Telecommunications chassis and card

A chassis and associated telecommunication circuit card are disclosed. The chassis has heat dissipation structures and may accommodate a high density of the circuitry cards. Embodiments may include one surface with one or more ridges for rigidity and ventilation and fin slots for receiving circuit card guide fins. Embodiments may include a surface with knockouts for receiving circuit card guides. Embodiments may also include multiple bracket hole patterns for mounting brackets for different racks or for a single multi-rack bracket having more than one mounting hole pattern. The circuit card includes conductor structures such as multiple board layers with paired and segregated conductors. The circuit card also includes some components positioned to cooperate with the ventilation structures of the chassis and includes some components chosen for low-power consumption or reduced flammability.

TECHNICAL FIELD

This invention relates to chassis for holding telecommunications cards such as repeater circuits. More specifically, the present invention relates to chassis and cards with structures for high card density and structures for mounting with multiple rack styles.

BACKGROUND

It is desirable for a chassis for holding telecommunication circuit cards to support a high density of cards, yet the chassis must effectively dissipate heat developed during operation. The cards installed in the chassis perform electrical operations, such as signal transception and amplification that generate a significant amount of heat. Typically, a chassis is installed in a particular rack that contains several other chassis stacked above and below. The heat that may develop within a chassis in the rack has the potential to harm circuit cards housed in the chassis above and below the chassis where the heat emanates from. Additionally, the rack housing the chassis may be one of several different rack types, such as an EIA rack style, a WECO rack style, or an ETSI rack style, and a different chassis may be required for each to ensure proper mounting.

The chassis must also provide external protection for the circuit cards it houses. Thus, the chassis cannot freely expose the circuit cards to areas outside the chassis when attempting to dissipate heat. Additionally, the chassis must provide a structural interconnection that maintains electrical continuity between the circuit cards and external transmission mediums such as copper wires or fiber optic cables while facilitating insertion and removal of the cards. A sufficient structure must be used to facilitate this circuit card modularity, which further limits the chassis' ability to provide outlets for heat.

Additionally, to reduce the chassis size for a given number of circuits, the circuit card density must be increased. Increasing circuit card density is difficult not only due to heat dissipation, but also because of electromagnetic noise that must be contained. Generally, increasing circuit card density involves employing smaller cards, and smaller cards require higher component density within the cards. Achieving effective heat dissipation with adequate electromagnetic noise containment may even be more difficult for smaller card designs with higher component densities.

Thus several factors must be accounted for in the chassis and card design. Chassis designs with large interior spaces for directing heat away from circuit cards may be undesirable because the chassis may become too large when accommodating a high density of circuits. Chassis designs with open exteriors for directing heat away from the circuit cards may be undesirable because the circuit cards may not be sufficiently protected from externalities such as falling objects or heat spreading from a chassis positioned above or below in the rack. Card designs that are relatively large require a larger chassis to house the same quantity of cards. Additionally, a different chassis must be provided for each rack style for proper mounting.

Thus, there is a need for a chassis and card design whereby the chassis may contain a high density of readily removable circuit cards while providing effective heat dissipation and electromagnetic noise containment and/or be mountable in multiple rack styles.

SUMMARY

The present invention provides a chassis and card design that may accommodate a high density of readily removable circuits while providing heat dissipation and electromagnetic noise containment features. Ventilation structures are employed to direct heat away from internal circuitry. Additionally, chassis designs of the present invention may provide exterior features that establish protection from externalities and prevent the harmful spread of heat to chassis or other equipment stacked above or below. Card designs of the present invention may provide conductor structures for containing electromagnetic noise and/or individual components placed in locations for coordination with the ventilation structures of the chassis. Additionally, the chassis may provide configurable mounting structures to enable a single chassis to be mounted in racks of different styles.

The present invention may be viewed as a chassis for housing telecommunications cards. The chassis includes a housing having a first and second horizontal surface and vertical sidewalls between the first and second horizontal surfaces. The first and second horizontal surfaces have a plurality of openings, and the first horizontal surface has a first ridge substantially perpendicular to a longitudinal axis of the vertical sidewalls. The chassis also includes a first horizontal cover overlaying the first horizontal surface, and the first horizontal cover has a first ridge that is aligned with the first ridge of the first horizontal surface.

The present invention may also be viewed as another chassis for holding telecommunications cards. The chassis includes a housing having a first and second horizontal surface and vertical sidewalls between the first and second horizontal surfaces. The first and second horizontal surfaces have a plurality of openings, wherein the second horizontal surface has a first ridge substantially perpendicular to a longitudinal axis of the vertical sidewalls, and the first ridge has a plurality of knockouts. Each knockout is for receiving a guide of a telecommunications card.

The present invention may also be viewed as a chassis for housing repeater cards. The chassis includes a housing with vertical sidewalls, a first horizontal surface, and a second horizontal surface, wherein the first horizontal surface has a first ridge extending substantially perpendicular to a longitudinal axis of the vertical sidewalls and a second ridge substantially parallel to the first ridge. The first ridge and the second ridge each have an elongated opening. The chassis also includes one or more repeater cards positioned between the first horizontal surface and the second horizontal surface, and the one or more repeater cards have a DC-DC converter and a transceiver. The DC-DC converter is positioned at least partially between the elongated opening of the first ridge and the second surface. The transceiver is positioned at least partially between the elongated opening of the second ridge and the second surface.

