CN1029445C - Satellite signalling system having signal beam with variable beam area - Google Patents

Abstract

The present invention relates to a satellite signaling system (20), such as a satellite paging system, which has signal coverage over a very wide area. The present invention is characterized in that an antenna used for providing a signal wave beam (27) with a variable wave beam section is installed on a satellite. The satellite controls the position of the antenna so that the antenna makes the wave beam point to a plurality of positions on the earth in a predetermined order. The antenna is designed to change the signal wave beam section (28) according to the position that the wave beam points to. Besides, the wave beam (27) comprises a data signal, and the velocity of the data signal can be changed according to the wave beam section (28).

Description

Satellite signalling system having signal beam with variable beam area

The present invention relates to have the very satellite letter signal system of bandwidth signals overlay area, specifically and not exclusively say, the present invention relates to for example can be used for the satellite letter signal system of satellite paging system.

The present age, satellite paging system comprised a fixed directional antenna that is installed on the synchronous satellite.Usually, in this system, antenna is fixed, and the signal beam of antenna footprint or " footprint " on earth can cover by the zone of satellite " look and "; That is to say, can cover about 1/3rd earth surface.

In the system of these prior arts, the intensity that is arrived ground by the signal of antenna emission is quite uniform in whole covering domain, yet its intensity is very faint.Consequent problem is consequently can not carry out paging in the overlay area because of ground signal is too weak, this in addition also be like this to the synchronous satellite of high transmit power, it for example is 400 watts synchronous satellite for a radiant power, concerning adopting with the selective call paging receiver of the up-to-date technology level of the POCSAG paging protocol of the bit rate of per second 510 bits, its signal margin only is 2db, in other words, signal intensity ratio on the ground only exceeds two decibels for driving the required minimum levels of paging equipment.So the radio frequency paging signal reaches 20dB because most of buildings will be decayed, these systems can not be used to be positioned at the signal calling user of building.

In order to one of method of this difficult problem of solving present system is by data rate being reduced to 60 bauds or reducing the bandwidth of paging receiver to get off, yet in such event, therefore can only provide the viewpoint of small number of users from paging system, make this paging system seem extremely expensive and the usefulness that do not sound feasible.That is to say that low rate can only provide the paging communication of low capacity.

With the present invention for same inventor and transfer describe in same assignee's the pending application and declared a kind of than the current techniques advanced person the satellite paging system of Duoing, it uses the antenna of little " footprint " or minor beam width and the intensity of ground signal is improved greatly, and the sensing of antenna beam controlled, make to cover different geographic regions with a corresponding radiation pattern and obtain wide overlay area with this.With the high strength ground signal level that obtains thus, and with the scanning motion of wave beam on ground, and the synchronous beep-pager battery saving technique of the opening and closing of paging receiver and beam scanning combines, the signaling data speed that then is 512 bauds or 1200 bauds all can be used, thus for realize very wide zone or global satellite for the paging system in base provides first can practical way.

Yet this method itself also has some limitations, at first, promptly enables to reach the signal rate of 512 bauds or 1200 bauds, its high not enough user to the very big quantity that the global paging service of final realization is provided.Secondly, system can only handle the difference that regional population occupies collection by the time length that changes a scanning beam given area pointed.At last, it can not utilize such advantage: the most collection that occupies of the population of developed country is in the highdensity city of population.

So, the purpose of this invention is to provide a kind of improved satellite letter signal system with big information throughput.

Another object of the present invention provides and a kind ofly can adapt to the different satellite letter signal system of the density of population.

Another purpose of the present invention provides a kind of satellite letter signal system that a higher rate signal rate can be provided selectively.

A further object of the present invention is the satellite letter signal system that economy is provided for the user of sufficient amount.

The invention provides a kind of satellite letter signal system, it comprises that a satellite and a coupled antenna are used to provide a signal beam that beam cross-section is variable.Satellite can be controlled the sensing of antenna, makes signal beam point to tellurian a plurality of position with predetermined order.Antenna can change the cross section of signal beam by signal beam position pointed.Signal beam comprises a data-signal, system changes data rate according to beam cross-section, for example, if signal beam be meant a densely populated position, then change antenna beam cross section and data rate to provide the data-signal of a little beam cross-section and a high data rate.If signal beam is meant in underpopulated position, then change antenna beam cross section and data rate to provide the data-signal of a big beam cross-section and a low data rate.

