DK160025B

DK160025B - Installation for locating buried cables or pipes

Info

Publication number: DK160025B
Application number: DK408983A
Authority: DK
Inventors: Leo Anker Jensen
Original assignee: Jydsk Telefon As
Priority date: 1982-01-14
Filing date: 1983-09-09
Publication date: 1991-01-14
Also published as: DK160025C; DK408983D0; DK408983A

Description

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Opfindelsen angår et anlæg til lokalisering af nedgravede 5 kabler eller rør og som angivet i krav l's indledning.The invention relates to a plant for locating buried cables or pipes and as stated in the preamble of claim 1.

Lokaliseringen af nedgravede rør eller kabler foregår normalt på den måde, at de ved nedlægningen indtegnes på et kort, ved hjælp af hvilket man så måler sig frem til det omtrentlige 10 sted for kablets eller rørets placering, hvis en fejl gør en opgravning nødvendig. Hvis tidsrøvende prøvegravninger skal undgås, må indtegningen på kortet foretages med stor nøjagtighed, og da kabler og rør ofte må nedlægges på steder, hvor mærkepæle ikke kan stå uforstyrret, må der foretages nøjagtige 15 landmålinger, hver gang kablerne eller rørene skal genfindes.The location of buried pipes or cables is usually carried out in the way that they are drawn on a card by the laying-off, which then measures the approximate location of the location of the cable or pipe if an error requires an excavation. To avoid time-consuming sampling excavations, the map must be carved with great accuracy, and since cables and pipes must often be laid in places where marking poles cannot be left undisturbed, accurate 15 land measurements must be made each time the cables or tubes are found.

Stedbestemmelse af faste eller bevægelige objekter ved hjælp af radiobølger er velkendt. Således angår f.eks. USA patentskrift nr. 3.848.254 en metode til lokalisering af køretøjer, 20 som består i, at en centralstation sender et signal til en sender, der er anbragt i køretøjet, hvilket signal starter udsendelsen af impulser moduleret på en bærebølge. Denne bærebølge modtages af et antal faste stationer, som demodulerer signalet og sender det til den centralstation, hvor der fore-25 tages en fasesammenligning og en deraf beregnet positionsbestemmelse af køretøjet.The location of fixed or moving objects by means of radio waves is well known. Thus, e.g. U.S. Patent No. 3,848,254 to a method of locating vehicles, 20 consisting of a central station transmitting a signal to a transmitter located in the vehicle, which signal starts the transmission of pulses modulated on a carrier. This carrier is received by a number of fixed stations which demodulate the signal and transmit it to the central station, where a phase comparison and a position determination of the vehicle are made.

Fra USA patent nr. 3.774.215 kendes et anlæg til stedbestemmelse af et køretøjs position under anvendelse af de i krav 30 l's indledning angivne midler. Målet med dette kendte system er at sikre en nøjagtig positionsbestemmelse af et antal bevægelige genstande, f.eks. skibe eller køretøjer eller lignende, ved hjælp af en kommunikations-station uden forstyrrelser fra kommunikationen fra andre kommunikations-35 stationer eller bevægelige genstande.US Patent No. 3,774,215 discloses a system for locating a vehicle's position using the means set forth in the preamble of claim 30 l. The goal of this known system is to ensure an accurate positioning of a number of moving objects, e.g. ships or vehicles or the like, by means of a communication station without interference from the communication of other communication stations or moving objects.

Denne og andre kendte metoder til radioteknisk positions-This and other known methods of radio-technical positioning

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bestemmelse er ikke anvendelige til lokalisering af nedgravede kabler og rør i overensstemmelse med opfindelsen, idet der må stilles følgende krav: 5) De geografiske data for de nedgravede kabler/rør skal opbevares permanent og på en sådan måde, at de kan visualiseres i form af et kort indeholdende oplysninger om kystlinier, veje, matrikelskel etc.provision is not applicable to the location of buried cables and pipes in accordance with the invention, subject to the following requirements: 5) The geographical data of the buried cables / pipes must be stored permanently and in such a way that they can be visualized in the form of a map containing information about coastlines, roads, landslides etc.

