Abstract:
A sub-orbital, high altitude communications system that has at least two ground stations and at least one high altitude relay station. Each of the ground stations includes apparatus for sending and receiving telecommunications signals. The relay stations include apparatus for receiving and sending telecommunications signals from and to the ground stations and from and to other relay stations. Apparatus is provided for controlling the lateral and vertical movement of the relay stations so that a predetermined altitude and location of each of the relay stations can be achieved and maintained. Apparatus is provided for retrieving relay stations so that they can be serviced for reuse.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims under 35 U.S.C. §120 the benefit of the filing date of prior U.S. application Ser. No. 08/929,752, now pending, which in turn claims under 35 U.S.C. §120 the benefit of the filing date of prior U.S. application Ser. No. 08/661,836, now abandoned, which in turn claims under 35 U.S.C. §120 the benefit of the filing date of U.S. application Ser. No. 08/100,037, now abandoned. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to a communication system, and more particularly to a communications system that is operative at the sub-orbital level yet well above any system which is connected to the ground.  
         BACKGROUND OF THE INVENTION  
         [0003]    Long distance telecommunications systems currently use space satellite transmission or ground based systems that rely upon towers, tall buildings, tethered balloons and the like.  
           [0004]    Satellite systems have been used for many years with a high degree of reliability. They are particularly advantageous since due to their altitude one satellite can send and receive signals from an area encompassing hundreds of thousands of square miles. However, satellites are expensive to manufacture and are expensive to launch and place in position. Further, because of the costs associated with their manufacture and launch, and the great difficulty in servicing them, extraordinary care must be taken to assure their reliability. Notwithstanding this, when a satellite fails, as assuredly they all—must do, either electronically, or by degradation of orbit, substantial expense is incurred in replacing it and the equipment it carries.  
           [0005]    Ground based systems do not have the high costs that are associated with satellite systems. However, because they are low, a particular relay station may only be able to send and receive signals over a few hundred square miles. Thus, to cover a large area, many such relay stations must be provided. Further, ground based systems suffer from line-of-sight problems in that mountains, tall trees, tall buildings and the like interfere with the propagation of telecommunications signals. Still further, it may not be possible to install a telecommunications relay station at a particular site where one is needed due to geographic or political factors, or merely because of the inability to obtain permission from a land owner or government.  
           [0006]    To some extent these problems are alleviated by using tethered balloons. However, tethered balloons are subject to the atmospheric conditions that exist at lower altitudes and are likely to be damaged as they are subject to weather conditions thereby requiring frequent replacement. Also, if they are flown at altitudes that enable them to relay telecommunications signals over a large enough area to make them economically feasible, the tethers become hazardous to aircraft.  
           [0007]    It would be advantageous to provide a stable, long duration, telecommunications system which is based on a sub-orbital, high altitude device which has the ability to receive telecommunication signals from a ground station and relay them to another similar device or to a further ground station.  
           [0008]    If the relay stations were made of high altitude, long duration lighter than air devices whose location could be controlled so as to be over a particular location on the earth, a means will have been created for providing relatively low cost telecommunication service such as a telephone service for remote areas without incurring the expense associated with satellite based communication systems, and without the disadvantages of a ground system or a tethered balloon system.  
         SUMMARY OF THE INVENTION  
         [0009]    Accordingly, with the foregoing in mind the invention relates generally to a telecommunications system that comprises at least two ground stations. Each of the ground stations includes means for sending and means for receiving telecommunication signals. At least one relay station is provided. The relay station includes means for receiving and sending telecommunication signals from and to the ground stations and from and to other relay stations.  
           [0010]    The relay stations are at an altitude of about 15 to 25 miles (i.e., within a portion of the stratosphere) and, thus, are capable of transmitting signals to a point on the earth directly below a relay station with a transmission time of about 80 μsec. Means are provided for controlling the lateral movement of the relay stations so that once a pre-determined altitude is reached, a predetermined location of each of the relay stations can be achieved and maintained. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The invention can be further understood by referring to the accompanying drawing of a presently preferred form thereof, and wherein  
         [0012]    [0012]FIG. 1 is a schematic showing a communications system constructed in accordance with a presently preferred form of the invention.  
         [0013]    [0013]FIG. 2 is a side elevation view of one of the relay stations comprising the invention.  
         [0014]    [0014]FIG. 3 is a view of a portion of FIG. 2 showing a propulsion system.  
         [0015]    [0015]FIG. 4 is a view of a portion of FIG. 2 showing another form of propulsion system.  
         [0016]    [0016]FIG. 5 is a view of a portion of a relay station.  
         [0017]    [0017]FIG. 6 is a view of a second embodiment of the portion of the relay station shown in FIG. 5.  
