WO1998037596A1 - Systeme de transmission bidirectionnel mettant en oeuvre une petite antenne en bande c pour la liaison descendante et en bande l pour la liaison ascendante - Google Patents

Systeme de transmission bidirectionnel mettant en oeuvre une petite antenne en bande c pour la liaison descendante et en bande l pour la liaison ascendante Download PDF

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Publication number
WO1998037596A1
WO1998037596A1 PCT/US1998/003441 US9803441W WO9837596A1 WO 1998037596 A1 WO1998037596 A1 WO 1998037596A1 US 9803441 W US9803441 W US 9803441W WO 9837596 A1 WO9837596 A1 WO 9837596A1
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WO
WIPO (PCT)
Prior art keywords
band
antenna
data rate
transmitting
frequency
Prior art date
Application number
PCT/US1998/003441
Other languages
English (en)
Inventor
Bruce B. Lusignan
George Hronopoulos
John Walter Johnson
Original Assignee
Lusignan Bruce B
George Hronopoulos
John Walter Johnson
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lusignan Bruce B, George Hronopoulos, John Walter Johnson filed Critical Lusignan Bruce B
Priority to AU64377/98A priority Critical patent/AU6437798A/en
Publication of WO1998037596A1 publication Critical patent/WO1998037596A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems

Definitions

  • 08/259,980 discloses a unique C-Band TV receive only antenna that is able to receive signals from a satellite in geosynchronous orbit that is transmitting television signals at power levels within FCC limitations, in which the antenna surface area is equivalent to that of a three foot diameter parabolic dish, although the surface area is distributed in a different manner than a parabolic surface.
  • the shape of the antenna aperture creates nulls in the antenna pattern that correspond places where signals from potentially interfering satellites at ⁇ 2°, ⁇ 4°, ⁇ 6°, ..., relative to the satellite of interest, in synchronous orbit might impinge upon the antenna surface.
  • the antenna is able to receive digital television broadcast, DVB, with anywhere from 3 to 10 TV channels per standard C-Band satellite transponder.
  • the number of channels depends on the program content (i.e., the compression rate), tolerance to artifacts, and satellite power.
  • the DVB data stream is also used to deliver other data to consumers, such as data on the world wide web sites, business documents, archives, video games, computer programs, etc.
  • U.S. Patent Application No. 08/542,493 discloses a low data rate return link (user to control hub station) for the above-mentioned antenna by developing a 6 Ghz feed using the same antenna areas but different combinations of amplitude and phase in the three main areas of the antenna.
  • This VSAT system serves as a small C-Band VSAT terminal that is competitive with current VSAT's because it is smaller and can fit on a user's premises more easily and is not subject to rain fade like Ku-band small VSAT terminals.
  • This technology provides a medium to high data rate link between a user and a central hub. However, some applications do not require a high data rate return link, and in such cases it is a waste to allocate such bandwidth for low data rate applications.
  • L-band Low-power communications
  • Some manufacturers of communications satellites are launching hybrid satellites combining C-band and Ku-band and now L-band in the same satellite.
  • the new addition of L-band is included to serve the maritime band and newly allocated mobile satellite band.
  • the lower frequency allows use of omnidirectional antennas that do not need to be pointed precisely at the satellite for effective communications. Both voice and data are offered through these services.
  • the capacity to deliver data is extremely limited through the L-band system.
  • the present invention is therefore directed to the problem of developing a low cost rapid implementation of a two-way data return link for C-band video service applications, without increasing the size of the overall antenna.
  • the present invention solves this problem by combining an L-band uplink with a C-band downlink in a communication system that employs the three dish design for the receive antenna and a small antenna disposed in the gaps of the three dish antenna for transmitting the L-band signals.
  • an apparatus for providing two-way communication includes a receive antenna having an aperture that creates nulls in a main beam of the antenna corresponding to a configuration of satellites in synchronous orbit that are transmitting potentially interfering signals, which receive antenna receives a high data rate signal at a first frequency band, and a transmit antenna disposed between gaps in the aperture of the receive antenna, wherein the transmit antenna transmits a low-data rate signal at a second frequency band and does not substantially interfere with reception of the high data rate signal.
  • the transmit antenna uses the positioning of the receive antenna for its positioning due to the fact that the second frequency is lower than the first frequency.
  • the transmit antenna has an antenna pattern with a main beam that is broader than a main beam of an antenna pattern of the receive antenna.
  • the first frequency is a C-band frequency
  • the second frequency is an L-band frequency.
  • Other possibilities for the first frequency include Ku-band, or Ka-band.
  • a method for providing a high data rate communication link to a user and a low data rate communication link from the user includes the steps of transmitting a high data rate C-band signal from a geosynchronous orbiting satellite to a user, receiving the high data rate C-band signals at a user site using a small C-band antenna having nulls in its antenna pattern corresponding to potentially interfering signals from a configuration of satellites, and transmitting a low data rate L-band signal to the geosynchronous orbiting satellite using a small L-band antenna being pointed at the geosynchronous satellite as a consequence of pointing the small C-band antenna at the geosynchronous orbiting satellite.
  • the low data rate L-band signal is relayed from the geosynchronous orbiting satellite to a central hub station on earth.
  • a device for transmitting video broadcast data to a user and receiving on-demand data from the user includes a central hub station for controlling operation of the device, a means for transmitting a single channel per carrier time division multiple access data signal to the central hub station using a first frequency, a means for receiving at a user site a direct video broadcast from the central hub station using a second frequency, wherein the first frequency includes an L-band frequency and the second frequency includes a C-band frequency, and a means for controlling a mix of data and video within the direct video broadcast at the central hub station based on an amount of incoming data relative to an amount of incoming video.
  • the means for transmitting includes a combined L-band C-band antenna having three equally sized parabolic dishes, a total surface of which is equivalent to that of a three foot diameter dish, and two Yagi antennas disposed between the parabolic dishes so that they do not block reception of signals by the parabolic dishes.
  • FIG 1 depicts a sketch of the Yagi L-band antennas mated with the C-band micro antenna for combined C-band reception and L-band transmission according to the present invention.
  • FIG 2 depicts a sketch of the Yagi L-band antennas located between antenna dish components of the C-band micro antenna according to the present invention.
  • FIG 3 depicts a sketch of the hybrid C-band/L-band VSAT receiver/transmitter layout according to the present invention.
