Linear COM3000 User manual

Linear Technologie • 11 rue du Puits Rochefort • 42 100 Saint-Etienne
Tél: [phone] • Fax: [phone] • www.lineartech.fr V.2017
INFRARED RECEIVER 8 CHANNELS LC3.IRRC08
Operation manual

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TABLE OF CONTENTS
1. Safety operation
2. System introduction
3. Infrared receiver unit
Page 3
Page 4
Page 9

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1. SAFETY OPERATION
Firstly, thank you very much for using LINEARCOM3000 conference system. To make sure
safety of equipment and user, please read this safety instruction carefully before installing
and using and operate seriously according to this manual. Also please keep this safety
instruction for future reference. Notices are as below :
1. Wiring during installation must follow national electric safety standards, national reproong
regulations and all related local regulations.
2. Protect the power cord from being walked on and do not stack things on the power cord,
particularly at plugs.
3. To make sure earth wire connecting well. Do not use 2 - pin plugs. Power supply : 220V
50 Hz.
4. Power supply cords :
- America, Japan : AC 110V ~ 120V 60 Hz
- Asia, Europe : AC 220V ~ 240V 50 Hz
5. The packaging of equipment is designed for protecting 1.5 meters dropping but please
prevent from stress and shocking during transportation, installation and storing.
6. Do not place the system equipments on too cold or too hot room.
7. Keep good ventilation to protect the machine.
8. Unplug the system during wet weather or when unused for long periods of time.
9. Must unplug the equipment before below operations :
- Taking down or resetting any part on machine
- Reconnecting any plug in system
10. Do not disassemble or maintain the product by non-authorized personnel to avoid
accident or damage. Warning label is as below :
11. Prevent from any chemicals or liquid.
12. Please check all the connections completely before turning on. Check the set-up of main
unit before usage.
13. If you nd top warning label on product, it means : Do not open the machine cover to
avoid electric shock. Also please do not place the useless part in the case. Any trouble,
please contact with the authorized personnel.
CAUTION
RISK OF ELECTRIC
SHOCK
DO NOT OPEN
This symbol is intended to alert the user of the presence of insulated
dangerous voltage within the product’s enclosure that may present
a risk of electric shock
This symbol is intended to alert the user of important operating and
maintenance (servicing) instructions in the literature provided with
the equipment
!

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Brief introduction
LINEARCOM3000 is a series product of digital infrared language distribution system. It uses
both digital infrared audio transmitting and control technique and an IR digital infrared chip.
They own LINEARCOM3000’s intellectual property. IRRC08 can be used in simultaneous
interpretation systems for multi-language conferences.
In simultaneous interpretation systems, the interpreter translates the speaker’s speech, the
translated audio transmits through the conference venue by modulated infrared radiation
and the delegates listen to wanted language by infrared receiver via earphone.
The system can also be used for other audio signal distribution occasions, such as urgent
mode, free mode audio signal output.
This system is compliant to IEC 61603-7 (international standard of digital infrared transmission)
and IEC60914 (conference systems-electrical and audio requirements, same as domestic
standard GB/T 15381-94), moreover, it is compatible with other IR systems, compliant to
IEC 61603-7. Parts of IEC 61603 are used in this manual for a better understanding of both
theory and technique of the system.
2. SYSTEM INTRODUCTION

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System composition
The system consists of a number (N) of audio sources, either analogue or digital, which are
connected to a transmitter. The transmitter processes the audio signals into an electrical
output to feed the infrared radiator. The infrared signal is received by the infrared receiver
that processes the signal and outputs an audio signal and/or associated data.
System radiation signal
IRR25 uses high frequency carrier signals (typically 2~8 MHz) to prevent interference by
modern light sources. Fully digital audio processing guarantees a constant high audio quality.
The signal processing in the main unit consists of the following main steps :
1. Code : Each analogue audio channel is converted to a digital signal; the digital signals are
compressed to increase the amount of information that can be distributed on each carrier
(compression ratio is related to required audio quality); groups of up to 4 digital signals are
combined into a digital information steam. Extra fault algorithm information is added. This
information is used by the receivers for fault detection and correction.
2. Modulation : A high frequency carrier signal is phase-modulated with the digital information
stream by digital wireless base station digital modulation technique.
3. Filter
4. Magnify
5. Radiation : Up to 8 modulated carrier signals are combined and sent to the IR radiators,
which convert the carrier signals to modulated infrared light.
In the IR receivers, a reverse processing is used to convert the modulated infrared light to
separate digital audio channels.

