U.S. patent application number 09/883716 was filed with the patent office on 2002-04-11 for method and apparatus for arranging cable connectors to allow for easier cable installation.
Invention is credited to Cloonan, Thomas J., Hickey, Daniel W., Johnson, David R., Mack, Thomas J..
Application Number | 20020042220 09/883716 |
Document ID | / |
Family ID | 24751829 |
Filed Date | 2002-04-11 |
United States Patent
Application |
20020042220 |
Kind Code |
A1 |
Cloonan, Thomas J. ; et
al. |
April 11, 2002 |
Method and apparatus for arranging cable connectors to allow for
easier cable installation
Abstract
A cable modern termination system (CMTS) having front and rear
sides is disclosed. A rear panel receives a plurality of connector
cards. At least one first connector card wherein each first
connector card has a row of connectors. At least one second
connector cards, wherein each second connector card has a row of
connectors, wherein connectors on the first connector cards are
staggered from connectors on the second connector cards when the
connector cards are inserted into the rear panel.
Inventors: |
Cloonan, Thomas J.; (Lisle,
IL) ; Hickey, Daniel W.; (Oswego, IL) ; Mack,
Thomas J.; (Palatine, IL) ; Johnson, David R.;
(Naperville, IL) |
Correspondence
Address: |
Joseph P. Krause
Vedder, Price, Kaufman & Kammholz
222 North LaSalle Street
Chicago
IL
60601
US
|
Family ID: |
24751829 |
Appl. No.: |
09/883716 |
Filed: |
June 18, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09883716 |
Jun 18, 2001 |
|
|
|
09685354 |
Oct 10, 2000 |
|
|
|
Current U.S.
Class: |
439/446 |
Current CPC
Class: |
H01R 24/52 20130101;
H05K 1/14 20130101; H01R 12/721 20130101 |
Class at
Publication: |
439/446 |
International
Class: |
H01R 013/56 |
Claims
We claim:
1. A cable modem termination system (CMTS) having front and rear
sides, comprising: a rear panel for receiving a plurality of
connector cards; at least one first connector card, wherein each
first connector card has a row of connectors; at least one second
connector cards, wherein each second connector card has a row of
connectors, wherein connectors on said first connector cards are
staggered from connectors on said second connector cards when said
connector cards are inserted into said rear panel.
2. The apparatus according to claim 1, wherein said connectors are
staggered so as to optimize the separation between connectors on
adjacent cards.
3. The apparatus according to claim 1, wherein first and second
connector cards are alternately inserted into said rear panel.
4. The apparatus according to claim 3, wherein a connector on a
connector card is approximately equidistant from closest connectors
on adjacent connector cards.
5. A method for arranging cable connectors on a panel of a cable
modem termination system (CMTS) to allow for easier cable
manipulation, comprising the steps of: staggering position of
connectors on a first connector card type with respect to position
of connectors on a second connector card type; and alternately
inserting first and second connector card types into said panel so
as to optimize the separation between connectors on adjacent
cards.
6. The method according to claim 5, wherein a connector on a
connector card is approximately equidistant from closest connectors
on adjacent connector cards.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation-in-part of U.S. patent application
Ser. No. 09/685,354, entitled METHOD AND APPARATUS FOR ARRANGING
CABLE CONNECTORS TO ALLOW FOR EASIER CABLE INSTALLATION filed on
Oct. 10, 2000 by Cloonan, which the prior application is assigned
to Cadant, Inc., the same assignee as in the present
application.
FIELD OF THE INVENTION
[0002] The present invention relates to a method and apparatus for
arranging cable connectors to allow for easier cable
installation.
BACKGROUND OF THE INVENTION
[0003] The world is on the verge of a revolution that promises to
change the way the Internet works and it is guaranteed to change
the way the entire world communicates, works and plays. The
revolution is the introduction of quality of service (QoS) to the
Internet. This QoS revolution is already beginning, because most
computer networking products (switches and routers) have already
added some type of QoS to their feature sets. Unfortunately, there
are many different forms of QoS from which to choose and they are
not all compatible with one another. Different standards committees
(DiffServ, RSVP, MPLS, etc.) are still deciding which of many
different QoS proposals will actually be used in the Internet, and
hybrid solutions will likely be developed in the very near future
that will enable the QoS revolution.