         [0018]    [0018]FIG. 7 is a view of a relay station being recovered. 
     
    
     DETAILED DESCRIPTION  
       [0019]    Referring now to FIG. 1, the system  10  comprises a ground based portion  12  and an air based portion  14 .  
         [0020]    The ground based portion  12  may comprise conventional telephone networks  16  with branches that are connected to a ground station  18  having suitable long distance transmitting and receiving means such as antenna  20 . The ground based portion  12  may also comprise mobile telephones of well known types such as cellular telephones that may be carried by individuals  22  or in vehicles  24 . The microwave antennae  20  are operative to transmit and receive a telecommunication signal to and from a sub-orbital, high altitude relay station  28  which is located at an altitude of between about 15 to 25 miles.  
         [0021]    Preferably, there are a plurality of relay stations  28 ; each one being at a fixed location over the earth.  
         [0022]    Each relay station  28  contains means for receiving a telecommunication signal from a ground station  20 , individual  22  or vehicle  24  and then transmitting it to another ground station  118 , individual  122  or vehicle  124  either directly or by way of another relay station  130 . Once the signal returns to the ground based portion  12  of the system  10 , the telecommunication call is completed in a conventional manner.  
         [0023]    The relay station  28  may comprise a lighter than air device  32 . A suitable device could be an inflatable device such as a high altitude super-pressure balloon of the type developed by Winzen International, Inc. of San Antonio, Tex. The superpressure balloon  32  is configured so that it floats at a predetermined altitude. The configuring is accomplished by balancing inflation pressure of the balloon and the weight of its payload against the expected air pressure and ambient temperatures at the desired density altitude. It has been observed that devices of this character maintain a high degree of vertical stability during the diurnal passage notwithstanding that they are subject to high degrees of temperature fluctuation.  
         [0024]    A plurality of tracking stations  36  are provided. The tracking stations include well known means which can identify a particular relay station  28  and detect its location and altitude.  
         [0025]    As will be explained, a thrust system is provided for returning a relay station  28  to its pre-assigned location should a tracking station  36  detect that it has shifted.  
         [0026]    Referring to FIG. 2, each of the- relay stations  28  includes a housing  40  which is supported by device  32 . The housing  40  contains a telecommunication signal transmitter and receiver  44  and a ground link antenna  48 . Antenna  48  is for receiving and sending telecommunications signals between ground stations  20  and the relay station  28 . The relay station  28  also includes a plurality of antennas  52  which are adapted to receive and transmit telecommunications signals from and to other relay stations. The housing  40  also contains a guidance module  56  that transmits the identity and location of the relay station to the tracking stations  36 . It receives instructions from the tracking station for energizing the thrust system. A guidance antenna  58  is provided to enable communication between the tracking station  36  and the guidance module  56 .  
         [0027]    A suitable re-energizable power supply Go is mounted on housing  40 , the power supply  60  may comprise a plurality of solar panels  64 . In a well known manner the solar panels capture the sun&#39;s light and convert it into electricity which can be used by the telecommunications equipment as well as for guidance and propulsion.  
         [0028]    In addition the power supply could also comprise a plurality of wind vanes  68 . The wind vanes may be arranged to face in different directions so that at least some of them are always facing the prevailing winds. The wind vanes  68  can be used to generate electric power in a well known manner which also can be used by the telecommunication equipment as well as for guidance and propulsion.  
         [0029]    As seen in FIG. 4, an alternate power supply  66  may be provided in the form of a microwave energy system of similar to that which has been developed by Endosat, Inc. of Rockville, Md. The microwave energy system includes a ground based microwave generator (not shown) that creates a microwave energy beam of about 35 GHz. This beam is directed to receptors  80  on the relay  28  and there converted to direct current.  
         [0030]    In a manner similar to the solar energy system, the microwave energy system could supply power sufficient to operate the telecommunications system on the relay station as well as provide power for guidance and propulsion. Further, the relay stations  28  may be provided with at least one microwave transmitter and suitable means for aiming the microwave transmitter at a microwave receiving means on another relay station  28  so that a source other than the ground based microwave generator is available to provide microwave energy to the relay stations.  
         [0031]    As seen in FIGS. 3 and 4 the navigation/thrust system for the relay station  28  may comprise a plurality of rockets or jets  90  or propellers  94 . The jets  90  and propellers  94  are arranged in a horizontal plane along mutually perpendicular axes which are supported by pods  100  on the housing  40 . By selective energization of various ones of the jets or propellers the relay station  28  can be directed to and maintained at a pre-determined location over the earth.  
         [0032]    If desired, additional jets or rockets  108  or propellers  112  could be located on vertical axes to assist in bringing the relay station to its pre-determined altitude on launch or restoring it should its drift from that altitude be more than an acceptable amount.  
