Abstract:
A fluid sensor comprises a sensor housing ( 12 ), a sensor package ( 14 ), an actuator ( 16 ) and a switch ( 18 ). The sensor package ( 14 ) is disposed within the sensor housing ( 12 ) and includes first and second screens and at least one sensing membrane. The sensing membrane is disposed between the first and second screens ( 36 ) and is adapted to expand when exposed to a predetermined quantity of a first predetermined fluid. The actuator ( 16 ) is disposed proximate the sensor package ( 14 ) within the sensor housing ( 12 ) and moveable between a first position and a second position through an intermediate position. The switch ( 18 ) is disposed proximate the actuator ( 16 ) and is operable between closed and open positions. When the actuator ( 16 ) is in the second position at least a portion of the actuator ( 16 ) depresses the switch ( 18 ) to control an-electrical, circuit connected therewith.

Description:
RELATED APPLICATION 
     This application claims the benefit, under 35 U.S.C. §365 of International Application PCT/US2008/003946 filed Mar. 26, 2008 which was published in accordance with PCT Article 21(2) on Oct. 2, 2008 in English and which claims the benefit of U.S. provisional patent application No. 60/920,055 filed Mar. 26, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to signal communications, and more particularly, to architecture for integrating a single wire multi switch (SWM) transceiver and the legacy LNB mode into the same satellite set top box. 
     2. Background Information 
     In a satellite broadcast system, one or more satellites receive signals including audio and/or video signals from one or more earth-based transmitters. The satellite(s) amplify and rebroadcast these signals to signal receiving equipment at the dwellings of consumers via transponders that operate at specified frequencies and have prescribed bandwidths. Such a system includes an uplink transmitting portion (i.e., earth to satellite(s)), an earth-orbiting satellite receiving and transmitting portion, and a downlink portion (i.e., satellite(s) to earth). 
     In dwellings that receive signals from a satellite broadcast system, signal receiving equipment may be used to frequency shift the entire broadcast spectrum of the satellite(s), and frequency stack the resultant output onto a single coaxial cable. However, as the number of satellites within a satellite broadcast system increases, and with the proliferation of high definition satellite channels, a point will be reached where the total bandwidth required to accommodate all of the satellites will exceed the transmission capability of the coaxial cable. It has become necessary for the satellite decoder industry to implement more satellite slots into their distribution systems. To provide for the increased number of satellite slot transmissions a more elaborate means for satellite configurations selection is required. The two primary methods, used now for selecting these various configurations are the legacy LNB power supply method and the new Frequency Translation Module (SWM) method. 
     The legacy LNB power supply method controls satellite RF tone on or off selection by voltage level and a superimposed, 600 mvp-p, 22 kHz tone. Tone selection is accomplished by either a constant tone or a Pulse Width Modulated (PWM) tone. The industry standard for the PWM tone is called DiSEqC and is defined in the Eutelsat DiSEqC Bus Functional Specification. The two stage, output voltage (13 or 18 volts) is typically used to select the polarity of incoming satellite signals and the tone selects various satellite slots in space. 
     The second method (SWM) is self powered, therefore, it does not require an LNB power supply, and uses a UART controlled 2.3 MHz, Frequency Shift Key (FSK) modulation scheme to communicate selection commands to the satellite configuration switch. Other modulation methods may be substituted for the UART modulation method. The SWM switch is designed to select a satellite signal transponder from a host of satellite receiver antennas and translate it, in frequency, to a single transponder. This new frequency shifted transponder band is then sent to the satellite decoder box through the connecting coax cable. 
     Present day satellite decoder systems need the ability to switch between these two communication methods and operate in either mode without being disturbed by the other system. If a satellite receiver system is capable of SWM operation, the conventional LNB power supply will be disabled such that all control and selection of the available satellite signals is done with the modulated 2.3 MHz, SWM communication channel. 
     However, a problem arises when multiple circuits are coupled to the RF conductor of the coaxial cable where each circuit is required to perform a different task. For example, the SWM requires the outdoor unit to 20V power supply to co-exist with the 2.3 MHz tone on the same RF cable. The low impedance of the 20V DC power supply may short the 2.3 MHz tone to ground and result in 2.3 MHz SWM failure. Furthermore, some current satellite systems required the 5 MHz to 30 MHz band to be reserved for home networking use. The low impedance of the 20 volt power supply will also short this frequency band to ground. 
     An additional concern arises in that the 2.3 MHz SWM tone could cause harmonics to arise on the shared RF cable. These harmonics may interrupt other working systems on the shared RF cable. The 2.3 MHz SWM tone can be as high as 0.7 volts. If such a voltage is applied on surge protection diode or a transistor b-e junction, harmonic could occur on the RF coax cable and affects other working unit on same conductor. 