[0004] The change is important, because it will eliminate the
current Internet routing model that provides the same "best effort"
service to all users, all packets, and all traffic flows. When QoS
is enabled in a ubiquitous, end to end fashion across the Internet,
differentiated services will be permitted, and all packets will be
treated differently. High priority packets will be routed with
lower latency and lower jitter, while low priority packets may
experience more delay and jitter. The throughput needs of each
application will determine the priority associated with its
corresponding traffic flows, and it is likely that advanced
application programs of the future will dynamically change the
priority of traffic flows to match the very needs of the user
through the entire duration of the session.
[0005] Since all packets will not be passed using the same priority
level, it follows that all packets cannot be billed using the same
charges in the future either. Future Internet users are likely to
pay differently for different classes of service, and they may even
be billed on a usage basis, e.g., per-minute, per packet, or per
byte, similar to the billing schemes used for long distance
telephone service today. The use of high priority traffic flow for
an application will undoubtedly result in higher Internet usage
costs than the use of low priority traffic flows and service level
agreements (SLAs) between the Internet user and their service
provider will detail the available priority and throughputs in and
their associated costs. These changes in the Internet billing model
represent an incredible revenue generating potential for access
providers that can provide and bill for these new differentiated
services, and multiple system operators (MSOs) are key members of
this group.
[0006] MSOs are positioned in an ideal location within the Internet
to play a major role in the QoS revolution, and they will be able
to capitalize on the resulting changes. This is because the MSOs
are positioned to act as the QoS gatekeeper into the future
Internet. They can perform this function because they have access
to each subscriber's service level contract and can appropriately
mark the priority of all packets that are injected into the
Internet by their subscribers. In fact, the MSOs head end
equipment, the cable modem termination system CMTS is actually the
first piece of trusted equipment not owned by the subscriber to
which subscriber packets must pass on their way to the Internet.
The CMTS is positioned at the head end office and it provides basic
connectivity between the cable plant and the Internet. FIG. 1
illustrates a simplified cable data system with a CMTS 30. The CMTS
30 is connected through Internet link 40 to the Internet 20. The
CMTS 30 is also connected through various cable links 50 to a
plurality of subscribers 60.
[0007] The MSO also provides customer subscription packages and is
able to offer (and bill for) many different subscriber service
levels. In addition, if the CMTS equipment permits it, the MSO will
also be able to offer dynamic service level upgrades to its
subscribers. Features contained within an MSOs CMTS must provide
most of these revenue generating QoS capabilities. This will result
in even greater increases in revenues if the MSOs can maintain
adequate counts on usage of different services levels consumed by
its subscribers.
[0008] As set forth above, this CMTS provides basic connectivity
between the cable plant and the local area network that interfaces
to an edge router on the Internet. The CMTS is responsible for
appropriately classifying, prioritizing, flow controlling, queuing,
scheduling and shaping all the traffic flows between cable data
subscribers and the Internet. As a result, this type of service
experienced by the cable data subscribers will primarily be
determined by the features in the CMTS core.
[0009] When selecting a CMTS for cable data deployment or
expansion, MSOs have several different options from which to
choose. The choice is complicated by a broad spectrum of prices and
features such as reliability levels, ease of use, controllability,
manageability, observability, support for various interfaces,
support for various counts and measurements, support for
proprietary features and feature upgrades, vendor service levels,
etc. The CMTS selection process is even further complicated by the
fact that a particular set of CMTS features that are required in
one head end area may actually be undesirable in a different head
end area because subscriber usage patterns and traffic profiles
within the one region may be entirely different from those in
another region.
[0010] Nevertheless, there is one CMTS feature that will
undoubtedly be desirable and necessary for most of the head end
that almost all of the MSOs as cable data service expands into the
future. This feature is scalability. When referring to the size of
a CMTS, the term scalable can be assigned two different meanings.
