Combining TPS and GPSSmartStation and SmartPole

High performance GNSS systems

Contents

1. TPS total stations and GPS RTK support each other perfectly

1.1 GNSS

2. SmartAntenna, SmartStation, SmartPole2.1 SmartAntenna 2.2 SmartStation2.3 SmartPole2.4 SmartStation versus SmartPole2.5 Modular hardware

3. A short note on RTK

4. SmartStation and how it is used4.1 Topographic survey 4.2 Surveying utilities in an urban environment4.3 Stakeout on a large construction site

5. SmartStation: three methods of orientation5.1 Orienting to a known point (Known BS Point)5.2 Orienting to a point the coordinates of which

are not yet known (Set Azimuth)5.3 Orienting to one or more known points and

transferring the height from one or more of these points (Ori & Ht Transfr)

6. SmartStation: post processing instead of RTK

7. SmartPole and how it is used7.1 SmartPole: position, orientation and height7.2 Property and detail survey7.3 Staking out

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8. GNSS Positioning8.1 Navigation position8.2 Differential GPS8.3 RTK, differential phase8.4 SmartCheck for total RTK reliability8.5 The range of RTK

9. Before using SmartStation and/or SmartPole9.1 Reference stations9.2 Communication link9.3 Coordinate system9.4 Configuration set

10. What the operator needs to know about RTK10.1 Number of satellites10.2 Obstructions10.3 Multipath10.4 Range and accuracy of RTK10.5 Standard reference stations and networks of

reference stations10.5.1 Standard reference stations10.5.2 Networks of reference stations10.5.3 SmartStation and SmartPole10.6 Communication between the reference and

SmartStation/SmartPole10.6.1 Radio modems10.6.2 Phone modems10.6.3 The Internet10.7 Type of position and coordinate quality indicator

11. SmartStation and SmartPole - new ways to survey

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1. TPS total stations and GPS RTK support each other perfectly

A conventional total station needslocal control points over which it canbe set up, from which it can traverse,and to which it can measure to resectits position.

A GPS RTK receiver can determine itsposition within a few seconds to centimeter-level accuracy using datafrom a GPS reference station that maybe 50km or more away.

A GPS RTK rover is fast and efficient touse but needs an open view of the skyin order to receive the satellite signals.RTK is best in wide, open areas.

A total station can measure and stakeout where RTK cannot be used:to building corners, to points undertrees and bushes, in city canyons etc.

SmartStation and SmartPole combine TPS surveying with cm-accuracy RTK to give youthe full advantages of bothsystems.

SmartStation and SmartPole are different tools and are used in different ways.

This book describes how to surveyand stake out using SmartStation andSmartPole. It also explains RTK in asimple way that will be understood byequipment operators that have neverused GPS before.

1

The SmartAntenna, used for bothSmartStation and SmartPole, is a GNSSreceiver.

GNSS stands for Global NavigationSatellite System. GNSS satellites includethe US GPS satellites, Russian GLONASSsatellites, and also satellites from several space-based augmentationsystems such as EGNOS and WAAS.

GPS is the main system. For simplicity,much of this book refers only to GPS.

1.1 GNSS

SmartStation SmartPole

2

2. SmartAntenna, SmartStation, SmartPole

SmartAntenna is a small, light, compact, dual-frequency, GNSS satellite receiver. SmartAntenna is used for both SmartStation andSmartPole. There are two versions of SmartAntenna: one for GPS only,one for GPS and GLONASS.

SmartStation comprises a TPS1200total station with a SmartAntenna. The receiver is controlled entirely fromthe total station. TPS and GPS are perfectly integrated.

With SmartStation there is no need to search for and set up over controlpoints, run traverses, or resect theposition.

With SmartStation you simply:• Set up wherever it is convenient.• Determine the position coordinates

in a few seconds to centimeter accuracy with RTK.

• And then survey and stake out with the total station.

SmartStation is more versatile than astandard total station and measuresto points and objects that can neverbe occupied with an RTK receiver.

2.1 SmartAntenna 2.2 SmartStation

Surveying withSmartStation

3

SmartPole comprises a new, hardlock,lightweight, telescopic pole with a precise 360° EDM reflector, RX1250TController and Smart Antenna. TheRX1250T controls the SmartAntennavia Bluetooth

Rand the remote

TPS1200 total station via a radio link.

SmartPole combines all the advantagesand flexibility of an RTK rover with theremote control of a total station.

With SmartPole, simply establish control points wherever you want with RTK and measure to them simultaneously with the total stationto resect its position.

Survey and stake out with RTK and/orthe remote total station. Use whichever is best, depending on the area and the points to be measured to.

2.3 SmartPole

Surveying with SmartPole

4

Although both SmartStation andSmartPole combine RTK with total station surveying, the techniques are different.

With SmartStation the entire survey iscarried out by and controlled from thetotal station. SmartStation is ideal formanually operated total stations.

With SmartPole the entire survey is carried out by and controlled from thepole. As the total station is remote controlled, only one operator is required. Measurements can be angleand distance from the total stationand/or RTK.

SmartPole is ideal for robotic total stations and provides total flexibility.