The present invention may be viewed as another chassis for holding telecommunications cards. The chassis includes a housing having first and second horizontal surfaces and first and second vertical sidewalls, and the first vertical sidewall having a plurality of holes. The chassis also includes a first bracket mounted to the housing, with the first bracket having a first side and a second side perpendicular to the first side. The first side of the first bracket has a first horizontal dimension and a first and second set of holes, and the second side of the first bracket has a second horizontal dimension different than the first horizontal dimension and has a first and second set of holes. When the first set of holes of the first side of the first bracket align with at least a portion of the plurality of holes of the first sidewall, the second set of holes of the first side of the first bracket are blocked by the first vertical sidewall. When the first set of holes of the second side of the first bracket align with at least a portion of the plurality of holes of the first vertical sidewall, the second set of holes of the second side of the first bracket are blocked by the first vertical sidewall.

The present invention may be viewed as another chassis for holding telecommunications cards. The chassis includes first and second horizontal surfaces and first and second vertical sidewalls separating the first and second horizontal surfaces, wherein the first vertical sidewall has a plurality of at least three holes. The chassis also includes a first bracket having a first side and having a second side substantially perpendicular to the first side, the first side having a set of at least two holes and the second side having a set of at least two holes. The set of at least two holes of the first side align with a first set of at least two but fewer than all of the plurality of holes of the first vertical sidewall when the first side abuts the first vertical sidewall. The set of at least two holes of the second side align with a second set of at least two but fewer than all of the plurality of holes of the first vertical sidewall when the second side abuts the first vertical sidewall. The first set includes at least one hole not included in the second set.

The present invention may be viewed as a method of installing brackets on a chassis. The method involves providing a housing having first and second horizontal surfaces and first and second vertical sidewalls, with the first vertical sidewall having a plurality of holes. The method also involves providing a first bracket having a first side and a second side perpendicular to the first side, wherein the first side of the first bracket has a first horizontal dimension and a first and second set of holes and wherein the second side of the first bracket has a second horizontal dimension different than the first horizontal dimension and has a first and second set of holes. When installing the first bracket such that the first side abuts the first vertical sidewall, the method involves aligning the first set of holes of the first side of the first bracket with at least a portion of the plurality of holes of the first sidewall and blocking the second set of holes of the first side of the first bracket by the first vertical sidewall. When installing the first bracket such that the second side abuts the first vertical sidewall, the method involves aligning the first set of holes of the second side of the first bracket with at least a portion of the plurality of holes of the first vertical sidewall and blocking the second set of holes of the second side of the first bracket by the first vertical sidewall.

The present invention may be viewed as another method of installing brackets on a chassis. The method involves providing a housing having first and second horizontal surfaces and first and second vertical sidewalls separating the first and second horizontal surfaces, wherein the first vertical sidewall has a plurality of at least three holes. The method further involves providing a first bracket having a first side and having a second side substantially perpendicular to the first side, with the first side having a set of at least two holes and the second side having a set of at least two holes. When installing the bracket such that the first side abuts the first vertical sidewall, the method involves aligning the set of at least two holes of the first side with a first set of at least two but fewer than all of the plurality of holes of the first vertical sidewall. When installing the bracket such that the second side abuts the first vertical sidewall, the method involves aligning the set of at least two holes of the second side with a second set of at least two but fewer than all of the plurality of holes of the first vertical sidewall, wherein the first set comprises at least one hole not included in the second set.

DETAILED DESCRIPTION

Various embodiments of the present invention will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies through the several views. Reference to various embodiments does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto.

FIGS. 1–7show an embodiment of the chassis100for holding telecommunications cards. The empty chassis100ofFIGS. 1–7has a horizontal surface102mounted to vertical sidewalls120,122. In this embodiment, each vertical sidewall120,122has a 90 degree bend at the front and rear ends allowing the sidewalls120,122to form partial front and rear panels of the chassis100. The vertical sidewalls120,122have a longitudinal axis that extends from the front to the back of the chassis100, which is from the front bend to the rear bend in the embodiment shown. The chassis100also has a horizontal surface142mounted to the vertical sidewalls120,122. Both horizontal surfaces102,142and both sidewalls120,122of this embodiment are made of a material such as cold-rolled steel. The cold-rolled steel may have a chromate plating to reduce electromagnetic interference.

Covers are provided over the first horizontal surface102and the second horizontal surface142. The first horizontal cover104overlays the first horizontal surface102and mounts directly to it. The second horizontal cover154underlays the second horizontal surface142and mounts directly to it. The covers104and154of this embodiment are made of a mesh surface such as aluminum having 63% of its area formed by densely populated openings. Other materials and air passage percentages are also applicable. The mesh material allows rising air to pass through while preventing objects from falling into or out of the chassis100that would otherwise enter the chassis100through large openings provided in the first and second horizontal surfaces102,142that are discussed below.