2Q I hvert fald den "mobile station", som anvendes til genfinding af kablet/røret, må kunne modtage de nødvendige data til en orientering i forhold til karakteristiske træk af landskab eller bebyggelser i det pågældende område. Dette medfører, at korrektionsberegninger og interpolationer må ske automatisk og 15 uden at belaste den mobile station med tungt edb-udstyr.2Q At least the "mobile station" used to retrieve the cable / tube must be able to receive the necessary data for orientation in relation to characteristic features of the landscape or buildings in the area concerned. This means that correction calculations and interpolations must be done automatically and 15 without burdening the mobile station with heavy computer equipment.

3) Den mobile station skal være så let, at den uden besvær kan bæres af en enkelt person og skal kunne betjenes af personer uden specialuddannelse. Dette medfører, at den mobile stations 20 sendeeffekt er ringe.3) The mobile station must be so light that it can be easily carried by a single person and can be operated by people without specialized training. This causes the transmitting power of the mobile station 20 to be low.

Det er derfor formålet med opfindelsen at anvise et anlæg til lokalisering af nedgravede rør eller kabler, hvorved det ikke alene er muligt at bestemme den geografiske position af røret 25 eller kablet, men også at lokalisere ethvert punkt på kablet eller røret med så stor grad af nøjagtighed, at det kan af-dækkes, uden at prøvegravninger er nødvendige.It is therefore an object of the invention to provide a system for locating buried pipes or cables, whereby it is not only possible to determine the geographical position of the pipe 25 or the cable, but also to locate any point on the cable or pipe with such a large degree of accuracy that it can be uncovered without the need for sample digging.

Dette opnås ved at udforme anlægget ifølge opfindelsen som 30 angivet i krav l's kendetegnende del.This is achieved by designing the plant according to the invention as set forth in the characterizing part of claim 1.

I et sådant anlæg vil en hovedstation på anfordring af en målestation aktivere udsendelsen af positionsbestemmende signaler fra en udvalgt gruppe af relæstationer til måle-35 stationen, som videregiver resultatet af positionsbestemmelsen til hovedstationen, der omregner det til en geografisk stedbestemmelse på grundlag af data, som findes i edb-anlæggets 3 DK 1 η Ω Ο ?. 5 Β datalager. I tilfælde af kabel/rørnedlægninger registreres stedbestemmelsen, og i tilfælde af genfinding af det nedgravede kabel/rør tilbagesendes stedbestemmelsen tillige med de karatkteristiske geografiske data for det pågældende sted med 5 markering af kablets/rørets position.In such a facility, a master station upon request of a measuring station will activate the transmission of position determining signals from a selected group of relay stations to the measuring station which transmits the result of the position determination to the main station which converts it into a geographical location determination on the basis of data which can be found in the computer system 3 DK 1 η Ω Ο?. 5 Β data storage. In the case of cable / pipe lay-offs, the location determination is recorded, and in the case of recovery of the buried cable / pipe the location determination is returned as well as the characteristic geographic data for that location with 5 marking of the cable / pipe position.

Hovedstationen kan og bør have midler til kontrol af stedbe-stememlsens nøjagtighed. Radiobølgers udbredelseshastighed varierer med luftens temperatur og fugtighed. Polarisa-10 tionsretning og fase kan ændres af reflektioner fra bygninger og metalgenstande.The main station can and should have means for checking the accuracy of the place vote. The propagation speed of radio waves varies with the temperature and humidity of the air. The polarization direction and phase can be altered by reflections from buildings and metal objects.