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Carriers
System is transmitting within the 2 ~ 8 MHz frequency band. It can transmit up to 8 di󰀨erent
carrier signals (depending on the transmitter type) Carriers 0 to 5 are according to IEC
61603-7.
Aspects of infrared distribution
A good digital infrared language distribution system ensures that all delegates in a conference
venue receive the distributed signals without disturbance. This is achieved by using enough
and well positioned radiators, so that uniform IR signal with adequate strength can be
received at any place of the conference venue.
When planning an infrared distribution system several aspects inuencing the uniformity and
quality of the infrared signal should be considered. These are discussed in the next sections.
Ambient lighting
IRRC08 can be operated without any problem even if uorescent lamps (with or without
electronic ballast or dimming facility) such as TL lamps or energy saving lamps are switched
on.
For venues with large, unscreened windows, more radiators should be added. For outdoor
use, a site test will be required to determine the required amount of radiators. With su󰀩cient
radiators, the receivers will work well, even in bright sunlight.
Objects, surfaces and reections
Just like visible light, infrared radiation is reected from hard surfaces and refracted by
hyaloid (glassy or transparent appearance) objects. Both objects in the conference venue
and structure of the walls and ceilings will inuence the distribution of infrared light.
Infrared radiation is reected from almost all hard surfaces. Smooth, bright or shiny surfaces
reect well. Dark or rough surfaces absorb a large part of the infrared energy. Normally
surfaces opaque to visible light are also opaque to infrared radiation. Shadows from walls
and furniture will inuence the transmission of infrared light. This can be solved by using a
su󰀩cient quantity of radiators. They should be positioned in a manner to provide an infrared
eld strong enough to cover the whole conference area. Take care not to direct radiators
towards uncovered windows, or most of this radiation will be lost.

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The direction and sensitivity of receiver unit
The sensitivity of a receiver is at its best when it is aimed directly towards a radiator. To
minimize the disadvantage of this aspect, IRRC08 receiver adopts an ingenious structural
design with peculiar 270° ultra wide angle to get perfect IR capture and sound quality at any
disposition.
The coverage area of radiator
The number of transmitted carriers and the output power of the radiator determine the
coverage area of a radiator. The total radiation energy of a radiator is distributed over
transmitted carriers. The coverage area becomes proportionally smaller if more carriers are
used. The receiver requires a strength of the IR signal of 4 mW / m2 per carrier to work well
(resulting in an 80 dB S/N ratio for uninterrupted audio channels)
The cross section of the 3 dimensional radiation with the reception level of participants is
the footprint (the dark grey area in gure 2.9 to gure 2.10) In this area, the direct signal is
strong enough to ensure proper reception when the receiver is directed towards the radiator.
The size and position of the footprint depends on the mounting height and the angle of the
radiator.
Area contrast of di󰀨erent installation height Area contrast between 15º and 45º to the ceiling
Positioning the radiators
Because infrared radiation can reach a receiver directly and / or via di󰀨used reections, it’s
important to take this into consideration when installing the radiators. For best reception
quality, receivers should pick up direct infrared radiation. In addition reections will improve
the signal reception. In big conference halls, infrared signal will be blocked by the people in
front of the receiver. For that reason the radiator should be installed at an appropriate height,
usually not below 2.5 meters.
For concentrically arranged conference venues, radiators located high up and faced to the
center from every angle can cover the area very e󰀩ciently. If the direction of the receiver
changes, e.g. changing seat direction, the radiators can be installed in the corners of the
room.
In the case the seating is always directed towards the IR emitting source, there are no
radiators needed at the back.