So, we are appreciated that, utilize the movably antenna of the signal beam of variable beam cross-section of emission and variable-data-rate, beam cross-section and data rate can be by each certain location in to change, so that on the ground signal strength signal intensity is enough to realize the paging in the building is covered during each position, and by changing data rate so that the throughput maximum of signal system.

Can recognize also simultaneously that can move by predetermined order because antenna is design, so signal beam can be aimed at the geographic area of appointment successively, its result makes antenna scan a very wide zone, thereby realizes intercontinental or global covering.

Satellite letter signal system of the present invention is described middle with reference to the accompanying drawings embodiment.

Fig. 1 is the schematic diagram of the satellite paging system of prior art;

Fig. 2 is the schematic diagram of satellite paging system of the present invention;

Fig. 3 is the block diagram that comprises system of the present invention;

Fig. 4 is the flow chart that describes the operation principle of Fig. 3 system in detail;

Fig. 5 A is the schematic diagram that a down link signal that is launched of the present invention is criticized row;

Fig. 5 B is the schematic diagram of a collection of signal of a composition diagram 5A series part;

Fig. 5 C is a schematic diagram of forming the signal frame that is shown in the some of criticizing among Fig. 5 B;

Fig. 6 is a block diagram that can be used for that class paging receiver of new satellite letter signal system;

Fig. 7 is the timing diagram that describes the battery saving circuit of the beep-pager among Fig. 6 in detail;

Fig. 8 A and 8B show the flow chart of work of decoder of the beep-pager of Fig. 6.

Consult Fig. 1 earlier.The satellite paging system 2 of prior art comprises a fixed antenna on the geosynchronous satellite that is installed in the earth 8.Work by satellite 6 control antennas 4.

Antenna 4 is to be shown in dotted line among its circumference of the signal beam 10(Fig. 1 that is designed to by its emission) wave beam cut and can cover earth surface that 4 on satellite can " look and " partly.

。As mentioned above, unless the data rate of signal beam 10 is reduced to below 60 bauds, otherwise because of signal strength signal intensity at the earth's surface is very low, and make satellite paging system 2 can not provide the paging in the building to cover.

Consult Fig. 2 now.For addressing these problems, the preferential embodiment according to the present invention, satellite paging system 2 comprise driving or antenna 22 movably on the geosynchronous satellite 24 that is contained in the earth 26.The motion of removable antenna 22 and operation are then by satellite 24 controls.

Satellite 24 can portable antenna 22, like this, with dashed lines 21 and 23 expressions among the signal beam 27(Fig. 2 that is launched) can point to the geographical position of stipulating on the earth, thus satellite can partly scan by " look and " earth surface whole its institute.Removable antenna scans each geographical position successively by predefined procedure with in the scheduled time.

Portable antenna 22 is to be provided with like this: make among signal beam 27(Fig. 2 of emission shown in the dotted line) signal data rate that a variable beam cross-section 28 arranged and become with beam cross-section 28.When removable antenna 22 each geographical position of scanning, beam cross-section that the satellite selection is best and corresponding signal data rate provide the signal of sufficient intensity to realize the paging covering in the building with the throughput and the earth surface to each position of optimization paging system 20.Beam cross-section and bit rate to the down link signal of each beam. position, then change, and be that the relation that the intensity at the signal on the required ground of building dependable communication is directly proportional with data rate is selected according to ground signal strength signal intensity inverse ratio beam cross-section.So to densely populated urban district, beam cross-section 28 can be reduced to and cover the required sectional area in this city, data rate then may be increased on the maximum that allows reliable reception semaphore request in the multi-story structure of city.On the contrary, in underpopulated rural areas, beam cross-section 28 will increase signal data rate and then reduce, to allow and can realize reliable paging covering in a very big zone.