I stærkt kuperet terræn eller ved permanent eller midlertidig anbringelse af relæstationer på høje bygninger kan højde-15 forskelle spille en rolle for målenøjagtigheden. Det er klart, at stedbestemmelsen ikke behøver at være et korrekt geografisk mål. Koordinaterne til et bestemt målepunkt, som er fastlagt ved radiobølger fra to eller flere relæstationer, skal kunne reproduceres med den krævede nøjagtighed, d.v.s. at måleresul-20 tatet for en bestemt position af målestationen skal være entydigt for denne position og forskelligt fra måleresultatet for en hvilken som helst anden position, men da det ikke er sikkert, at stedbestemmelsen foretages ved hjælp af den samme gruppe relæstationer ved genfindelse som ved nedlægninger, kan 25 en korrektion af højdeforskelle være nødvendig. Denne korrektion kan foretages ved, at relæstationerne har to antenner anbragt med en kendt højdeforskel, således at det ud fra tidsforskellen mellem ankomsten af signaler fra de to antenner er muligt at korrigere for højdeforskelle. Det er også muligt at 30 oplagre topografiske data i edb-anlægget, således at korrektionerne kan udføres automatisk.In severely hilly terrain or by permanently or temporarily placing relay stations on tall buildings, height-15 differences can play a role in measuring accuracy. Obviously, the location provision need not be a proper geographical target. The coordinates of a particular measurement point, determined by radio waves from two or more relay stations, must be reproducible with the required accuracy, i.e. that the measurement result for a particular position of the measuring station must be unambiguous for that position and different from the measurement result for any other position, but since it is not certain that the location determination is made by the same group of relay stations for recovery as at closures, a correction of height differences may be necessary. This correction can be made in that the relay stations have two antennas arranged with a known height difference, so that from the time difference between the arrival of signals from the two antennas it is possible to correct for height differences. It is also possible to store topographical data in the computer system so that the corrections can be performed automatically.

Dersom der anvendes midlertidige relæstationer, kan disse have et måleudstyr svarende til de mobile målestationer, således at 35 deres placering i forhold til permanente relæstationer kan fastlægges og indlæses i edb-anlæggets programbibliotek. Det kan være af betydning at forsyne samtlige relæstationer med etIf temporary relay stations are used, they may have a measurement equipment similar to the mobile measuring stations, so that their location relative to permanent relay stations can be determined and loaded into the computer system's program library. It may be important to supply all relay stations with one

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4 sådant udstyr, som kan aktiveres fra hovedstationen. Denne kan så ved efter tur at behandle de enkelte relæstationer som målestationer fastlægge den indbyrdes afstand mellem dem. Hvis de derved opnåede data ikke stemmer overens med oplagrede 5 data, kan der eventuelt beregnes korrektioner for ændringer af radiobølgernes udbredelseshastighed på grund af atmosfæriske forhold.4 such equipment which can be activated from the main station. This can then in turn treat the individual relay stations as measuring stations to determine the distance between them. If the data thus obtained does not match the stored data, corrections may be calculated for changes in the propagation speed of the radio waves due to atmospheric conditions.

Den mobile målestation skal som nævnt ovenfor ikke være 10 tungere, end den kan bæres af en enkelt person, hvorfor den kun skal indeholde det nødvendige udstyr til kommunikation med hovedsenderen og til modtagning af signaler fra nærliggende relæstationer samt de nødvendige elektroniske tællere til at måle de relative tidspunkter for ankomsten af signaler. Disse 15 tællere kan startes af det først ankomne signal, men kan også startes af et signal fra hovedsenderen.As mentioned above, the mobile measuring station must not be 10 heavier than it can be carried by a single person, therefore it must contain only the necessary equipment for communication with the main transmitter and for receiving signals from nearby relay stations as well as the necessary electronic counters for measuring the relative times of arrival of signals. These 15 counters can be started by the first arrived signal, but can also be started by a signal from the main transmitter.

Markeringen af kablet/røret eller af stedet, hvor målestationen befinder sig, kan foregå på den måde, at den i for-20 længelse af målestationens antenne er en "pegepind", f.eks. et teleskoprør, med hvilket operatøren peger på kablet/røret, samtidig med at der sendes et signal til hovedstationen om, at der nu kommer resultat af en positionsmåling eller en anmodning om en positionsangivelse.The marking of the cable / tube or of the location at which the measuring station is located may be in the way that it is an extension of the antenna of the measuring station as a "pointer", e.g. a telescope tube, with which the operator points to the cable / tube while sending a signal to the main station that a result measurement or request for a position indication is now being obtained.

