Secure videoconferencing equipment switching system and method

Examples of systems described herein include videoconferencing systems having audio/visual components coupled to a codec. The codec may be configured by a control system. Communication networks having different security levels may be alternately coupled to the codec following appropriate configuration by the control system. The control system may also be coupled to the communication networks.

TECHNICAL FIELD

Examples described herein relate to videoconference systems, and more particularly, to systems for switching communication networks and peripheral devices between videoconference systems.

BACKGROUND OF THE INVENTION

Videoconference systems are generally systems of equipment used to transport audio and video information. Examples of standards of communication used to transport information between videoconference systems include H.320, which defines communication via ISDN telephone communication channels and H.323, which defines communication using both UDP/IP and TCP/IP (interne) communication protocols (typically via Ethernet).

It is often important to provide videoconference facilities with communication network access matched to the security requirements of the information present in the audiovisual data. For example, two networks may be provided for communications—one with a higher level of security than the other. This is sometimes referred to as a red/black system, where the “red” network refers to the more secure network. Communications that require more security than the less stringent security available on the “black” network must be conducted over the “red” network.

One approach to providing videoconference facilities with access to several networks, each with a different security level, is simply to provide more than one of each component necessary to form the videoconference system, or a portion of the videoconference system. For example, in a common room set up for videoconferencing on two different networks—one secure, and one not secure—two of all the necessary components (cameras, microphones, cables, and the like) would be provided, with one set being used for the red network, and the other for the black network. The need to provide duplicates of all of the videoconferencing equipment adds significant cost to the system.

One approach that substantially avoids the need for duplicate components is to utilize a patch bay. The patch bay contains links to the common audio/visual peripheral components (cameras, microphones, display devices, and the like), the red network(s), the black network(s), the red videoconference system coder/decoder (codec), and the black codec. Connections are established using patch cords between groups of connectors. For example, the black codec may first be connected to the common audio/visual peripheral components (A/V components) and the black network(s), and—by moving the requisite cables—the red codec may be connected to the common A/V components and the red network(s). Such a patch bay can be expensive, and is generally inefficient, prone to error, and limited in life due to physical wear on the connectors. In the event of a configuration error, highly confidential information may be communicated on the non-secure network.

Another approach was described in U.S. Pat. No. 7,477,614, which patent is hereby incorporated by reference in its entirety for any purpose. Systems described therein include videoconferencing systems having two codecs—one for communication with a secure communication network and another with a lower security communication network. A switching system was provided to couple audio/visual components to either the secure codec, the less secure codec, or in some cases to disconnect the audio/visual components from both codecs.

DETAILED DESCRIPTION

Certain details are set forth below to provide a sufficient understanding of embodiments of the invention. However, it will be clear to one skilled in the art that embodiments of the invention may be practiced without various of these particular details. In some instances, well-known circuits, control signals, timing protocols, electrical components, and software operations have not been shown in detail in order to avoid unnecessarily obscuring the described embodiments of the invention.

FIG. 1is schematic illustration of a system100according to an embodiment of the present invention. A switching unit105includes an electromechanical relay network, including relays140,142,144, and146. The electromechanical relay network is provided to make connections to communication networks, the networks125,130, and135shown inFIG. 1. As will be described further below, a single codec115may be utilized on multiple communication networks, with the electromechanical relay network making the connections between the codec115and the communication networks. Audio/visual or other electrical components may be coupled to the codec115, either directly or indirectly.

In this manner, as will be described further below, the electrical components110may be utilized on any of the communication networks. A control system120is also provided that may be connected to the communication networks, but may also have a direct connection to the codec115. The control system120may configure and control the codec115for connection to a selected communication network.

The audio/visual components110may include, but are not limited to one or a plurality of: cameras, microphones, video monitors, keyboards and the like. Generally any equipment to be used to couple information, including data, to or from the codec115may be connected to the codec115. The switching unit105functions to direct the audio, visual, data and/or control signals output from the codec115to one or more of the networks125,130, and135, which may have different security levels. The switching unit105may be implemented in a variety of ways and provides isolation between secure and unsecure or less secure networks, and isolation between connected and unconnected modes.

