Telephonic communications – Repeater
Reexamination Certificate
2002-11-26
2004-09-28
Isen, F. W. (Department: 2654)
Telephonic communications
Repeater
C361S730000
Reexamination Certificate
active
06798878
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to passively cooled repeater housings for use in a telecommunication network's wire transmission local loop outside plant and more specifically to repeater housings having improved thermal transfer characteristics, improved performance under solar loads and direct access to repeaters and voltage surge protectors.
2. Description of the Related Art
In the telecommunications industry, voice, data and video transmission signals are transmitted over wire, fiber optic and wireless networks. Although the fiber optic and wireless networks were designed to meet the current demand for high speed signal transmission, the massive investment in the wire network, or the “copper plant” as it is commonly referred to, necessitates its continued use. The cost and time involved to completely replace the millions, if not billions, of miles of copper (or aluminum) wires in the United States alone with fiber optic lines and wireless networks is prohibitive. Although originally designed to carry only voice grade signals, the continued development of increasingly sophisticated digital signal processing (DSP) techniques such as T-carrier, ISDN, Direct Digital Service (DDS) and most recently, High bit-rate-Digital Subscriber Line (HDSL) allow the telecommunications industry to transmit rapidly growing volumes of high speed signals over the copper plant in a more cost effective manner than conversion to the newer transmission technologies in all but the high volume networks.
As shown in
FIG. 1
, a typical telecom network
10
includes number of central offices
12
that transmit a massive amount of very high speed signals between offices over inter-office trunks
14
and a number of local loops
16
that distribute portions of the signals from a central office
12
to a customer premises
18
and between customer premises
18
. A clear distinction has existed between the offices' inter-office trunks
14
and the local loops
16
. First, each central office will typically service many user premises. As a result, the cost of replacing the copper plant for the central offices' inter-office trunks is much lower than replacing it for all the individual users. Second, the signal traffic between central offices is typically much higher volume and much higher speed than is required, in the local loop.
As a result, inter-office trunks
14
have bean largely converted from copper wire to the more sophisticated fiber optics, microwave transmission and even satellite transmission systems while the local loops have used the updated DSP technologies in conjunction with the existing and even new installation copper
20
. However, for the last several years, the explosive growth in demand for high speed telecommunications services such as those required for business networking and the Internet has been stressing the capabilities of the copper network in the local loop.
One particular area in which the copper network is being stressed occurs in the “outside plant”, i.e. that part of the local loop that lies outside the controlled environments of telecom or user buildings, generally regarded as the lowest technology link in the network and symbolized by the lineman on a pole or in a manhole.
As signals are transmitted over the copper wires in the outside plant they degrade and lose signal integrity. As a result, the industry has developed circuits called “mid-span repeaters” or simply “repeaters” that regenerate a degraded signal. Depending upon the transmission technology used, the repeaters are placed every three to twelve thousand feet along the transmission path.
Repeaters are manufactured by numerous suppliers to support a variety of copper transmission technologies. Several industry standard connector and case standards are followed to allow repeaters from different suppliers and of different technologies to be interchanged.
FIGS. 2
a
and
2
b
illustrate a standard 239 mini-repeater
22
often used with older T-1 technology and a standard 239 double-wide repeater
24
that is commonly used with the ISDN, DDS and HDSL technologies. The T-1 239 mini-repeater generates approximately 0.75 watts of waste heat whereas an HDSL 239 double-wide, while only twice as big, generates up to 6 watts of waste heat. Because of the nearly order of magnitude increase in power consumption, the 239 double-wide is frequently provided with slits that facilitate air flow over the hot parts to convectively remove heat. The power consumption of ISDN and DDS repeaters is also substantially greater than T-1 239 mini-repeaters, but less than that of the more sophisticated HDSL repeaters.
Because mid-span repeaters are used in the outside plant, frequently in manholes
28
, they must be placed in a repeater housing
26
such as the AT&T '809 Apparatus Case
30
shown in
FIGS. 3
a
and
3
b
, the SPC Series 7000 Enclosure
32
shown in
FIGS. 3
c
and
3
d
, or the generic cabinet style enclosure
34
shown in
FIG. 3
e
. The primary function of these known repeater housings is to provide an environmental enclosure that shields the repeaters from the elements; wind, rain, dust, solar energy, animals, vandals etc. They are oftentimes formed from strong corrosion resistant materials such as stainless steel or hard plastic and are hermetically sealed, often under a positive pressure. In mild environments the repeater housing do not have be corrosion resistant and above ground cases are often vented.
The housings must accommodate standard sized repeater modules that are built by a number of vendors. The housings must also provide physical access to repeater modules and voltage surge protectors so that they can be removed and replaced in the field in a “plug-in” manner without having to disassemble the module or disturb the operation of other repeaters. Furthermore, to improve reliability and avoid the expense of requiring electrical power at each repeater site, the housing must be passively cooled to remove the waste heat generated by the repeaters. It is well understood in the telecommunications industry that thermal stress can cause short term failures, intermittent operation deviations and significantly shorten the life of electronic equipment. Most telecom electronics is installed in buildings that provide a controlled and relatively benign thermal environment In contrast, repeaters deployed in the outside plant must work in the harsh, natural environment.
The AT&T '809 apparatus case
30
shown in detail in FIG.
4
and the double size '819 apparatus case described in AT&T Practice 640-525-307 Issue 5 April 1986 is a molded plastic rectangular housing that is lightweight, does not corrode, and optimizes the use of available space. The '819 obsoleted AT&T's earlier '479 apparatus case described in AT&T Practice 640-527-107 Issue 3, March 1986 that had the same general shape but was constructed from cast iron, and thus extremely heavy and subject to corrosion.
The '809 includes a molded base
36
for receiving a stub cable
38
from a splice case in the local loop and a mounting bracket
40
for mounting the case on the wall of a manhole, for example. Pressure and pressure relief valves are also provided in the base. Stub cable
38
is split into individual wires that are run through base
36
and wire-wrapped to the backside of repeater/protector connectors
42
, which have a female PCB edge connector
44
for mounting the repeater module and multiple sockets.
46
for mounting gas tube style voltage surge protectors
48
.
A molded housing
50
having an array of plastic stubs
52
is bolted on base
36
so that stubs
52
define slots
54
over the respective repeater/protector connectors
42
for separating and supporting the repeater modules. A molded cover
56
is then bolted on top of housing
50
. The cover can be removed to gain direct access to the top of the enclosed repeater modules for easy installation and replacement. The illustrated '809 case is designed, physically and electrically, to hold
12
Anacapa Technology, Inc.
Isen F. W.
Storm Donald L.
Westman Champlin & Kelly P.A.
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