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Ved nedlægning af kablet/røret kan intervallerne mellem markeringerne gøres afhængige af, hvor retlinet kablet/røret nedlægges det pågældende sted, idet hovedstationens edb-anlæg kan bestemme et vilkårligt punkt på kablet/røret ved inter-30 polation. Intervallernes længde kan bestemmes skønsmæssigt af operatøren, men den mobile station kan også udføres til montering på kabelploven eller rendegraveren, og traktoren for disse forsynes med organer til elektronisk måling af kørselshastighed og ratdrejningen, hvilke målinger så automatisk 35 styrer intervallerne mellem positionsmarkeringerne.When laying the cable / pipe, the intervals between the markings can be made dependent on where the rectilinear cable / pipe is laid down at that location, since the main station's computer system can determine any point on the cable / pipe by interpolation. The length of the intervals can be estimated by the operator, but the mobile station can also be designed for mounting on the cable plow or backhoe, and the tractor for these is provided with means for electronically measuring travel speed and steering wheel, which measurements then automatically control the intervals between the position markings.

Kommunikationen mellem hovedstation og målestation kan fore- 5The communication between the main station and the measuring station can be 5

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tages på forskellig vis. Dersom hovedstation er bemandet, hvilket ikke er en nødvendighed, kan der føres samtale på sædvanlig måde, og operatøren kan medføre et kort over den pågældende egn. En sådan off-line kommunikation er ikke praktisk.are taken in different ways. If the main station is staffed, which is not a necessity, calls may be conducted in the usual manner and the operator may carry a map of the area concerned. Such off-line communication is not practical.

5 Målestationen bør foruden det nødvendige tidsmåleudstyr være forsynet med en dataskærm og mindst én af hovedstationerne have midler til at optegne de geografiske data for den pågældende egn i form af kortskitser samtidig med en markering af et nedlagt kabel/rør og en markering af målestationens posi- 10 tion. Kommunikationen med hovedstationen kan foregå ved hjælp af et simpelt tastatur. Målestationen kan kort sagt være udformet som en "intelligent" terminal for hovedstationens datalager.5 The measuring station should, in addition to the necessary measuring equipment, be equipped with a data screen and at least one of the main stations must have the means to record the geographical data for that area in the form of map sketches, at the same time marking a dropped cable / pipe and marking the position of the measuring station. 10 tion. Communication with the main station can be carried out using a simple keyboard. In short, the target station can be designed as an "intelligent" terminal for the main data storage.

15 En realisation af opfindelsen forklares i det følgende under henvisning til tegningen, på hvilken fig. 1 skematisk viser et anlæg ifølge opfindelsen, 20 fig. 2 viser et simplificeret blokdiagram for en målestation, fig. 3 viser et simplificeret blokdiagram for en hovedstation, og 25 fig. 4 viser et blokdiagram for automatisk styring af frembringelsen af geografiske koordinater ved kabelnedlæggelse.An embodiment of the invention is explained below with reference to the drawing, in which: FIG. 1 is a schematic view of a plant according to the invention; FIG. 2 shows a simplified block diagram of a measuring station; FIG. 3 shows a simplified block diagram of a main station, and FIG. 4 shows a block diagram for automatically controlling the generation of geographical coordinates by cable laying.

30 X fig. 1 er vist symboler for nogle landskabselementer, som normalt er aftegnet på et kort: bygninger B, bakker eller høje H, større træbeplantninger W, veje R og kystlinier K. Rundt omkring i det viste terræn er placeret relæstationer RS1-RS4.30 X FIG. 1, symbols for some landscape elements are usually shown on a map: buildings B, hills or high H, larger tree plantations W, roads R and coastlines K. Relay stations RS1-RS4 are located around the terrain shown.

