IRDC, Part 1: Physical Layer
Vishay Semiconductors
Infrared Data Communication According to IrDA® Standard
Part 1: Physical Layer
What is IrDA?
IrDA is the abbreviation for the Infrared Data Association, a non-profit organization for setting standards
in IR serial computer connections. The following is an
original excerpt from the IrDA Web site
(http://www.irda.org).
Executive Summary
IrDA was established in 1993 to set and support hardware and software standards which create infrared
communications links. The Association's charter is to
create an interoperable, low-cost, low-power, halfduplex, serial data interconnection standard that supports a walk-up, point-to-point user model that is
adaptable to a wide range of applications and
devices. IrDA standards support a broad range of
computing, communications, and consumer devices.
International in scope, IrDA is a non-profit corporation
headquartered in Walnut Creek, California, and led by
a Board of Directors which represents voting membership worldwide. As a leading high technology standards association, IrDA is committed to developing
and promoting infrared standards for the hardware,
software, systems, components, peripherals, communications, and consumer markets.
Industry Overview
Infrared (IR) communications is based on technology
which is similar to the remote control devices such as
TV and entertainment remote controls used in most
homes today. IR offers a convenient, inexpensive and
reliable way to connect computer and peripheral
devices without the use of cables. IrDA connectivity is
being incorporated into most notebook PCs to bring
the most cost-effective and easy to use support available for wireless technologies.
There are few US, European or other international
regulatory constraints.
Manufacturers can ship IrDA-enabled products globally without any constraints, and IrDA functional
devices can be used by international travellers wherever they are, and interference problems are minimal.
Standards for IR communications have been developed by IrDA. In September 1993, IrDA determined
the basis for the IrDA SIR Data Link Standards. In
June 1994, IrDA published the IrDA standards which
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8
includes Serial Infrared (SIR) Link specification, Link
Access Protocol (IrLAP) specification, and Link Management Protocol (IrLMP) specification. IrDA
released extensions to SIR standard including
4 Mbit/s in October 1995. The IrDA Standard Specification has been expanded to include high speed
extensions of 1.152 Mbit/s and 4.0 Mbit/s. This extension will require an add-in card to retrofit existing PCs
with high speed IR, and a synchronous communications controller or equivalent.
In 1995, several market leaders announced or
released products with IR features based on IrDA
standards. These products include components,
adapters, printers, PCs, PDAs, notebook computers,
LAN access, and software applications. In November
1995, the Microsoft Corporation announced it had
added support for IrDA connectivity to the Microsoft
Windows 95 operating system, enabling low-cost
wireless connectivity between Windows 95 based
PCs and peripheral devices.
IrDA's interoperable infrared serial data link features
low power consumption with data speeds up to
4 Mbit/s, allowing a cordless 'walk-up-to' data transfer
in a simple, yet compelling way. Applications are in
both consumer and commercial markets with a universal data connection relevant in the use of docking
and input units, printers, telephones, desktop/ laptop
PCs, network nodes, ATMs, and handheld mobile
peers (PDA meets PDA). Yesterday’s systems with
IR capabilities such as Newton, Omnibook, Wizard
and Zoomer are not easily compatible with each other
or other complementary devices. IrDA is the response
in which many segments of the industry have committed themselves to realizing the opportunity of a general standard providing data links which are noninterfering and interoperable.
The IrDA - Standard
The current IrDA physical layer standard is version
1.4 and includes all changes and add-ons up to VFIR
with 16 Mbit/s. Version 1.4 replaced version 1.3 which
is obsolete as are all former versions from 1.0 to 1.2.
Referring to these versions currently can describe
only historical steps of the IrDA - development.
Document number: 82513
Rev. 1.4, 20-Sep-06
IRDC, Part 1: Physical Layer
Vishay Semiconductors
How IrDA Transmission Works
The transmission in an IrDA-compatible mode (sometimes called SIR for serial IR) uses, in the simplest
case, the RS232 port, a built-in standard of all compatible PCs. With a simple interface, shortening the
bit length to a maximum of 3/16 of its original length
for power-saving requirements, an infrared emitting
diode is driven to transmit an optical signal to the
receiver.
