System and method for satellite-based transmission of voice signals using an otherwise dedicated wireless channel

In a wireless communication system (20) configured for default communication of subsectional signals of a first transmit signal (72/73) over multiple wireless channels (46), a signal selector (82) and method (138) detect an intent to convey a voice signal (86) over one of the wireless channels (46) from a handset (58). The signal selector (82) and method (138) prevent communication of one of the subsectional signals (72A) over the wireless channel (46) for a predetermined interval, and enable a transmission attempt of the voice signal (86). When a complete dialed digits sequence is detected within the time interval, the handset (58) is enabled to utilize the wireless channel. However, when a transmission attempt of the voice signal (86) is unsuccessful or when transmission of the voice signal (86) terminates, the signal selector (82) and method (138) restore default communication of subsectional signals of the first transmit signal (72/73).

RELATED INVENTION

The present invention is related to “System And Method For Satellite-Based Transmission Of Signals Using Multiple Channels,” by Glen P Abousleman, U.S. patent application Ser. No. 10/404,791, filed 1 Apr. 2003, which is incorporated by reference herein.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of wireless communication systems. More specifically, the present invention relates to a system and method for the transmission of voice signals over a satellite-based communication network using an otherwise dedicated wireless channel.

BACKGROUND OF THE INVENTION

Technological advances in recent years have made it easier for individuals and groups in geographically disperse societies to be interconnected through physical travel and communication systems. Major advances in the telecommunications infrastructure have been developed and are continuously evolving to meet the needs of people who regularly travel, communicate, and do business internationally. For example, satellite-based global communication networks have arisen to serve the needs of global travelers and communicators. One such network, first activated in 1998, is the Iridium® commercial system. The Iridium® commercial system is a satellite-based global digital communication network designed to provide wireless communications through hand-held devices located anywhere near or on the surface of the Earth.

FIG. 1illustrates a highly simplified diagram of a satellite-based communication network20, dispersed over and surrounding Earth through the use of orbiting satellites22occupying orbits24. Network20uses six polar orbits24, with each orbit24having eleven satellites22for a total of sixty-six satellites22. As such, network20exemplifies the Iridium® commercial system.

Satellites22communicate with radio communication individual subscriber units (ISU's)26over subscriber links28. In addition, satellites22communicate with earth terminal/gateway systems30, which provide access to a public switched telephone network (PSTN)32or other communications facilities, over earth links34. Earth terminal/gateway systems30(referred to hereinafter as gateways30) relay data packets (e.g., relating to calls in progress) between ISU's26and the PSTN32to other communication devices, such as a wireline telephone36. Satellites22also communicate with other nearby satellites22through cross-links40. For simplicity of illustration, only one each of ISU's26, gateways30, and a wireline telephone36are shown inFIG. 1.

With the exemplary constellation of sixty-six satellites22, at least one of satellites22is within view of each point on the Earth's surface at all times, resulting in full coverage of the Earth's surface. Any satellite22may be in direct or indirect data communication with any ISU26or gateway30at any time by routing data through the constellation of satellites22. Accordingly, communication network20may establish a communication path for relaying information through the constellation of satellites22between any two ISU's26, or between ISU26and gateway30.

Network20may accommodate any number, potentially in the millions, of ISU's26. Subscriber links28encompass a limited portion of the electromagnetic spectrum that is divided into numerous channels, and are preferably combinations of L-Band frequency channels. Subscriber links28may encompass one or more broadcast channels42, that ISU's26use for synchronization and message monitoring, and one or more acquisition channels44that ISU's26use to transmit messages to satellites22. Broadcast channels42and acquisition channels44are not dedicated to any one ISU26but are shared by all ISU's26currently within view of a satellite22.

Subscriber links28also include wireless traffic channels46, also known as voice channels. Traffic channels46are two-way channels that are assigned to particular ISU's26from time to time for supporting real-time communications. Each traffic channel46has sufficient bandwidth to support a two-way voice communication. For example, each of traffic channels46within the Iridium® network are capable of approximately 2.4 kilobits/second (kbps) raw data throughput.