According to one definition, a scalable CMTS should allow growth
along a graduated path from very small sizes to very large sizes
without imparting any large costs increments onto the MSO at any
step along the graduated growth path. According to a second
definition, a scalable CMTS should be capable of reaching the
maximum capacity for size permitted by the underlined CMTS
technology. For many reasons, MSOs might want to look for both of
these scalability features when making their CMTS purchasing
decisions.
[0011] The first of these features (graduated growth) is desirable
in a CMTS because cable data services almost always greeted with
incredible popularity when ever it enters a new subscription area.
This typically leads to the dramatic increase in subscribers within
a very short interval of time. To accommodate the sporadic usage
increases, the CMTS must be able to rapidly increase the number of
downstream and upstream channels being delivered to the
subscribers. Any delay in this channel increase may force an MSO to
temporarily over subscribe the existing cable data channels. The
densely packed subscribers on the over subscribed channels are
likely to complain and/or lose interest in the service giving the
competitors with cable data service a chance to steal
subscribers.
[0012] Even an established cable data service area where the
upstream and downstream channel counts have been nicely matched to
the current subscriber base, the subscriber demand for bandwidth
will continually increase over time as new bandwidth hungry
Internet applications are introduced. This increase in bandwidth
demand will manifest itself as an increase in the subscription rate
for higher service level agreements and that will force the MSOs to
pack fewer subscribers on a given channel, and that will again
require the CMTS to be able to rapidly increase the number of
channels even if it is providing to the same number of customers.
This illustrates a second reason why graduated growth is a
desirable feature in a MSOs CMTS.
[0013] The second definition of scalability (maximum capacity) is
also a desirable feature within a CMTS, because the ultimate
subscriber rates for cable data service are likely to approach the
20-25% levels within these established service areas. Thus, a
typical head end supporting 60,000 cable TV subscribers may need to
support up to 15,000 cable data subscribers. If future bandwidth
demands limit the MSOs to only 500 cable data subscribers per
downstream channel, then the maximum equipped CMTS should be
capable of supporting up to 30 downstream channels. In addition, if
the typical head end requires 4 upstream channels to be associated
with each downstream channel, then the maximally equipped CMTS
should be capable of supporting up to 120 upstream channels.
Unfortunately, accommodating all of these (30+120)=150 connections
out of the CMTS will require a large amount of cabling. Each of the
150 required connections must be transported on a coaxial cable. In
a well designed system with high availability, the system repair
time should be kept to a minimum, so the bundle of cables emanating
from the CMTS will likely be coming from the backside of the system
chassis to allow office technicians to rapidly replace faulty
circuit cards by pulling them off the front side of the system
chassis without having to remove and restore the cabling that
emanates from the backside of the chassis.
[0014] Another feature that will undoubtedly be required at most
feature at CMTS products is flexibility. In particular, CMTS' must
be able to accommodate the many different traffic profiles
throughout the usage area. This implies that the equipment of the
CMTS chassis will be different with each head end office because
the equipment must be customized to match the input demands of the
customers connected to each head end.
[0015] As an example, in some areas, this may require circuit cards
that require one upstream channel for each downstream channel also
known as 1D:1U circuit cards. In other areas, this may require
circuit cards support for upstream channels for each downstream
channel which is also known as a 1D:4U circuit card. In still other
areas, this may require circuit cards that support each upstream
channels with each downstream channel also known as a 1D:8U circuit
card. Many other types of useful circuit cards can also be
envisioned including, but not limited to, 1D:3U circuit cards,
2D:8U circuit cards, 2D:4U circuit cards, and 2D:2U circuit cards.
In to general, any type of circuit cards of type nD:nU can be
envisioned wherein m and n are nonnegative integers.
[0016] To make matters even worse, the CMTS chassis within a single
head end office is likely to require several different types of
front circuit cards to accommodate different traffic profiles on
different cables leaving the head end office. Thus, a single CMTS
might need to be equipped with b 1D:1U circuit cards, c 1D:4U
circuit cards, d 1D:8U circuit cards, e 1D:3U circuit cards, f
2D:8U circuit cards, g 2D:4U circuit cards, h 4D:4U circuit cards
and i MD:NU circuit cards where b, c d, e, f, g, h, i, m and n are
non-negative integers.