This type of transmission covers the data range up to
115.2 kbit/s which is the maximum data rate supported by standard UARTs (see figure 1). The minimum demand for transmission speed for IrDA is only
9600 bit/s. All transmissions must be started at this
frequency to enable compatibility. Higher speeds are
a matter of negotiation of the ports after establishing
the links.
Higher speeds require special interfaces which operate at 1.152 Mbit/s and use a similar pulse-shortening
process as in the RS232-related mode, but with a
pulse reduction to 1/4 of the original pulse length. The
fastest data rate supported by IrDA is 4.0 Mbit/s (often
called FIR), operating with 125-ns pulses in a 4-PPM
(PPM = Pulse-Position Modulation) mode. The typical
interfaces for the various modes are shown in figure
2. In the following chapter "IrDA Standard - Physical
Layer", the definitions of the IrDA standard are given.
Optical output power and receiver sensitivity are set
to a level where a point-and-shoot activity (r15q) is
sufficient for point-to-point communication, but prevents the pollution of the ambient by straying needless power. Transmission over a distance of at least
1 m is ensured. The detector front end receives the
transmitted signal, re-shapes the signal and feeds it
to the port. The system works in a half-duplex mode
that allows only one transmission direction to be
active at any given time.
For frequencies up to 115.2 kbit/s, the minimum output intensity is defined with 40 mW/sr. For higher
speeds, a higher output intensity of 100 W/sr minimum is used. The sensitivity thresholds are
40 mW/m2 and 100 mW/m2 for SIR and FIR respectively.
The wavelength chosen for the standard is between
850 nm and 900 nm.
An additional IrDA standard was generated in 1997
(voted Feb. 1998) for Control applications, the socalled IrControl standard.
This standard is using the IEC1603-1 sub carrier frequency allocation with a carrier at 1500 kHz. The
transmission capacity is 72 kbit/s. This system has
still some compatibility problems with the SIR/FIR
Document number: 82513
Rev. 1.4, 20-Sep-06
IrDA Standard. One of the disadvantages is that the
detector circuitry is different from the other, baseband system. Therefore, integrating both into one
application is expensive. Using IrControl and SIR/FIR
in one application would imply that two IR hardware
channels must be built-in. The Very Fast IR (VFIR,
min. 16 Mbit/s transfer rate over more than 1 m)
established in 1999.
What do I need to enable
IrDA Transmission?
The simplest way of optical interfacing in the SIR
mode is shown in figure 1. For pulse shaping and
recovery, the Vishay Semiconductors device
TOIM4232 is recommended. The front end including
transmitter and receiver should be realized for example by the integrated transceiver module TFDU4100
or other devices of the 4000 series. The TFDU4100
can also be directly connected to Super I/Os.
A transimpedance amplifier is used in the receiver for
input amplification. Its output signal is fed to the comparator input, whose reference level is adjusted to
efficiently suppress noise and interferences from the
ambient.
Additionally, the digital pulse-shaping circuit must be
inserted for shortening the pulse to be emitted to
1.6 Ps (i.e., 3/16 of the bit length at 115 kbit/s) and
pulse recovery of the detected signal to comply with
the IrDA standard. Only the active low bits (0) are
transmitted.
For the high-speed mode, the TFDU6102 or other
devices from the 6000 series are recommended to be
operated with e.g NSC’s or SMC’s IrDA-compatible
Super I/O circuits. Circuit proposals for the various
modes can be found in our application section. A
block diagram is shown in Figure 2.
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9
IRDC, Part 1: Physical Layer
Vishay Semiconductors
IR output
Pulse shaping
UART16550/ RS232
TOIM4232
Pulse recovery
Transmitter
4000 series
transceiver
Receiver
IR input
17255
Figure 1. Block diagram of one end of the overall SIR link
Up to 115.2 kbit/s
I/O
Output driver
and IRED
1.152 Mbit/s
0.576 Mbit/s
IR transceiver
module
4.0 Mbit/s
Detector
and receiver
IR output
Active output
interface
Active input
interface
IR output
17256
Figure 2. Block diagram of one end of the link for signaling rates up to 4.0 Mbit/s
The IrDA standard documentation can be found on
the IrDA web site http://www.irda.org. The documents
which are public and can be downloaded are shown
on the next page.