De kan som vist have antenner placeret på hustage, på bakke- 35 toppe eller bygninger fremstillet til det specielle formål.As shown, they may have antennas located on rooftops, hill tops or buildings made for the special purpose.

En mobil målestation MS anvendes i fig. 1 til genfindelse afA mobile measuring station MS is used in FIG. 1 for the recovery of

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et nedgravet kabel antydet med den punkterede linie C. Alle stationerne kommunikerer som antydet ved stor-punkterede linier med en ikke vist hovedstation HS, som på anfordring af den person, der betjener målestationen, sender en kortskitse 5 til denne, som vises på en dataskærm D. Den mobile station med dataskærm er vist i større målestok nederst i fig. 1. Samtidig starter hovedstationen en cyklisk aktivering af et antal relæstationer, på figuren RSI, RS2 og RS3, som så udsender afstandsbestemmende signaler, der modtages af målestationen, 10 som måler tidspunktet for signalernes ankomst i forhold til et referencetidspunkt, der f.eks. kan være tidspunktet for det først ankomne signal. Resultatet af målingen sendes til hovedstationen HS, der ud fra kendskabet til relæstationernes placering og topografiske forhold omregner resultatet til 15 koordinater, som vises på dataskærmen D. På dataskærmen er også kabelføringen vist tillige med det punkt på kablet, som skal undersøges. Kabellængden fra et fikspunkt til fejlstedet er udmålt ved sædvanlig fejlmålingsapparatur, og da kabellængden fra markeringspunkt til markeringspunkt er kendte data 20 opmagasineret i datalageret, kan fejlstedets position let beregnes.a buried cable indicated by the dotted line C. All the stations communicate as indicated by large dotted lines with a main station HS not shown, which, on request of the person operating the measuring station, sends a map outline 5 to it which is displayed on a computer screen D. The mobile station with computer screen is shown on a larger scale at the bottom of fig. 1. At the same time, the main station initiates a cyclic activation of a number of relay stations, in the figures RSI, RS2 and RS3, which then transmit distance-determining signals received by the measuring station, 10 which measures the time of the signals arrival relative to a reference time, e.g. may be the time of the first arrival signal. The result of the measurement is sent to the main station HS which, based on the knowledge of the location and topographical conditions of the relay stations, converts the result to 15 coordinates, which are displayed on the data screen D. The data on the data screen is also shown along with the point on the cable to be examined. The cable length from a fixed point to the fault location is measured by conventional fault measurement apparatus, and since the cable length from marker point to marker point is known data 20 stored in the data store, the position of the fault location can be easily calculated.

Når den mobile station er kommet tilstrækkelig nær til det ønskede punkt, kan hovedstationen skifte fra kortskitsen til 25 et koordinatnet, som svarer til et areal på nogle få kvadratmeter omkring fejlstedet og således tillader en stedbestemmelse, der er tilstrækkelig nøjagtig til at markere det sted, hvor der skal graves for at blotlægge kablet.Once the mobile station has reached sufficiently close to the desired point, the main station can switch from the map sketch to a coordinate network corresponding to an area of a few square meters around the fault location, thus allowing a location determination sufficiently accurate to mark the location. where to dig to expose the cable.

30 Den sikreste positionsbestemmelse fås ved at anvende mindst tre relæsendere. Som eksempel antages, at RSI, RS2 og RS3 i cyklisk rækkefølge styret af hovedstationen bringes til at udsende kortvarige ultrahøjfrekvente impulser, som modtages af målestationen, der bestemmer tidsforskellen ^3-t2 35 tg-t^ over passende antal impulscykler og sender resultatet til hovedstationen, som beregner middelværdi og standardafgivelse af måleresultaterne. Dersom standardafvigelserne er 730 The safest position determination is obtained by using at least three relay transmitters. By way of example, it is assumed that RSI, RS2 and RS3 in cyclic order controlled by the main station are emitted short-duration ultra-high frequency pulses received by the measuring station which determines the time difference ^ 3-t2 35 tg-t ^ over the appropriate number of pulse cycles and sends the result to the main station , which calculates the mean and standard output of the measurement results. If the standard deviations are 7

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større end den krævede målenøjagtighed, må de kasseres og nye målinger foretages, eventuelt ved at aktivere flere eller andre relæsendere. To af de tre tidsforskelle er nok til en stedbestemmelse, men den tredie bør tages med som kontrol.greater than the required measurement accuracy, they must be discarded and new measurements made, possibly by activating more or other relays. Two of the three time differences are enough for a location determination, but the third should be taken into account.