[0017] Given that backside cabling is likely to become more popular
over time, as high availability CMTS' become more popular, it is
apparent that a fundamental problem will develop. The problem is
centered around the difficulties that will be encountered by the
cable office technicians that are responsible for correctly
installing and maintaining the many cables that must be connected
to the backside of the high capacity next generations CMTS chassis.
Correct connection for the many cables to the backside of the
chassis is itself a difficult task.
[0018] As described above, there can be, for example, 150
connectors on the back side of the CMTS chassis. FIG. 2 illustrates
a connector pattern on the back side of a known CMTS chassis. In
this example, the connectors are situated on four cards 204, 206,
208 and 210. The first connectors (212, 214, 216, 218) on each of
the cards are situated in a straight line. Likewise, the second
connectors on each card are situated in a straight line. This
pattern remains uniform throughout the four cards. When cables have
been connected to some or most of the connectors, it becomes
difficult to connect new cables to the remaining connectors simply
because there is very little room between the connectors. Likewise,
it can be very difficult to disconnect a cable from a connector
when the surrounding connectors are attached to cables. For
example, when a technician wants to connect a cable to connector
220 and cables are already connected to connectors 214, 216, 218,
222, 224, 226, 228 and 230, the technician may have a hard time
connecting the cable to connector 220 for the lack of space for
maneuvering his hand in the space around the connector 220.
SUMMARY OF THE INVENTION
[0019] The invention alleviates some of the problems caused by the
high density of connectors on the back of the CMTS chassis by
staggering the position of connectors on adjacent cards so as to
optimize the amount of space between each connector.
[0020] According to one embodiment of the present invention, a
cable modern termination system (CMTS) having front and rear sides
is disclosed. A rear panel receives a plurality of connector cards.
At least one first connector card wherein each first connector card
has a row of connectors. At least one second connector cards,
wherein each second connector card has a row of connectors, wherein
connectors on the first connector cards are staggered from
connectors on the second connector cards when the connector cards
are inserted into the rear panel.
[0021] According to another embodiment of the invention, a method
for arranging cable connectors on a panel of a cable modem
termination system (CMTS) to allow for easier cable manipulation is
disclosed. The position of connectors on a first connector card
type are staggered with respect to position of connectors on a
second connector card type. First and second connector card types
are alternately inserted into the panel so as to optimize the
separation between connectors on adjacent cards.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The teachings of the invention can be readily understood by
considering the following detailed description with conjunction
with accompanied drawings, in which:
[0023] FIG. 1 illustrates an exemplary cable data system;
[0024] FIG. 2 illustrates a prior art connector pattern on the back
side of a CMTS chassis;
[0025] FIG. 3 illustrates a CMTS according to one embodiment of the
invention;
[0026] FIG. 4 illustrates a back plane of a CMTS according to one
embodiment of the invention;
[0027] FIG. 5 shows a perspective view of a circuit card cage and
card edge connectors that are mounted in the cage in two different
horizontal lanes.
[0028] FIG. 6 shows a perspective view of an exemplary circuit card
including a front plate on which there are mounted a plurality of
coaxial cable connectors.
DETAILED DESCRIPTION
[0029] FIG. 3 illustrates a cable modem termination system (CMTS)
apparatus according to one embodiment of the invention. The CMTS
apparatus of FIG. 3 is comprised of a cable interface (301) that is
coupled to a buffer circuit (305). The buffer circuit (305) is
coupled to an Ethernet interface (310). In the preferred
embodiment, each of the individual circuits (301, 305, and 310)
reside physically on separate circuit boards. In alternate
embodiments, any circuits having substantially the same function
can reside on one circuit board or even one integrated circuit. In
other words, the present invention is not limited to three separate
circuit boards.