For example, to a satellite paging system with 400 watts of Effective Radiated Powers (ERP), diameter of section is that 800 miles wave beam can provide the ground signal intensity that is higher than paging level 20dB when signal rate is 600 bauds, and this signal strength signal intensity is enough to provide a good paging in building to cover a big underpopulated rural area.Because ground signal intensity becomes quadratic power to change approximately with the beam cross-section diameter, then diameter is reduced to 200 miles when dwindling four times from 800 miles, can make signaling data speed increase to 9600 bauds and still can remain the required same signal strength signal intensity nargin of paging service that guarantees in good building is realized in densely populated urban district.

Satellite paging system 20 of the present invention is worked in the following manner.Consult Fig. 3, beep-page message from a large amount of continental rise paging system terminals is sent to earth base terminal 70 by public telephone network or some other communication network, terminal 70 is handled incoming message, the output paging signal that obtains thus is added to uplink transmitter 76 together with the control signal from ground station's satellite controller 74, and transmitter 76 utilizes well-known optics or telecommunication technology that they are transmitted on the satellite 24.By the paging data signal with in order to control satellite work and and then control the uplink signal that the required signal of removable antenna 72 work forms by satellite and send to uplink receiver 78 by transmitting antenna 80 and reception antenna 72 by uplink transmitter 76.The uplink signal that is sent out offers satellite control system 90 and this controller of satellite controller 82(and then controls the work of removable or dirigible antenna 72 by the paging data signal with for control satellite work) signal form.Should be understood that the uplink data can be to send than being used for the much higher data rate of downgoing line transmission.

By with the sensing of the removable antenna 88 of joining antenna control systems 94 controls of satellite paging controller 82, it is scanned by predefined procedure and the scheduled time specified geographic location to earth surface.When the wave beam of removable antenna 88 referred to a certain location, then downstream transmitter 86 will be via paging signal generator 84 in distributing to the time slot of this position, with the paging signal of foregoing batch form emission corresponding to assigned address.

During work, satellite 24 scans the surface of the earth 26 by with predefined procedure removable antenna 88 being pointed to one period scheduled time of tellurian specified geographic location.When removable antenna 88 referred to a certain location, beam cross-section 28 and signaling data speed were adjusted to therewith on the corresponding value of ad-hoc location.Then satellite 24 in distributing to the time slot of this position with batch form emission corresponding to the paging signal of assigned address.

Be used for the satellite paging controller 82 of application drawing 3, control logic is shown in the flow chart of Fig. 4.

Satellite paging system 20 is activated (frame 102) and next geographical position selected (frame 104).Antenna 22 is moved so that signal beam points to next geographical position (frame 106).On 108 frame beam cross-sections 28 were adjusted to value corresponding to this next geographical position, signaling data speed was adjusted on the value corresponding to this next geographical position when 110 frames.After setting these values, signal beam 27 is switched on (frame 112), and paging signal is launched when 114 frames.Paging signal is launched in a predetermined time slot, and if time slot stop, then routine fork is with shutdown signal wave beam 27(frame 118).If satellite paging system is interrupted, then routine finishes at frame 122.If do not detect mutual interrupt signal when frame 120, then routine is back to frame 104 and opens routine thus again to select next geographical position.

Fig. 5 shows the exemplary expression by a signal of satellite antenna 22 emissions.Signal 40 is time-division multiplex binary system paging signals, and it comprises crowd 42-50 of a sequence.Criticize every batch of geographical position among the 42-50 corresponding to an appointment in the scanning area that covers by satellite 24.For example, criticize 42 and can criticize 44 corresponding to Boston, criticize 46 corresponding to Chicago corresponding to New York, or the like.Be transmitted into suitable position in order with every batch.For example, the POCSAG signaling protocol is used as the signaling format of each batch.

Fig. 5 B shows every batch (for example, 42) and comprises a preorder 62 and follow-up N frame 64.