Techniques are being developed to utilize such satellite-based networks to transmit large data files and real-time video, in addition to voice communications. Such a technique is described in the aforementioned related invention, “System And Method For Satellite-Based Transmission Of Signals Using Multiple Channels,” U.S. patent application Ser. No. 10/404,791. The technique extends the capability of voice optimized traffic channels, within a wireless communication system, for the transmission of data and video.

Even though the technique enables the transmission of data and video over voice optimized traffic channels, a need has arisen for a system and method for effectively enabling voice signal transmission over data and video transmission. More particularly, due to the real-time nature of voice transmissions, voice signal transmission should supersede the data and/or video in the event of a current transmission of data and/or video.

SUMMARY OF THE INVENTION

Accordingly, it is an advantage of the present invention that a system and method are provided for satellite-based transmission of voice signals using an otherwise dedicated wireless channel.

It is another advantage of the present invention that a system and method are provided efficiently commandeer a wireless channel for transmission of a voice signal.

Another advantage of the present invention is that a system and method are provided that enable a voice signal to supersede current data and/or video signal transmission.

Yet another advantage of the present invention is that implementation of the system and method are transparent to the existing infrastructure of the satellite-based communication network.

The above and other advantages of the present invention are carried out in one form within a wireless communication system configured for default communication of subsectional signals of a first transmit signal over multiple wireless channels, by a method for utilizing one of the multiple wireless channels for transmission of a second transmit signal. The method calls for detecting an intent to convey the second transmit signal over the one of the multiple wireless channels. The method further calls for preventing communication of one of the subsectional signals via the one wireless channel, and enabling a transmission attempt of the second transmit signal in response to the preventing operation.

The above and other advantages of the present invention are carried out in another form within a wireless communication system by an apparatus for selectively utilizing wireless channels. The apparatus includes a first signal source for providing subsectional signals of a first transmit signal and a second signal source for providing a second transmit signal. Transceivers are in default communication with the first signal source, one each of the transceivers supporting one each of the wireless channels for transmitting the subsectional signals over multiple ones of the wireless channels. A signal selector is in communication with each of the first signal source, the second signal source, and one of the transceivers. The signal selector includes a detector element for detecting an intent to convey the second transmit signal over one of the multiple wireless channels. A disable timer is in communication with the detector element for preventing communication of one of the subsectional signals via the one wireless channel for a predetermined time interval. The signal selector further includes an enable element for enabling a transmission attempt of the second transmit signal during the predetermined time interval, the enable element synchronizing an operation of the second signal source with the one of the transceivers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 1-2,FIG. 2shows a simplified diagram of a portion of satellite-based communication network20in which inverse multiplexer (IMUX) systems50are employed. IMUX systems50are adapted for use with a satellite-based communication network, such as network20, exemplifying the Iridium® commercial system. IMUX systems50extend the capability of voice-optimized wireless traffic channels46, within network20, for the transmission of data and video, without the addition of terrestrial or airborne network infrastructure. The present invention is adapted for use within IMUX systems50for effectively commandeering wireless channels for the transmission of voice signals, even when IMUX systems are currently transmitting data and/or video signals. For clarity of understanding, IMUX systems50will be discussed hereinbelow.

Although the present invention is described in terms of its use with the Iridium® commercial system, the present invention is not limited to such a use. Rather, the present invention is applicable to land-based communication systems, as well as to other existing or upcoming satellite-based communication networks. The existing or upcoming satellite-based communication networks may have low-earth or medium-earth orbits, may entail orbits having any angle of inclination (e.g., polar, equatorial or another orbital pattern), and may utilize more or fewer orbits. The present invention is also applicable to satellite constellations where full coverage of the Earth is not achieved (i.e., where there are “holes” in the communications coverage provided by the constellation) and constellations where plural coverage of portions of the Earth occur (i.e., more than one satellite is in view of a point on the Earth's surface). In addition, all gateways30and ISUs26of network20are or may be in data communication with other telephonic devices dispersed throughout the world through PSTN32and/or conventional terrestrial cellular telephone devices coupled to the PSTN through conventional terrestrial base stations.