[0030] The cable interface (301) is responsible for interfacing the
CMTS to the home cable modern apparatus. The cable interface (301)
also provides the functions of modulation and demodulation.
[0031] The cable interface circuit is comprised of a downstream
packet flow path and an upstream packet flow path. The downstream
packet flow path is comprised of a data throughput monitor (320)
that is coupled to a flow limiter (315). The data throughput
monitor (320) has an input that is coupled to the buffer circuit
(305) from which the data packets flow and a feedback from the
upstream path. The feedback from the upstream path is to allow a
first CM to talk with other CMs. The data throughput monitor (320)
has the task of determining the rate of data packet flow.
[0032] In the preferred embodiment of the CMTS, the downstream data
packet flow rate is typically either 30 or 40 Mbps for each 6 MEZ
channel, using QAM techniques. Alternate embodiments use other flow
rates. The cable company decides which data packet flow rate should
be used depending on the outcome desired by the company. The lower
data rate is less susceptible to noise while the higher data rate
can include more data per unit of time for the customers.
[0033] The data packet flow rate signal is fed into the flow
limiter (315). This signal controls the flow limiter function. If
the flow is greater than a predetermined level, T.sub.max, the data
packet flow can be limited. The flow limiter (315) reduces the data
rate by dropping packets until the flow is reduced to below
T.sub.max.
[0034] Another input to the flow limiter (315) is the "limiting
type" input. This control input is set by the cable company
depending on how strict they wish a customer to adhere to the
rules. If the "limiting type" input is set to "soft-limiting", the
flow limiter (315) allows the data rate to go above the set data
rate by a predetermined amount without dropping any packets.
[0035] Some cable companies may strictly limit a customer to
T.sub.max. In this case, the "limiting type" control input is set
to "hard-limiting". If the data rate goes over the set hard limit,
the flow limiter (315) drops any packets that force the customer to
exceed T.sub.max. The output of the flow limiter (315) is coupled
to the cable that runs to the customers' cable modems.
[0036] The output of the flow limiter (315) is input to the
modulator (355). This block (355) performs the QAM needed to
transmit the data to the CMs.
[0037] The upstream data path is comprised of a demodulator and
filter (360) that converts the QAM signal into data bits in order
to be processed by the other blocks in the upstream path. The
demodulated data bits are input to a data throughput monitor (325)
that is coupled to the upstream port from the customer's CM. This
data throughput monitor (325) has the same functionality as the
downstream monitor (320) of monitoring the data rate but in the
upstream direction to the Internet.
[0038] In the preferred embodiment, the upstream data rate can be
in the range of 320 kbps to 10.24 Mbps. Alternate embodiment use
other rates.
[0039] The upstream data throughput monitor (325) is coupled to a
flow limiter (330). This flow limiter has similar functionality to
the flow limiter (315) in the downstream path. The upstream path
flow limiter (330) has the data rate input from the data throughput
monitor (325) as well as the "limiting type" control input that, in
the preferred embodiment, is set to either "hard-limiting" or
"soft-limiting" depending on the cable company rules. As in the
downstream flow limiter (315), the upstream flow limiter, depending
on the "limiting type" input, drops all packets that force the
customer to exceed T.sub.max.
[0040] The upstream path further comprises a congestion control
block (335) that is coupled to the upstream data path out of the
flow limiter (330). The data packets from the upstream data path
flow through the congestion control block (335) to the buffer
circuit (305). The function of the congestion control block (335)
is to drop packets when the buffer depth is reaching a maximum
point. By dropping the packets before they reach the buffer, the
buffer will not overflow.
[0041] In order to accomplish the task of congestion control, the
congestion control block (335) has control inputs that are used to
determine when to drop packets and which packets to drop. In the
preferred embodiment, these control inputs include the data rate
signal from the upstream data throughput monitor (325), a buffer
depth signal from the buffer (305), and a priority signal.
[0042] The data rate signal from the upstream data throughput
monitor (325), as described above, quantizes the data rate and
feeds that value to the congestion control block (335). The buffer
circuit depth signal from the buffer circuit (305) instructs the
congestion control block (335) as to the depth of the buffer. In
other words, if the buffer (305) is 75% full, the buffer depth
signal instructs the congestion control block (335) of this.
