| Q2-1 |
Is infrared communication affected by rain or snow ? |
| A2-1 |
Communication distance is decreased when infrared is absorbed and scattered by rain drop, snow and fog. But there is no problem in general area because all weather usage is considered in system design. The influence of rain is relatively small compared with snow and fog. |
| 2-1 |
In the case of rain, snow and fog the communication distance is decreased
because infrared is absorbed and scattered and the propagation rate is
decreased. Moreover the propagation rate is affected by the amount of rain
and snow per hour. In the case of fog the situation is the same. But there
is no problem in general area because the communication distance in the
specification of any manufacturer is designed with the consideration of
all weather usage. For example in the area of deep fog the communication
distance will be decreased, but there is no problem in the range within
the specified distance. |
| Q2-2 |
Is the license necessary for infrared communication ? |
| A2-2 |
The license is not necessary. Therefore infrared communication is immediately enable to be used after setting. |
| Q2-3 |
What happens when infrared is interrupted by walking person ? |
| A2-3 |
There is no problem in the case of the interruption by walking person. But the communication is impossible when the interruption is continued. Please take care of the setting place. |
| 2-3 |
Interrupted packet data is lost because the line is equivalent to be cut
off. But the signal is automatically repeated after the removal of interruption
by the function of the upper layer. However there is the case that the
connection is released by time-out setting of used OS or network. There
is no problem in the case that the interruption is less than 1 minute. |
| Q2-4 |
Is there any influence when bird passes across the transmission path ? |
| A2-4 |
Even if bird passes across the transmission path, there is no problem practically
because there is repeat function in the network. |
| 2-4 |
Practically there is no problem in infrared communication. In the receiving
point the diameter of infrared beam is about 2m and there is no influence
because only a portion of the beam is shielded. When the transmitting point
is interrupted by bird, data is lost instantaneously. But there is no problem
because of repeat function. |
| Q2-5 |
Is infrared communication usable for now-using personal computer ? |
| A2-5 |
Personal computer is not needed to be exchanged. But peripheral equipment
is needed when it is connected to the network first. |
| 2-5 |
Equipment is not needed to be exchanged or added if Local Area Network
based on 10BASE-T (Ethernet) is deployed in office. Moreover Network Interface
Card and Hub are usable without modification. |
| Q2-6 |
What equipment is needed in addition ? |
| A2-6 |
Infrared transmitter, infrared receiver, LAN card and USB-connection box
are needed. Please make a contact to the manufacturer for the detailed
information. |
| Q2-7 |
Is there any influence of the sunshine for the outdoor use ? |
| A2-7 |
When the sunshine is received by the receiving element, the receiving circuit
is saturated and the operation is impossible because of the high power
of the sunshine. Please take care not to receive the direct sunshine by
the method that for example the equipment is not set at the direction of
east and west or the shielding panel is attached. |
| Q2-8 |
Is there any influence of fluorescent lamp and incandescent lamp ? |
| A2-8 |
There is no problem if the direct light is not received at the receive part. |
| Q2-9 |
Is it usable through the window glass ? |
| A2-9 |
It is usable through the window glass. |
| 2-9 |
It depends on the characteristics of the glass and the path-direction.
It is generally usable because of low loss of infrared if window glass
is almost colorless and transparent. Infrared communication between two
buildings through window glass is possible because the spectrum of used
infrared is near by the visible light if the space between buildings is
visible by our eyes. We recommend that laser beam is set perpendicularly
or at 45 degree against the surface of glass because there is the influence
of angles of incidence and reflection in the case that rain drops are stuck
on the glass. |
 |
Infrared reduction rate depending on the kinds of window glass
- ordinal glass (4.7mm thick) = about 18%
- mirror glass (5.8mm thick) = about 40%
- frosted glass (3.8mm thick) = about 30%
Reduction rate 18% means that the light 100% is reduced to the light 82%. |
|
| Q2-10 |
Where is it effective in indoor use ? |
| A2-10 |
- the place where the layout is changed frequently and the electromagnetic interference against precise equipment and medical equipment is worried.
- Example : hospital, laboratory, airport
- the place where the layout is changed frequently and the leakage of information
is worried.
- Example : government and municipal offices, local autonomy, position managing personal information for example school, position managing secret data in general company
- the place where the layout is expected to be changed easily and economically.
- Example : school, exhibition hall
|
| 2-10 |
Infrared has the sharp directivity because of the short wave length compared
with radio wave. Infrared communication system is getting sunshine because
of its characteristics. It is very effective in hospital where electro-sensitive
medical equipment is used and in laboratory where electro-sensitive precise
equipment is used. And high quality information can be transmitted in and
between buildings in overcrowded information city because there is no interference
against radio signal. Moreover it is effective in the place where high
security is requested and the place where personal information and important
company information are handled. |
| Q2-11 |
Where is it effective in outdoor use ? |
| A2-11 |
It is effective in the case that network is deployed over river or railway
and in the case of restoration of disaster because the construction is
easy. |
| 2-11 |
It is effective in the case that the restriction is severe on network route,
for example the cross over river where the authorization of construction
is difficult, the route between offices where the deployment is difficult
because there is road or railway between them, the network between public
institution and regional information center or museum. Moreover it is effective
as the permanent service tool for the access network of school internet
because the running cost is hardly needed. |
| Q2-12 |
What is the take-care point in the indoor setting ? |
| A2-12 |
The setting place must be selected so that the beam is not interrupted. |
| 2-12 |
The system must be set where the beam is not interrupted by obstacles on
the line of sight and the beam is not reduced by steam or smoke. The consideration
is needed not to receive the direct sunshine or the reflected beam by the
receiving element, for example the system is not deployed at the direction
of east and west or the shielding panel is attached. |
| Q2-13 |
What is the take-care point in the outdoor setting ? |
| A2-13 |
It should be set at the strongest place of the building and the structure.
It is the most suitable where the shaking or the temperature change is
minimum and the unauthorized person can not enter. It is generally suitable
at the inside of the handrail around the roof or at the wall of the roof-tower.
If it is wooden house, the equipment with the protection against the influence
of temperature and shaking is suitable, for example the equipment with
large beam diameter or automatic axis adjuster. |
icsa@arib.or.jp