The physical layer is responsible for the definition of
hardware transceivers for the data transmission. The
physical layer is therefore discussed in the following
chapters which define the properties of the front end
devices manufactured by Vishay Semiconductors.
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Document number: 82513
Rev. 1.4, 20-Sep-06
IRDC, Part 1: Physical Layer
Vishay Semiconductors
Standards available for public access
and download on www.irda.org
Standards, specifications and guidelines are available under the addresses
http://www.irda.org/standards/standards.asp
http://www.irda.org/standards/guidelines.asp
http://www.irda.org/standards/specifications.asp
The following documents describe the IrDA
Standards:
IrDA SIR Data Specification
(http://www.irda.org/standards/pubs/IrData.zip)
containing
IrDA Serial Infrared Physical Layer Link Specification IrPHY 1.4
(http://www.irda.org/standards/pubs/IrPHY_1p4.pdf)
IrDA Serial Infrared Link Access Protocol (IrLAP)
IrDA Serial Infrared Link Management Protocol
(IrLMP)
IrDA Tiny TP
IrDA Point and Shoot Profile
Test Specification
Document number: 82513
Rev. 1.4, 20-Sep-06
Other available documents
IrDA Financial Messaging (IrFMTM) Point and Pay
Specification
IrDA Financial Messaging (IrFMTM)Test Specification
IrDA IrLAPFast Connect Application Note
IrDA Adapter Application Profile and Test
Specification
IrDA Control Specification
IrDA Infrared Communications Protocol
(IrCOMM 1.0)
IrDA Infrared Tiny Transport Protocol (IrTinyTP 1.1)
IrDA Infrared LAN Access Extensions for Link
Management Protocol (IrLAN 1.0)
IrDA Object Exchange Protocol (OBEXTM) Ver.1.3
IrDA Object Exchange Protocol (OBEXTM) Test
Specification Ver.1.0.1
IrDA Minimal IrDA Protocol Implementation (IrLite)
IrDA Plug & Play Extensions to IrLMP 1.0
IrDA Infrared Mobile Communications (IrMC)
IrDA Infrared Transfer Picture Specifications
(IrTranP)
IrDA Dongle Interface specifications
IrDA Infared for Wrist Watches specification (IrWW)
Serial Port Profile, IrModem Profile and Test Specs
Serial Interface for Transceivers
IrDA Point and Shoot
IrDA Point and Shoot Application Profile
IrDA Point and Shoot Test Specification
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11
IRDC, Part 1: Physical Layer
Vishay Semiconductors
IrDA-Standard - Physical Layer
Specification
In SIR mode, the data is represented by optical pulses
between 1.6 μs and 3/16 of the bit length of the
RS232 data pulse in SIR mode. Pulse-length reduction is also applied in the higher frequency modes.
The limits of the standards are shown in tables 1 and
3. The optical radiant intensity and detector sensitivity
are adjusted to guarantee a point-to-point transmission in a cone of r15qover a distance of at least 1 m.
The radiant intensity and the sensitivity of the front
end can be increased to ensure a transmission over
3 m (see figure 3). Data from the optical interface
standard are documented in tables 2 to 4.
Media Interface Specification
Overall Links
There are two different sets of transmitter/ receiver
specifications. The first, referred to as Standard, is for
a link which operates from 0 to at least 1 meter. The
second, referred to as the Low Power Option, has a
shorter operating range, and is only defined up to
115.2 kbit/s. There are three possible links (see Table
1 below): Low Power Option to Low Power Option,
Standard to Low Power Option; Standard to Standard. The distance is measured between the optical
reference surfaces.The Bit Error Ratio (BER) shall
be no greater than 10-8. The link shall operate and
meet the BER specification over its range.
Signaling Rate and Pulse Duration: An IrDA serial
infrared interface must operate at 9.6 kbit/s. Additional allowable rates listed below are optional. Signaling rate and pulse duration specifications are
shown in table 2.