At last, Fig. 5 C shows the exemplary expression of the frame in Fig. 5 A.Frame 61 comprises a synchronous code 63 and follow-up corresponding to by this wholesale unique address identification code 65 of penetrating the geographical position that is covered.The subsequent address signal of identification code 65 is used for to predetermined beep-pager addressing.

The form of frame 61 makes and can utilize synchronous code 63 that the battery in beep-pager is saved the scanning sequence synchronised of operating with removable antenna.If satellite 24 transmits to its geographical position, then in a single day by after synchronous, it just is powered with the decoding paging signal beep-pager of working in a specific geographical position.This can make the beep-pager battery that the long life-span is arranged.

In addition, the work at present position of the identification code of frame 61 identification beep-pager.So if beep-pager is outside normal operation region, then identification code 65 provides the positional information an of different working modes that may be displayed on the display or can be used to start beep-pager (for example " roaming " pattern) to beep-pager.

Utilize the synchronous code 62 of suitable batch signal, in the satellite-signal emission process, the beep-pager in paging system is to extremely suitable synchronously the criticizing of their battery economy systems.After in case the beep-pager quilt is synchronous, the paging signal that it is suitable that it is promptly decoded.

A more detailed description is made in the work that receives according to the paging in Fig. 6, the 7 and 8 pairs of new satellite systems now.

Fig. 6 is the block diagram that is applicable to the paging receiver in the satellite paging system.Except an exception, it is exactly the selective call paging receiver of the routine known in the prior art.This exception be exactly the signal rate and the detection bandwidth of receiver be the position of depending on receiver.These parameters then both can be set by giving each position different beep-pager of manufacturing in the satellite system, also can make these parameters by being stored in the information change in yard plug-in unit.About the details of beep-pager how to make a variable bit-rate and decode bandwidth the U.S. Patent No. 4 that is entitled as " Radio Commanication Receiver With Apparatus for Altering the Bit Rate of the Receivcr " at the Davis that transfers assignee of the present invention, detailed description is arranged in 816,820.

Receiver among Fig. 6 has used a decoder 124 based on microprocessor, and it is decoded as Fig. 5 A by programmed, the signaling protocol shown in 5B and the 5C.In the assignee's who transfers the phase inventor who is entitled as " Universal Paging Device With Poqer Conservafion " Davis U.S. Patent No. 4518961, done introduction.Radio receiver is by antenna 128 received signals.The output of receiver 126 is delivered to microprocessor decoder 124 through low pass filter 130 and data amplitude limiter 132.Low pass filter 130 carries out communication with receiver control logic 134, and control logic then is subjected to the control of microprocessor 124.Also can see, microprocessor decoder 124 also with sign indicating number card address Chooser 136, output 138 and carries out communication by customer controller and user.

Specifically, decoder is programmed to be searched for the signal from satellite, makes the timing synchronised of its decode operation and riding then.For synchronous with signaling waveform, decoder stays open before it solves down link signal always.Then, make decoder operation and received signal Synchronization with well-known simultaneous techniques, this comprises with received signal sets up bit synchronous and frame synchronization.The bit synchronous process comprises that the bandwidth of adjusting low pass filter makes it be matched with the bit rate of received signal.Finish after this step, receiver utilize then in the program ROM that both can be included in microprocessor decoder 124 or be included in information in yard card address apolegamy memory 136.The predetermined regularly synchronised of transmission with the downgoing line of the operation of its battery saving circuit and satellite.As a result, only at satellite during geographic area, beep-pager place transmits, receiver battery economy system just drives beep-pager.For example, Fig. 7 A shows preorder 62 and its follow-up synchronous code and subsequent identification partly once more.Identification partly and address number 130 formed and be referred to as to organize 1 zone.Shown in Fig. 7 A, each group all comprises first and second addresses successively, and synchronous code repeats once through 8 groups.So if programme receiver in response to the address of organizing 4, then the battery saving circuit in the receiver will be at following drive beep-pager.During the search operation 132 of searcher receiver preorder 62 and synchronous code 63, during the time interval 134 that is sending in group 4 address with in each synchronous code at interval during 136.