Whichever system you use, you savetime, speed up work, reduce costs andincrease profits.

The SmartAntenna can be used invarious ways:

(i) On a TPS1200 total station for SmartStation.

(ii) On a pole with 360° reflector and RX1250(T) Controller for SmartPole.

(iii)On a pole with any RX1250 type Controller for an independent RTK rover.

Combine and use equipment, as youprefer, according to the work you haveto do.

2.4 SmartStationversus SmartPole 2.5 Modular hardware

(ii)(i) (iii)

3. A short note on RTK

To determine position using RTK,SmartStation and SmartPole combinethe satellite data taken bySmartAntenna with the satellite datataken by a reference receiver that isset up on a known point.

The reference data are transmitted toSmartStation and/or SmartPole byradio, phone or the Internet.

The reference will often be a public reference station that transmits datafor use by all GPS rover units in thesurrounding area. However, it couldalso be a private reference receiverthat is set up on a known point specifically to support SmartStation orSmartPole.

RTK stands for Real Time Kinematicand is extremely reliable. Using RTK,SmartStation and SmartPole determineposition within a few seconds to centimeter-level accuracy.

5SmartPole SmartStationReference

6

4. SmartStation and how it is used

With SmartStation, the SmartAntennais on the TPS 1200 total station. TheSmartStation operator has total control over the equipment and measurements. SmartStation is idealfor manually operated total stations.

As the position of SmartStation isdetermined by RTK, control points are not needed. Simply set upSmartStation wherever it is convenient. Various orientationmethods are available.

With SmartStation on a tripod, theSmartAntenna setup is much morestable than that of a standard RTKrover on a handheld pole. Stabilityassists the RTK computation andimproves the range.

Using RTK, SmartStation will usuallydetermine its position within a fewseconds to centimeter-level accuracyat 50km or more from a reference station.

The following examples illustrate how SmartStation is used and the advantages that it provides.

7

The taskA topographic survey is needed. Dueto trees, vegetation and the nature ofthe work, a total station is more suitable than a standard RTK rover for surveying the detail.

There are no control points in the areaon which a total station survey can bebased. However, there is a referencestation about 40km away that transmits data for use by RTK rovers.

The conventional wayFix a series of control points throughout the area using standardGPS equipment. Transfer the coordinates into the total station.Occupy the control points with thetotal station, orient to other controlpoints, and survey the detail.

Points have to be occupied twice,once with GPS and once with the totalstation. Two sets of equipment areneeded. Two crews may be needed.

The SmartStation waySet up SmartStation wherever it isconvenient and where there is a reasonably open view of the sky.

At the first point P1, determine the position with RTK. Orient to a secondpoint P2 that will be used but is notyet fixed. Survey the detail from P1.

Set up at P2 and determine the position with RTK.

As the bearing P1-P2 is nowknown, SmartStation will automatically re-compute thecoordinates of all of the detailpoints surveyed from P1.

Orient to P1 and survey the detailfrom P2.

Continue in this way.

The advantages• No traversing.• Control established where required

by RTK.• Points occupied only once.• Only SmartStation is needed.• Only one crew is needed.• Re-computation made automatically

in SmartStation.• Consistent high accuracy.• The survey takes less time.

4.1 Topographic survey

8

P1

P2

P3

P5

P6 P4

9

Mapping public utilitiesThe positions of all manholes, covers,hydrants, distribution boxes etc. forwater, gas and electricity have to bedetermined. High buildings and treesalong the roads make it difficult touse RTK rovers. As many objects areclose to buildings or under trees, theycan be measured to with total stationsbut cannot be occupied by GPS rovers.The city operates a GPS reference station.

Using a total stationControl points exist but traffic, parkedvehicles and other obstructions makeit very difficult to set up over themand to orient between them. If a standard total station is used, a lot of traversing in a very difficult environment is necessary. Both carefulplanning and improvisation are needed. The work is awkward andslow.

Using SmartStationSet up SmartStation where RTK fixesare possible, such as at road intersections, open spaces and evenon the tops of buildings. Use pairs orclusters of SmartStation setups (e.g.P1-P2, P2-P3, and P4-P5) as explainedin the previous example. Measureangles and distances to the objectsthat have to be surveyed.

If the correct circle orientation is only available after the measurements have been taken,SmartStation will re-compute allthe coordinates automatically.

The advantages• Control points not needed.• No awkward traversing.• Positions determined by RTK.• Re-computation in SmartStation.• Consistent high accuracy.• Fast, flexible, convenient.• Much easier, saves time.

4.2 Surveying utilities in an urban environment

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P1

P2

P3

P4

P5

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Stakeout jobA large number of markers have to be placed and many components positioned. Control points exist butoften get damaged or are covered byequipment, material, vehicles etc.

There is a GPS reference station transmitting data to RTK rovers but,due to obstructions and the type ofconstruction, most points cannot beset out with RTK.

Conventional stakeoutStakeout with a total station is possible but difficult and time consuming. Traversing is needed toget around obstructions. Temporarypoints, which can be used for stakeout, have to be established. The work plan has to be revised constantly. Equipment and materialhave to be moved, which slows boththe survey and construction work.