For all signaling rates up to and including 115.2 kbit/s
the minimum pulse duration is the same (the specification allows both a 3/16 of bit duration pulse and a
minimum pulse duration for the 115.2 kbit/s signal
(1.63 μs minus the 0.22 μs tolerance). The maximum
pulse duration is 3/16 of the bit duration, plus the
greater of the tolerance of 2.5 % of the bit duration, or
0.60 μs.
For 0.576 Mbit/s and 1.152 Mbit/s, the maximum and
minimum pulse durations are the nominal 25 % of the
bit duration plus 5 % (tolerance) and minus 8 % (tolerance) of the bit duration.
For 4.0 Mbit/s, the maximum and minimum single
pulse durations are the nominal 25 % of the symbol
duration plus and minus a tolerance of 2 % of the
symbol duration. For 4.0 Mbit/s, the maximum and
minimum double pulse durations are 50 % of the symbol plus and minus a tolerance of 2 % of the symbol
duration. Double pulses may occur whenever two
adjacent chips require a pulse.
The link must meet the BER specification over the link
length range and meet the optical pulse constraints.
Low Power Low Power
Link Distance Lower Limit, meters
Minimum Link Distance Upper Limit, meters
Standard Low Power
Standard Standard
0
0
0
0.2
0.3
1.0
Table 1: Link Distance Specifications
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Document number: 82513
Rev. 1.4, 20-Sep-06
IRDC, Part 1: Physical Layer
Vishay Semiconductors
UART
Start
Frame
Data Bits
Stop
Bit
0
Bit
0
1
1
0
1
0
UART
0
1
1
Frame
IR Frame
Start
Data Bit
s
Stop
Bit
0
Bit
1
1
0
0
0
1
1
0
1
IR Frame
Bit T ime
Pulse Width = 3/16 Bit Time
17257
Signaling Rate
Modulation
Rate Tolerance
% of Rate
Pulse Duration
Minimum
Pulse Duration
Nominal
Pulse Duration
Maximal
2.4 kbit/s
RZI*)
r 0.87
1.41 μs
78.13 μs
88.55 μs
9.6 kbit/s
RZI*)
r 0.87
1.41 μs
19.53 μs
22.13 μs
19.2 kbit/s
RZI*)
r0.87
1.41 μs
9.77 μs
11.07 μs
38.4 kbit/s
RZI*)
r0.87
1.41 μs
4.88 μs
5.96 μs
57.6 kbit/s
RZI
*)
r0.87
1.41 Ps
3.26 μs
4.34 μs
115.2 kbit/s
RZI*)
r0.87
1.41 μs
1.63 μs
2.23 μs
0.576 Mbit/s
RZI
*)
r0.1
295.2 ns
434.0 ns
520.8 ns
1.152 Mbit/s
RZI*)
r0.1
147.6 ns
217.0 ns
260.4 ns
4.0 Mbit/s
Single pulse
Double pulse
4 PPM
4 PPM
r0.01
r0.01
115.0 ns
240.0 ns
125.0 ns
250.0 ns
135.0 ns
260.0 ns
HHH (1.13)
r0.01
38.3 ns
41.7 ns
45.0 ns
16 Mbit/s
Table 2: Signaling rate and pulse-duration specification
*) RZI = Return to Zero Inverted
Document number: 82513
Rev. 1.4, 20-Sep-06
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13
IRDC, Part 1: Physical Layer
Vishay Semiconductors
1.6 μ s or 3 /16
NRZ
≤ 115.2 kbit/s
RZ I - IR
0.576 Mbit/s
1.15 2 Mbit/s
17258
1/ 4 Bit cell
4.0 Mbit/s
One complete
Symbol
chip 1
chip 2
chip 3
chip 4
Ct = 125 ns
Dt = 500 ns
17259
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14
Data Bit Pair
(DBD)
4PPM Data Symbol
(DD)
00
01
10
11
1000
0100
0010
0001
Document number: 82513
Rev. 1.4, 20-Sep-06
IRDC, Part 1: Physical Layer
Vishay Semiconductors
HHH (1,13) Modulation Code for the 16-Mbit/s VFIR Standard
The HHH (1, 13) modulation code has the following
salient features:
• Code Rate:
2/3 ,
• Maximal Duty Cycle:
1/3 (~ 33 %) ,
• Average Duty Cycle:
~ 26 % ,
• Minimal Duty Cycle:
1/12 (~ 8.3 %) ,
• Run-Length Constraints:
(d, k) = (1, 13) ,
• Longest Run of '10' s:
yyy'000'101'010'101'000'yyy ,
• Chip Rate at Data Rate 16 Mbit/s:
24 Mchips/s ,
• System Clock at Data Rate 16 Mbit/s:
N × 12 MHz (where N t 4).
