KR950012830B1 - Satellite signaling system - Google Patents

Abstract

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Description

Satellite signal display system

The state-of-the-art satellite paging system includes a fixed position antenna mounted on a satellite in synchronous orbit. Typically in such a system, the antenna and its beam pattern are all fixed such that the drop or "fall prediction point" of the signal beam covers a portion of the earth that is "tapped" with respect to the satellite, ie 1/3 of the earth's surface.

The ground level strength of the signal transmitted by the antenna is very uniform over the covered area, but the signal strength is very weak. Ground level signal strength is very weak to allow paging coverage in buildings because this causes problems even for the most enhanced synchronous satellites. For example, for a synchronous satellite with 400 watts of radiation, a state-of-the-art select call paging receiver using the POCSAG paging protocol at a bit rate of 512 bits per second has been observed to have a signal margin of only 2 dB. That is, the average signal strength on the ground is only 2 dB above the minimum level required to operate the paging device.

One solution is to use a lower bit rate of 60 boards or less to significantly reduce the paging receiver. However, this makes the system extremely expensive and impractical in the light of the few users who can be served by the paging system. In other words, a low bit rate can support only a small volume of paging traffic.

It is therefore an object of the present invention to provide an improved satellite signal display system in which the above mentioned disadvantages are overcome or at least reduced.

According to the present invention, a ground station for receiving a paging signal from an earth-bound paging terminal, an uplink wireless transmitter and antenna for sending a paging signal and a control signal to a satellite, a satellite in the orbit around the earth and the paging signal and A satellite signal indicating system comprising an up-link receiver on a satellite for receiving a control signal, and a down-link radio transmitter coupled to an antenna with a steerable beam, wherein the beam of antenna is transmitted on earth as the paging signal is transmitted to earth. A satellite signal indication system is provided that is directed within a predetermined sequence to a plurality of locations of.

In addition, because the antenna is movably installed in a predetermined sequence, the beam can be directed to a specific area sequentially, which in turn causes the antenna to scan a very wide beam area, thus providing intercontinental or earth coverage. Will be recognized.

In another embodiment of the invention, a paging receiver in the system is a battery that synchronizes the operation of the down-link beam with the silver-off operation such that the receiver is "on" or fully operational when the beam is transmitted to the local area of the pager. It includes a saber circuit.

The satellite signal display system according to the present invention is described through an embodiment with reference to the accompanying drawings.

The present invention relates to a satellite signal display system having a signal coverage over a very wide area. The present invention relates in particular to satellite signal display systems such as, but not limited to, those that may be used in satellite paging systems.

1 is a diagram of a satellite paging system of the prior art.

2 is a diagram of a satellite paging system in accordance with the present invention.

3 is a view showing the operation of the satellite signal display system of the present invention.

4 is a flowchart illustrating satellite beam operation.

5A to 5E are diagrams showing the arrangement of signals transmitted by the satellite paging system of the present invention.

6 is a block diagram of a typical paging receiver suitable for use in connection with the satellite paging system of the present invention.

7A and 7B are timing diagrams detailing the operation of the battery saver circuit of the pager receiver shown in FIG.

8A and 8B are flowcharts showing the operation of the pager shown in FIG.

Referring first to Figure 1, the prior art satellite paging system 2 comprises a fixed antenna 4 mounted on a satellite 6 which is a synchronous orbit around the earth 8. The operation of the antenna 4 is controlled by the satellite 6.

The antenna 4 is installed such that the signal beam 10 transmitted therefrom (indicated by dashed lines 9 and 11 around it) has a beam area covering a portion of the earth's surface that is visible to the satellite 4. The beam is generally a spot beam.

As mentioned above, the satellite paging system 2 cannot provide paging coverage in buildings because the signal strength at the earth's surface is very weak unless the data rate is reduced to 60 boards or less.

The signal from the ground base terminal 31 is transmitted to the receiving antenna 30 on the satellite 6 via the antenna 33.

Referring to FIG. 2, to overcome these problems, according to a preferred embodiment of the present invention, the satellite paging system 20 is movable or maneuvered on a satellite 24 in a synchronous orbit around the earth 26. Capable antenna 22. The movement and operation of the movable antenna 22 is controlled by the satellite 24.