  • FIG 4 depicts a hub station layout used in the present invention.
  • the present invention combines the L-band receiver on the satellite with the high bandwidth data delivery system of the C-band system disclosed in the above- mentioned patent applications.
  • the end result is a two-way communication system that is small, versatile and inexpensive. Since the L-band transmitters are already licensed for use by the FCC in mobile applications, no further licensing efforts need be undertaken. Often, these efforts can take longer than the equipment development.
  • the most expensive portion of a conventional L-band communications system is the transmission from the satellite to a small L-band receiver.
  • This satellite-to- VSAT down link requires high satellite power is due to the size of the user's L-band receiver and its corresponding small omnidirectional antenna.
  • the L-band signal On the uplink user-to- satellite the L-band signal reaches the satellite, which relays the L-band signal back to a central hub station on earth, which is significantly larger and requires much less satellite power, and hence is less expensive.
  • the most expensive portion of a C-band communications system is the uplink from the user to the satellite and back to the earth station. This is due to the small size of the transmitting antennas and the resulting power to transmit up to the satellite on the user-to-satellite-to-hub link. Furthermore, the cost of the down link is paid for by the broadcaster, whereas the cost of the uplink is paid for by the individual user.
  • the present invention essentially removes the most inefficient portions of each of these two systems and combines the remaining portions to create a hybrid communication system that is extremely efficient to operate.
  • the L-band uplink is cheaper to operate than the 4/6 Ghz C-band uplink, even though the parabolic dish is used in both transmit and receive operations.
  • the present invention provides a hybrid combination of modulation techniques to take advantage of the efficiencies provided in each.
  • the present invention uses a multichannel per carrier modulation technique, such as MPEG television standards that use QPSK modulation in the Direct Video Broadcast (DVB) standard.
  • MPEG television standards that use QPSK modulation in the Direct Video Broadcast (DVB) standard.
  • DVB Direct Video Broadcast
  • one or more data channels can be multiplexed with compressed television for sending data to a user.
  • the present invention uses these data channel to transmit voice and/or on-demand data to the user. This voice and/or data is in TDM format within the MPEG data stream.
  • the L-band uplink uses a QPSK or equivalent energy efficient single channel modulation. It is adjusted to the data rate maximum desired by the service, for examples 10 kilobits per second (kb/s) if compressed voice was the most intense incoming data application. Stations are commanded in turn to use the incoming channel by a demand access protocol.
  • the L-band communication portion of this system is a relatively low data rate link. More specifically, this link transmits signals such as voice, or low data applications, but not video applications or higher.
  • the C-band communications portion of this system is a relatively high data rate link.
  • This link transmits video signals, compressed television, or other broadband signals.
  • these signals are in MPEG format, which can be MPEG-2, MPEG-3 or MPEG-4.
  • these television signals are part of the one-way direct-to-home (DTH) television distribution to the service area.
  • the two-way low data rate applications will normally occupy only a small portion of the DTH television service capacity.
  • a low data rate channel at L-band up to the satellite and down to the L-band hub station receiver carries either voice or data from the users to the hub center.
  • the normal digital data channel on one of the MPEG-II data streams in the DVB channel carries voice or data to the user from the hub center.
  • a two-way voice or low data rate channel exists from the user to the Hub center.
  • it can be routed to the appropriate location using known other communication links, such as the public telephone switched network, or the Internet.
  • a hybrid system exists due to the presence of the L-band uplink, which permits broader applications. For example, any application that requires a large downlink but only a relatively small uplink can be satisfied by the present invention, as well as applications for low data rate transmissions in each direction.
  • One such example is direct broadcast interactive television, where the user receives a television broadcast and responds back with some data (e.g., order information or billing information).
  • the operational simplicity is optimal if the L-band and C-band equipment is located within the same hub station.
  • the central hub station equipment receives incoming signals from L-band receivers and transmits data to the C-band input data ports to be transmitted to the satellite.
  • the "land" side of the equipment will be connected to data banks in the hub, to fiber or microwave links to the city networks, or to other satellite links to foreign destinations.
  • the data stream coming down to the user with the DVB signals carries packets used to manage responses solicited from remote users. (A number of techniques are available).
  • This data stream received from the C-band DVB data stream enables each user periodically to originate a data request.
  • the data request is transmitted at the indicated time by the user's L-band transmitter on a frequency assignment designated by the data packet desired.
  • the incoming packet is received back at the hub station and interpreted by the processor.
  • the message is returned through the DVB data stream with a packet addressed to the user. This is suitable for a pay per view order.
  • the message can be used to acknowledge an order, trigger a security decoder for a scrambled channel, or direct the user equipment to a DVB channel carrying a near on demand movie as well.
  • the response may deliver a large data file to the user; the Encyclopedia Britannica, for example, a library of video games, all photos of Marilyn Monroe ever made, all new web pages of the last week, etc.
  • a third application is voice.