Document number: 82513
Rev. 1.4, 20-Sep-06
The HHH(1,13) code is a Run Length Limited (RLL)
code that provides both power efficiency and bandwidth efficiency at the high data rate. The signaling
rate of the code is 24 Mchips/s allowing a rise and fall
time of 19 ns. LED on time is further improved by having a 26 % average duty cycle for random data. The
lower duty cycle is achieved by scrambling the incoming data stream. The run length constraints
(d, k) = (1, 13) ensure an inactive chip after each
active chip, i.e. only single-chip-width pulses occur.
This feature allows a source or a receiver to exhibit a
long tail property. To take full advantage of the d = 1
feature of HHH(1, 13) in strong signal conditions,
clock and data recovery circuitry should be designed
to ignore the level of the chip following an active chip
and assume these chips are inactive. The 13 in
HHH(1, 13) denominates that the maximum number
of chips without a signal is 13. That limits the lower
cutoff frequency of the system and optimizes threshold trigger stability in receiver designs. The modulation code is enhanced with simple framesynchronized scrambler/descrambler mechanisms as
defined and described in the IrDA IrPhy 1.4 standard.
While such a scheme does not eliminate worst-case
duty cycle signal patterns in all specific cases, the
probabilities of their occurrence are reduced significantly on average. This leads to a better "eye" opening and reduced jitter in the recovered signal stream
for typical payload data.
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15
IRDC, Part 1: Physical Layer
Vishay Semiconductors
Active Output Interface
The active output interface (IRLED) emits an infrared
signal. Key parameters for this interface, defined by
IrDA physical layer specification are shown in table 3.
A complete specification is available from IrDA.
Data Rates
Type
Minimum
Peak wavelength, Op, Pm
Specification
All
Both
0.85
0.90
Maximum intensity in angular range, mW/sr
All
Std
-
500*)
Low Power
-
500*)
115.2 kbit/s and below
Minimum intensity in angular range, mW/sr
Std
40
-
Low Power
3.6
-
Std
100
-
Low Power
9
-
All
Both
r 15
r 30
All
Both
See table 2
See table 2
-
600
-
40
Above 115.2 kbit/s
Half angle, degrees
Signaling rate (also called clock accuracy)
Rise time tr ,10 % to 90 %,
fall time tf , 90 % to 10 %, ns
115.2 kbit/s and below
115.2 kbit/s to 4.0 Mbit/s
Both
16 Mbit/s
Pulse duration
Optical overshoot, %
Maximum
-
19
See table 2
All
Both
See table 2
All
Both
-
25
115.2 kbit/s and below
Both
-
r 6.5
Edge Jitter, relative to reference clock, % of nominal duration 0.576 and 1.152 Mbit/s
Both
-
r 2.9
Edge Jitter % of nominal chip duration
4.0 Mbit/s
Both
-
r 4.0
16.0 Mbit/s
Std
-
r 4.0
Edge Jitter, % of nominal pulse duration
Table 3: Active output specification
*)For a given transmitter implementation, the IEC 60825-1 AEL Class 1 limit may be less than this.
See section 2.4 above and Appendix A.
Tolerance Field of Angular Emission
The optical radiant intensity is limited to a maximum
of 500 mW/sr and an angle of r 30q to enable the
independent operation of more than one system in a
room. In figure 3, the tolerance field of an infrared
transmitter's emission is shown. A typical far field
characteristic of a transmitter is also shown in this
figure.