     Additionally, all the circuitry of the SWM system must be protected from voltage and current surges generated by environmental conditions, such as lightning. The SWM system must coexist with this surge protection and harmonic cancellation circuitry. Thus, it is desirable to have a circuit which can withstand high surge and has low capacitance to ground without disturbing the RF program signals, the SWM tone or DC supply voltages while addressing the above stated problems. The present invention described herein addresses these and/or other problems that presently exist. 
     SUMMARY OF THE INVENTION 
     In accordance with an aspect of the present invention, an apparatus is provided. The apparatus comprises a first DC voltage block coupled between a source of a first RF signal having a first frequency and a first transmission line, a second DC voltage block coupled between a source of a DC potential and a source of reference potential, and a first band reject filter for rejecting said first frequency, coupled between said source of the DC potential and the first transmission line. 
     In accordance with another aspect of the present invention, the apparatus further comprises a third DC voltage block coupled between a source of a second RF signal and a second transmission line, said second RF signal having a second frequency, a second band reject filter for rejecting said second frequency, coupled between said first transmission line and the second transmission line, and a low pass filter coupled between the first transmission line and the source of reference potential. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a diagram showing an exemplary environment for implementing the present invention; 
         FIG. 2  is a block diagram showing further details of the SWM of  FIG. 1  according to an exemplary embodiment of the present invention; 
         FIG. 3  is a diagram showing further details of the LNB and IRD LNB control transceivers according to an exemplary embodiment of the present invention; 
         FIG. 4  is a block diagram showing further details of the SWM linear switch block according to an exemplary embodiment of the present invention; 
         FIG. 5  is a block diagram showing details of a transceiver passive linear switch according to an exemplary embodiment of the present invention; 
         FIG. 6  is a block diagram showing details of a multi tone transceiver passive linear switch according to an exemplary embodiment of the present invention; 
         FIG. 7  is a block diagram showing details of a 6 port linear network SWM LNB switch according to an exemplary embodiment of the present invention; 
         FIG. 8  is a block diagram showing details of a two stage surge protector according to an exemplary embodiment of the present invention; 
     
    
    
     The exemplifications set out herein illustrate preferred embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, and more particularly to  FIG. 1 , a diagram of an exemplary environment  100  for implementing the present invention is shown. Environment  100  of  FIG. 1  comprises a plurality of signal receiving means such as signal receiving elements  10 , such as antennas or portions of an antenna or transmission line inputs or low noise block amplifer any other means for receiving an information bearing signal, frequency translating means such as SWM  20 , a plurality of signal splitting means such as signal splitters  40 , and a plurality of signal receiving and decoding means such as IRDs  60 . The signal receiving elements  10  may be operative to shift the frequency of received signals to frequencies more conducive to transmission via transmission lines such as coaxial cables. For example, a low noise block amplifier used in satellite television signal reception may be operative to frequency shift the received signal from around 12 GHz o 1 GHz, or from “Ka” band to “L” band. According to an exemplary embodiment described herein, the aforementioned elements of environment  100  are operatively coupled to one another via a transmission medium such as coaxial cable, although other types of transmission mediums may also be used according to the present invention. Environment  100  may for example represent a signal communication network within a given household and/or business dwelling. 
     Signal receiving elements  10  are each operative to receive signals including audio, video, and/or data signals (e.g., television signals, etc.) from one or more signal sources, such as a satellite broadcast system and/or other type of signal broadcast system. According to an exemplary embodiment, signal receiving element  10  is embodied as an antenna such as a satellite receiving dish, but may also be embodied as any type of signal receiving element. 
     SWM  20  is operative to receive signals including audio, video, and/or data signals (e.g., television signals, etc.) from signal receiving elements  10 , and process the received signals using functions including signal tuning and frequency translation functions to generate corresponding output signals that are provided to IRDs  60  via coaxial cable and signal splitters  40 . According to an exemplary embodiment, SWM  20  may communicate with up to 12 IRDs  60  within a single dwelling. For purposes of example and explanation, however,  FIG. 1  shows SWM  20  connected to 8 IRDs  60  using simple two-way signal splitters  40 . Further exemplary details regarding SWM  20 , and its ability to communicate with IRDs  60  will be provided later herein. 
     Signal splitters  40  are each operative to perform a signal splitting and/or repeating function. According to an exemplary embodiment, signal splitters  40  are each operative to perform a 2-way signal splitting function to facilitate signal communication between SWM  20  and IRDs  60 . 
