Electricity: electrical systems and devices – Safety and protection of systems and devices – Circuit interruption by thermal sensing
Reexamination Certificate
1999-04-07
2001-11-20
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Circuit interruption by thermal sensing
C361S115000, C361S695000
Reexamination Certificate
active
06320734
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention generally relates to communication devices, and more particularly to a digital multiplex radio communication device which transmits and receives an STM (synchronous transfer mode) multiplex radio signal over an SDH (synchronous digital hierarchy) network. The digital multiplex radio communication device is linked to the SDH network by plural working channel lines and a protection channel line.
(2) Description of the Related Art
The framework and specifications of the synchronous digital hierarchy (SDH) network interface have been provided by the ITU-T (International Telecommunication Union- Telecommunication Standardization Sector). Recently, attention is being given to the use of the SDH (synchronous digital hierarchy) network for public switched communication networks.
FIG. 17
shows a conventional digital multiplex radio communication device
10
. This communication device
10
is installed in, for example, an in-house space of a base-station site. The conventional digital multiplex radio communication device
10
transmits and receives an STM-based multiplex radio signal over an SDH network, and it is linked to the network by “N” channel lines, the “N” channel lines including “N−1” working channel lines and a protection channel line (where N is an integer).
As shown in
FIG. 17
, the conventional digital multiplex radio communication device
10
generally has a frame
11
, a common component
12
, a transmitter component
13
, a receiver component
14
, a control component
15
, a modulation/demodulation component
16
, and a power supply component
17
.
As shown in
FIG. 17
, the frame
11
includes a front surface and a back surface. The common component
12
is arranged at an upper portion of the back surface of the frame
11
. The transmitter component
13
, the receiver component
14
, the control component
15
, the modulation/demodulation component
16
, and the power supply component
17
are arranged, in this order, on the front surface of the frame
11
in a vertical downward direction of the communication device
10
.
The common component
12
includes a plurality of filters
20
, and the filters
20
are arranged in a horizontal left-to-right direction of the communication device
10
. Each of the filters
20
has an output connected to an antenna (not shown).
A shelf
27
having a plurality of shelf stages is attached to the frame
11
. The transmitter component
13
includes a number of transmitter boards
21
, corresponding to the “N” channel lines, and the transmitter boards
21
are arranged in the uppermost shelf stage of the shelf
27
in the horizontal left-to-right direction of the device
10
. Similarly, the receiver component
14
includes a number of receiver boards
22
, corresponding to the “N” channel lines, and the receiver boards
22
are arranged in one of the shelf stages of the shelf
27
in the horizontal left-to-right direction of the device
10
. The control component
15
includes a number of control boards
23
, corresponding to the “N” channel lines, and the control boards
23
are arranged in one of the shelf stages of the shelf
27
in the horizontal left-to-right direction of the device
10
. The modulation/demodulation component
16
includes a number of modulation boards
24
and a number of the demodulation boards
25
, both corresponding to the “N” channel lines, and the modulation and demodulation boards
24
and
25
are arranged in one of the shelf stages of the shelf
27
in the horizontal left-to-right direction of the device
10
. The power supply component
17
includes a number of power supply boards
26
, corresponding to the “N” channel lines, and the power supply boards
26
are arranged in the lowermost shelf stage of the shelf
27
in the horizontal left-to-right direction of the device
10
.
In the communication device
10
of
FIG. 17
, a group of the transmitter board
21
, the receiver board
22
, the control board
23
, the modulation board
24
, the demodulation board
25
and the power supply board
26
is provided for every channel line. Since the communication device
10
is linked to the network by the “N” channel lines, it is necessary that the communication device
10
includes “N” groups of these elements.
Further, in the communication device
10
of
FIG. 17
, the transmitter board
21
, the receiver board
22
, the control board
23
, the modulation board
24
, the demodulation board
25
and the power supply board
26
, included in each group, are interconnected by a cable or a wire back board (not shown). Further, a number of pipe cables
28
, corresponding to the “N” channel lines, are provided to respectively connect the filters
20
of the common component
12
and the transmitter boards
21
of the transmitter component
13
. A number of pipe cables
29
, corresponding to the “N” channel lines, are provided to respectively connect the filters
20
of the common component
12
and the receiver boards
21
of the receiver component
14
. Each of the pipe cables
28
is connected at one end to one of the transmitter boards
21
by using a nut, and connected at the other end to one of the filters
20
. Each of the pipe cables
29
is connected at one end to one of the receiver boards
22
, and connected at the other end to one of the filters
20
.
The communication device
10
of
FIG. 17
employs a natural air-cooling, and the transmitter boards
21
, the receiver boards
22
, the control boards
23
, the modulation boards
24
, the demodulation boards
25
and the power supply boards
26
are arranged in a somewhat scattering manner. The communication device
10
does not take any measure to effectively cool the heat-radiating boards in the frame, such as the power supply boards
26
, during operation. It is difficult that only the natural air-cooling maintains the communication device
10
in a good heat-radiation condition during operation.
As the communication device
10
must include the “N” groups of the transmitter boards
21
, the receiver boards
22
, the control boards
23
, the modulation boards
24
, the demodulation boards
25
and the power supply boards
26
in order to install the base-station equipment for each of the “N” channel lines, and the communication device
10
requires a comparatively wide area of the in-house space of the site to install the base-station equipment for each of the “N” channel lines. However, in the case of the communication device
10
, the capacity of the frame
11
to accommodate these boards is limited to the equipment for the four channel lines. For example, when the installation of the seven channel lines on the site of the user is needed for desired base-station equipment, it is necessary to install two digital multiplex radio communication devices
10
mentioned above. Hence, the cost of the base-station equipment in such a case becomes high, which may cause the user to face a difficulty in installing the desired base-station equipment.
Moreover, in the communication device
10
of
FIG. 17
, the “N” groups of the transmitter boards
21
, the receiver boards
22
, the control boards
23
, the modulation boards
24
, the demodulation boards
25
and the power supply boards
26
are arranged in the scattering manner. When a malfunction in the communication device
10
occurs, it is necessary to disassemble the communication device
10
into various boards, in order to find out a defective board in the communication device
10
, replace it with a new board, and confirm that the communication device
10
regains a normal operation by the replacement. Before the transmitter boards
21
and the receiver boards
22
are removed from the shelf
27
, it is necessary to loosen the nuts by using a tool and disconnect the pipe cables
28
and
29
from the transmitter boards
21
and the receiver boards
22
. Hence, the communication device
10
requires much expense in time and effort to recover the communication device
10
from the malfunction.
SUMMARY OF THE INVENTION
An ob
Iwahashi Yasuo
Kiyanagi Hiroyuki
Shibuya Yasuhiro
Sonobe Hideki
Suzuki Toshiaki
Fujitsu Limited
Jackson Stephen W.
Rosenman & Colin LLP
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