Radiant intensity (mW/sr)
550
500
450
400
350
IrDA tolerance field
300
250
200
Typical characteristic
150
100
(V)FIR
50
0
- 90
17260
SIR
- 75
- 60
- 45
- 30
- 15
0
15
30
45
60
75
90
Angle of emission (°)
Figure 3. Tolerance field of angular emission
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Document number: 82513
Rev. 1.4, 20-Sep-06
IRDC, Part 1: Physical Layer
Vishay Semiconductors
Active Input Interface
When a infrared optical signal impinges on the active
input interface (PIN photodiode), the signal is
detected, conditioned by the receiver circuitry, and
transmitted to the IR receive decoder.
Specification
Maximum irradiance in angular range, mW/m
Data Rates
Type
Minimum
Maximum
All
Both
-
500
115.2 kbit/s and below
Low Power
9.0
-
Std
4.0
-
Low Power
22.5
-
Std
10.0
-
All
Both
15
-
4.0 kbit/s and below
Std
-
10
Low Power
-
0.5
Both
-
0.10
2
Minimum irradiance in angular range, mW/m2
Above 115.2 kbit/s
Half angle, degrees
Receiver latency allowance, ms
16.0 Mbit/s
Table 4: Active input specification
Active Input Specification
The following five specifications form a set which can
be measured concurrently:
Maximum irradiance in angular range, mW/m2
Minimum irradiance in angular range, mW/m2
Half-angle, degrees
Bit Error Ratio, (BER)
Receiver Latency Allowance, ms
These measurements require an optical power
source and means to measure angles and BERs.
Since the optical power source must provide the
specified characteristics of the Active Output, calibration and control of this source can use the same
equipment as that required to measure the intensity
and timing characteristics. BER measurements
require some method to determine errors in the
received and decoded signal. The latency test
requires exercise of the node's transmitter to condition the receiver.
Definitions of the reference point etc., are the same as
for the Active Output Interface optical power measurements except that the test head is now an optical
power source with the in-band characteristics (peak
wavelength, rise and fall times, pulse duration, signaling rate and jitter) of the Active Output Interface. The
optical power source must also be able to provide the
maximum power levels listed in the Active Output
Specifications. It is expected that the minimum levels
can be attained by appropriately spacing the optical
source from the reference point.
Document number: 82513
Rev. 1.4, 20-Sep-06
Figure 4 illustrates the region over which the Optical
High State is defined. The receiver is operated
throughout this region and BER measurements are
made to verify the maximum and minimum requirements. The ambient conditions of A.1 (page 20) apply
during BER tests; BER measurements can be done
with worst case signal patterns. Unless otherwise
known, the test signal pattern should include maximum length sequences of "1"s (no light) to test noise
and ambient, and maximum length sequences of "0"s
(light) to test for latency and other overload conditions.
Latency is tested at the Minimum Irradiance in angular Range conditions. The receiver is conditioned by
the exercise of its associated transmitter. For rates up
to and including 1.152 Mbit/s, the conditioning signal
should include maximum length sequences of "0"s
(light) permitted for this equipment. For 4.0 Mbit/s
4 PPM operation, various data strings should be
used; the latency may be pattern dependent. The
receiver is operated with the minimum irradiance levels and BER measurements are made after the specified latency period for this equipment to verify
irradiance, half angle, BER and latency requirements.
The minimum allowable intensity value is indicated by
"minimum" in figure 5, since the actual specified value
is dependent upon the data rate, SIR or FIR.
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17
IRDC, Part 1: Physical Layer
Vishay Semiconductors
Low Power Standard and Full Range Operation
The message that a Low Power device must be a
special design is often propagated, but is incorrect.
Full standard devices can be operated easily with
reduced IRED drive current to fulfill the low power
specification. However, devices specially designed
for Low Power applications with low profile package
are not able to cover the full standard because of limited efficiency and little drive current capability.