     IRDs  60  are each operative to perform various signal receiving and processing functions including signal tuning, demodulation and decoding functions. According to an exemplary embodiment, each IRD  60  is operative to tune, demodulate and decode signals provided from SWM  20  via signal splitters  40 , and enable aural and/or visual outputs corresponding to the received signals. As will be described later herein, such signals are provided from SWM  20  to IRDs  60  responsive to request commands from IRDs  60 , and such request commands may each represent a request for a desired band of television signals. With a satellite broadcast system, each request command may for example indicate a desired satellite and/or a desired transponder. The request commands may be generated by IRDs  60  responsive to user inputs (e.g., via remote control devices, etc.). 
     According to an exemplary embodiment, each IRD  60  also includes an associated audio and/or video output device such as a standard-definition (SD) and/or high-definition (HD) display device. Such display device may be integrated or non-integrated. Accordingly, each IRD  60  may be embodied as a device such as a television set, computer or monitor that includes an integrated display device, or a device such as a set-top box, video cassette recorder (VCR), digital versatile disk (DVD) player, video game box, personal video recorders (PVR), computer or other device that may not include an integrated display device. 
     Referring to  FIG. 2 , a block diagram providing further details of SWM  20  of  FIG. 1  according to an exemplary embodiment of the present invention is shown. SWM of  FIG. 2  comprises switching means such as cross over switch  22 , a plurality of tuning means such as tuners  24 , a plurality of frequency converting means such as frequency up converters (UCs)  26 , a plurality of amplifying means such as variable gain amplifiers  28 , signal combining means such as signal combiner  30 , transceiving means such as transceiver  32 , and control means such as controller  34 . The foregoing elements of SWM  20  may be implemented using integrated circuits (ICs), and one or more elements may be included on a given IC. Moreover, a given element may be included on more than one IC. For clarity of description, certain conventional elements associated with SWM  20  such as certain control signals, power signals and/or other elements may not be shown in  FIG. 2 . 
     Cross over switch  22  is operative to receive a plurality of input signals from signal receiving elements  10 . According to an exemplary embodiment, such input signals represent various bands of radio frequency (RF) television signals. With a satellite broadcast system, such input signals may for example represent L-band signals, and cross over switch  22  may include an input for each signal polarization used within the system. Also according to an exemplary embodiment, cross over switch  22  selectively passes the RF signals from its inputs to specific designated tuners  24  responsive to control signals from controller  34 . 
     Tuners  24  are each operative to perform a signal tuning function responsive to a control signal from controller  34 . According to an exemplary embodiment, each tuner  24  receives an RF signal from cross over switch  22 , and performs the signal tuning function by filtering and frequency down converting (i.e., single or multiple stage down conversion) the RF signal to thereby generate an intermediate frequency (IF) signal. The RF and IF signals may include audio, video and/or data content (e.g., television signals, etc.), and may be of an analog signal standard (e.g., NTSC, PAL, SECAM, etc.) and/or a digital signal standard (e.g., ATSC, QAM, QPSK, etc.). The number of tuners  24  included in SWM  20  is a matter of design choice. 
     Frequency up converters (UCs)  26  are each operative to perform a frequency translation function. According to an exemplary embodiment, each frequency up converter (UC)  26  includes a mixing element and a local oscillator (not shown in FIGS.) that frequency up converts an IF signal provided from a corresponding tuner  24  to a designated frequency band responsive to a control signal from controller  34  to thereby generate a frequency up converted signal. 
     Variable gain amplifiers  28  are each operative to perform a signal amplification function. According to an exemplary embodiment, each variable gain amplifiers  28  is operative to amplify a frequency converted signal output from a corresponding frequency up converter (UC)  26  to thereby generate an amplified signal. Although not expressly shown in  FIG. 2 , the gain of each variable gain amplifier  28  may be controlled via a control signal from controller  34 . 
     Signal combiner  30  is operative to perform a signal combining (i.e., summing) function. According to an exemplary embodiment, signal combiner  30  combines the amplified signals provided from variable gain amplifiers  28  and outputs the resultant signals onto a transmission medium such as coaxial cable for transmission to one or more IRDs  60  via signal splitters  40 . 
     Transceiver  32  is operative to enable communications between SWM  20  and IRDs  60 . According to an exemplary embodiment, transceiver  32  receives various signals from IRDs  60  and relays those signals to controller  34 . Conversely, transceiver  32  receives signals from controller  34  and relays those signals to one or more IRDs  60  via signal splitters  40 . Transceiver  32  may for example be operative to receive and transmit signals in one or more predefined frequency bands. For example, communications may be made by RF signal in a low frequency band, such as 2.3 MHz, with UART modulation scheme. 