5 Dersom der skal korrigeres for højdeforskelle, er det nødvendigt at have den tredie differens med.5 If height differences are to be corrected, it is necessary to include the third difference.

I fig. 2 er vist et stærkt forenklet principskema for den mobile målestation. Grundelementerne i denne station er en 10 antenne 1, der ved hjælp af omskiftere 2, kan kobles enten til en sender 3 eller en modtager 4. Modtageren er via en demodulator 5 tilsluttet en kontroldel 6 med en dataskærm 7 og mikrotelefon 8. Kontroldelen 6 er også tilsluttet senderen 3 over en modulator 9. I kontroldelen er indbygget de elektro-15 niske tællere, som bestemmer den relative ankomsttid for impulser fra relæsendere tillige med de faste "instrukser", som er nødvendige for, at målestationen kan fungere som dataterminal .In FIG. 2 is a highly simplified principle diagram for the mobile measuring station. The basic elements of this station are a 10 antenna 1 which can be connected by means of switches 2 to either a transmitter 3 or a receiver 4. The receiver is connected via a demodulator 5 to a control part 6 with a data screen 7 and microphone 8. The control part 6 is The transmitter 3 is also connected to a modulator 9. The control part incorporates the electronic counters which determine the relative arrival time of pulses from relay transmitters as well as the fixed "instructions" necessary for the measuring station to function as a data terminal.

20 Som vist i fig. 3 består hovedstationen i store træk af en sender 10 og en modtager 11, der begge er tilknyttet et kontrolorgan 12 over henholdsvis en modulator 13 og en demodulator 14. Kontrolorganet har indbygget de nødvendige organer for manuel og automatisk betjening, d.v.s. at den fungerer som 25 central styreenhed for indlæsning og udlæsning af data og bearbejdning af disse. Kontrolorganet har adgang til et datalager 15. Dette datalager kan være fælles for flere hovedstationer, ligesom dele af det nødvendige udstyr til behandling af indkommende og udgående data kan være fælles.20 As shown in FIG. 3, the main station consists in large part of a transmitter 10 and a receiver 11, both of which are connected to a control means 12 over a modulator 13 and a demodulator 14 respectively. The control means has the necessary means for manual and automatic operation, i.e. that it functions as a central control unit for loading and unloading data and processing them. The controller has access to a data store 15. This data store may be common to several main stations, as may parts of the necessary equipment for processing incoming and outgoing data.

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En væsentlig fordel ved opfindelsen er, at de geografiske data for et nedlagt kabel kan fås af det samme udstyr, som bruges til genfindingen, altså at de nødvendige data for genfindingen kan produceres af samme udstyr som det, der er forklaret i 35 beskrivelsens almindelige del. Det er væsentligt, at hovedstationens datalager ikke fyldes med unødvendige positionsangivelser. Ifølge opfindelsen kan som nævnt afstanden mellemA major advantage of the invention is that the geographical data for a downed cable can be obtained from the same equipment used for the recovery, that is, the necessary data for the recovery can be produced by the same equipment as explained in the ordinary part of the description. . It is essential that the data base of the main station is not filled with unnecessary location information. According to the invention, as mentioned, the distance between