The first horizontal surface102is contoured to provide two ridges300,304dividing three recessed areas103,302, and306, as is best seen inFIG. 12. The two parallel ridges300,304extend across the width of the chassis100perpendicularly to the longitudinal axis of the vertical sidewalls120,122. The first area103of the first horizontal surface extends beyond the coverage area of the first horizontal cover104. The first horizontal cover104of this embodiment is also contoured to provide two ridges105,108and two recessed areas106and110. The ridge105of the first horizontal cover104is aligned with and overlaps ridge300of the first horizontal surface102. The ridge108of the first horizontal cover104is aligned with and overlaps ridge304of the first horizontal surface102. The recessed area106of the first horizontal cover104overlaps with recessed area302of the first horizontal surface102, and the recessed area110of the first horizontal cover104overlaps with recessed area306of the first horizontal surface102.

The first horizontal surface102includes a first row of fin slots118in area103that are for receiving a fin of a circuit card, discussed below. The first row of fin slots118extends into the ridge300and the fin slots are perpendicular to the longitudinal direction of the ridge300. The first horizontal surface102also includes a second row of fin slots196that extend across the area302from the ridge300to the ridge304. The first horizontal surface102also includes a third row of fin slots202in area306that extends into the ridge304. The fin slots of each row align with fin slots in the other rows and guide each circuit card as it is inserted into the chassis100. The ridges300,304add rigidity to the first horizontal surface by allowing the fin slots to be broken into sets of rows while allowing the fin of the card to pass by as it is being inserted. The rigidity of the first horizontal surface102would be reduced if the ridges300,304were not present because each fin slot would need to be continuous to facilitate circuit card entry rather than being broken into three sections as shown.

The first horizontal cover104has a row of fin slots116in the area106that align with the row of fin slots196in the area302of the first horizontal surface102. The first horizontal cover104also has a row of fin slots114in the area110that align with the row of fin slots202in the area306of the first horizontal surface102. The rows of fin slots in the first horizontal cover104also allow the fin of the circuit card to be guided as it is inserted into the chassis100. Similar to the first horizontal surface102, the rigidity of the first horizontal cover142would be reduced if the ridges105,108were not present because each fin slot would need to be continuous to facilitate circuit card entry rather than being broken into two sections as shown.

In the embodiment shown, the chassis100has open interior regions on each side defined by the wrap-around vertical sidewalls120,122. The first horizontal surface102has ventilation holes112over the left region in the area103and ventilation holes150over the right region in the area103. Also in the area103, the first horizontal surface has ventilation holes152placed between each fin slot of the first row118. The second horizontal surface has ventilation holes148under the left region and ventilation holes146under the right region.

Because the chassis is empty inFIGS. 1–7, card slot covers132are mounted to the chassis100to avoid exposing the interior of the chassis100. The rear of the chassis100is enclosed by a backplane128that is attached to each wrap-around vertical sidewall120,122. The backplane128provides connections between cables and the circuit cards housed by the chassis100. The backplane128includes external connectors130that connect to cables routed to the rear of the chassis rack (not shown) where the chassis100is installed.

The rear of the chassis100includes a cover134made from a material such as lexan that may be placed over a portion of the backplane128where circuit leads and pins from card connectors, discussed below, are present. A cable bar136may also be installed to hold the cables connected to the external connectors130. A chassis ground connector138may also be included for grounding the chassis100.

The second horizontal surface142may include a first ridge183spanning the width of the chassis100and being parallel to the ridge300of the first horizontal surface102. The first ridge183may include a row of knockouts144for receiving a guide of a circuit card. The knockout144is a portion of the ridge183that has been removed to create a passage for the guide. As shown, the card slot covers132have a guide131that fits into the knockout144to stabilize the bottom of the card slot cover132. As shown inFIG. 12, the second horizontal surface142may also include a second ridge185positioned near the backplane128and extending substantially parallel to the ridge183across the width of the chassis100. An area182is provided between the second ridge185and the backplane128. The second ridge185also includes knockouts147for receiving the guide of the circuit cards.

The chassis100of this embodiment also includes mounting brackets124,126. These brackets124,126mount to the vertical sidewalls120,122and also to the vertical rails of a chassis rack (not shown). The brackets124,126of this embodiment facilitate mounting the chassis100in different racks. The bracket124,126has a first side123,129that abuts the vertical sidewall120,122, such as inFIGS. 1 and 2, and another side125,127that is perpendicular to the first side123,129and that abuts the rack rail when mounting the chassis100.

The first side123,129has a first horizontal dimension and the second side125,127has a second horizontal dimension different than the first horizontal dimension. The differing horizontal dimensions of the sides of the bracket124,126allow the bracket124,126and chassis100to be used for racks with different mounting widths. For one rack mounting width, the first side123,129abuts the chassis100and the other side125,127abuts the rail of the rack. For another rack mounting width that is less wide, the second side125,127abuts the chassis100and the first side123,129abuts the rack rail.

As best seen inFIG. 11, the side129of the bracket126has a bracket hole pattern established by bracket holes164,166, and168. Side123of bracket124has the same bracket hole pattern. The sidewalls120,122of the chassis100have a bracket hole pattern that matches the bracket hole pattern of the sides123and129. As seen inFIG. 12, this bracket hole pattern of the chassis100includes bracket holes165,167, and169. The bracket holes of the chassis100align with the bracket holes of the bracket124,126when mounting the brackets124,126.