         [0033]    The tracking stations  36  and guidance module  56  are operative to energize selected ones of the jets or propellers for selected intervals to return the relay stations  28  to their pre-determined locations.  
         [0034]    When the system  10 , is operating the customer will be unaware of its existence. Thus, when a call is placed, the telecommunications signal will be conveyed from the caller&#39;s telephone by way of a conventional network to the ground station  18  associated with that location. The microwave antenna  20  will then beam a telecommunications signal corresponding to that telephone call to the nearest relay station  28 . Switching circuity of a well known type will direct the signal to another ground station  120  near the recipient. If the recipient is further, the signal will be sent to a further relay station  130  from which it will be directed to a mobile telephone carried by an individual  122  or in a vehicle  124  or to a ground station  140  near the recipient. The signal received by the ground station  120  or  140  will be transmitted to the recipient&#39;s telephone by way of a conventional telephone network. once a communication link is established between two telephones by way of the ground stations and relay stations, the parties can communicate.  
         [0035]    Drifting of the relay stations  28  from their pre-determined locations will be detected by the tracking stations  36 . The tracking stations  36  will then energize the thrust members on the relay stations  28  to return them to their predetermined locations.  
         [0036]    As best seen in FIGS. 2, 5,  6  and  7  a recovery system  150  for the relay stations  28  is provided. As will be more fully explained, the recovery system includes a deflation device  152  and a remote controlled recovery parachute  154 .  
         [0037]    Referring to FIGS. 2 and 5 one embodiment of the deflation device  152  includes a housing  160  that is formed integrally with the suitable lighter than air device  32 . The housing  160  includes an outwardly extending and radially directed flange  164  that is integrally connected to the device  32  as by welding or by adhesive. The flange  164  supports a downwardly directed, and generally cylindrical wall  168  that supports a bottom wall  172 . As seen in FIG. 5, the bottom wall  172  is defined by an open lattice so that the housing  160  is connected to the interior of the device  32  and is at the same pressure.  
         [0038]    Near its upper end the cylindrical wall  168  supports an inwardly directed flange  176 . A frangible cover  184  is connected to the flange in airtight relation. This can be accomplished by connecting the cover to the flange by an adhesive, or with a suitable gasket between them, or by fabricating the cover as an integral part of the housing  160 .  
         [0039]    The cylindrical wall  168 , bottom wall  172  and cover  184  define a chamber that contains the remote control recovery parachute  154 .  
         [0040]    A small chamber  190  is formed on the underside of the cover  184  by a wall  192 . A small explosive pack  194  which is contained within the chamber  190  is responsive to a signal received by antenna  196 .  
         [0041]    The parachute  154  has its control lines  198  connected to a radio controlled drive member  200  that is contained within the housing  160 . The drive member  200  may include electric motors that are driven in response to signals from the ground to vary the length of the control lines in a well known manner to thereby provide directional control to the parachute.  
         [0042]    To recover the relay station a coded signal is sent to the device where it is received by antenna  196 . This results in the explosive charge  194  being detonated and the frangible cover  184  being removed.  
         [0043]    Since the cover  184  is designed to break, the explosive charge can be relatively light so that it does not damage the parachute  154 .  
         [0044]    In this regard the wall  192  helps to direct the explosive force upwardly against the cover rather than toward the device  32 .  
         [0045]    After the cover has been removed, the gases will begin to escape from the interior of the device  32  through bottom wall  172  and the opening in the top of the housing. The force of air exiting from the device  32  when the cover is first removed will be sufficient to deploy the parachute.  
         [0046]    As seen in FIG. 7, the parachute  154  will support the device  32  by way of its control lines  198 . As explained above, the relay station  28  can be directed to a predetermined location on the ground.  
         [0047]    In the embodiment shown in FIG. 6 flange  164  supports cover  204  with an annular airtight gasket between them. The cover  204  is held against the flange  164  by a plurality of circumferentially spaced clamping brackets  210 . The clamping brackets are retractably held in engagement with the cover  204  by electrically driven motors  212 . The motors are energized in response to signals from the ground to retract the brackets  210 .  
         [0048]    When the brackets  210  are retracted, the pressure of the gases escaping from the device  32  will dislodge the cover and permit the parachute to be deployed.  
         [0049]    After the relay station has been serviced, the recovery system  150  can be replaced and the device  32  can be re-inflated and returned to the service.  
         [0050]    While the invention has been described with regard to particular embodiments, it is apparent that other embodiments will be obvious to those skilled in the art in light of the foregoing description. Thus, the scope of the invention should not be limited by the description, but rather, by the scope of the appended claims.