Irradiance (or Incidence) (W/m 2 )
(Vertical axis is not drawn to scale)
5 kW/m 2
Undefined Region
Optical
Undefined Region
High
State
minimum
- 30
17261
- 15
0
15
30
Angle (Degrees)
Figure 4. Optical High State Acceptable Range
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Document number: 82513
Rev. 1.4, 20-Sep-06
IRDC, Part 1: Physical Layer
Vishay Semiconductors
Transmission Distance
From figure 5, the transmission distance as a function
of the sensitivity (necessary irradiance on the detector) can be read. For example: Sensitivity given as a
minimum irradiance on the detector of 40 mW/m2,
combined with an intensity of 40 mW/sr, results in a
transmission distance of 1 m. A combination of a
detector with a minimum irradiance of 10 mW/m2 and
an emitter with 250 mW/sr can transmit over almost
five meters. Vishay Semiconductor transceivers work
well with standard remote control receivers and can
therefore be operated as remote control transmitters.
The physical layer properties of the devices are
defined under ambient conditions listed in an appendix which has been reprinted in the following chapters.
107
Ie = 500 mW/sr
Ie = 240 mW/sr
106
Ie = 100 mW/sr
Ie = 40 mW/sr
105
Irradiance (mW/m 2)
IrDA FIR Standard specified sensitivity
IrDA SIR Standard specified sensitivity
104
Remote Control, guaranteed sensitivity
Remote Control, typical sensitivity
103
102
101
100
10-1
10-2
0.01
0.1
1
Distance (m)
10
100
17262
Figure 5. IrDA and Remote Control maximum transmission distance. For Remote Control
receivers operating with IrDA transmitters a sensitivity of 0.7 mW/m2 can be assumed.
Document number: 82513
Rev. 1.4, 20-Sep-06
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19
IRDC, Part 1: Physical Layer
Vishay Semiconductors
Appendix A. Test Methods
Note - A.1 is Normative unless otherwise noted. The
rest of Appendix A and all of Appendix B are Informative, not Normative {i.e. it does not contain requirements, but is for information only}. Examples of
measurement test circuits and calibration are provided in IrDA Serial Infrared Physical Layer Measurement Guidelines.
A.1. Background Light and Electromagnetic Field
There are four ambient interference conditions in
which the receiver is to operate correctly. The conditions are to be applied separately:
• Electromagnetic field: 3 V/m maximum (Refer to
IEC 61000-4-3. test level 2 for details) (For
devices that intend to connect with or operate in
the vicinity of a mobile phone or pager, a field of
30 V/m with frequency ranges from 800 MHz to
690 MHz and 1.4 GHz to 2.0 GHz including 80 %
amplitude modulation with a 1 kHz sine wave is
recommended. Refer to IEC 61000-4-3 test level 4
for details. The 30 V/m condition is a recommendation; 3 V/m is the normative condition.)
• Sunlight: 10 kilolux maximum at the optical port
This is simulated with an IR source having a peak
wavelength within the range 850 nm to 900 nm
and a spectral width less than 50 nm biased to provide 490 μW/cm2 (with no modulation) at the optical port. The light source faces the optical port.
This simulates sunlight within the IrDA spectral
range. The effect of longer wavelength radiation is
covered by the incandescent condition.
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• Incandescent Lighting: 1000 lux maximum. This
is produced with general service, tungsten filament, gas-filled, inside-frosted lamps in the
60 Watt to 150 Watt range to generate 1000 lux
over the horizontal surface on which the equipment under test rests. The light sources are above
the test area. The source is expected to have a filament temperature in the 2700 to 3050 degrees
Kelvin range and a spectral peak in the 850 nm to
1050 nm range.
• Fluorescent Lighting: 1000 lux maximum This is
simulated with an IR source having a peak wavelength within the range 850 nm to 900 nm and a
spectral width of less than 50 nm biased and modulated to provide an optical square wave signal
(0 μW/cm2 minimum and 0.3 μW/cm2 peak amplitude with 10 % to 90 % rise and fall times less than
or equal to 100 ns) over the horizontal surface on
which the equipment under test rests. The light
sources are above the test area. The frequency of
the optical signal is swept over the frequency
range from 20 kHz to 200 kHz. Due to the variety
of fluorescent lamps and the range of IR emissions, this condition is not expected to cover all circumstances. It will provide a common basis for
IrDA operation.
Document number: 82513
Rev. 1.4, 20-Sep-06