[0043] The priority signal that is input to the congestion control
block (335) informs the congestion control of the priority of each
packet. This is important in determining which packets to drop.
[0044] A group of packets is assigned a priority based on the
customer's level of service plan. If the customer has signed up for
the basic service plan and paid the smallest fee for the most basic
service, his packets are assigned a low priority. This priority is
embedded in a packet identification that is assigned to the group
of packets and is decoded when the group of packets enters the
cable interface.
[0045] If the customer has signed up for the premium service plan
with the cable company, his packets are assigned the highest
priority. If the customer has signed up for any service plans that
are in between the premium and the basic plans, this priority is
also assigned to each packet. As described before, the priority is
added to the packet identification for a particular group of
packets.
[0046] A customer may also decide to dynamically change his service
level for a given session. In this case, different packet groups
from that particular customer will have different priorities
assigned to different packet identifications.
[0047] As described subsequently in other figures, the congestion
control block (335) of FIG. 3 uses the priority assigned to a group
of packets to determine how to process that particular group of
packets. The output of the congestion control block is input to the
buffer circuit's upstream data flow input.
[0048] The buffer circuit (305) stores the packets until the
Ethernet circuit (310) has time to process that packet. The packets
are fed from the buffer circuit (305) to the Ethernet circuit (310)
as more processing time is freed up.
[0049] The downstream path of the Ethernet circuit (310) is
comprised of a data throughput monitor (350) that is coupled to the
connection to the Internet. This monitor (350) provides
substantially the same function as the previously described data
throughput monitors on both the upstream and downstream paths.
[0050] The data packets from the Internet flow from the data
throughput monitor (350) to the Ethernet's circuit flow limiter
(345). This flow limiter (345) has substantially the same
functionality as the above described flow limiters. This flow
limiter also has the same inputs as described previously: the
quantized data rate and the "limiting type" control input.
[0051] The data packets flow from the flow limiter (345) to the
congestion control block (340). As in the upstream congestion
control block (335), the Ethernet's downstream congestion control
block (340) has the three control inputs to determine which packets
to drop: the quantized data rate, the buffer depth signal, and the
packet priority signal. The congestion control block then drops a
particular packet based on these control signals.
[0052] The downstream data flows from the congestion control block
to the buffer circuit (305). The buffer circuit (305) stores the
packets until the cable interface circuit has the processing time
to work on additional packets.
[0053] The buffer circuit (305) is comprised of 128 MB of RAM, in
the preferred embodiment. Alternate embodiments use other values of
RAM or even other types of memory instead of RAM. The alternate
types of memory include hard drives or other types of temporary
memory.
[0054] Most of the functions illustrated in FIG. 3 may be
implemented in various ways. These functions can be performed in
software by a processor or multiple processors performing each
function. Each function can also be implemented in discrete logic
hardware, a digital signal processor, or some other form of
programmable logic.
[0055] FIG. 4 shows an elevation view of several circuit card
panels onto which coaxial cable connectors 404 have been affixed.
The placement of coaxial cable connectors 404 on circuit card
panels (The circuit card panels are shown as the broken-line
rectangles surrounding the small-diameter circles that represent
the coaxial connectors.) is such that the coaxial cable connectors
on a first type of panel 450 are vertically displaced, vertically
staggered or vertically offset from the connectors 404 on a second
type of panel 460.
[0056] FIG. 6 shows a perspective view of an exemplary circuit card
620. A front plate 600 is attached at one end of the circuit card
620 and has attached to it several coaxial cable connectors 610.
The coaxial cable connectors 610 are wired to electrical circuits
and components on the card 620 (not shown). A series of electrical
contacts 630 comprise a so-called edge connection by which
electrical connections are made to circuits on the card 620 when
the card 620 is inserted into an edge connector. Instead of using
one front plate 600 to mount several coaxial cable connectors 600,
an equivalent (for claim construction purposes) would be using two
or more separate slates (as shown by the broken lines in the single
plate 600) by which the individual connectors 610 would be attached
to the front edge 640 of the circuit board 620. For purposes of
claim construction the use of separate, individual mountings of
coaxial cable connectors to the circuit board are considered to be
equivalent to a single plate to which several connectors are
attached.