Network20includes a first communication station52and a second communication station54. First and second communication stations52and54may be located on or near the surface of the earth, in isolated or populous areas, and remote from or nearby one another. First and second communication stations52and54, respectively, are deployed in a “mobile-to-mobile” configuration. In the “mobile-to-mobile” configuration, first and second communication stations52and54are enabled to communicate with one another. But nothing requires stations52and54to move. The mobile-to-mobile link may be routed through one of gateways30, which yields an approximate usable data rate of 2.4 kbps for the exemplary Iridium®-based network. Alternatively, the mobile units communicate with one another, completely bypassing one of gateways30. As a consequence of the mobile-to-mobile configuration, limited gateway modems are freed up for other users, and maximum data throughput is increased from the data rate of 2.4 kbps over each of traffic channels46to approximately 3.4 kbps for the exemplary Iridium®-based network.

Alternatively, first communication station52and a third communication station (not shown), may be deployed in a “mobile-to-PSTN” configuration. In the “mobile-to-PSTN” configuration, first communication station52and the third communication station are enabled to communicate with one another via satellite-based communication network20and PSTN32infrastructure. An exemplary “mobile-to-PSTN” configuration is discussed in detail in connection with the related invention “System And Method For Satellite-Based Transmission Of Signals Using Multiple Channels,” U.S. patent application Ser. No. 10/404,791.

FIG. 2further depicts a discontinuous bi-directional arrow55between satellites22. This discontinuous arrow55indicates that a number of cross-links40and satellites22may be employed to form the communication path between first communication station52and second communication station54, as known to those skilled in the art. Alternatively, and as known to those skilled in the art, the communication path need not include two or more satellites22. Rather, the communication path may include only one of satellites22with switching taking place at the satellite to another antenna beam.

First communication station52includes a first one of IMUX systems50, referred to hereinafter as first IMUX system50A. First communication station52also includes a first user/net terminal56and handsets58in communication with first IMUX system50A. Similarly, second communication station54includes a second one of IMUX systems50, referred to hereinafter as second IMUX system50B. A second user/net terminal60and handsets62are in communication with second IMUX system50B. User/net terminals56and60represent any of a wide variety of equipment, including any form of computer, telecommunication, and/or input/output device, which may provide or receive data in any of a wide variety of formats. Such equipment include interface devices for coupling stations52and/or54to a local or wide area network, the Internet, phone lines, and the like.

For simplicity of illustration, the present invention is described in terms of a transmit signal, represented by arrows64, originating at first IMUX system50A for transmission toward second IMUX system50B. However, it should be understood that each of IMUX systems50within network20functions similarly. For voice transmission, connections need not be between first IMUX system50A and second IMUX system50B, but can be between either IMUX system50A or50B and any telephone throughout the globe, as facilitated by network20.

IMUX systems50maintain the capability of two-way voice communication provided by network20, and concurrently facilitate the transmission of large data files and real-time video imagery using network20. A transmitting one of IMUX systems50, i.e., first IMUX system50A, facilitates the transmission of large data files and real-time video imagery by splitting an input data or video signal (discussed below) received via first user/net terminal56, and transmitting different portions of the data or video signal as transmit signal64over separate traffic channels46. A receiving one of IMUX systems50, i.e., second IMUX system50B, combines the different portions of transmit signal64to recover the original data or video signal. The net result of such a system is that the effective bandwidth multiplication is directly proportional to the number of traffic channels46used.

FIG. 3shows a block diagram of one of IMUX systems50, i.e., first IMUX system50A. First IMUX system50A generally includes a signal management element66and a processor/memory element68in communication with signal management element66.

Signal management element66includes a data input/output (I/O) port70for receiving a data signal72and/or a video signal73for transmission over network20(FIG. 1). Data signal72may be a large data file previously generated by and/or collected at first user/net terminal56. Video signal73may be imagery generated at first user/net terminal56(FIG. 2) using a multimedia software application, such as that used for videoconferencing. Data I/O port70may include one or more receptacles to accommodate, for example, an Ethernet connection, a serial connection, a Universal Serial Bus (USB) connection, and so forth.

An inverse multiplexer/demultiplexer74is in communication with data I/O port70via an IMUX input76. IMUX74further includes IMUX outputs78, a number of which corresponds to a number of wireless traffic channels46over which first IMUX system50A is configured to communicate. IMUX74may be implemented as an application specific integrated circuit, or may be implemented in a digital signal processor, and is preferably a commercially available device.