     Controller  34  is operative to perform various control functions. According to an exemplary embodiment, controller  34  receives request commands for desired bands of television signals from IRDs  60 . As will be described later herein, each IRD  60  may transmit its request command to SWM  20  during a separate time slot that is assigned by controller  34 . With a satellite broadcast system, a request command may indicate a desired satellite and/or a desired transponder that provides a desired band of television signals. Controller  34  enables signals corresponding to the desired bands of television signals to be transmitted to corresponding IRDs  60  responsive to the request commands. 
     According to an exemplary embodiment, controller  34  provides various control signals to cross over switch  22 , tuners  24 , and frequency up converters (UCs)  26  that cause the signals corresponding to the desired bands of television signals to be transmitted to IRDs  60  via a transmission medium such as coaxial cable. Controller  34  also provides acknowledgement responses to IRDs  60  responsive to the request commands which indicate the frequency bands (e.g., on the coaxial cable, etc.) that will be used to transmit the signals corresponding to the desired bands of television signals to IRDs  60 . In this manner, controller  34  may allocate the available frequency spectrum of the transmission medium (e.g., coaxial cable, etc.) so that all IRDs  60  can receive desired signals simultaneously. 
     Referring to  FIG. 3  a diagram of an exemplary environment  300  for implementing the present invention is shown showing further details of the interconnectivity between the SWM  20  and IRD  60  of  FIG. 1 . Environment  300  of  FIG. 3  comprises a protection circuit  31 , a transceiver  32 , and a signal combiner  30  within the SWM  20 . Within the IRD  60 , a tuner  36 , a transceiver  37 , an LNB power supply  38 , a DiSEqC encoder/decoder  39 , and a protection circuit  35 . 
     Protection circuit  31  is operative to pass desired signals, such as 22 kHz tone on DC voltage, SWM control signals, and television signals without distortion while protecting the SWM circuitry from lightning surge and other environmental electrical disturbances. According to an exemplary embodiment, protection circuit  31  comprises surge protection diodes implemented to absorb energy from positive and negative lightning surge events. The surge protection diodes are configured not to present a non-linear conduction path to the 2.3 MHz SWM signal. 
     Signal combiner  30  is operative to perform a signal combining (i.e., summing) function. According to an exemplary embodiment, signal combiner  30  combines the amplified signals provided from variable gain amplifiers  28  and outputs the resultant signals onto a transmission medium such as coaxial cable for transmission to one or more IRDs  60  via signal splitters  40 . 
     Transceiver  32  is operative to enable communications between SWM  20  and IRDs  60 . According to an exemplary embodiment, transceiver  32  receives various signals from IRDs  60  and relays those signals to controller  34 . Conversely, transceiver  32  receives signals from controller  34  and relays those signals to one or more IRDs  60  via signal splitters  40 . Transceiver  32  may for example be operative to receive and transmit signals in one or more predefined frequency bands. 
     Protection circuit  35  is operative to pass desired signals, such as SWM control signals, 22 kHz DiSEqC signals, and television signals without distortion while protecting the IRD  60  circuitry from lightning surge and other environmental electrical disturbances. According to an exemplary embodiment, protection circuit  35  comprises surge protection diodes implemented to absorb energy from positive and negative lightning surge events. The surge protection diodes are configured not to present a non-linear conduction path to the 2.3 MHz SWM signal or the incoming television signals transmitted from the SWM  20 . 
     Tuner  36  is operative to perform a signal tuning function responsive to a control signal from IRD controller in response to a channel selection from the user. According to an exemplary embodiment, the tuner receives an RF signal via protection circuit  35 , and performs the signal tuning function by filtering and frequency down converting (i.e., single or multiple stage down conversion) the RF signal to thereby generate an intermediate frequency (IF) signal. The RF and IF signals may include audio, video and/or data content (e.g., television signals, etc.), and may be of an analog signal standard (e.g., NTSC, PAL, SECAM, etc.) and/or a digital signal standard (e.g., ATSC, QAM, QPSK, etc.). 
     Transceiver  37  is operative to enable communications between SWM  20  and IRDs  60 . According to an exemplary embodiment, transceiver  37  receives various signals from SWM  20  and relays those signals to the IRD controller. Conversely, transceiver  37  receives signals from IRD controller and relays those signals to the SWM via coaxial cable and protection circuits  31  and  35 . Transceiver  37  may for example be operative to receive and transmit signals in one or more predefined frequency bands. 