In the embodiment ofFIG. 1, the Ethernet network135and ISDN network125may be unclassified, or less secure networks, while the Ethernet network130may be a classified, or more secure network. The switching unit105may be implemented using DC actuated electromechanical relays to positively isolate signals coupled from the secure network130from signals coupled from the lower security network135and/or the lower security ISDN network125, and in an unconnected mode to isolate the codec115from all the networks125,130, and135. Although solid state relays may be used for portions of the switching unit105in some embodiments, solid state relays may not provide an actual physical disconnection and are subject to leakage and cross-talk, and therefore may not be used in some embodiments. The switching unit105develops two or more separate DC control signals to drive relays throughout the switching system to make or sever the connections as described herein. For example, a first DC control signal may be designated to control a “red”, or higher security system, while a second DC control signal is designated to control a “black”, or lower security system. The switching unit105is designed to prohibit more than one of the DC control signals from being energized at any given time.

In this manner, the switching unit105mediates communication between a single set of audio-visual components and a single codec115and communication networks125,130, and135. The same audio-visual components may be used on the secure and less secure networks. The same codec115is also used in both the secure and less secure networks. The codec115may be implemented as known in the art, and generally provides analog-to-digital and digital-to-analog conversion. The communication networks125,130, and135are depicted as an ISDN network and Ethernet networks, respectively; however, any type and any number of different communication networks may be coupled to the switching unit105for connection to the codec115. Further, the switching unit105may be connected to any number of codecs and similarly switch additional codecs between available networks.

As described above, the switching unit105may be implemented using electromechanical relays. The relay140connects and disconnects the codec115from the ISDN network125. The relay142has three additional positions for the codec115—connected to the Ethernet network130, the Ethernet network135, and disconnected from both Ethernet networks130and135.

Utilizing a single codec115to couple signals from the audio/visual components110to and from selected ones of the networks125,130, and135, may present challenges. In particular, it may not be desirable to have information stored in the codec115while the codec115is coupled to the classified network130to leak to the unclassified networks125or135when the codec115is later coupled to an unclassified network. Accordingly, in some embodiments a control system120is provided that may control operation of the codec115, and particularly, provide a control signal to the codec115when appropriate to reboot the codec115, load and erase configuration files from the codec115, or load or erase memory of the codec115. The control system120will be described further below and may also be used to advantageously control other components in the system, or provide diagnostics. Accordingly, the control system120may in some embodiments only be connected to a lower security or unclassified network, such as the Ethernet network135ofFIG. 1. By allowing connection only to a lower security or unclassified communication network, the control system120may advantageously be prevented from altering the system while it is connected to a classified or higher security network, such as the network130ofFIG. 1.

A relay146is also provided in the switching unit105to couple one or more power outlets150to other connected components. The relay146may also allow power to be disconnected from all components coupled to the switching unit105. In some embodiments, the relay146may control power to classified, or higher security components, and may allow power to be decoupled from classified components when the unclassified networks are being used.

Control of the relays in the switching unit105will be described further below; however, inFIG. 1, a control panel160is shown that may provide a control signal to the switching unit105indicative of a mode in which to operate. Each of the relays is then latched in a position dictated by the mode. As will be described further below, the switching unit105may also include a processor170and memory172. The processor170may receive the control signal indicative of a mode from the control panel160. The memory172may store relay settings corresponding to each mode. The processor170may access the relay settings stored in the memory172and provide corresponding control signals to the relays. The processor170may also be coupled to the control system120. The processor170may provide an indication of a selected mode to the control system120which may control the codec115in accordance with the selected mode, as will be described further below. The control system120may also communicate with the processor170, memory172, or both, to reconfigure, delete, or add modes and corresponding relay settings stored in the memory172.

FIG. 2depicts an embodiment of the control panel160ofFIG. 1. The embodiment of the control panel160shown inFIG. 2is a manual control panel having an interface250. The interface250shown inFIG. 2may be a key actuated rotary switch operable to be in one of three positions220,223, and226. The position226indicates that the more secure (“red”) videoconference system is being accessed, such as the classified Ethernet network130ofFIG. 1. The position220indicates that a less secure (“black”) videoconference system is being accessed, such as the unclassified Ethernet network135or the unclassified ISDN network125, or both, ofFIG. 1. The position223indicates that the codec115is disconnected and isolated from both the classified and unclassified Ethernet networks shown inFIG. 1. In some embodiments, following unclassified or “black” use of the system, the control panel must pass through the isolated or disconnected position before being placed in the classified or “red” position. Various colored lights may accompany the key turn positions for a clear visual indication of the system status, if desired. Although only three positions220,223,226are shown inFIG. 2it is to be understood that more may be used in other embodiments, depending on the number of videoconference systems or communication networks accessible to the switching unit105.