When using the side125,127to mount to the rack rail, a rack hole configuration on the side125,127is available. This rack hole configuration includes the rack holes176,178, and180. This setup is applicable for racks such as an ETSI rack where the distance between adjacent rack holes176,178, and180is 25 millimeters. The ETSI rack and mounted chassis can be seen inFIGS. 49 and 50.

The ETSI rack ofFIGS. 49 and 50includes rails342and344. The rails342,344have mounting holes with consistent spacing. The rails342and344and associated mounting holes of the ETSI rack are spaced further apart horizontally than those of the EIA or WECO racks. Therefore, the chassis100includes brackets124and126mounted such that the wide sides125and127extend from the chassis100while the narrow sides123and129abut the vertical sidewalls120,122of the chassis100.

The rack holes176,178, and180of the brackets124,126align with three contiguous mounting holes346,348, and350of the rails342,344. The chassis100is fastened to the rails342,344through screws that engage the rack holes176,178, and180and the mounting holes346,348, and350. Multiple chassis100may be stacked one directly atop the next within the ETSI rack.

With reference toFIG. 11, the side125of the bracket124has a bracket hole pattern established by bracket holes158,160, and162. Side127has the same bracket hole pattern. The sidewalls120,122of the chassis100have a bracket hole pattern that matches the bracket hole pattern of sides125and127. As seen inFIGS. 11 and 12, this bracket hole pattern of the chassis100includes brackets holes159,161, and163.

When using the side123,129to mount to the rack rail, a rack hole configuration on the side123,129is available. This rack hole configuration includes the rack holes170,171,172, and174. This setup is applicable for racks such as an EIA or WECO rack where the distance between adjacent rack holes170,171, and172is 0.5 inches and the distance between the adjacent rack holes172and174is 1.25 inches. The EIA rack and mounted chassis can be seen inFIGS. 43 and 44for a first mounting method andFIGS. 45 and 46for a second mounting method. The WECO rack and mounted chassis can be seen inFIGS. 47 and 48.

The EIA rack ofFIGS. 43,44,45, and46includes rails322and324. The rails322,324have paired mounting holes with one spacing distance between each hole of the pair and a greater second distance between adjacent holes of different pairs. Because the rails322and324and associated mounting holes of the EIA rack are spaced more closely horizontally than those of the ETSI rack, the chassis100includes brackets124and126mounted such that the narrow sides123and129extend from the chassis100while the narrow sides125and127abut the vertical sidewalls120,122of the chassis100.

For the first method of mounting shown inFIGS. 43 and 44, the rack holes171,172, and174of the brackets124,126align with three contiguous mounting holes326,328, and330of the rails322,324. The mounting holes326and328are of one pair, and mounting hole330is paired with mounting hole332. Both the mounting hole332of the rails322,324and the rack hole170of the brackets124,126are unused in this method. The chassis100is fastened to the rails322,324through screws that engage the rack holes171,172, and174and the mounting holes326,328, and330. Multiple chassis100may be stacked one atop the next in the EIA rack using this first mounting method and a small gap will be provided between each chassis100.

For the second method of mounting shown inFIGS. 45 and 46, the rack holes171,172, and174of the brackets124,126align with three mounting holes326,328, and332of the rails322,324. Mounting hole330of the rails322,324and rack hole172of brackets124,126are unused in this method. The chassis100is fastened to the rails322,324through screws that engage the rack holes171,172, and174and the mounting holes326,328, and332. Multiple chassis100may be stacked one atop the next in the EIA rack using the second mounting method as well and a small gap will be provided between each chassis100.

The WECO rack ofFIGS. 47 and 48includes rails334and336. The rails334,336have mounting holes with consistent spacing distance between each adjacent mounting hole. Because the rails334and336and associated mounting holes of the WECO rack are spaced horizontally the same distance as those of the EIA rack and are more closely spaced horizontally than those of the ETSI rack, the chassis100includes brackets124and126mounted such that the narrow sides123and129extend from the chassis100while the narrow sides125and127abut the vertical sidewalls120,122of the chassis100.

The rack holes170and172of the brackets124,126align with two contiguous mounting holes338and340of the rails334,336. The rack holes171and174of the brackets124,126are unused with the WECO rack. The chassis100is fastened to the rails334,336through screws that engage the rack holes17and172and the mounting holes338and340. Multiple chassis100may be stacked one directly atop the next in the WECO rack.

FIGS. 8–10and13–15show the chassis100loaded with circuit cards208. Each circuit card208has a handle156that extends from a faceplate210of the circuit card208that the user may grip to insert or remove a circuit card208from the chassis100. The faceplate210of each of the cards fills the card slot openings that are otherwise occupied by card slot covers132.

InFIG. 13, the first horizontal cover104is removed to show the first horizontal surface102as is also shown inFIG. 12. The first horizontal surface102includes the recessed area103adjacent to the first ridge300. The first ridge300includes a row of elongated openings194. The first ridge300is also adjacent to the recessed area302. The recessed area302includes the second row of fin slots196. Between each adjacent pair of fin slots196lies openings from a first row192, a second row190, and a third row186. Over the left and right empty regions lie additional large ventilation holes198and188, respectively.