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If the path of the infrared signals is blocked, e.g. under balconies, at least one additional
radiator is needed to cover the ‘shaded’ area.
Overlapped footprints and multi-path e󰀨ect
If footprints of two radiators overlap, the total coverage area maybe larger than the sum of
the two separate footprints. In an area with overlap e󰀨ect, the individual radiation signals of
two radiators are added, resulting in an increase of the radiation intensity, larger than the
required intensity.
However, due to the di󰀨erences in the delays of the signals from two or more radiators,
the signals may cancel out each other (multi-path e󰀨ect). In a worst-case situation, loss of
reception at some positions (black spots) may be the consequence.

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Increased coverage area caused by added
radiation power
Reduced coverage area caused by
di󰀨erences in cable signal delay
The lower the carrier frequency, the less susceptible the receiver is for di󰀨erences in signal
delays.
The signal delays can be compensated by adjusting the delay compensation switches on
the radiators.
LINEARCOM3000 infrared receiver unit can receive up to 32 language channels. Both
rechargeable Ni-HM battery and disposable battery can be used. The receiver is equipped
with channel selector, volume control, power switch, Ø 3.5 mm stereo earphone jack. A LCD
displays channel number, received signal intensity, battery capacity and volume.
Function and feature
• Steam line design, accord with clay engineering.
• Adopt full digital conference technology, compliant to IEC61603-7 and IEC 60914
international standard.
• Compatible with the infrared simultaneous interpretation system which is compliant to
IEC61603-7.
• New digital lock function, totally stop outside disturbing and wiretapping.
• Adopt 2-8 MHz, infrared receiver will not be disturbed by high frequency driving light
source.
• 4CH, 8CH, 16CH, 32CH audio channels.
• When without earphone, press «Power» key, LCD could display last channel No and
battery.
• LCD display, can display channel no, signal intensity, volume and battery power.
• It can adjust the volume individually and has 270° reception angle.
3. INFRARED RECEIVER UNIT

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Technical parameter of digital infrared receiver
Channel 8 CH
Modulation mode Digital wireless base station
Carrier frequency 2-8 MHz
Audio processing IR-DSP
Distortion <0.2%
SNR >102 dB
Working voltage 3.7V
Earphone load 320 hm 250 mW
Earphone output 3.5 mm socket x1
ON Plug earphone and press “ON/OFF” key
OFF Disconnect the earphone / no signal shut o󰀨 automatically / press
«Power» key 2 seconds to turn o󰀨 it
OFF delay Disconnect the earphone in 0 second / no signal about 2 minutes
Battery Lithium battery or alkaline battery
Battery life 30 hours
LCD display Channel, signal, power weak reminder
Dimension 155 x 49 x 27 mm
Weight 0.1 kg
Color Black, grey
• Adopt high capacity rechargeable lithium battery. It will have no power consumption
under power o󰀨 or disconnecting earphone.
• In the district of infrared signal, quantity of receivers is unlimited.
• Shield automatically unwork channels; working channel quantity is same as available
channel quantity.
• Channel resolution and SNR reach to 102 dB; it can perfectly resolve crosstalk and noise
ect normal problems. Working with mute function (it will mute automatically, when signal
too lower, have no noise), listeners have comfortable, natural and high quality audio
nishing.
• Receivers have guard function, built-out guard advice equipment.
• 2 hanging modes, gallus mode and clip mode. It can be hold in pocket or hanged, even
taken on desk.
• Extra low power consumption. Can continue to work for 30 hours if you use our original
lithium ion battery. Also you can use alkaline battery.
• A charge box can accommodate 36 / 72 / 108 receivers. Convenient to transport and
carry.
• 3.5 mm stereo earphone output.