  • a compressed voice service requires a channel with a data rate of about 10 kb/s in each direction.
  • the voice to the user on C-band is time division multiplexed on the DVB data channel.
  • the voice from the user is single channel per carrier on the L-band.
  • Each 5 MHZ DVB channel will carry about 500 channels of 10 kbit/sec cellular digital voice.
  • the downlink cost is about 50 per hour or 0.001 /min.
  • the incoming L-band link will cost more depending on the design used.
  • the direct receive antenna is the design disclosed in U.S. Patent Application No. 08/259,980 (which has been previously incorporated by reference) receiving vertical and horizontal polarizations from the satellite.
  • the L-band transmit antenna is a wire Yagi antenna, a preferred realization of which is either one or two antennas mounted between the circles. Referring to FIG 1, the combined antenna 1 of the present invention is shown.
  • the combined antenna 1 includes the three parabolic dish antenna 2, 3, 4 disclosed in the previous patent is shown, along with two L-band antennas 5, 6.
  • the C-Band antenna 2, 3, 4 is exactly as described in the prior patent, however, other variations are possible as described therein.
  • the L-band transmit antennas are located in the gaps between the central reflector 3 and the two side reflectors 2, 4. By placing these transmit antennas 5, 6 in these gaps, the transmit antennas 5, 6 do not interfere with the receive signal.
  • the L-band transmit antenna 5, 6 consists of two Yagi antennas. These antennas 5, 6 have gain in their main lobes, which when pointed at the satellite of interest provides over ten times the gain of an omnidirectional antenna.
  • the uplink power can be significantly reduced relative to an omnidirectional antenna, which is normally used in L-band mobile applications.
  • FIG 1A shows an example of a single polarization version of the Yagi antenna 5 used in the present invention in both side view and front view.
  • FIG 1 B shows an example of a multiple polarization version of the L:-band antenna used in the present invention in both front view and side view. Note that in the multiple polarization example, two wires 21, 22 perpendicular to the directional axis 23 are placed at 90° from each other to obtain both vertical and horizontal polarizations, whereas in the single polarization example only one wire 21 perpendicular to the directional axis 23 is used.
  • the horizontal and vertical polarizations can also be connected by phase networks (not shown) to create right-hand and left-hand circular polarizations.
  • the feed structure might be more complicated than the separate Yagi antennas 5, 6.
  • the Yagi antenna 5, 6 is the same as the home television rooftop antenna, only smaller because the frequency is twice as high as the UHF band used in broadcast television.
  • the crossed antenna option (shown in FIG IB) allows transmissions on vertical and horizontal or circular polarization, if the satellite uses circular polarization ro receive.
  • the Yagi antennas 5, 6 are just thin wire on a metal tube. They can be made springy and as thin as necessary, still meeting survival requirements. If painted black they will be hardly noticed next to the C-band reflectors 2, 3, 4.
  • the Yagis 5, 6 are located between the circles of the C-band antenna 2, 3, 4 so they will not interfere with the C-band antenna receive pattern. See FIG 2.
  • the present invention provides a vast array of two-way services with virtually no change to the DTH TV unit.
  • the present invention would even be able to be added as a retrofit to a receive only antenna since they share common electronics.
  • the L-band only uses the antenna structure of the C- band to point it at the same satellite. It even bypasses the indoor electronics (IRD) used in the present invention.
  • the incoming C-band signal is received by the three parabolic dishes, and coupled to the backplate 9 and combiner components 11, which are located in an electronics package 9 mounted on the back of the antenna 1.
  • the C-band signals are then sent to the receiver (not shown) in the Star Video IRD 12 located within the house.
  • the IRD 12 is connected to the television (not shown) and/or the computer (not shown).
  • data from the computer or television is input to the IRD box 12 by the user and is sent to the L-band transmitter 11, converted to an L-band transmission signal and passed up to the electronics package 9 behind the antenna.
  • the L-band signals are then sent to the L-band transmitter amplifier 10, which amplifies the signals and couples them to the Yagi antennas 5, 6 for broadcast.
  • the broadcast L-band signals are then transmitted to the satellite, since the C-band dishes are already pointed at the satellite within the tolerance of the L-band signals.
  • the satellite receives the L-band signals and transmits them back down to the hub station 13 as shown in FIG 4.
  • the L-band downlink is received by the combined C-band and L-band dish 14, passed to the demand multiplexer 18, and on to the two-way service module 20, which then passes the signals to the appropriate place via land links.
  • the video servers 19 output DVB television signals to the multiplexer 17, which creates a signal C-Band signal that is transmitted to the satellite by the combined C-band and L-band dish 13.
  • separate C-band 15 and L-band 16 dishes can be used depending upon the space and cost requirements.
  • the satellite then broadcasts the C-Band signals back to earth, which are received by the three parabolic dish antenna 2, 3, 4 of the present invention.
  • Data requests are sent through the video servers 19 or via land links.
  • DVB data in passes directly to the multiplexer.
  • the exact mix of channels dedicated to data and video is altered in the multiplexer to accommodate the data channels and vice versa.
  • Data requests can be Internet packets, or other computer data, or simply billing and order information from the user about the direct broadcast video service.
  • the present invention is a unique combination of L-band on demand single carrier per channel time division multiple access modulation on the incoming side or to the hub station with outgoing direct video broadcast data channels with time division multiplexing voice and on demand data delivery. This combination of two previously independent techniques results in a significant cost reduction for the services.