     The LNB power supply  38  is operative to generate the required operating DC power for the LNBs when the system is operating in Legacy LNB mode. According to an exemplary embodiment, the LNB power supply  38  is a conventional LNB power supply comprising a DC to DC, switching power supply feeding a linear regulator which can superimpose a 22 kHz tone onto the DC output voltage. The LNB power supply has the ability to power down or disable the output. The output of the linear regulator is typically a push-pull type, but can equally be other configurations, such as emitter follower type output. 
     The DiSEqC encoder and decoder  39  is operative to utilize a 22 kHz signal or other required control tones to communicate to the LNBs when the IRD is operating in the Legacy mode. The DiSEqC encoder and decoder  39  may be further operative to generate and transmit 22 kHz current pulses to communicate with the LNBs. According to an exemplary embodiment, there are two 22 kHz tone modes, constant tone and two-way pulse width modulated (PWM) tone control mode. When the LNB regulator is transmitting tone, the DiSEqC encoder and decoder  39  provides a low impedance output to the switch  33 . 
     Referring now to  FIG. 4 , a block diagram showing further details of the SWM linear switch block  400  according to an exemplary embodiment of the present invention is shown. The SWM linear switch block  400  comprises two main portions, a two stage surge protection circuit  401  and a 6 port linear network switch circuit  402 . According to the exemplary embodiment, the SWM linear switch block  400  is present within the IRD, and comprises a coupling to the RF input  405 , a tuner  410 , a 2.3 MHz high impedance negative surge path  415 , a 2.3 MHz high impedance positive surge path  420 , a low impedance surge path  425 , a first DC blocker 22 kHz blocker 2.3 MHz pass circuit  430 , a 2.3 MHz transceiver  435 , a second DC blocker 22 kHz blocker 2.3 MHz pass circuit  440 , a 5-30 MHz linear impedance circuit  445 , a 2.3 MHz band rejecter circuit  450 , a first DC blocker 22 kHz pass 2.3 MHz pass circuit  460 , a 22 kHz transceiver  455 , a 22 KHz blocker circuit  465 , a DC power supply  470 , a second DC blocker 22 kHz pass 2.3 MHz pass circuit  475  and a third DC blocker 22 kHz blocker 2.3 MHz pass circuit  480 . 
     The coupling to the RF input  405  is operative to receive RF signals from the LNB and is further operative to provide a control signals from the 2.3 MHz transceiver  435  and the 22 kHa transceiver  455  to the SWM and legacy LNB circuitry outside of the IRD. The RF input  405  is generally the point most likely to be the point of entry to the circuitry of lightning surge and other environmental electrical disturbances. The 2.3 MHz high impedance negative surge path  415  is operative to conduct negative surges to ground, while presenting high impedance to 2.3 MHz signals. The 2.3 MHz high impedance positive surge path  420  is operative to conduct positive surges to low impedance surge path  425 , while presenting high impedance to 2.3 MHz signals. The low impedance surge path  425  is operative to conduct operative to conduct the 2.3 MHz to ground, to block the conduction of the 22 KHz tone to ground, operative to conduct the high current surge pulse to ground. An exemplary implementation of the low impedance surge path  425  is a zener diode. Thus, any high current surge passing through the 2.3 MHz high impedance positive surge path  420  will be clamped by the zener diode. Another exemplary implementation of the low impedance surge path  425  is a transient voltage suppressor (TVS) diode. The first DC blocker 22 kHz blocker 2.3 MHz pass circuit  430  is operative to conduct the 2.3 MHz signal to ground and to compensate for any non linear effects resultant from the low impedance surge path  425 . 
     The 2.3 MHz transceiver  435  is operative to transmit and receive commands to the SWM using a 2.3 MHz signal. A second DC blocker 22 kHz blocker 2.3 MHz pass circuit  440  is operative to conduct the 2.3 MHz SWM signal, but prevent 22 KHz signals and DC voltages from being conducted to the 2.3 MHz Transceiver  435 . The 5-30 MHz linear impedance circuit  445  is operative to transmit and receive 22 KHz signals, 2.3 SWM signals, and DC voltage to the LNB, antenna, or other switching circuitry. 22 kHz signals may employ the DiSEqC communications protocol. Furthermore, the 5-30 MHz linear impedance circuit  445  is operative to prevent transmission of the RF satellite signals present at the RF input  405  through to the transceivers  435   455  and the DC power supply  470 . 
     The 2.3 MHz band rejecter circuit  450  is operative to conduct a DC voltage from the DC power supply  470  and the 22 kHz signal from the 22 kHz transceiver  45 . The 2.3 MHz band rejecter circuit  450  is further operative to impede the conductance of the 2.3 MHz signal. Specifically, the band rejecter circuit  450  prevents the 2.3 MHz SWM control signals from being conducted to the DC power supply  470 . 
