathode tube (CRT) affecting receiver comes from electro magnetic interference (EMI). closer receiver CRT, stronger interference. resistance heavily determined selecting suitable location receiver set. influence receivers mainly caused raster scanning, deflection frequencies their harmonics. These frequencies 15.625 (625 25)/31.25 15.75 (525 30)/31.5 kHz. disturbance signal caused deflection does have constant amplitude, modulated depending pattern screen. There exist critical patterns, which produce signal which similar remote control burst signal. During normal operation, these patterns normally short duration cause only temporary disturbance (producing unwanted output pulses receiver output). However, fixed picture (e.g. test pattern screen shown during programming makes critical signal, then impact receiver more serious. there continuous disturbance pulses output receiver, then
Document Number: 80072 Rev. 1.5, 21-Apr-09
longer controllable remote control. Vishay TSOP receiver modules have kinds countermeasures against interference; internal metal shielding Automatic Gain Control (AGC). internal metal shielding effective protection against because metal shield situated very close sensitive photo diode. Being inside plastic package, shielding remains invisible user shiny reflection behind front panel appliance. will suppress remaining influence from using same mechanism described disturbance from fluorescent lamps. will reduce gain receiver until spurious pulses present output. receiver with AGC4 AGC3 have lowest probability spurious pulses caused pattern. internal metal shielding Vishay's receivers good also protection against other frequency sources, such switch mode power supplies, motor drives, vacuum fluorescent displays, etc. circuit design makes Vishay receivers robust against high frequency sources, such mobile phones, wireless phones, wireless antennas, etc.
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Disturbance Sources
Disturbance Sources
17063
Fig. Internal Metal Shielding against
SUPPLY VOLTAGE DISTURBANCE
further negative influence TSOP receiver modules come from noise supply voltage. Such disturbance caused switching power supply which well filtered, other digital circuits which produce spikes supply line. contrast other receiver, Vishay's devices have internal voltage stabilisation. Hence performance receiver modules hardly affected ripple supply voltage long amplitude less than
TSOP receiver
application circuit figure filters supply voltage that transient spikes ripply attenuated. This might useful protect receiver from electrical overstress maintain reiliable function case very strong ripple. resistor optionally used steeper slope output rising edge required. Each Vishay receivers type available supply voltages range between Please product matrix more details.
Supply voltage
0.22
17064-1
Fig. Application Circuit with Filter Supply Voltage Ripple
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Document Number: 80072 Rev. 1.5, 21-Apr-09

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