Adjacent to the recessed area302is the second ridge304of the first horizontal surface102. The second ridge304includes a row of elongated openings195. Adjacent to the second ridge304is the recessed area306that includes a row of fin slots202. Between each adjacent pair of fin slots202lie openings from a row of openings200. Over the left and right empty regions lie additional ventilation holes204and206, respectively.

FIGS. 16 and 17shows exploded views of the chassis100without the first horizontal cover104and the second horizontal cover154. From these exploded views, the wrap-around structure of the vertical sidewalls120and122can be seen. Additionally, the placement of the ridges300,304in the first horizontal surface102in relation to the placement of the ridges183,185in the second horizontal surface142is visible as is the pattern of openings in both surfaces.

FIG. 18shows a right side view of the empty chassis100with the right vertical sidewall122removed. The left vertical sidewall120can be seen as no cards are positioned in the chassis100to obstruct the view of the sidewall120. This side view illustrates the mounted relationship of the card connector224and the external connector130of the backplane128. Also illustrated byFIG. 18is the alignment and overlapping position of the ridges105and108of the first horizontal cover104in relation to the ridges300and304, respectively, of the first horizontal surface102. The ridges183and185of the second horizontal surface142can be seen as can the second horizontal cover154which does not include a ridge aligned with the ridge185in this embodiment.

FIG. 19shows an exterior view onto the second horizontal surface142of the chassis100with the mesh cover154removed. The second horizontal surface142includes the first row of knockouts144at the front of the chassis100. On each side of the knockouts144are ventilation holes308and310over the empty side areas of the chassis. As shown, the bracket124is mounted with its narrow side extending outwardly from the chassis100while the bracket126is mounted with its wide side extending outwardly.

The second horizontal surface142includes the second row of knockouts147positioned near the rear of the chassis100. Four rows of openings are positioned between the first row of knockouts144and the second row of knockouts147including a first row312, a second row314, a third row316, and a fourth row320. In the embodiment shown, the holes of a row alternate between long and short from one column to the next adjacent column. Between the rear of the chassis100and the second row of knockouts147are several smaller openings318that provide additional ventilation.

BecauseFIG. 19shows an empty chassis100, the positioning of the ventilation structures of the first horizontal surface102relative to ventilation structures of the second horizontal surface142can be seen. The elongated opening194of the ridge300of the first horizontal surface102can be seen through the first row312and second row314of openings in the second horizontal surface142. Likewise, the elongated opening195of the ridge304can be seen through the second row of knockouts147. The first row186, second row190, and third row192of openings of the first horizontal surface that lie between ridges300and304can be seen through the openings316and320indicating a partial vertical alignment of openings between the first horizontal surface102and the second horizontal surface142. The third row of fin slots202of the first horizontal surface102and the rear row of openings200can be also been seen through the second row of knockouts147.

To further illustrate the relation of the ventilation structures of the second horizontal surface142in relation to those of the first horizontal surface102,FIG. 20shows an empty chassis100viewed onto the first horizontal surface102with the first horizontal cover104removed. The second row of knockouts147can be seen through the rear row of openings200. The knockouts147can also be seen through the elongated opening195of the ridge304. The third row316and fourth row320of openings of the second horizontal surface142can be seen through the first row186, second row190, and third row192of openings of the first horizontal surface102. The first row312and second row314of openings of the second horizontal surface142can be seen through the elongated opening194of the ridge300. The first row of knockouts144can be seen through the first row of fin slots118.

Air rises through the bottom of the chassis100and passes by the circuit cards208installed between the first horizontal surface102and the second horizontal surface142as the components of the circuit cards208warm the air. In the embodiment shown, because the openings of each horizontal surface are not directly aligned, the warmed air is not able to rise directly from bottom to top within the chassis100but may be channeled forward, backward, and/or side-to-side before passing through the nearest hole in the first horizontal surface102.

FIG. 21shows the chassis100filled with circuit cards208and having three cards partially inserted. The circuit cards include a fin212on one edge that is received by the fin slots of the first horizontal surface102and the first horizontal cover104. The circuit card208also has a guide214on an opposite edge that fits within the knockout144of the ridge183of the second horizontal surface142.

FIG. 22more clearly shows the cooperation between the fin slots118of the first horizontal surface102and the fin212of the circuit card208. The cooperation between the guide214and the knockout144of the first ridge183of the second horizontal surface142is also shown. The card208is positioned with the fin212in the slot118and the guide214in the knockout, and the card208is inserted until the faceplate210abuts the front edge216of the first horizontal surface102. At that point, a connector225of the card208engages a card connector224of the backplane128discussed below. Also, in this embodiment holes218,220, and222of the guide214have at least partially aligned with holes312,314, and316in the second horizontal surface142once the card208is fully inserted. This alignment is more clearly shown inFIG. 35.