     The first DC blocker 22 kHz pass 2.3 MHz pass circuit  460  is operative to conduct the 22 kHz signal from the 22 kHz transceiver  455 , but to prevent 2.3 MHz signals and DC voltages from being conducted to the 22 kHz Transceiver  455 . The 22 kHz transceiver  455  is operative to transmit and receive 22 kHz control signals. These 22 kHz control signals are generally formatted according to the DiSEqC standard. The 22 KHz blocker circuit  465  is operative to conduct the DC power and any 2.3 MHz signal, but to impede the 22 kHz signal generated by the 22 kHz transceiver  455 . A second DC blocker 22 kHz pass 2.3 MHz pass circuit  475  is operative to isolate the DC voltage to from the source of reference potential, but to pass both 22 kHz and 2.3 MHz signals to ground. The third DC blocker 22 kHz blocker 2.3 MHz pass circuit  480  is operative to isolate the DC voltage and the 22 kHz signal from ground but to conduct the 2.3 MHz signals to ground. 
     The DC power supply  470 , is operative to supply any or all of the needed DC voltages to the SWM or the legacy LNBs. For example, the SWM can be operated on a 20v DC supply, whereas the legacy LNBs are generally operated using 13, 14 and/or 18 volts DC. 
     RF Input Tuner  410  is operative to receive and tune satellite signals from the RF signal input and the SWM. An exemplary satellite signal band has a frequency range of 940 MHz to 2150 MHz. 
     The SWM linear switch block  400  is configured in such a manner that it is operative to conduct voltages and signals in the direction toward the RF input  405 , and away from the DC power supply. Thus, as can be seen in the exemplary embodiment of  FIG. 4 , the DC power is conducted across both the 22 KHz Blocker  465  and the 2.3 MHz band rejecter  450 . Any 22 kHz or 2.3 MHz that is conducted through the 22 KHz Blocker  465  and the 2.3 MHz band rejecter  450  circuits respectively are then couple to ground to prevent interference to DC power supply or the other transceivers. 
     Referring now to  FIG. 5 , a block diagram showing details of a transceiver passive linear switch  500  according to an exemplary embodiment of the present invention is shown. The transceiver passive linear switch  500  comprises a DC blocker circuit  505 , a band rejecter circuit  510 , and a band pass circuit  515 . 
     The DC blocker circuit  505  is coupled between a source of a tone transceiver (Tone Tx/Rx) and a coupling to the RF signal path which couples the transceiver passive linear switch  500  to the SWM. The DC blocker circuit  505  is operative to conduct the SWM tone used to communicate with the SWM. The DC blocker circuit is further operative to block any DC supply voltage present on the RF conductor from coupling into the tone transceiver. The DC block circuitry  505  can be configured as a bandpass filter operative to conduct only the frequencies of interest originating from the tone transceiver. Furthermore, the DC block circuitry  505  can be configured as a high pass filter with the cutoff below the frequency of interest of the tone originating from the tone transceiver. 
     The band rejecter circuit  510  is operative to conduct the DC supply voltage to the RF signal path, but to prevent the SWM tone from being conducted to the source of DC voltage. The band rejecter circuitry can be configured as a band reject filter operative to prevent the conduction of only the frequencies of interest originating from the tone transceiver. Furthermore, the band rejecter circuitry  510  can be configured as a parallel high pass filter and low pass filter with the cutoff of each filter overlapping such that the SWM tone is always prevented from being conducted to the source of DC power. 
     The band pass circuit  515  is operative to conduct and unwanted RF signals to ground, but to prevent the DC voltage supplied by the DC voltage source from being coupled to ground. 
     Thus, the transceiver passive linear switch  500  is operative to conduct DC supply voltage to the RF signal path, but prevents SWM control tones from being coupled through the band rejecter circuit  510  to the source of DC power. Any tone energy that does get conducted through the band reject circuit  510  can be coupled to ground, and diminished as a source of interference by the band pass circuit  515 . 
     Referring now to  FIG. 6 , a block diagram showing details of a multi tone transceiver passive linear switch  600  according to an exemplary embodiment of the present invention is shown. The multi tone transceiver passive linear switch  600  according to an exemplary embodiment of the present invention comprises a first, second, and third DC blocker circuit  615   630   645 , a first, second and third band rejecter circuit  610   625   640 , a first, second, and third band pass circuit  605   620   635  and a linear impedance  650 . 
