GB2192516A

GB2192516A - Transmitting data between a central radio station

Info

Publication number: GB2192516A
Application number: GB08710716A
Authority: GB
Inventors: Bernhard Plum
Original assignee: THEIMEG ELEKTRONIKGERAETE GmbH
Current assignee: THEIMEG ELEKTRONIKGERAETE GmbH
Priority date: 1986-06-26
Filing date: 1987-05-06
Publication date: 1988-01-13
Anticipated expiration: 2007-05-06
Also published as: EP0250621B1; GB2192516B; GB8710716D0; DE3664030D1; EP0250621A1

Description

1 GB 2 192 516 A 1 SPECIFICATION solves the circuit arrangement aspect of

the problem by the operative features of claim 6.

A method of transmitting data between a central The subclaims disclose other features of the inven data radio station and a number of mobile data radio tion.

stations on a single carrier frequency 70 Data transmission between the central station and the mobile stations therefore proceeds within a tele The invention relates to a method of transmitting, metering frame comprising a large number of addre data between a central data radio station and a ssable points, with a time rasterwhich is selected in numberof mobile data radio stations on a singlecar- dependence upon the numberof addressable points rierfrequency,the central station and mobile 75 and which the central station synchronizes bythe stations having send-receive facilities. transmission of synchronization signalsfor all the Methods of this kind are of use more particularly mobile stations. All the data to betransmitted are forthe remote control of locomotives, unloading fac- transmitted in theform of coded serial telegrams ilities and similar moving objects as can be seen,for each starting with a startsign and ending with a stop example, from DE-PS 2 756 613. 80 sign so thatthe particular receiver concerned can The routes of a number of vehicles, such as taxis or give an unequivocal acknowledgement of receipt of lorries, can of course be controlled by radio tele- the telegram. The addressable points available for phony from a control centre with a view to optimiz- telegram transmission are busied stochastically with ing their use. information telegrams by the data terminals; a tele- The general idea behind all these uses is that the 85 gram transmission at one or more stochastically prof itability of a production or transport system or of busied addressable points occu rs only when the a business is determined mainly by a rational flow of mobile station readyto transmit identifies such point material and that if transport operations areto be op- or points as free dueto non-receiptof information timized withoutthe processing of cost-intensive doc- from third mobile stations. When a stochastically umentation there must be considerable transpar- 90 selected addressable point has been busied, one orn ency in the information flowwithin events between otherfree addressable points is orare busied stocha storage and operation. To meetthis requirement, stically. The central station has associated with it in a data must be made known rapidly if it is to be pos- telemetering frame at least one addressable point sible to decide in good time aboutwhich transport which can be used for data transmission from the operations need to be performed as priorities and in 95 central station to the mobile stations on which the which sequence and form they need to be formed. central station can associate with a particular mobile Data concerning transport operations which have station for data transmission to the central station.

alreadyfinished have only statistical value in this Any data transmission between mobile stations and context. the central station is acknowledged thereby by Radio transmission of data of this kind has pre- 100 means of a radio signal forwhich there is an acknow viously been by radio telephony systems. However, ledgement of receiptslot atthe end of each addres the same are notfreefrom disturbances, nor arethey sable point.