FIGS. 23–26are several views of the backplane128. The backplane128is a printed circuit board and it has external connectors130mounted to one side and card connectors224mounted to the other side. A power supply connector226is also mounted to the side with the external connectors130. The connector225of the circuit card208mates to the card connector224once the card208is fully inserted in the chassis100, and the card connector224establishes electrical communication between the card208and the external connector130. As shown inFIG. 2, the backplane128of the chassis100is vertical relative to the horizontal surfaces102,142, and the vertical backplane128is positioned between and perpendicular to the two vertical sidewalls120,122.

FIGS. 27–33are several views of the circuit card208. The circuit card208includes the fin212, guide214, faceplate210, finger156, and connector225previously discussed. The circuit card208also includes a printed circuit board234that has circuitry236mounted to it. The circuitry236may be repeater circuitry as discussed below. Light emitting diodes (LEDs), such as power LED228, channel A LED230, and channel B LED232, may protruded from the faceplate210. The LEDs228,230, and232may illuminate as one or more colors as controlled by circuitry236to indicate the state of operation of the circuitry236.

FIG. 34shows the card208mounted in the chassis100in relation to the first horizontal surface102and its ventilation structures. The fin212of the card208is positioned within the first row118, second row196, and third row202of fin slots. The card208is fully inserted once the faceplate210has contacted the front edge216. The card208includes several components such as a capacitor236, a DC-DC converter238, a transceiver248, relay244, and programmable logic device246that are positioned, in this embodiment, relative to the structures of the first horizontal surface102. These components are discussed in more detail below.

The capacitor236lies beneath the area103that restricts upward ventilation and causes air to be channel toward rearward areas of the chassis100. The DC-DC converter238lies partially beneath the elongated opening194of ridge300. The elongated opening194increases the ventilation over the DC-DC converter238which generates a significant amount of heat. The DC-DC converter238also partially lies beneath the row of openings192. The relay244and programmable logic device246lie beneath the row190and row186of openings. The transceiver248lies partially beneath the elongated opening195of the second ridge304which increases the ventilation over the transceiver248that also generates a significant amount of heat.

FIG. 35shows the card208mounted in the chassis100in relation to the second horizontal surface142and its ventilation structures. The guide214of the card208is positioned within a knockout of the first row144of the first ridge183as the card208is being inserted. In this embodiment, once the card208is fully inserted, the guide214rests partially within a knockout of the second row147of the second ridge185. The first hole218of the guide214comes to rest over the second row of openings314of the second horizontal surface142. The second hole220of the guide220comes to rest over the third row316and fourth rows320of openings. The third hole222comes to rest over the second row of knockouts147in the second ridge187. Thus, air is able to pass through the openings and knockouts of the second horizontal surface and pass through the guide214to absorb heat from the components of the card208.

In the embodiment shown, the capacitor236lies over the first row of openings312. The DC-DC converter238lies over the first row312and second row314of openings and over the first guide opening218. The relay244and programmable logic device246lie over the third row316and fourth row320of openings and over the second guide opening220. Amplifiers252,254and256,258included in this embodiment on the card208lie over the knockouts147and the third guide opening222.

FIGS. 36A and 36Bshow a side view of an embodiment of the repeater circuit board234of a card208suitable for installation in the chassis100. As discussed with reference toFIGS. 34 and 35, the repeater circuit board234has several components positioned on the board234in relation to the horizontal surface area103, the ridges300,304and the rows of openings186,190,192,312,314,316, and320of the horizontal surfaces102,142of the chassis100. The repeater circuit board234includes a power supply capacitor236, a DC-DC converter238, and a transceiver248previously discussed. The board234has the LEDs228,230, and232that provide the external visual indications of the repeater circuit's operation. Other components of the board234include but are not limited to relays240,242, and244, a programmable logic device (PLD)246, an oscillator250, isolation transformers260,262, and264,266, and first channel and second channel amplifiers252,254and256,258.

The embodiment shown inFIGS. 36A and 36Bmay be employed as a bridging repeater circuit that receives a low-level monitor signal through connector225and recreates the signal in a higher level suitable for network transmission and sends it out through connector225. The bridging repeater circuit board234ofFIGS. 36A and 36Bmay be used where a digital signal cross-connect (DSX) of the network becomes faulty and must be replaced without interrupting signal transfer. The bridging repeater circuit bypasses the faulty DSX without interrupting signal transfer by receiving monitor signals from healthy DSXs and providing high-level signals to the healthy DSXs until the healthy DSXs are permanently connected together to bypass the faulty DSX.

The capacitor236of the embodiment shown is positioned such that the uncovered horizontal surface area103of the first horizontal surface102is directly above it because the capacitor236does not need the extra ventilation provided by the larger openings186,190,192located between the ridges300,304that are covered by the mesh cover104. The DC-DC converter238of this embodiment may be a model that is highly flame resistant to enhance the flame containment of the chassis100. An epoxy encased DC-DC converter238such as the Ericsson PFK 4611SI is suitable in this embodiment. A monitor jack, which might ordinarily be placed between the LEDs230and232, is also absent in this embodiment to reduce the material on the board234that is susceptible to burning.