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Note : When the receiver is not used, please disconnect the earphone. This ensures that the
receiver is totally switched-o󰀨 and no energy is consumed from the batteries or the battery
pack.
Operation
The receiver only works if an earphone is connected and the receiver switches to stand-
by state. Push shortly on the power switch button to switch on the receiver. The channel
number is shown on the LCD. The channel can be changed with the channel selector.
Channel number is in accordance with the channel conguration set up in the main unit.
When working, battery icon and antenna icon will be displayed on LCD to indicate current
battery and signal status. A battery symbol is visible on the display when the batteries
or the battery pack is almost empty and needs recharging but it still might work for 2 hours.
When the signal is interrupted for a short time, the receiver mutes the earphones output.
If the IR receiver does not get an adequate IR signal for more than 2 minutes (e.g. when a
delegate leaves the conference room), the receiver automatically switches to stand-by state.
The volume can be adjusted and displayed on LCD (the range is from 0 to 31) If the earphone
is disconnected, the receiver is automatically switched o󰀨.
The infrared receivers are operable either with disposable batteries (2 x AA alkaline cells)
or with a rechargeable battery pack. Install the batteries or the battery pack with the correct
polarity, as indicated in the battery compartment. A separate connection cable is required if
a battery pack is used. The charging circuitry will not work if this cable is missing, preventing
thus also charging of disposable batteries by mistake. The battery pack is equipped with a
temperature sensor to prevent overheating during charging.
Infrared receiver schematic diagram
Functions and indications
1. Infrared red ltering glass2
2. LCD
3. Pocket clamp
4. Power switch
5. Charging contacts
6. Earphone jack
7. Volume selector
- “VOLUME+” is volume increasing
- “VOLUME-” is volume decreasing
8. Channel selector
“CHANNEL+” is channel increasing
“CHANNEL-” is channel decreasing
9. Battery box : 3.7V rechargeable battery

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Note : When without earphone, press «Power» key, LCD could display last channel No and
battery.
Testing the coverage area
To make sure that the whole area is covered with adequate IR radiation and avoiding thus
black spots, an extended reception quality test should be done. The test can be done in two
ways :
• Testing during installation
1. Check that all radiators are connected and powered up;
2. Set the main unit in the test-mode. For each channel, a test tone frequency will be
transmitted;
3. Set a receiver to the highest available channel and listen to the received signal
through the headphones;
4. Test all positions and directions.
• Testing all positions and directions
Walk around the conference venue under the test mode of the main unit or the receiver;
test every position where the signal must be received. If an area is detected as having bad
reception or even no reception at all, two main causes should be taking into consideration :
01 bad coverage : The receiver cannot pick-up adequate infrared radiation. This may
be because the tested position is out of the footprint of the installed radiators or the radiation
is blocked by obstacles such as a column, an overhanging balcony or other large objects.
Check whether you used the correct footprints for the system design or not. Check if the
radiators are used which are switched to half power operation by mistake. If bad reception
is caused by a blocked radiation path, try to remove the blocking obstacle or add an extra
radiator to cover the shaded area with more IR energy.
02 black spots : IR signals coming from two radiators may cancel out each other (multi-
path e󰀨ect) when reaching the receiver. Bad reception only happens on some special path.
Multi-path e󰀨ect is conrmed being the cause of bad reception if the bad signal received by
the receiver is improving the instant a radiator is a) changing its direction b) shaded -o󰀨 or
simply switched-o󰀨. IR radiation, reected from a surface with a high reectivity may also
cause multi-path e󰀨ect.
Check that the signal delay compensation switches on the radiators are set to the correct
value. Check the system design. If necessary, reduce the distance between the two radiators
that cause the problem and/or add an extra radiator.
Please note that due to the physical characteristics of the signal distribution, it is not possible
to avoid multi-path e󰀨ects completely.

Linear Technologie • 11 rue du Puits Rochefort • 42 100 Saint-Etienne
Tél: [phone] • Fax: [phone] • www.lineartech.fr