The movable antenna 22 is installed such that the transmitted signal beam 27 (indicated by dashed lines 21 and 23 in FIG. 2) has a sufficiently small beam area, which is on the earth's surface to allow paging coverage in the building. Spot area 28 to provide sufficient signal strength. Since the ground level signal strength varies with the second power of the radius on Earth, reducing the radius from 12,874.52 kilometers to 1,287,452 by a factor of 10 provides 100 hours or 20 dB, providing a relatively more ground level. For example, a synchronous satellite with a spot beam diameter of 1,287,452 kilometers of 400 EPR (EPR) provides a ground signal strength of 22 dB above the threshold for 512 baud POCSAG signal indication. This is sufficient to provide good in-building paging coverage.

The steerable antenna 22 can be moved by the satellite 24 such that the spot area 28 can be directed to a specific location on the earth's surface, so that the satellite 24 is "visible" to it. The entire surface of the earth can be scanned. The movable or steerable antenna 22 can scan each position for a predetermined sequence and for a predetermined time. Techniques for implementing an electronically steerable antenna are well known as antenna technology and thus repeated descriptions are avoided here. See, for example, US Pat. Nos. 4,489,325 and 4,595,926.

The satellite paging system according to the present invention operates in the following manner.

Referring to FIG. 3, a paging signal from ground base terminal 70 and a control signal from ground station satellite controller 74 are applied to up-link transmitter 76. An up-link signal composed of a signal necessary for controlling the operation of the satellite, which in turn controls the operation of the movable antenna 72 and a paging neat signal, via the transmit antenna 80 and the receive antenna 72. From 70 to up-link receiver 78. It should be appreciated that the up-link data can be transmitted at much higher data rates than those used for downlink transmission.

The output of the up-link receiver 78 is connected to the satellite control system 81 and the satellite paging controller 82. Paging signal generator 84 receives information and control signals from satellite paging controller 82 and sends paging information of the type described above via downlink transmitter 86 and movable antenna 88 to paging receiver 92. Send to pager user 90 with.

The movable antenna 88 is directed by an antenna control system 92 coupled to the satellite paging controller 82 to look at a particular location on the earth's surface for a predetermined time in a given sequence. When the beam of the movable antenna 88 is directed to a specific location, the down-link transmitter 86 via the paging signal generator 84 corresponds to the particular location during the time slot assigned to that location, as described above. Will send a paging signal.

It operates to synchronize the battery saver in a suitable arrangement for signal transmission from the satellite using an appropriate signal synchronization code as described below. Once the pager is addressed in sync, it will decode the paging signal.

4 is a flowchart describing a satellite beam steering operation. After the system is initialized (102), the next beam position is selected (104). The beam is moved to the selected location 106 and the satellite beam is activated 112. The paging signal then sent to a particular location is transmitted 114 for a predetermined time period 116. Over time, if the satellite beam is turned off 118 and the system is not disabled (120), the next beam position is selected (104).

5A shows an embodiment 40 representing one of the signals transmitted from the satellite antenna 22. The signal 40 is a time-division multiplex binary paging signal and includes a sequence of batches 42-50. Coincides with a particular location in the scan area that is covered by satellites 24 of each arrangement 42-50. For example, batch 42 may match New York, batch 44 may match Boston, batch 46 Chicago, or the like. Each batch is sent to the appropriate location according to the sequential basis. In an example, the POCSAG signal display protocol is used for the signal display format in each batch.

5B shows that each arrangement (eg 42) includes a preamble 62 followed by an N frame 64.

Finally, FIG. 5C shows a display 61 representing one of the frames of FIG. 5A. The frame 61 includes a synchronization code 63 followed by a unique area identification code 65 that matches the topographical position covered by the batch transmission. The confirmation code 65 is followed by an address signal 66 to address a given pager.

The format of the frame 61 enables the operation of the battery saver in the pager to be synchronized with the scanning sequence of the movable antenna 24 by using the synchronization code 63. A pager operating within a particular topographic location will be powered up by decoding the paging signal once the satellite 24 is sent to its topographic location once it is synchronized. This provides good pager battery life.