FIGS. 37A–Eshow the alarm circuitry272of the repeater circuit board234. The alarm circuitry272controls the LEDs228,230, and232. During normal operation, the LEDs228,230, and232are one color, such as green, to indicate normal operation. The power LED228turns red if the logic power plane270loses voltage from the output of the DC-DC converter238. This occurs due to relay242changing state in response to the loss of logic power thereby causing voltage received directly from the backplane connector225to activate the red diode of LED228instead of the green diode.

The channel A LED230and channel B LED232are electrically connected to the PLD246and to a logic ground plane268. The PLD246receives power from the logic power plane270and receives control signals from the transceiver248. When a channel is operating normally, the PLD246causes the green diode of the LED to illuminate.

If the transceiver248detects that channel A has no signal, then LOS0line passing from the transceiver248to the PLD246is triggered causing the PLD246to light the red diode along with the green diode of LED230to create a yellow illumination. If the transceiver248detects that channel B has no signal, then LOS1line passing from the transceiver248to the PLD246is triggered causing the PLD246to light the red diode along with the green diode of LED232to create a yellow illumination. If either channel has a loss of signal, then a minor alarm signal is generated and provided through the backplane connector225by relay244changing state due to a control signal from the PLD246. The minor alarm line is electrically linked to a chassis ground plane280.

If the transceiver248detects that it has failed, then the DFM line passing from the transceiver248to the PLD246is triggered causing the PLD246to light the red diode and turn off the green diode of LEDs230and232to create a red illumination. A major alarm signal is also generated and provided through the backplane connector225by relay240changing state due to a control signal from the PLD246. The major alarm line is electrically linked to the chassis ground plane280as well with coupling capacitors.

The PLD246and relays240,242, and244may be selected so as to minimize power consumption and reduce the amount of heat being generated by each circuit board234in the chassis100. The Atmel model ATF16V8BQL PLD draws only 100 milliwatts when active and is a suitable PLD for controlling the relays240and244and LEDs230and232. The NAIS TX-S relay draws only 50 milliwatts when active and is a suitable relay for controlling the LED228and the major and minor alarm signals.

FIGS. 38A–Gshows an embodiment of the transceiver circuitry located on the board234. The transceiver248, such as the Level One model LXT332, is electrically connected to the logic power plane270and the logic ground plane268. The transceiver248is also electrically linked to a channel A power plane274, a channel A ground plane278, a channel B power plane276, and a channel B ground plane282. Each channel of this embodiment has its own power and ground plane to avoid cross-talk and to avoid electrical noise from the power supply circuit ofFIGS. 39A and 39Band chassis100. The transceiver248is electrically linked to the oscillator250that is electrically connected to the logic power plane270and logic ground plane268. The oscillator250provides a reference frequency signal to the transceiver248.

The transceiver248receives its input signals for each channel from the input amplifiers252,254and256,258. The input amplifiers252,254and256,258receive input signals from the backplane connector225through the isolation transformers. Channel A input signal passes through isolation transformer264to the input amplifiers256,258, and channel A output signal passes through isolation transformer266. Channel B input signal passes through isolation transformer260to the input amplifiers252,254, and channel B output signal passes through isolation transformer262. As shown inFIGS. 36A and 36B, the input isolation transformer264and output isolation transformer266of channel A are contained in one unit. Similarly, the input isolation transformer260and output isolation transformer262of channel B are contained in another unit. Likewise, input amplifiers252and254of channel B are housed in one integrated circuit chip, and input amplifiers256and258of channel A are housed in another integrated circuit chip.

The input amplifiers252,254for the tip and ring connections, respectively, of channel B are electrically connected to the channel B power plane276and also to the channel B ground plane282. Likewise, the input amplifiers256,258for the tip and ring connections, respectively, of channel A are electrically connected to the channel A power plane274and also to the channel A ground plane278. Providing power to the amplifiers of differing channels from different power and ground planes reduces cross-talk and other electromagnetic interference. The input amplifiers252,254and256,258increase the amplitude of the monitor signal received by the bridging repeater circuit board234ofFIGS. 36A and 36Bto a level within the sensitivity range of the transceiver248. The transceiver248is then able to recreate the signal having the higher level suitable for network transmission.

In the bridging repeater circuit embodiment ofFIGS. 38A–G, the line build-out function of the transceiver248is fixed at a specific signal level and shape because a consistent cable length is generally used when connecting the bridging repeater circuit between the healthy DSXs. Thus, line build-out variability is not needed. Resistors284are arranged to provide a fixed connection between certain line build-out pins of the transceiver248to the logic power plane270while providing a fixed connection between other line-build out pins of the transceiver248to the logic ground plane268.

FIGS. 39A and 39Bshows the power supply circuitry. The backplane connector225receives −48V DC power and provides it through the board234to the DC-DC converter238. The −48V line and the −48 V return line are linked by the capacitor236to eliminate ripple. These lines are also coupled to the chassis ground plane280. The DC-DC converter238outputs a voltage that is electrically connected to the logic power plane270, the channel A power plane274, and the channel B power plane276. The DC-DC converter238has a return that is electrically connected to the logic ground plane268, the channel A ground plane278, and the channel B ground plane282. Ferrite beads are used to isolate each power plane connected to the DC-DC converter238and each power plane is AC coupled to each ground plane.