In an exemplary embodiment, first IMUX system50A is a four channel IMUX system50. Accordingly, inverse multiplexer/demultiplexer74includes four IMUX outputs78, each of which are in communication with four corresponding signal selectors82, as represented by first inputs80. Although IMUX system50A is a four channel IMUX system50, it should be understood that a different number of channels may be employed within one of IMUX systems50. In addition, a pair of four channel IMUX systems may be arranged in a master/slave configuration to achieve an eight channel IMUX system. Additionally, N IMUX systems50may be connected to one another to provide a 4N channel IMUX system.

Signal management element66further includes one or more voice ports84for receiving a voice signal86. In the exemplary four channel embodiment, IMUX system50may include four voice ports84for accommodating up to four individual voice signals86from handsets58. Hence, the four voice ports84are in communication with four corresponding signal selectors82, as represented by second inputs88. Signal selectors82are in communication with corresponding L-band transceivers92(represented by outputs90), which are in turn, in communication with external antennas94. A switch96and an indicator98are associated with each of voice ports84, and are preferably located on an external panel of IMUX system50. Switch96and indicator98will be discussed below in connection withFIG. 4

Processor/memory element68controls L-band transceivers92and coordinates the flow of data signal72, video signal73, and voice signals86to and from first IMUX system50A. As such, processor/memory element68is responsive to the detection of data signal72, video signal73, and voice signals86for controlling the flow of communication over wireless traffic channels46.

Inverse multiplexing is a process of dividing a high-bandwidth data stream into multiple subsectional signals that can be routed independently through a carrier's network. IMUX74functions to split data signal72and/or video signal73into a number of subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D) and to process and present subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D) to first inputs80of switches82. IMUX74may also perform error detection and synchronization procedures as required, utilizing methodology known to those skilled in the art.

The number of subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D) is determined by processor/memory element68in response to a number of wireless traffic channels46that may be available for transmission of subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D). Subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D) are subsequently realigned at the far end, i.e., by another of IMUXs74at another of IMUX systems50, into the original high-bandwidth data signal72and/or video signal73.

Exemplary methodology for splitting data signal72and/or video signal73into subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D), and processing and presenting subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D) to first inputs80of signal selectors82is discussed in detail in connection with the related invention “System And Method For Satellite-Based Transmission Of Signals Using Multiple Channels,” U.S. patent application Ser. No. 10/404,791. However, the present invention need not be limited to such methodology. Rather, other existing or upcoming inverse multiplexing systems that split a first transmit signal into multiple subsectional signals may alternatively be employed. Consequently, for purposes of the present invention, the utilized inverse multiplexer system, such as the exemplary IMUX74, is referred to hereinafter as a first signal source74relative to signal selectors82. Each of handsets58may be considered a second signal source relative to signal selectors82to distinguish them from first signal source74. However, the nomenclature “handsets” will continue to be used throughout the following discussion.

FIG. 4shows a block diagram of one of signal selectors82employed within IMUX system50(FIG. 3) in accordance with a preferred embodiment of the present invention. Although only one of signal selectors82is shown, the following discussion applies to the other signal selectors82of IMUX system50(FIG. 3) as well. Signal selector82is in selective communication with first signal source74, handset58, and one of L-band transceivers92. Signal selector82enables the transmission of voice signal86over an otherwise dedicated traffic channel46. In particular, signal selector82enables the transmission of voice signal86to supercede the transmission of one of subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D). In this exemplary illustration, the transmission of voice signal86, i.e. a voice call, can supersede the transmission of subsectional signal72A, i.e., a transmission of a data file. However, subsectional signal need not be a data file transmission, but may instead by a video transmission, i.e., subsectional signal73A.

In a preferred embodiment, signal selector82is configured to communicate subsectional signal72A of data signal72(i.e., a first transmit signal) over traffic channel46. That is, traffic channel46is nominally dedicated to the transmission of subsectional signal72A, whether or not subsectional signal72A is present at first input80. This nominal configuration of signal selector82is represented by a signal pass-through100. In addition, a data terminal ready (DTR) signal102is provided via processor (PC)68to L-band transceiver92so that first signal source74is enabled to utilize L-band transceiver92to transmit subsectional signal72A.