Although embodiments of systems, control panels, and switching units are described herein in terms of three operational modes, it is to be understood that generally any number of modes may be implemented with a corresponding number of relay configurations. In some instances, one or more modes may have a same relay configuration.

In some embodiments, the control panel160ofFIG. 1may be implemented as a remote control panel. An embodiment of the control panel160ofFIG. 1implemented as a remote control panel is shown inFIG. 3. The control panel160ofFIG. 3is implemented using a touch panel LCD display305mounted in a wall box310that may be mounted, for example, in a standard room light switch location. The LCD display305provides an indication of a current state at a location315. In the example ofFIG. 3, the current state is shown as “D” for a disabled state, indicating neither the classified nor the unclassified Ethernet network is connected to the codec115ofFIG. 1. Other settings are displayed in locations320and325in FIG.3—namely the “U” unclassified selection and “C” classified selection, described above with reference to positions226and220of the manual control switch ofFIG. 2. In the embodiment ofFIG. 3, however, the states are selected by touching the option on the LCD display305. In this manner, the switching unit105may be controlled remotely from an easily accessible room location. In some embodiments, the remote control panel160ofFIG. 3may require a secure user login prior to activation or presenting the “C” classified option. In some embodiments, following unclassified or “black” use of the system, an operator must select the isolated or disconnected position before being allowed to select the classified or “red” position. In some embodiments, the user may select the classified position after unclassified, and the system will automatically first enter the disabled or isolated state followed by transfer to the unclassified state.

A summary of the operation of the switching unit105ofFIG. 1will now be described with reference toFIG. 4.FIG. 4is a table showing position of the relays140,142, and144in each of three modes—classified, isolated, and unclassified. Recall these modes can be accessed with positions226,223, and220, respectively of the manual control panel ofFIG. 2, or with options325,315, and320, or the remote control panel ofFIG. 3. If classified mode is selected, the control panel160sends a control signal to the switching unit105indicating classified mode is selected. The switching unit then develops appropriate control signals for the relays140,142, and144. As indicated inFIG. 4, relay140will be open, relay142will be connected to network130, and the relay144will be open. In this manner, the classified network130is coupled to the codec115and the unclassified networks125and135are isolated from the codec115. Additionally, the control system120is isolated from the unclassified network135.

In the isolated mode, the control panel160sends a control signal to the switching unit105indicative of isolated mode. The switching unit105then develops control signals for the relays140,142, and144. As shown inFIG. 4, the relays140and142will be open, while the relay144will be closed. In this manner, the classified and unclassified networks are isolated from the codec115; however, the control system120may still be coupled to the unclassified network135for diagnostic or other purposes.

In the unclassified mode, the control panel160sends a control signal to the switching unit105indicative of unclassified mode. The switching unit105then develops control signals for the relays140,142, and144. As shown inFIG. 4, the relays140and144will be closed, and the relay142connected to the network135. In this manner, the unclassified networks125and135are coupled to the codec115and the control system120is also coupled to the unclassified network135.

Note that in all three modes, a connection may be maintained between the control system120and the codec115. In some embodiments, the connection between the control system120and the codec115may be implemented with an RS232 interface; however, other interfaces may be used. The control system120may accordingly control codec115operation in any of the modes, and provide diagnostic or other metrics over multiple modes of codec operation.

The description above with reference toFIG. 4describes the final position of the relays140,142, and144in each of the three described modes. However, as has been described above, in some embodiments, additional steps may be taken to ensure information stored in the codec115during classified operation is not accessible to unclassified networks. Accordingly, configuration of the codec will now be described for transitions between the three modes described above.

In the isolated or disabled mode, the codec115is powered off. Referring toFIG. 1, in some embodiments the codec115may be powered off by receiving a control signal indicative of power down from the control system120. That is, a signal indicative of the disabled mode may be provided to the processor170, which then provides a signal to the control system120indicative of disabled mode. Responsive to the indication of disabled mode, the control system120may provide a signal to the codec115to power down.

When transitioning from isolated or disabled state to unclassified mode, the codec115may simply be powered on prior to or simultaneously with connecting the networks125and135to the codec115. The control system120may receive an indication of unclassified mode from the processor170, and responsive to the indication of unclassified mode, provide a signal to the codec115to power on.