[0057] With respect to FIG. 1, in the preferred embodiment, the
staggered or offset displacement of coaxial cable connectors 404 on
adjacent circuit cards (406 is adjacent to 408; 410 is adjacent to
412) is accomplished by using two different types of circuit card
panels. The circuit card panels, which are depicted in FIG. 4 as
the broken-line rectangles surrounding the small-diameter circles
that represent the coaxial connectors are attached to their
corresponding circuit cards (circuit boards) offset from the
circuit card bottom (or top) edges yielding two different types of
circuit cards. In the preferred embodiment, circuit cards
identified by reference numerals 406 and 410 are considered to be
"odd" cards; circuit cards identified by reference numerals 408 and
412 are considered to be "even" cards. With respect to FIG. 6.
"odd" and "even" cards can be made by mounting the front plate 600
at two different offset positions on the card 620 front edge 630.
An alternative and equivalent wavy to made "odd" and "even" cards
would be to mount the coaxial cable connectors 610 into the front
plate 600 at two different offset positions requiring the use of
two "different" front plates 600. All of the various ways of
changing the relative location of the coaxial cable connectors on
the card edge are considered to be equivalent.
[0058] When an "odd" card is inserted into a particular card edge
connector in the CMTS card cage, and when an "even" card is
inserted into an adjacent back plane connector, the relative
placement of the coaxial cable connectors on an "odd" card with
respect to the same-function connectors on an "even" card is offset
from the connectors on the even card.
[0059] In an alternate embodiment, displaced coaxial connectors on
adjacent circuit cards can be achieved by using circuit card edge
connectors.
[0060] FIG. 5 shows a simplified perspective view of a card cage
500 at one end of which are located several circuit card edge
connectors 502, 504, 506, 508 and 510. In this alternate
embodiment, a top 501 and bottom 503 side (or face) of the card
cage lie in parallel planes. Each of the edge connectors are
identical (accept the same size circuit card and the same number of
edge connector pins) except that the connectors of one set of edge
connectors 502, 506 and 510 are mounted to the card cage 500
translationally offset from the second set of edge connectors 504
and 506. The translational offset of the two sets of connectors
with respect to each other can be considered to be vertical or
horizontal, depending upon the orientation of the card cage 500.
(By rotating the orientation of FIG. 5 ninety degrees, the
connectors 502, 504, 506, 508 and 510 become horizontally displaced
with respect to each other; coaxial cable connectors attached to
the cards then become horizontally displaced as opposed to
vertically displace.)
[0061] All of the edge connectors in FIG. 5 are mounted into the
card cage 500 such that their longest dimensions (their length, L)
are parallel to each other and orthogonal to a plane 512 to which
the first set of edge connectors 502, 506 and 510 is tangent to.
The second set of connectors 504 and 508 are parallel to the first
set but translationally offset (staggered) in a direction
orthogonal to the plane 512. The second set of connectors has one
end tangent to a second plane 514 that is substantially parallel to
the first plane 512.
[0062] When circuit cards are mounted into the connectors depicted
in FIG. 5, the cards inserted into the first set of connectors will
rest at a first elevation below that of the circuit cards inserted
connectors of the second set. It can be seen that the ends of the
connectors of one set of connectors is substantially tangent to the
plane 512 while the ends of the connectors of the second set of
connectors is substantially tangent to another plane 514 that is
shown as parallel to plane 512 but vertically displaced. Stated
alternatively, the connectors of both sets are identical except
that every other connector is offset from it's neighbor. By
staggering the connectors into which circuit cards are to be
installed instead of using two different styles of cards as in the
first embodiment, a single type of circuit card can be used but
because the adjacent cards are inserted into staggered edge
connectors. In the aforementioned alternate embodiment, an entire
card is staggered as are any coaxial cable connectors on the front
plates of the adjacent albeit different cards. Unlike the preferred
embodiment wherein two different types of cards (different because
of different card plates into which the coaxial cable connectors
are mounted) must be used adjacent to each other, the alternate
embodiment can use a single card type, which when inserted into
staggered connectors produces an equivalently staggered connector
arrangement.