In general, signal selector82includes a detector, in the form of a front panel interface circuit104, for detecting an intent to convey voice signal86over traffic channel46supported by L-band transceiver92. By way of example, front panel interface circuit104may detect a user-initiated actuation of switch96that signals and intent to convey voice signal86.

A disable timer106is in communication with front panel interface circuit104. In addition, disable timer106is interposed in a signal path108of DTR signal102. In response to the detection of the intent to convey voice signal86, disable timer106functions to interrupt signal pass-through100so that wireless channel46may be seized for the transmission of voice signal86. Additionally, even while IMUX system50(FIG. 3) is currently transferring subsectional signal72A, the transmission of subsectional signal72A will be dropped in favor of voice signal86. Related invention “System And Method For Satellite-Based Transmission Of Signals Using Multiple Channels,” U.S. patent application Ser. No. 10/404,791, describes methodology for managing the transmission of first transmit signal72over the remaining ones of multiple traffic channels46.

This interrupt is created by utilizing DTR signal102to drop the data call, i.e. interrupt transmission of subsectional signal72A via signal pass-through100. The disable timer106further provides a window of opportunity, i.e., a predetermined time interval, to dial a phone number at handset58and establish the transmission of voice signal86, i.e., a voice call. Should the predetermined time interval expire prior to establishing transmission of voice signal86, traffic channel46is seized again for the transmission of subsectional signal72A. Disable timer106may be implemented in either hardware or software.

A hardware implementation of disable timer106may include, for example, a 555-timer circuit whose primary components are a pulse generator and toggle circuitry. Disable timer106is started when a user actuates switch98, which produces a timed pulse that transitions DTR signal102from a HIGH to a LOW state. By toggling this DTR signal102from HIGH to LOW, transmission of subsectional signal72A via signal pass-through100is dropped. As long as DTR signal102is held LOW, the transmission of subsectional signal72A cannot be restored thereby providing a time interval for establishing the transmission of voice signal86. In an exemplary embodiment, the pulse generator produces a two minute pulse during which DTR signal102is held LOW.

The toggle of DTR signal102from HIGH to LOW can be accomplished by either logic circuitry or a mechanical relay. With the use of logic data, an RS-232 signal (+/−15V) is reduced to TTL logic voltage levels (0 and +5V). This signal is then combined with the signal of the timer circuit and the desired output is boosted to RS-232 voltage levels and passed to L-band transceiver92via signal path108.

With the use of a mechanical relay, when disable timer106is enabled, the relay disconnects the DTR pin and connects it to a LOW logic level thereby dropping the transmission of subsectional signal72A. While DTR signal102is held low, indicator98illuminates or otherwise indicates that data transmission capability is disabled and voice signal transmission is currently enabled.

By way of another example, a software implementation of disable timer106may be employed. When switch96is actuated,an application being executed by processor68(FIG. 3) can delay a redial attempt restoration of the transmission of subsectional signal72A to provide a time interval during which transmission of voice signal86can be established. Yet another method that may be used to interrupt transmission of subsectional signal72A is by using a simple push button switch to momentarily toggle DTR signal102from HIGH to LOW.

Signal selector82further includes a handset enable element110for enabling a transmission attempt of voice signal86during the predetermined time interval, i.e., the two minute duration set by disable timer106. In a preferred embodiment, L-band transceiver92is an Iridium® 9522 L-Band Transceiver (LBT). Handset58utilizes L-band transceiver92to access traffic channel46, and receives its power via L-band transceiver92. Handset enable element110provides synchronization and power at an appropriate voltage, for example, the twelve volts necessary to power handset58.

Accordingly, an enable link112is coupled between handset enable element110and L-band transceiver92. Enable link112conveys an enable logic signal (ENABLE)114, provided by L-band transceiver92, to handset enable element110. Similarly, an input power link116is coupled between handset enable element110and L-band transceiver92. Input power link116conveys power at a first voltage (VIN)118, provided by L-band transceiver92, to handset enable element110.

A DC-DC converter120portion of handset enable element110converts the power at first voltage (VIN)118to a second voltage (VOUT)122. An output power link124subsequently conveys power at second voltage (VOUT)122to handset58coupled to IMUX50(FIG. 3) via the corresponding voice port84(FIG. 3).