When transitioning from disabled to classified mode, the codec115is also powered on as described above. However, the codec115may also be configured for classified communications, and then rebooted. That is, the control system120may receive an indication of classified mode from the processor170. Responsive to the indication of classified mode, the control system120may configure the codec for classified communication. The configuration may include a variety of configuration procedures. For example, a configuration file suitable for use in communicating over the classified network130may be stored in the control system120. The configuration file may be loaded into the codec115responsive to an indication of classified mode. The control system120may also erase or reset memory associated with the codec115as part of configuring the codec for classified communications. This may include erasing or resetting unclassified network information from the codec115and loading the classified network information, such as IP addresses, subnet mask, and DNS information. Following configuration for classified communication, the control system120may reboot the codec115. The control system120may check that the codec115has been rebooted and configured for classified communication. Following the check, the control system120may provide an indication to the processor170that the codec115is configured for classified communication. Responsive to the indication the codec115is configured for classified communication, the processor170may provide control signals to the relays to couple the classified network130to the codec115. Accordingly, the transition of the relay142to the classified network130may be delayed until after the codec115has been configured for classified communication and rebooted.

When transitioning from an unclassified to an isolated or disabled mode, the control system120powers the codec115off.

When transitioning from a classified to an isolated or disabled mode, the control system120receives an indication from the processor170of the disabled mode. Responsive to the indication of the transition from the classified to the disabled mode, the control system120may delete or otherwise reset memory associated with the codec115to remove any possibly classified data and network settings. The classified configuration file loaded in the codec115may be removed and stored in the control system120. The control system may reboot the codec115.

When transitioning from classified, through isolated or disabled, to unclassified, the codec115is disconnected from the communication networks as in the disabled state. A similar process as described above with respect to the transition from classified to disabled mode may be performed. The codec may be rebooted prior to connection to the unclassified networks. The control system120may provide an indication to the processor170that the codec115has been rebooted and cleared for unclassified communication. Following an indication that the codec115is configured for unclassified communication, the processor170may provide the control signals to couple the unclassified networks to the codec115. That is, processor170may decouple the codec115from the networks as described above for transition to the disabled state, but the control signals to couple the unsecure network to the codec115may be delayed until the control system120provides an indication that the codec115has been configured for unclassified communication. It may not be necessary to power down the codec, as is typically done in isolated or disabled mode.

When transitioning from unclassified, through isolated or disabled, to classified, the codec115is disconnected from the communication networks, configured to classified mode as described above, and rebooted, prior to connection to the classified network130. It may not be necessary to power down the codec, as is typically done in isolated or disabled mode.

Having described a general configuration of a switching unit and videoconferencing system according to embodiments of the present invention, a more detailed description of embodiments of the switching unit and operation of the switching unit will now be described.

FIG. 5is a schematic illustration of an implementation of the switching unit105. The control panel160may be connected to an RJ45 interface502of the switching unit105. Although an RJ45 interface to the control panel160is shown, other interfaces may also be implemented. The control system120ofFIG. 1may be connected to the switching unit105using a DIN 9-pin interface503. The control system120may communicate using an RS232 protocol to a control system interface505of the switching unit105. The control system interface505may communicate signals between the control system120and the processor170. The processor170and memory172may receive signals from the control panel160and control system interface505, as shown. Any suitable processors and memory may be used, and although only a single box for each is shown inFIGS. 1 and 5, any number may be present. The processor170may also have a test interface515, which may be implemented as a standard JTAG interface. This allows for testing and confirmation of the operation of the processor170and diagnostics for the switching unit105.

A power supply520may also be provided in the switching unit105coupled to a power source521through a power source interface522. The power supply520may convert 110V/220V supplied power to +3 or +5 or +12V DC power for use by the relay drivers, described below. Power filters525may also be provided, along with power regulators and fuse protection, as desired. The power filters525may also have a test interface530.

Relay drivers535are provided coupled to the processor170. The processor170provides control signals to the relay drivers to set the relays using DC control signals, as has been described above, developed based on the power supplied by the power supply520and filters525. The processor may receive an indication of a selected mode from the control panel160, access stored relay settings in the memory172corresponding to the selected mode, and provide signals to the relay drivers535to achieve the relay settings for the selected mode.

The relays shown inFIG. 5will now be described with reference toFIG. 1. The relays536and537provide connection to power supplies for black, or less secure, and red, or more secure, electrical components, respectively, over the DIN 9-pin interfaces538and539. A general purpose input/output (GPIO) interface540may also be provided along with GPIO relays541to connect with legacy components.