fast enough to be available in a computerfor evalua- Data transmission proceeds at an average speed of tion. Since in a large concern many radio telephony at least 1200 bits/second; depending upon the HF systems operate simultaneously in variousfrequ- 105 components used this speed can be increasedto ency ranges, for example, paging systems, mobile 7200 bits/second. Forimproved security oftransmis walkie-talkies for fire-brigades, work safety and the sion an additional data item of at least8 bits isappen like, it becomes impossible for these data to betransdedto eachtelegram afterthe useful information mitted rapidly and without disturbance. Also, data and ensures that any two telegrams differfrom one transmitted by radio telephony must be fed into the 110 another by at least 4 bits- i.e., a Hamming distance of computer manually, another time-consu m ing step. at least D = 4 is provided fortelegram security. To Radio telephony equipment having digitalized further increase transmission security one or more speech transmission is not commercially available at addressable points within the telemetering frame is present. or are associated with each mobile station, so that a Both of the methods or systems mentioned are 115 mobile station can busy one or more addressable therefore unsuitable fortime-optimized two-way points stochastically by a single or repeated elec transmission of a large number of widelyvarying tronic dicing, and whichever addressable point or quantities of data between a central station and points of the diced points is or are free is or are used mobile radio stations. for data transmission between the mobile station It isthereforethe object of the invention to provide 120and the central station. Electronic dicing ensures that a novel method and a circuit arrangementforthe any mobilestation can have associated with it afree practice thereof, which method is more satisfactory time raster inwhichthe discrete communications of than the conventional methods for rapid two-way the mobile station can be received reliably atthe cen transmission of data on a single carrier frequency be- tral station. In the unexpected event of one ormore tween a central station and mobile data radio 125 overlaps of addressable points to be busied and stations, with the abilityto deal with different quan- addressable points already busied, no com tities of data, within a predetermined telemetering munications will be lost since the telemetering frame frame. has provision fortransm ission times for the acknow The invention solves the method aspect of this ledgement of receipt of a received data item, so that problem by the operative features of claim land 130 the particular mobile station concerned identifies 2 GB 2 192 516 A 2 complete data transmission. In otherwords,the frame; ready-to-transmit mobile station "hears", bythe reFigure4is a block schematic diagram of thecon ceiptof other mobile stations which are actually trolling central radio station, and transmitting, whetherthat addressable pointof a Figure5is a block schematic diagram of a mobile telemetering frame which has been allocated to it by 70 data radio station.

dicing is or is notfree. A material transport system has been chosen as All useful data such asjob numbers, pallet num- embodimentforthe method to be described here bers and similar identification numbers and mal- inafter of data transmission between a central sta functioning and operating reports and requestsfor tion US and mobile data radio stations MDFI to C, longer transmission time in orderto transmit longer 75 MDFn, butthe invention is not limited to such telegramsto the central station are transmitted in the system.

time raster. As previously stated, the central station All data required to be exchanged between the acknowledges each transmission by an acknowled- central station and the mobile stations are transmit gement of receipt signal. Also, the selection of addre- ted serially by radio on a single carrier f requency.To ssable points is so devised that after expiry of the 80 this end, the data are converted into PPM (pulse timefor reportsfrom the mobile stationsto the cen- pause modulated) serial telegrams each having a tral station, an own transmission time is available. start sign Stp and a stop sign Spp, as shown byway Preferably, the transmission time which thetele- of example in Figure 1 for data item 10010111001, metering frame has forthe central station is dis- plus an 8-bit additional data item. The telegrams to posed in the pauses between two data telegrams. 85 be transmitted are associated with a telemetering The advantage of this feature is thatthe central sta- frame which is shown in Figure 2 and which is sub tion can always enquire aboutthe instantaneous divided into addressable points corresponding to ac state of the reachable mobile stations which are in tual circumstances; in the present case thetele radio contact. Another advantage is that, thanks to metering frame is subdivided into five addressable the stochastic busying of addressable points by a 90 points RP1 - RP5 corresponding to five transmitting mobile station, at least one message can in all prob- times RS1 - RS5 forthe mobile stations MDF.

ability be transmitted from the mobile station to the Disposed after each addressable point is an ackno central station within a single transmitting cycle. In wledgement-of- receipt signal time Q1 - Q5 in which the case of a fixed association of one addressable the central station acknowledges correct receiptof a pointfor each mobile station, a numberof cycles 95 data telegram. This acknowledgement of receipt is may have to elapse before a message can be sent given whenever notransmission times forthe from a mobile station to a central station since, dep- mobile stations are programmed'in the telemetering ending upon position, propagation conditions and frame. However, the central station can during this transmission tolerances, a number of mobile acknowledgement-of-receipt signal time transmit a stations may heterodyne one another in operation. 100 synchronization signora transmission request,thus The stochatic busying feature therefore provides achieving optimal use of single high-frequency time compensation orcorrection. Also, because of transmission channel.

the acknowledgement of receiptsignals given bythe Therethen follows an addressable point Q7 as central station,the single high-frequency channel normal transmitting time forthe central station, which is availablefor data transmission and which 105 which can if required allocate such timeto a mobile must be used for transmissions in both directions station. Atthe end of thetelemetering framethere can be divided up accurately timewise. The central follows a further addressable point Q9forthe neces station recognizesfrorn the addressthe mobile sta- sary acknowledgement of receipt signal to betrans tion with which it has had radio contact. mitted from the central station.