Handset58desirably operates utilizing a 12 VDC power supply synchronized to a high state126if ENABLE signal114. Thus, power at second voltage122is combined with ENABLE signal114into a single signal input and provided to handset58via output power link124. That is, when ENABLE signal114is in high state126, DC-DC converter120is enabled to convert the received power at first voltage118, for example, 5 VDC, to second voltage122, for example, 12 VDC.

Signal selector82additionally includes a reset circuit (LBT RESET)128in communication with L-band transceiver92. In particular, a second enable link130is in communication with each of enable link112and reset circuit128. Second enable link130conveys ENABLE signal114, provided by L-band transceiver92, to reset circuit128. In addition, a reset link132is in communication with each of reset circuit128and L-band transceiver92.

In an exemplary scenario, when handset58is unplugged from voice port84, L-band transceiver92powers down, and ENABLE signal114is set to a low state134. In a preferred embodiment, IMUX system50(FIG. 3) should be in a continuously ready state for transmitting subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D). Accordingly, when L-band transceiver92powers down, subsectional signal72A cannot be transmitted over traffic channel46, until L-band transceiver92is powered on.

Reset circuit128is a negative edge triggered timer that detects when ENABLE signal114is in low state134and outputs a short reset pulse136over reset link132to L-band transceiver92. This short reset pulse136alternates the current OFF state of L-band transceiver to an ON state.

Referring toFIGS. 4-5,FIG. 5shows a flow chart of a voice signal management process138performed in connection with signal selector82. Process138enables the utilization of one of wireless voice traffic channels46that is otherwise dedicated to the transmission of subsectional signal72A. Although process138is described in connection with signal selector82ofFIG. 4, it should be readily appreciated that process138applies equally to each of signal selectors82of IMUX system50.

Process138begins at a task140. During a first iteration of task140, IMUX system50(FIG. 3) is configured for default communication of data signal72and/or video signal73(i.e., a first transmit signal) as subsectional signals72A (73A),72B (73B),72C (73C), and72D (73D). That is, IMUX system50is powered up, L-band transceiver92is powered up, and signal selector82enables the transmission of subsectional signal72A over traffic channel46.

Following task140, a task142is performed. Task142monitors for an intent to convey voice signal86. The intent to convey is a user-initiated sequence of events that depend upon the current configuration of IMUX system50and handset58.

Referring toFIG. 6in connection with task142,FIG. 6shows a table144of user-initiated operations performed in connection with the voice signal management process138. As discussed previously, signal selector82is configured for default communication of subsectional signal72A. Handset58may be in one of three configurations relative to IMUX system50. These configurations include a first scenario146in which handset58is disconnected from voice port84(FIG. 3) of IMUX system, a second scenario148in which handset58is connected to voice port84and handset58is currently powered off, and a third scenario150in which handset58is connected to voice port84and handset58is currently powered on.

In first scenario146, an intent to convey voice signal46entails the detection of handset58being plugged into voice port84, power being cycled on handset58, and a user-initiated actuation of switch96(FIG. 3) to disable the transmission of subsectional signal72A for the predetermined time interval. In second scenario148, the intent to convey voice signal46entails the detection of power being cycled on handset58and a user-initiated actuation of switch96. In third scenario150, the intent to convey voice signal46merely entails the detection of a user-initiated actuation of switch96.

Referring back to voice signal management process138(FIG. 5), in response to task142, a query task152determines whether an intent to convey voice signal86is detected. When none of the above intent to convey operations are detected, process138loops back to task142for continued monitoring of an intent to convey voice signal86. Alternatively, when one of the series of intent to convey operations are detected, ending with the user-initiated actuation of switch96, process138proceeds to a task154.

At task154, any communication of subsectional signal72A is interrupted. In particular, the actuation of switch96produces a timed pulse that transitions DTR signal102from a HIGH to a LOW state, thus interrupting any transmission of subsectional signal72A via signal pass-through100.

A task156, performed in connection with task154, starts the disable timer. In the configuration of signal selector82described above, as long as DTR signal102is held LOW, the transmission of subsectional signal72A cannot be restored thereby providing a time interval for establishing the transmission of voice signal86. In an exemplary embodiment, the timed pulse may be approximately two minutes during which DTR signal102is held LOW.