FIG. 40shows a ground layer of the circuit board234. The ground layer includes the chassis ground plane280that extends around the periphery286of the circuit board234and is electrically connected to the chassis ground provided through the chassis ground connector138of the chassis100. The chassis ground plane280surrounds the logic ground plane268, the channel A ground plane278, and the channel B ground plane282. The chassis ground plane280, logic ground plane268, channel A ground plane278, and channel B ground plane282are copper sheets that are isolated from each other within the single ground layer of the printed circuit board234.

FIG. 41shows a power layer of the circuit board234that is adjacent to the ground layer and separated from it by a dielectric layer. The power layer includes the logic power plane270, the channel A power plane274, and the channel B power plane276. The logic power plane270substantially overlaps with the logic ground plane268of the ground layer. The channel A power plane274substantially overlaps with the channel A ground plane278. Likewise, the channel B power plane276substantially overlaps with the channel B ground plane282. This arrangement minimizes electrical noise and cross-talk.

FIGS. 42A and 42Bshow a component layer of the circuit board234. The electrical components previously discussed are typically mounted to the component layer. The transceiver248is mounted in transceiver area294. The isolation transformers260,262, and264,266are mounted in transformer areas296and298. It is generally desirable to minimize the distance between the isolation transformer areas296,298and the transceiver area294. A distance of one and one-third inches or less is suitable.

Also located on the component layer are chassis ground pads290and292. These chassis ground pads290and292are electrically connected to the chassis ground plane280. The metal faceplate210of the circuit card208mounts to holes within the chassis ground pads290and292and metal-to-metal contact is established between the chassis ground pads290,292and the faceplate210. This metal-to-metal contact maintains the faceplate210at chassis ground.

FIGS. 51A and 51Bshows an alternative circuit board layout whereby additional surge protection is provided. The embodiment shown inFIGS. 51A and 51Bcontains input amplifiers252,254and256,258but lacks line build-out switches. This embodiment has Schottky diode banks360and362positioned between the isolation transformers260,262and264,266and the transceiver248. Each diode bank of this embodiment includes four Schottky diodes. Additionally, this embodiment has a transient voltage suppressor364positioned between the DC-DC converter238and the bottom of the circuit board234which is close to the surface142when installed in the chassis100.

FIGS. 52A and 52Bshow the transceiver and the configuration of the Schottky diodes from each bank360and362. This configuration of Schottky diodes can be used with the transceiver configuration shown inFIGS. 38A–G. One Schottky diode of the bank360is tied between the channel A power plane274′ and the channel A tip output. Another Schottky diode of the bank360is tied between the channel A power plane274′ and the channel A ring output. Another Schottky diode of the bank360is tied between the channel A tip output and the channel A ground plane278′. The last Schottky diode of the bank360is tied between the channel A ring output and the channel A ground plane278′.

Channel B output is configured the same way with one Schottky diode of the bank362being tied between the channel B power plane276′ and the channel B tip output. Another Schottky diode of the bank362is tied between the channel B power plane276′ and the channel B ring output. Another Schottky diode of the bank362is tied between the channel B tip output and the channel B ground plane282′. The last Schottky diode of the bank362is tied between the channel B ring output and the channel B ground plane282′.

FIGS. 53A and 53Billustrate the power supply circuit that includes additional surge protection. The DC-DC converter238of the circuit has an output line and a return line that ultimately provide the channel A power and ground, channel B power and ground, and the logic power and ground. A transient suppressor364is tied between the output line and the return line of the DC-DC converter238.

FIG. 54shows the ground layer of the circuit board234utilizing the additional surge protection. In this embodiment, the chassis ground plane280′ surrounds the periphery286of the ground layer and is electrically connected to the chassis ground provided through the chassis ground connector138of the chassis100. The chassis ground plane280′ surrounds the channel A ground plane278′, logic ground plane268′, and the channel B ground plane282′. As with the previous embodiment, chassis ground plane280′, logic ground plane268′, channel A ground plane278′, and channel B ground plane282′ are copper sheets that are isolated from each other within the single ground layer of the printed circuit board234.

In this embodiment, the logic ground plane268′ is positioned such that it is partially between the channel A ground plane278′ and the channel B ground plane282′. The diode bank360is located on the component layer and in the area368positioned over the channel A ground plane278′. Similarly, the diode bank362is located in the area366positioned over the channel B ground plane282′.

FIG. 55shows a power layer of the circuit board234that is adjacent to the ground layer shown inFIG. 54and separated from it by a dielectric layer. The power layer includes the logic power plane270′, the channel A power plane274′, and the channel B power plane276′. The logic power plane270′ substantially overlaps with the logic ground plane268′ of the ground layer embodiment shown inFIG. 54. The channel A power plane274′ substantially overlaps with the channel A ground plane278′ of the ground layer embodiment shown inFIG. 54. Likewise, the channel B power plane276′ substantially overlaps with the channel B ground plane282′ of the ground layer embodiment shown inFIG. 54. As can be seen, the bank360of diodes is located on the component layer in the area368positioned over the channel A power plane274′. The bank362of diodes is positioned over the channel B power plane276′.