     The DC blocker circuits  615   630   645 , band rejecter circuits  610   625   640 , and band pass circuits  605   620   635  operate in a manner similar to that described with reference to  FIG. 5 . However, each DC blocker circuit  615 ,  630 ,  645  is operative to conduct a tone of a differing frequency to the RF signal path. For example, the first DC blocker  615  is operative to conduct a 22 kHz tone to the RF signal path. The second DC blocker  630  is operative to conduct a 2.3 MHz signal to the RF signal path. The third DC blocker circuit  645  is operative to conduct a 3.1 MHz signal to the RF signal path. 
     Similarly, the band rejecter circuits  610   625   640  are operative to conduct the DC power supply voltage to the RF signal path, but to prevent any tone signal from being conducted back to the DC power supply. For example, the third band reject circuit  640  is operative to conduct DC voltage, the 2.3 MHz tone signal, and the 22 kHz tone signal, but to prevent the conduction of the 3.1 MHz tone signal. The second band rejecter circuit  625  is operative to conduct DC voltage and the 22 kHz tone signal, but to prevent the conduction of the 2.3 MHz tone signal and the 5 MHz tone signal. The first band rejecter circuit  610  is operative to conduct DC voltage, but to prevent the conduction of the 22 kHz tone signal, the 2.3 MHz tone signal and the 3.1 MHz tone signal. 
     The band pass circuits  605   620   635  are operative to isolate the DC voltage from the source of ground potential, yet to couple unwanted tone and RF signals to the source of reference potential. Thus, the first band pass circuit  605  is operative to isolate the DC signal from the source of reference potential, but to couple all unwanted tone and RF signals, such as the 22 kHz, 2.3 MHz and 3.1 MHz signals, to the source of reference potential. The second band pass circuit  620  is operative to isolate the DC supply voltage and the 22 kHz tone from the source of reference potential, and to couple the 2.3 MHz and 3.15 MHz signals to the source of reference potential. The third band pass circuit  635  is operative to isolate the DC supply voltage, the 2.3 MHz and the 22 kHz tone from the source of reference potential, and to couple the 3.1 MHz signal to the source of reference potential. 
     The linear impedance  650  is operative to provide impedance to the RF signal to the tuner. This impedance is operative to prevent the coupling of the RF satellite signals to ground. 
     Referring now to  FIG. 7 , a block diagram showing details of a 6 port linear network SWM LNB switch  700  according to an exemplary embodiment of the present invention is shown.  FIG. 7  depicts a specific embodiment of the 6 port linear network switch  402  depicted in  FIG. 4 . The 6 port linear network SWM LNB switch comprises a coupling to the RF input  4 , a coupling to a surge protection circuit  6 , a coupling to a source of reference potential or ground  5 , a coupling to a source of DC voltage  1 , a coupling to a 22 kHz transceiver  2  and a coupling to a 2.3 MHz transceiver  3 . The 6 port linear network SWM LNB switch  700  further comprise a DC blocker 22 kHz blocker 2.3 MHz pass circuit  740 , a 5-30 MHz linear impedance circuit  745 , a 2.3 MHz band rejecter circuit  750 , a first DC blocker 22 kHz pass 2.3 MHz pass circuit  760 , a 22 KHz blocker circuit  765 , a second DC blocker 22 kHz pass 2.3 MHz pass circuit  775  and a third DC blocker 22 kHz blocker 2.3 MHz pass circuit  780 . 
     A second DC blocker 22 kHz blocker 2.3 MHz pass circuit  740  is operative to conduct the 2.3 MHz SWM signal, but prevent 22 KHz signals and DC voltages from being conducted to the 2.3 MHz Transceiver  3 . In this exemplary embodiment, the second DC blocker 22 kHz blocker 2.3 MHz pass circuit  740  is implemented using a 100 nF capacitor C 13 . The 5-30 MHz linear impedance circuit  745  is operative to transmit and receive 22 KHz signals, 2.3 SWM signals, and DC voltage to the LNB, antenna, or other switching circuitry. Furthermore, the 5-30 MHz linear impedance circuit  745  is operative to prevent transmission of the RF satellite signals present at the RF input  4  through to the transceivers coupling points  2   3  and the DC power supply  770 . In this exemplary embodiment, the 5-30 MHz linear impedance circuit  745  is implemented using a 4.7 μH inductor L 3 . 
     The 2.3 MHz band rejecter circuit  750  is operative to conduct a DC voltage from the source of DC voltage  1  and the 22 kHz signal from the coupling to the 22 kHz transceiver  2 . The 2.3 MHz band rejecter circuit  750  is further operative to impede the conductance of the 2.3 MHz signal. In this exemplary embodiment, the 2.3 MHz band rejecter circuit  750  is implemented using a parallel RLC circuit with a 680 pF capacitor C 2 , a 6.8 μH inductor L 2  and a 1 kΩ resistor R 2 . 