Fig. 8 A and 8B are the flow charts of describing operation of receiver.After the initialization, receiver is opened (140 frame),, behind predetermined period, receiver cut out (145) in a predetermined search (frame 144) search bit synchronously (142 frame) in the cycle.If bit synchronous obtains (146 frame) before this predetermined search cycle stops, then receiver begins the search (148) of its synchronous code again.Again the assumes synchronization sign indicating number be before the predetermined search cycle stops (152 frame) then position code will detect (154 frame), and battery is saved timing circuit by synchronous (156 frame).Receiver begins to search for an address signal (158 frame) then.If an address signal detected (160) then will produce alarm signal (162 frame).If address signal is not detected (160 frame), then receiver continues address signal of search, when the indication of battery saving timing circuit is the battery saving now (164 frame).If the end of criticizing does not also detect (166 frame), then timer will place frame wait (168 frame) down.If detected the end of criticizing, then timer places and waits for next batch (170 frame).Which kind of situation no matter is at an appropriate time (174) receiver will be opened (172) afterwards.

After initialization, receiver is opened, and attempts to set up in the cycle synchronously at a predetermined search.The search of bit synchronous comprised the data with the various bit rates that are used for system are searched for.If bit synchronous obtains before this predetermined search cycle stops, then receiver will begin its search to synchronous code.Hypothesis again, synchronous code is detected before the predetermined search cycle stops, and then position code will be detected and battery saving timing circuit will be by synchronously.Receiver will begin the search address signal then.If detect an address signal, then and then produce an alarm signal.If do not detect address signal, then receiver will continue the search address signal when the indication of battery economy system timing circuit is the battery saving now.If also do not detect the end of criticizing, then timer will be placed in the wait next frame.If the end of criticizing has been detected, then timer will be placed in and wait for following batch, and in any case, receiver will be opened in the suitable time.

So, be appreciated that the invention of being declared can provide the paging of the building clam of practicality to cover in very broad zone.

Can recognize that also the invention of being declared can be used to provide the paging of real nationwide or intercontinental scope to cover.In addition, the present invention can also match by existing continental rise paging system, can obtain real nationwide covering when a calling user leaves its common geographical position.

Claims (2)

1, a kind of satellite paging system, this system comprises: satellite and one is antenna movably, this antenna and described satellite connect mutually provides a signal beam with variable beam cross-section, wherein the described signal beam that is provided by described removable antenna comprises a data-signal that variable-data-rate is arranged, this satellite paging system also comprises a beep-pager, in order to receive the decode above-mentioned data-signal, this system is characterized in that:

The antenna control system device links with above-mentioned removable antenna, controls above-mentioned signal beam to cover a section in a plurality of predetermined beams cross section in order to information to be provided to above-mentioned removable antenna;

The satellite paging control device, be connected with above-mentioned antenna control system device, have a kind of data rate in the multiple pre-determined data rate in order to limit above-mentioned data-signal, above-mentioned a kind of pre-determined data rate is according to the above-mentioned cross section in above-mentioned a plurality of predetermined beams cross section and definite; And

Paging signal generator and downgoing line transmitter installation, with above-mentioned removable antenna and with above-mentioned satellite paging control device coupling connection mutually, the above-mentioned a kind of data rate in the above-mentioned multiple pre-determined data rate that is limited with above-mentioned satellite paging control device is launched above-mentioned data-signal.

2, a kind of method that is used for the satellite paging system paging, this system comprises a removable antenna, cover a beam cross-section in order to produce signal beam, this signal beam has a paging signal with the data rate emission, and this method is characterized in that comprising step:

Start above-mentioned satellite paging system;

Select next geographical position, receive this paging signal;

Move above-mentioned removable antenna so that above-mentioned signal beam is aimed at above-mentioned next geographical position;

Regulate this beam cross-section to the corresponding numerical value in next geographical position on;

The data rate of regulating this paging signal to the corresponding numerical value in next geographical position on;

Make above-mentioned signal beam connection work, to launch this paging signal;

Launch this paging signal at a predetermined time slot;

This signal beam is turn-offed does not work;

Return above-mentioned selection step, so that this method continues to carry out.

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