A task158performed in conjunction with tasks154and156indicates the interruption of data communication. That is, indicator98illuminates, or otherwise signals a user that signal selector82is currently configured to enable establishment of the transmission of voice signal86(i.e., a second transmit signal).

Next, a task160monitors for a dialed digits sequence. This dialed digits sequence is typically a phone number entered at handset58for an intended recipient, followed by actuation of a SEND key. Referring to table144(FIG. 6) momentarily, each of first, second, and third user-initiated scenarios entails entering a number and actuating a SEND key following the actuation of switch98(FIG. 3).

With reference back toFIG. 6, a query task162is performed in connection with monitoring task160. Query task162determines whether a complete dialed digits sequence has been detected. In other words, query task162determines whether a phone number is entered and the SEND key is actuated. When query task162determines that the dialed digits sequence is incomplete, process138proceeds to a query task164.

Query task164determines whether the predetermined time interval, for example, two minutes has expired. When the predetermined time interval has not expired, indicating a continued window of opportunity for completing the dialed digits sequence, process138loops back to task160for continued monitoring of a completed dialed digits sequence.

However, when query task164determines that the time interval has expired, process138loops back to task140so that default communication for transmission of subsectional signal72A is restored. In the configuration of signal selector82described above, the predetermined time interval expires when the timed pulse drops low. This expiration of the timed pulse causes DTR signal102to transition from the LOW state to the HIGH state, thus restoring the ability to transmit subsectional signal72A over traffic channel46.

Referring back to query task162, when query task162determines that the dialed digits sequence is complete, process138proceeds to a query task166. Query task166determines whether a voice call is established. That is, query task166determines whether L-band transceiver92is currently seized for transmission of voice signal86. When L-band transceiver92is not currently busy transmitting voice signal86, process138loops back to task140so that default communication for transmission of subsectional signal72A is restored, as discussed above. L-band transceiver92may not be seized if completion of the dialed digits sequence did not yield a successful connection between handset58and the intended recipient. As such, L-band transceiver92is relinquished for an attempted transmission of voice signal86and default communication is restored for a possible transmission of subsectional signal72A.

However, when query task166determines whether L-band transceiver92is currently seized for transmission of voice signal86, process138proceeds to a task168. Task168monitors for call termination. That is, task168monitors for the conventional circuit switching channel release mechanisms performed at IMUX system50(FIG. 3).

A query task170is performed in connection with task168. Query task170determines whether the voice call, i.e., the transmission of voice signal86, has been terminated and traffic channel46has been released per conventional mechanisms. When the transmission of voice signal86has not been terminated, process138loops back to monitoring task168.

However, when transmission of voice signal86has been terminated, process138loops back to task140so that default communication for transmission of subsectional signal72A is restored, as discussed above, and first transmit source74is once again permitted to transmit subsectional signal72A over wireless traffic channel46. Thus, voice signal management process138describes the function of signal selector82for efficiently commandeering a wireless traffic channel for the transmission of voice signal86.

In summary, the present invention teaches of a signal selector and a method for satellite-based transmission of voice signals using an otherwise dedicated wireless channel. The signal selector and method enable default communication of data and/or video from a first signal source. The first signal source facilitates the transmission of large data files and real-time video imagery over low-data-rate wireless channels optimized for voice communication by inverse multiplexing an input transmit signal, and transmitting different portions of the data or video signal over separate wireless traffic channels as subsectional signals. However, the signal selector incorporated into the IMUX system, efficiently commandeers a wireless channel for transmission of a voice signal by interrupting the default communication of data and/or video for a predetermined time interval and allowing a transmission attempt from the handset. When a voice call transmission attempt is unsuccessful or when a voice call is terminated, the signal selector and method automatically restore the IMUX system to default communication of data and/or video supplied as subsectional signals from the inverse multiplexer. Accordingly, the IMUX system and method facilitate bandwidth-expandable communications capability for the transmission of voice, video, and data without the need for additional terrestrial or airborne infrastructure to the existing infrastructure of the satellite-based communication network.

Although the preferred embodiments of the invention have been illustrated and described in detail, it will be readily apparent to those skilled in the art that various modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims. For example, transmit signals exhibiting different data types than those specified may be transmitted via the present invention.