     The first DC blocker 22 kHz pass 2.3 MHz pass circuit  760  is operative to conduct the 22 KHz signal from the coupling to the 22 KHz transceiver  2 , but to prevent 2.3 MHz signals and DC voltages from being conducted to the coupling to the 22 kHz Transceiver  2 . In this exemplary embodiment, the first DC blocker  22  kHz pass 2.3 MHz pass circuit  760  is implemented using a capacitor C 12 . The 22 KHz blocker circuit  765  is operative to conduct the DC power and any 2.3 MHz signal, but to impede the 22 kHz signal generated by the 22 kHz transceiver  455 . In this exemplary embodiment, the 22 KHz blocker circuit  765  is implemented using a parallel RLC circuit with a 220 nF capacitor C 1 , a 180 μH inductor L 1  and a resistor R 1 . 
     A second DC blocker 22 kHz pass 2.3 MHz pass circuit  775  is operative to isolate the DC voltage to from the source of reference potential, but to pass both 22 kHz and 2.3 MHz signals to ground. In this exemplary embodiment, the second DC blocker 22 kHz pass 2.3 MHz pass circuit  775  is implemented using a 100 μF capacitor C 3 . The third DC blocker 22 kHz blocker 2.3 MHz pass circuit  780  is operative to isolate the DC voltage and the 22 kHz signal from ground but to conduct the 2.3 MHz signals to ground. 
     Referring now to  FIG. 8 , a block diagram showing details of a two stage surge protector circuit  800  according to an exemplary embodiment of the present invention is shown.  FIG. 8  depicts a specific embodiment of the two stage surge protector circuit  401  depicted in  FIG. 4 . The two stage surge protector circuit  800  comprises a 2.3 MHz high impedance negative surge path  815 , a 2.3 MHz high impedance positive surge path  820 , a low impedance surge path  825 , a first DC blocker 22 kHz blocker 2.3 MHz pass circuit  830 , a linear impedance circuit  845 , a 2.3 MHz band rejecter circuit  850 , a 22 KHz blocker circuit  865 , SWM circuitry  810  and LNB SWM power supply circuit  890 . 
     The coupling to the RF input is operative to receive RF signals from the LNB and is further operative to provide a coupling the SWM circuit  810  and LNB SWM power supply circuit  890 . The RF input  405  is generally the point most likely to be the point of entry to the circuitry of lightning surge and other environmental electrical disturbances. The 2.3 MHz high impedance negative surge path  815  is operative to conduct negative surges to ground, while presenting high impedance to 2.3 MHz signals. In this exemplary embodiment, the 2.3 MHz high impedance negative surge path  815  is implemented using three parallel resistor diode pairs D 3  D 4  D 5  R 30  R 29  R 28  in series. The 2.3 MHz high impedance positive surge path  820  is operative to conduct positive surges to low impedance surge path  825 , while presenting high impedance to 2.3 MHz signals. In this exemplary embodiment, the 2.3 MHz high impedance positive surge path  820  is implemented using three parallel resistor diode pairs D 6  D 7  D 8  R 31  R 32  R 33  in series. The low impedance surge path  825  is operative to conduct operative to conduct the 2.3 MHz to ground, to block the conduction of the 22 KHz tone to ground, operative to conduct the high current surge pulse to ground. An exemplary implementation of the low impedance surge path  825  is a zener diode D 2 . Thus, any high current surge passing through the 2.3 MHz high impedance positive surge path  820  will be clamped by the zener diode. The first DC blocker 22 kHz blocker 2.3 MHz pass circuit  830  is operative to conduct the 2.3 MHz signal to ground and to compensate for any non linear effects resultant from the low impedance surge path  825 . In this exemplary embodiment, the 2.3 MHz high impedance positive surge path  820  is implemented using a 10 nF capacitor C 4 . 
     In this exemplary embodiment the 2.3 MHz band rejecter circuit  850  is implemented using a 4.7 μH inductor L 3 , and the 22 KHz blocker circuit  865  is implemented using a 6.8 μH inductor L 2 . SWM circuitry  810  is operative to transmit and receive SWM and DiSEqC control signals. The LNB SWM power supply circuit  890  is operative to supply DC voltage to the LNB and SWM circuits as required. 
     As described herein, the present invention provides an architecture and protocol for enabling signal communications between an SWM and an IRD within a dwelling. While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.