[0063] According to one embodiment of the invention, the connectors
on circuit cards in the back side of the CMTS chassis (The
designation of a "back" side as opposed to a "front" side is
subjective. For purposes of claim construction, "front" and "back"
sides of a chassis are considered to be equivalent.) The coaxial
connectors are staggered in such a manner so as to optimize the
distance between adjacent connectors.
[0064] FIG. 4 illustrates a (back or front) side of a CMTS chassis
402 according to one embodiment of the invention. In this example,
the connectors 404 are arranged on four cards 406, 408, 410 and 412
respectively. Cards 406 and 410 are even cards while cards 408 and
412 are odd cards. In prior systems such as the one illustrated in
FIG. 3, the edge connectors ON for each of the cards are situated
in the same position horizontal plane. In other words, the first
connectors on each of the cards are lined up in a straight line. By
using two different types of connector plates however wherein one
the connectors are higher (or lower) than the connectors of the
other plate, when the two different card types are inserted into
the edge connectors the coaxial cable connectors are staggered in
adjacent cards.
[0065] According to one embodiment of the invention, the locations
of the connectors on the even cards are staggered from the
positions of the connectors on the odd cards. As illustrated in
FIG. 4, the first connectors 420 and 422 on even cards 406 and 410
respectively are positioned higher than the first connectors 424
and 426 of the odd cards 408 and 412. Furthermore, the first
connectors 424 and 426 are positioned higher than the second
connectors 428 and 430 on even cards 406 and 410. It will be
understood that more than two different types of cards can be used
so long as the resulting pattern of connectors are staggered with
respect to adjacent connectors on adjacent cards.
[0066] According to one embodiment of the invention, the amount of
stagger is determined using geometric principles. According to this
basic geometry. Optimum spacing is considered to be a vertical
displacement (or horizontal displacement in instances where circuit
cards are installed in vertically-offset horizontal planes) of
adjacent connectors on adjacent cards by which the spacing or
separation of connectors is maximized. (In the preferred embodiment
a positioning of coaxial connectors on an adjacent circuit card
front plate.) By way of example, if the vertical distance between
coaxial cable connectors of one card front relate is equal to 1
inch, and if the horizontal distance between a vertical line
extending through the center conductors on adjacent circuit cards,
(both of which presumably have coaxial cable connectors equally
spaced apart) is also one inch, an optimum offset of the connectors
between adjacent cards (i.e. the vertical displacement of adjacent
connectors) is approximately 1/2 inch such that the distance
between staggered connectors would be calculated to be
=((1).sup.2+(1/2).sup.1/2={square root}1.25.. In the preferred
embodiment, the stagger between connectors of the odd cards and
even cards is such that the connectors on the odd cards are
staggered so that the connectors are approximately equidistant from
connectors on adjacent cards, and vice versa. For example,
connector 424 is situated so as to be equidistant from connectors
420, 422, 428 and 430. This stagger pattern provides more room
between connectors and thus helps to alleviate some of the
connection/disconnection problems associated with high density
cabling. To maximize the advantage of these staggering patterns,
the cards need to be alternated between odd and even when installed
but the invention is not limited thereto. In the alternate
embodiments i.e. wherein the circuit card edge connectors are
staggered in the card cage, it is not necessary to install
different types of circuit cards (i.e. "odd" or "even" cards) in
adjacent card slots.
[0067] While exemplary systems and method embodying the present
invention are shown by way of example, it will be understood, of
course, that the invention is not limited to these embodiments.
Modifications may be made by those skilled in the art, particularly
in light of the foregoing teachings. For example, each of the
elements of the aforementioned embodiments may be utilized alone or
in combination with elements of the other embodiments.
* * * * *