Abstract

Cette invention se rapporte à un ensemble antenne et émetteur en bande L à faible débit d'informations qui est combiné à un ensemble antenne et récepteur en bande C à débit d'informations élevé de manière à assurer la liaison avec un émetteur en bande C et un récepteur en bande L sur un satellite sur orbite géosynchrone. L'antenne de réception est conçue avec trois réflecteurs paraboliques permettant la réception des polarisations verticales et horizontales en provenance du satellite. L'antenne de transmission en bande L est une antenne Yagi filaire montée entre deux réflecteurs.
PCT/US1998/003441 1997-02-21 1998-02-23 Systeme de transmission bidirectionnel mettant en oeuvre une petite antenne en bande c pour la liaison descendante et en bande l pour la liaison ascendante WO1998037596A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU64377/98A AU6437798A (en) 1997-02-21 1998-02-23 Two-way communication system utilizing small c-band antenna for downlink and l- band for uplink

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US80425597A 1997-02-21 1997-02-21
US08/804,255 1997-02-21

Publications (1)

Publication Number Publication Date
WO1998037596A1 true WO1998037596A1 (fr) 1998-08-27

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PCT/US1998/003441 WO1998037596A1 (fr) 1997-02-21 1998-02-23 Systeme de transmission bidirectionnel mettant en oeuvre une petite antenne en bande c pour la liaison descendante et en bande l pour la liaison ascendante

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AU (1) AU6437798A (fr)
TW (1) TW407405B (fr)
WO (1) WO1998037596A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1246374A1 (fr) * 2001-03-19 2002-10-02 Globalstar L.P. Système de communication globale par satellite LEO avec terminaux d'utilisateur à deux émetteurs-recepteurs
WO2006039229A1 (fr) * 2004-09-30 2006-04-13 Symbol Technologies, Inc. Appareil rfid multifrequence et procedes de lecture d’etiquettes rfid
US7205953B2 (en) 2003-09-12 2007-04-17 Symbol Technologies, Inc. Directional antenna array
CN116094579A (zh) * 2023-04-07 2023-05-09 湖南鲸瓴智联信息技术有限公司 一种高低速协同的低轨卫星通信系统和方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5258771A (en) * 1990-05-14 1993-11-02 General Electric Co. Interleaved helix arrays

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5258771A (en) * 1990-05-14 1993-11-02 General Electric Co. Interleaved helix arrays

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1246374A1 (fr) * 2001-03-19 2002-10-02 Globalstar L.P. Système de communication globale par satellite LEO avec terminaux d'utilisateur à deux émetteurs-recepteurs
US7205953B2 (en) 2003-09-12 2007-04-17 Symbol Technologies, Inc. Directional antenna array
WO2006039229A1 (fr) * 2004-09-30 2006-04-13 Symbol Technologies, Inc. Appareil rfid multifrequence et procedes de lecture d’etiquettes rfid
US7423606B2 (en) 2004-09-30 2008-09-09 Symbol Technologies, Inc. Multi-frequency RFID apparatus and methods of reading RFID tags
CN116094579A (zh) * 2023-04-07 2023-05-09 湖南鲸瓴智联信息技术有限公司 一种高低速协同的低轨卫星通信系统和方法

Also Published As

Publication number Publication date
TW407405B (en) 2000-10-01
AU6437798A (en) 1998-09-09

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