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8 markeringspunkterne varieres i overensstemmelse med, om kablet er nedlagt omtrent retlinet eller danner kurver. Princippet heri er vist skematisk i fig. 4, hvor der er et apparat 16, som måler drejningsvinklen af rattet af en traktor, og et 5 apparat 17, som måler omdrejningerne af et traktorhjul og dermed kørselshastigheden. Måleresultaterne omsættes til elektriske størrelser, der styrer frekvensen af en impulsgenerator 18, som for hver impuls bevirker aktivering af en målestation 19 som beskrevet i fig. 2.The 8 marking points are varied according to whether the cable is laid down approximately rectilinear or forms curves. The principle herein is shown schematically in FIG. 4, wherein there is an apparatus 16 which measures the angle of rotation of the steering wheel of a tractor, and an apparatus 17 which measures the revolutions of a tractor wheel and hence the speed of travel. The measurement results are converted to electrical magnitudes that control the frequency of an impulse generator 18, which for each impulse causes the activation of a measuring station 19 as described in FIG. 2nd

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Claims

An installation for locating buried cables or pipelines comprising 5 a) a plurality of relay stations (RS1-RS4), each comprising a transmitter and wherein at least one of the relay stations is positioned at a fixed position with precisely known geographical location, 1) at least one mobile measuring station (MS, 19) having a display panel (D, 7) and a transmitter / receiver (1-4) adapted to determine data representative of the difference in distance for position signals transmitted from the relay stations to the respective measuring station and to forward this data, c) at least one fixed or mobile main station (HS) comprising a transmitter / receiver (10,11), and wherein the main station is equipped with a computer (12) adapted to calculate the geographical position of each measuring station (d) that each measurement is based on the 20 data received from each measuring station and on the basis of the geographical data of the relay stations, and to forward the result to the respective measuring stations; ation (MS, 19) comprises circuitry (6) adapted to measure the delay between the arrival times of the position signals from the activated relay stations, which delays represent said difference data, e) that a memory ( 15) containing topographical data for the area characteristics in which the cable or pipeline is buried, as well as position data for the course of the cable or pipeline in relation to the area characteristics, which position data is entered in the computer's storage during the burial and which is compared with data received from each measuring station, DK 160025 B 10 f) each main station (HS) is arranged to, upon request from a measuring station, start transmitting position signals from a selected group of relay stations (RS1-RS4) and forwarding the calculated geographic positions for each measuring station for the latter station together with the corresponding topographical and g) that the display panel (D, 7), in response to the transmitted data 10 from the main station, is arranged to provide a graphical representation of the course of the cable or pipeline in its environment along with the position of the associated measuring stations.

Installation according to claim 1, characterized in that the main stations have means for checking the accuracy of the measurement results and in case of inaccuracy causing the transmission of signals from other relay stations.

Installation according to claim 2, characterized in that the main stations are equipped with instruments such as lighting meter, hygrometer, barometer, thermometer etc. for recording the weather conditions during the measurement and that this data is included in the data processing of the measurement result (12). 25

Installation according to claim 2 or 3, characterized in that the fixed stations are equipped with instruments for recording wind direction, wind speed and wind speed and in particular for recording the fluctuations of the antenna mast, and that these data are included in the data processing of the measurement result (12).

System according to claim 2, characterized in that the control means include means for automatic correction for height differences between the relay stations' antennas and the measuring station's antenna.

System according to claim 5, characterized in that DK 160025 B 11 relay stations located in a heavily hilly terrain transmit signals from two antennas located above each other at a known distance.

Installation according to any one of the preceding claims 1-6, characterized in that at least the non-permanent relay stations have an equipment corresponding to the measuring stations for determining their location in relation to other relay stations. 10

System according to any one of the preceding claims 1-7, characterized in that each measuring station is designed as a data terminal for a main station.

System according to claim 8, characterized in that each measuring station has a "pointer" in the form of a telescopic tube, arranged so as to determine the vertical of the station antenna.

Installation according to claim 8, characterized in that each 20 measuring station is designed for placement on a cable plow or an excavator, the tractor of which is provided with measuring means (16,17) for measuring speed and steering wheel and for converting the measurements to electrical control signals. to an impulse generator (18) which, for each pulse, activates the production of a position determination by means of activated relay stations and recording the position determinations in a main station's data store.