In addition, the confirmation code 65 of the frame 61 confirms the current operating position relative to the pager. Thus, if the pager is outside its operating area, confirmation code 65 may be displayed on the display or used to enable different operating modes of the pager, such as, for example, a "roaming" mode. Provide position information to the pager.

6 is a block diagram of a paging receiver suitable for use in the satellite paging system of the present invention. This is a conventional select call paging signal that includes a wireless receiver 122 that receives a signal via an antenna 120. The output of the wireless receiver 122 is applied to the microcomputer decoder 124 which processes the information contained in the received signal. As shown, the microcomputer decoder 124 communicates with the user via an output signal indicator 126, code plug address and selection memory 128, and paging control. The operation of a paging receiver of the type shown in FIG. 6 is well known and described in US Pat. No. 4,518,916, filed May 21, 1980, entitled "Space Paging Device with Power Retention."

To operate within the satellite paging system of the present invention, the microprocessor decoder 124 is programmed to decode the signal presentation protocols shown in FIGS. 5A, 5B, and 5C. In particular, the decoder is programmed to search for a signal from the satellite and synchronize its decoding operation to the timing of the beam operation. In order to synchronize the signal indication waveform, the decoder first remains on until it decodes another link signal. This then uses a well-known synchronization technique to synchronize the received signal with its decoding operation. Accordingly, the receiver synchronizes the operation of its own battery saving circuit with a predetermined timing of the satellite's downlink transmission using information that may be included in the program ROM or code plug of the microcomputer decoder and the selection memory. As a result, the receiver battery saver operates the pager during the interval when the satellite transmits to the topographic location where the pager is installed. For example, FIG. 7A shows the preamble 62 and the synchronization code 63, which in turn are followed by the area identifying unit 65 in the arrangement 42 (FIG. 5A). The area checking unit 65 and the address number 2 130 take the form referred to as group 1. Each successive group has a first and a second address as shown in FIG. 7A. The synchronization code 63 is repeated after the eighth group. Thus, when the receiver is programmed to respond to group 4 addresses, the battery saver circuit of the receiver is in the time that the receiver searches for the preamble 62 and the synchronization code 63, and during the time the group 4 address is transmitted, And each synchronization code interval 136 activates the pager. Of course, the pager is not active during deployments 44, 46, 48 and 50 corresponding to other topographical positions.

8A and 8B are flowcharts describing the operation of the receiver. After initialization, the receiver is turned on 140 and the receiver is turned off 145 to search for the bit synchronization 142 for a predetermined search period 144. If bit synchronization is achieved prior to the end of this predetermined search period 146, the receiver will search for the synchronization code 148 again. Again, assuming that a synchronization code is detected 150 prior to expiration of a given search period 152, the location code will be decoded 154 and the battery saver timing circuit will be synchronized 156. The receiver will then begin searching for the address signal 158. If the address signal is detected 160, an alert signal will be generated 162. If no address signal is detected, the receiver will continue to search for the address signal until the battery saver timing circuit indicates that it is time to sebe 164 the battery. If the end of the batch is not detected 166, the timer will be set to wait for the next frame 168. If the end of the batch is detected, the timer will be reset to wait for the next batch 170. In either case, the receiver will turn on after a suitable time 174.

By using an adjustable antenna, the claimed invention can provide practical in-building paging coverage over a very large area. In addition, when the phaser battery saver operation is synchronized to the beam operation, the scanning operation of the beam can be used to provide wide area coverage as well as to extend the pager battery life.

It should be appreciated that the claimed invention can be used to provide national or continental paging coverage. In addition, a paging subscriber can be used in conjunction with a bath paging system to provide nationwide coverage when leaving its usual location.