Other advantages of the method according to the 110 The total cycle of the telemetering frame is in this invention are that, more particularly when it is used casex seconds and is subdivided into y milliseconds for stores control, the time-optimized transmission forthe points RP1 - RP5 and z milliseconds for additi of all available data between a central station and onal addressable pointsto be distributed bythe cen mobile stations without the use of written document- tral station - i.e., additional transmitting time.

ation helpsto reduce stocks substantially, ensures a 115 Thanks to this subdivision of the telemetering quickerturnover of stocks and thus greatly reduces frame, differences in transmission times which occur the capital locked up in stores. Similar con- in practice because the quantities of data to betrans siderations applyto the working means used such as mitted from the various mobile stations vary, and vehicles and personnel. Also, leaks can be clealtwith vice versa, can be transmitted in time frames having more simplythan previously withoutthe risk of 120 identical time slots. Also, malfunction reports can be error. transmitted with priority during these transmission The invention will be described hereinafterwith re- times.

ference to an embodiment shown in the drawings As can also be gathered from Figure 2, atthe start wherein: of each telemetering frame the central station trans Figure 1 diagrammatically illustrates a PPM tele- 125 mits a synchronization signal SYNC which in the pre gram forthe data content 100 10111001; sent case appears everyx seconds. The signal SYNC Figure2 is a diagram of thetime raster of the is followed bythe five addressable points RP1 - RP5 - addressable points of a telemetering frame for a cen- i.e.,RS1 - RS5 -for transmissions fro, m the mobile tral station and n mobile data radio stations; stations, whose transmission times are shown on 6_5 Figure 3shows the timing of thetelemetering 130line 2 of Figure 2.

3 GB 2 192 516 A 3 Each mobile station has an electronic dicing circuit in the telemetering frame, the control unit busying arrangement 16 for stochastically determining at the first free addressable points found forth etrans least one of a number of available addressable mission of an existing outer telegram. Since each points. The or each first free diced addressable point mobile station has an HF receive facility, it can deter is used by the mobile station to transmit its data to 70 mine by the receipt of mobile stations actually trans the central station. Since any mobile station can miffing whetherthe or each addressable points listen outthrough its own receive facility to the traffic found by dicing is or are actually free orwhether it or of the other mobile stations associated with thetele- they are actually transmitting.

metering frame, it is a simple matterto ascertain

Claims

whetherthe addressable point allocated by dicing is 75 CLAIMS

actuallyfree, Each addressable point includes trans mission time forthe central station to acknowledge 1. A method of transmitting data between a cen receipt of the received telegram, c.f Q 1 - Q 5 on line 1 tral data radio station and a number of mobile data of Figure
2. radio stations on a single carrier frequency, the cen- Figure
3 shows the timing of a synchronization 80 tral station and mobile stations having send-receive telegram for RO-Rn addressable points forthe facilities, characterised bythe following features:

mobile stations. Atthe start of each telemetering A computer is associated with the central station frame the central station sends a synchronization and the mobile stations are associated with mobile signal SYNC to all the mobile stations which then objects, more particularly vehicles; reply eitherwith "ready" or "not ready" orwith the 85 All data are transmitted in the form of serial PPM useful information in them consecutively in accord- telegrams; ance with the address of the points RO-Rn, in the Each telegram starts with a start signal and ends manner hereinbefore described. The central station with a stop signal between which identification and transmits its communications in the time slots "A" useful data items and a number of additional data between two signals SYNC, cf line 2 of Figure 3,for 90 signs following the useful items and operative to se example, Travel from 0 to P. cure the transmission are provided; Figure 4 is a block schematic circuit diagram of the Data transmission is by way of a telemetering central station ZFS. The same comprises a radio frame which comprises a number of addressable communication computer 1 and a program and work points and which has a time raster corresponding to store 3 with which a control unit 2 is associated. The 95 the number of addressable points, the central station central station can communicate with other higher- synchronizing the time raster by transmitting a syn rank computers by way of a series interface (RS 232C chronization signal after identical periods of time; or 20mA current loop). The computer 1 comprises its The addressable points available fortelegram microprocessor with the memory 3 and send-receive transmission are busied stochastically with data tele software for sem iduplex operation on the high frequ- 100 grams by the mobile stations; ency. The computer 1 is also connected by way of an A telegram transmission at one or more stochas HF interface 4to an HF send-receive facility 5. An ant- tically busied addressable point or points occurs en na changeover facility 6 and an N F modem 8 are only when the mobile station ready to transmit ident also provided. As a result of th is construction of the ifies such point or points as f ree due to non-receipt of central station, for a connection of 1 ton mobile 105 data from third mobile stations; stations to the central station, a reduced transmitter When a stochastically selected addressable point output power of at most 1 W can be used. To increase has been busied, one or n otherfree addressable the ranges possible on this low output power, multi- points is or are busied stochastically; antenna working is used and is controlled bythefac- The central station has associated with it in the ility 6 by means of the computer. A number of ant- 110 telemetering frame at least one addressable point ennas can be connected bywayof a line or of other which can be used for data transmission from the HF send-receivefacilities to the facility 6for im- central station to the mobile stations orwhich the proved aperture illumination of the movementzone central station can associatewith a particular mobile in afactory area orwithin a store. Byway of the NF station for data transmission to the central station; modem a number of lower-rank central stations can 115 Any data transmission between the mobile be connected and can have one or more antennas stations and the central station is acknowledged connected to them byway of an HF send-receivefac- thereby by means of a radio signal forwhich there is ility and start-up controls and control for impedance an acknowledgement of receipt slot atthe end of and signal matching, so that ranges can be in- each addressable point.

creased. 120 2. A method according to claim 1, characterised Every mobile station MDF has a circuit arrange- in that stochastic busying of an addressable point by ment of the kind shown in Figure 5 and comprising a mobile station is effected by a single orn-times el an HF send-receive facility 10, a CPU (central pro- ectronic dicing, and whichever addressable point or cessing unit) control with interface 11 and a control points of the diced points is or are free is or are used unit 12 connected to a memory 13. A display device 125 for data transmission between the mobile station 14 and a keyboard 15 are also provided. For stocha- and the central station.

stic busying of a free addressable point in thetele- 3. A method according to claim 2,characterised metering frame, the control unit has associated with in that to increase traffic capacity two or more diced it an electronic die 16 which in known manner calls addressable points of the telemetering frame are up one or more addressable points of those available 130 busied by a mobile station.
4 GB 2 192 516 A 4 4. A method according to claims 1 -3, characterised in that n addressable points of the telemetering frame are associated with the central stationfordata transmission ordered thereby.
5. A method according to claim 1, characterised in thatclata transmission proceeds atan adjustable speed of from at least 1200 to at most:7 200 bits/ second.
6. An arrangement forthe practice of the method according to claims 1 - 5, characterised in that a radio communication computer (1) for organising data transmissions between the central station and the mobile stations is provided in the central station (M) and has connected to it, bywayof a control unit (2), a program and work memory (3) and, byway of an HF interface (4), an HF send-receive facility (5) and possibly an antenna changeover switch (6) and a NF modem (8), and a circuit arrangement comprising an HF send- receive facility (10), a CPU control (11) and a control unit (12), together with a.memory (13), a display device (14), a keyboard (15) and an electronic dicing circuit arrangement (16) associated with the control unit (12), is associated with each mobile station WDR
7. An arrangement according to claim 6, characterised in that byway of a series interface (RS1 232C12OmA current loop) the radio computer (1) can communicate with other computers.
8. An arrangement according to claims 6 and 7, characterised in that lower-rank central stations (ZFSn) orfurther HF send-receive facilities can be associated with the central station (ZFS) by way of the NF modem (8).
9. A method as claimed in claim land substanti- ally as herein described.
10. An arrangement as claimed in claim 6 and substantially as herein described with reference to the accompanying illustrative drawings.

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