The switching unit105ofFIG. 5is shown configured for possible connection with up to four ISDN networks. There are four sets of relays550-553shown. The relays550are configured to couple and decouple the codec interface555with the ISDN interface556. So, for example, the ISDN connection of the codec115ofFIG. 1may be coupled to the codec interface555of the switching unit105, and the ISDN network125may be coupled to the ISDN interface556. The relays550may then serve the function of relay140described inFIG. 1. The relays551,552, and553, make similar connections between the additional codec and ISDN interfaces shown. Each set of relays may further include appropriate terminations, and jumpers may be included as well to reconfigure the RJ45 interfaces into interfaces compatible with other standards.

The relays565are provided to couple an Ethernet interface569to a connected codec, such as an Ethernet interface of the codec115ofFIG. 1, to either of two Ethernet networks, as has been described above. A first network is available at Ethernet interface566and the second at Ethernet interface567. So for example, the relays565may include the relay142ofFIG. 1and the interface566may be coupled to the Ethernet network135while the interface567is coupled to the Ethernet network130.

Finally, relays570are provided to couple another interface571to a control system to another Ethernet interface to the unclassified Ethernet network135. Recall from above that separate interfaces to the unclassified Ethernet network135may be used to maintain a connection between the unclassified Ethernet network135and the control system120while the codec115is unconnected from the unclassified Ethernet network135in disable mode. So, for example, the relays570may include the relay144ofFIG. 1. By having separate sets of relays570and565, note that a connection to unsecured Ethernet network135may be severed from the codec115by disconnecting the relays565, but maintained with the control system through the relays570. This may allow for continued reporting of metrics and other diagnostic information when the system is in an isolated mode, by isolating the codec115, but allowing, the connection between the control system and the Ethernet network135in disabled mode.

An example of operation of the switching unit105will now be described. The memory172may store relay settings corresponding to the various modes available to the switching unit105. For example, a table similar to the table shown inFIG. 4may be stored in the memory172. A signal indicative of a mode, such as ‘classified’ mode, is provided by the control panel to the processor170. The processor is configured to look-up the relay settings associated with the mode and couple one or more control signals to the relay drivers535to place the relays in the switching unit105in the positions indicated in the table. The processor170and memory172may implement their functionality in hardware, software, firmware, or combinations thereof.

At startup, or at other times during operation, the processor170may test the relays by sensing current and voltage through the relay drivers535. If test results indicate the relays are in positions other than those indicated by the table entries for the present mode, the processor170may provide control signals to the control system120, the relay drivers535, and/or other components to shut the system down, by, for example, disconnecting the power, or disconnecting relays. In this manner, failure of one or more relays may be detected and the system protected in the event of relay or control failure.

As has been described above, the relay settings for each mode may be stored in the memory172. The modes and relay settings may be added, deleted, or changed by a control system through the control system interface505. The control system may also make changes remotely when the relays570allow communication between the control system and an Ethernet communication network. Additionally, the control system may make metrics available over the Ethernet network135, such as room usage metrics. In this manner, the metrics data may be retrieved anywhere accessible to the Ethernet network135.

A schematic illustration of a system600according to an embodiment of the present invention is shown inFIG. 6. A rear view of several components is shown, to provide a view of their electrical connections. The components shown inFIG. 6may be mounted together in standard computer racking equipment, or may be located separately. The codec115, switching unit105, and control system120are shown. The control system120may include its own processor and memory, and may have connected input/output devices. Also shown is a power strip605. Interconnections between the components will now be described.

The power strip605may be plugged into any of a variety of “black” or unsecure or less secure components. This may include, for example, computers, audio/visual equipment including, for example, displays, monitors, cameras, microphones. The power strip605is connected to the “black power” interface538of the switching unit105. In this manner, the power strip605may be energized when the switching unit105closes the relay to the black power control538. Another power strip, a “red” or more secure or classified power strip may also be provided (although not shown inFIG. 6). The classified power strip may be plugged into classified components, such as classified or “red” computers. The classified power strip may be coupled to the “red power” interface539of the switching unit105to allow power to the classified components when the switching unit105closes a relay to the red power interface539.