Claims (14)

An antenna coupled to the satellite for supplying a satellite orbital earth signal beam, the beam comprising a data beam with multiple signal arrangements and a small beam area, the satellite being arranged to control the position of the antenna, Means for directing the signal beam in a sequence of positions to a plurality of locations on the earth, the signal arrangements being arranged in a predetermined sequence and the plurality of signal arrangements each having a fine code representing a corresponding one of the plurality of positions And a portable selection signal receiver located in one of the plurality of locations for system updating the signal beam, the portable selection signal receiver being activated to receive one of the plurality of batches corresponding to one of the plurality of locations. Satellite signal display system comprising a signal receiver. 2. The system of claim 1, wherein said portable select signal receiver comprises means for decoding said signal beam, said decoding means determining the position of a receiver in response to said confirmation code. The system of claim 1, wherein said small beam area is no greater than 800 square miles. An antenna having an adjustable beam, a first receiver for receiving paging information and control information, a first transmitter connected to the antenna and the first receiver and the adjustable beam for transmitting a paging signal corresponding to the paging information. And control means connected to said antenna and said first receiver to control said antenna to direct to a plurality of locations in response to said control information. 5. The satellite signal display system of claim 4, comprising a second transmitter for transmitting the paging information and control information to the first receiver. 5. The receiver of claim 4 wherein the paging signal comprises a data signal having a plurality of signal batches in a predetermined sequence, each batch corresponding to one of the locations and by receiving the paging signal. Satellite signal display system comprising a. 7. The satellite signal display system according to claim 6, wherein each arrangement has an acknowledgment code for indicating one of the positions and the at least one selection call receiver comprises decoding means for decoding the acknowledgment code. 7. The system of claim 6, wherein at least one select call receiver in one of the locations is responsive to one of a plurality of arrangements corresponding to the location. First means for transmitting paging information to said satellite, said second means for transmitting a paging signal comprising a plurality of signal arrangements arranged in a predetermined sequence from said satellite to a plurality of locations in said predetermined sequence, Second means each arrangement corresponding to one of the plurality of positions, and at least one pager receiver present in one of the plurality of positions, wherein the at least one pager receiver is selectively only in the arrangement corresponding to the position in which it is installed A satellite paging system comprising a responding pager receiver. 10. The satellite paging system of claim 9, wherein each arrangement corresponding to one of the plurality of locations comprises an identification code indicating one of the plurality of locations. 10. A satellite according to claim 9, wherein said second means comprises a movable antenna for providing a signal beam having a small beam area, said antenna being arranged to direct said beam to said plurality of positions in said predetermined sequence. Paging system. A selective call radio receiver for receiving information from a satellite that sequentially transmits signals to a plurality of predetermined areas, respectively, comprising: a receiver unit for receiving the signal, and the satellite may transmit information to one of a plurality of predetermined areas in which a wireless receiver is installed; And a battery saver circuit for activating the receiver portion when transmitting and deactivating the receiver portion when transmitting the satellite to one of the plurality of predetermined regions different from one of the plurality of predetermined regions. Receiving means for receiving a selection call receiver message comprising a receiver confirmation code and a receiver location code, encoding means for encoding the selection call message into a paging signal arrangement, wherein each batch has a selection call message having a similar receiver location code A ground station comprising encoding means, and up-link transmission means for transmitting the signal placement and satellite control signals, and up-link receiving means for receiving the paging signal placement and the satellite control signal; Satellite means comprising transmission means for transmitting a paging signal arrangement to a topographical position, and control means coupled to the transmission means for determining the topographic position in response to the satellite control signal, and reception for receiving the paging signal arrangement Means, and the satellite control signal is received And a plurality of select call receivers comprising power holding means for powering said receiving means at a predetermined time when indicating a broadcast in a terrain where burrs are installed. A method of displaying satellite signals from a ground station to a plurality of communication receivers located at a number of locations on the earth, the method comprising the steps of: (a) transmitting from the ground station system a batch of signals and communication information comprising control information, ( b) receiving the signal at a first antenna connected to satellite orbital earth; (c) aiming a second antenna connected to the satellite at one of the plurality of locations, one of the plurality of locations being controlled Determining in response to the information, (d) providing a signal beam having a drop prediction point from the second antenna, wherein the drop prediction point is determined in response to the control information, and (e) the plurality of Activating one of the plurality of communication receivers located at one of the locations, (f) a communication comprising placement of the communication information Transmitting a signal from the antenna to one of the plurality of locations, (g) receiving the communication signal comprising the placement of the communication information by one of the plurality of communication receiver certificates, (h) the plurality of communication Deactivating one of the receivers, and (i) repeating steps (a) through (h) after the plurality of locations.