Interfaces of the codec115are shown inFIG. 6. As shown, the interfaces may include audio and video input and output ports. The signal lines of audio/visual or other electrical components may be coupled to the codec115. The components may include, for example, computers, displays, cameras, microphones, DVD players, or other signal sources or receivers. The codec115may communicate signals between the audio and visual input and output ports and ISDN connections610or IP connection615of the codec115. Accordingly, the ISDN connections610are coupled to respective ones of the switching unit interfaces555,557,559and561as shown. Similarly, the IP interface615of the codec is coupled to an IP interface569of the switching unit105. The switching unit may control which networks are made available at the interfaces555,557,559,561and569. In this manner, the switching unit105controls the networks coupled to the codec115.

A rear view of the switching unit105is shown inFIG. 6to illustrate the electrical interfaces. The black power interface538and red power interface539may be coupled to red and black power strips. The GPIO interface540may be coupled to legacy components communicating over general purpose110. The control panel160(not shown inFIG. 6) may be coupled to the switching unit at the interface502. The control system120may be coupled to the switching unit at the interfaces503and571. The two interfaces, as described above, may allow the switching unit105to connect and disconnect an Ethernet network to the interface571while maintaining a control connection to the control system120through the interface503. ISDN networks are coupled to the interfaces556,558,560and562. The switching unit105may control the coupling of these networks to the codec interfaces at555,557,559and561. The unclassified Ethernet network135is coupled to the switching unit at interfaces566and568. The interface568may be used by the switching unit105to connect and disconnect the control system120from the Ethernet network135, through the interface571. The interface566may independently be used by the switching unit to connect and disconnect the codec115from the Ethernet network135, through the interface569. Power is coupled to the switching unit105at the interface522. Classified Ethernet network130is coupled to the switching unit105at the interface567. The switching unit105may couple the classified network to the codec115through the interface569. Note that the classified Ethernet network130is spaced from the interface569, in some embodiments by at least two inches, to maintain isolation between the classified Ethernet network130and the unclassified Ethernet network125when the unclassified Ethernet network is connected to the interface569.

Interfaces to the control system120are also shown inFIG. 6. Although not shown inFIG. 6, the control system120may include a processing unit and memory. The memory may store configuration files to be loaded into the codec115for different modes of communication, as generally described above. The processor may be configured to perform diagnostics and control the codec115. Input and output devices may also be coupled to the control system120for administration of the control system120and for viewing or storing diagnostic information.

The control system120may be coupled to the switching unit105using the interface571of the switching unit coupled to an interface620of the control system120. The control system120may also be coupled to the switching unit105over an RS-232 connection between the interface503and625. A direct connection between the codec115and the control system120may be made between an interface630of the codec115and an interface635of the control system120. In this manner, a connection between the codec115and the control system120may be maintained independent of the switching unit105in some embodiments. So, for example, the control system120may control the codec115including rebooting the codec115, or loading or removing configuration files from the codec115, using the connection between the interfaces630and635, responsive to an indication of a desired mode received by the control system120from the switching unit105, as has been described above.

Embodiments of the switching unit105may advantageously be supplied in a 1 rack unit (1 RU) configuration having a height of 1 and ¾ inches. The compact configuration of the switching unit105advantageously may save space in computing rack. A dense printed circuit board may be used to provide the interconnections within the switching unit. In particular, in some embodiments, a twelve-layer printed circuit board may be used to provide many planes and reduce the overall space required by the switching unit105. In some embodiments, two printed circuit boards may be used, a motherboard configured to provide Ethernet, power, and control connectivity, and a daughterboard configured to provide ISDN connectivity. The daughterboard may be placed above or below the motherboard.

The switching unit105may meet stringent isolation requirements between outputs. Some embodiments may provide isolation in excess of 50 dB at frequencies associated with high speed Ethernet and ISDN. Several aspects of the design of the switching unit105may contribute to the isolation performance. The relays may be selected for achieving hi-isolation between contacts that are not in the signal path. When the relay is in the normally closed mode, the normally open contacts have very low cross-talk with the normally closed contacts. The printed circuit boards may be designed to provide maximum signal isolation and minimize crosstalk between signal lines. In particular, as described above, a multi-layer printed circuit board, such as a twelve layer board, may be used where every signal type uses an entire plane and an associated ground plane. The signal may be therefore considered encapsulated similar to a coaxial transmission line. Grounds for the various signal types may not be interconnected with each other with “via” holes. Maintaining separate ground planes for the signal types may also improve the isolation. All PCB ground planes may then be grounded at one common location.