SmartStation stakeoutControl points are not required. Simplyset up SmartStation wherever it's convenient and let RTK determine theposition.

Set up at P1 and fix the position withRTK. Set up at P2, fix the positionwith RTK and orient to P1. Now stakeout from P2.

Work in this way establishing pairs orgroups of points from which to stakeout. As the positions are determinedby RTK, the pairs or groups do nothave to be connected by total stationmeasurements.

The advantages• Set up where it's convenient.• No control points needed.• No traversing needed.• Positions by RTK.• Fewer obstructions.• Less downtime• Faster stakeout.• Faster construction.• High accuracy.

4.3 Stakeout on a large construction site

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P1

P2

P3

P5

P6

P4

13

RTK determines the coordinates andheight of the point over whichSmartStation is set up. The horizontalcircle has to be set by orienting toanother point (or points). The point(or points) used should be sufficientlyfar away to provide a good orientation. There are three ways inwhich the orientation can be carriedout.

5.1 Orienting to a knownpoint (Known BS Point)

Set up SmartStation at a point P1.Determine the position of P1 with RTK. Point accurately to a second point P2, the coordinates of which areknown and are stored in SmartStation.SmartStation computes the bearingP1>P2 and sets the horizontal circlereading correctly. You can now measure angles and distances, surveyand stakeout, with SmartStation.

P2 can be a standard control point, thecoordinates of which have been storedin SmartStation. P2 can also be a pointthat has been occupied by SmartStationand the coordinates of which havebeen determined by RTK.

With this method, the position coordinates (E, N) and the height (H)are determined by RTK.

5. SmartStation: three methods of orientation

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Grid North

Hz = 0

Known point Known BS Point P2

P1

15

In this method, the orientation is to apoint whose coordinates will be determined later.

Set up SmartStation at a point P1 anddetermine the position with RTK. Pointaccurately to a second point P2, thecoordinates of which have not yet beendetermined.

You can now measure angles anddistances and survey from P1. Note,however, that as the bearing P1>P2 isnot yet known, the horizontal circlereadings (bearings) and, therefore, thecoordinates of the surveyed points willnot be the final ones. After all thepoints and detail have been surveyedfrom P1, move to P2.

Set up SmartStation at P2 and determine the coordinates with RTK.SmartStation does the following fullyautomatically:• Computes the bearings P1>P2 and

P2>P1.

• Applies the correct bearing P1>P2 toall of the measurements taken at P1and recomputes the coordinates automatically.

Orient to P1. SmartStation sets thehorizontal circle reading correctly. You can now measure angles anddistances and survey from P2.

Note that P2 does not have to beoccupied immediately after P1. The coordinates of P2 can be determined (or input) at any time,whenever convenient. As soon as the coordinates of P2 are determined (or input), SmartStation will re-compute the coordinates of all points surveyed from P1.

The advantage of the method isthat there is no need to determinecontrol points before starting surveying. Simply go to the site,setup SmartStation wherever it'sconvenient and start work.

Determine the control points whereyou can see the detail to be surveyed as you go along.

When using this method, the positioncoordinates (E, N) and the height (H)are determined by RTK.

Note that this method cannot be usedfor stakeout. For stakeout, either of theother two methods (5.1 or 5.3) has tobe used. For stakeout you must firstorient to a known point (or points).

5.2 Orienting to a point the coordinates of which are not yet known (Set Azimuth)

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Grid North

Difference

Final Hz = 0

Initial Hz = 0

Initial

Final

Coordinates determined later

P2

P1

Set Azimuth

17

After pressing the CALC (calculation)key, SmartStation does the following:• Sets the horizontal circle based on

the orientation to all of the points • Computes the height of P1 from the

height of the control points.

With this method, the position coordinates (E, N) are determined byRTK. You can accept the height (H) computed from the control points orthe height (H) determined by RTK.This method of orientation has manyoptions and provides total flexibility.

You can now measure angles anddistances, survey and stakeout, withSmartStation.

When heights have to be based on aparticular height datum for the area,e.g. for irrigation, drainage, water,construction and engineering surveys,it can be advantageous to accept theheight computed from the controlpoints.

This method is similar to 5.1, exceptthat it provides the following options:• The orientation can be made to one

or more points (maximum 10 points). • The height can be derived from one

or more of the control points (heighttransfer from control points).

• Or the height that is determined by RTK can be accepted.

Set up SmartStation at P1 and determine the position with RTK. Youcan now point to one or more (up to10) control points. The control pointscan have:• Position coordinates (E, N) and

height (H).• Position coordinates (E, N) only.• Height (H) only.

If a control point has only a height(e.g. a benchmark), the distance has to be measured.

5.3 Orienting to one or more known points and transferring the height from one or more of these points (Ori & Ht Transfr)

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Circle orientation and height transfer

Ori & Ht Transfr

P1

E, N, H

E, N

H

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6. SmartStation: post processing instead of RTK

The vast majority of users will alwaysuse SmartStation with RTK.

If, however, in remote areas, there areno reference stations within suitablerange transmitting RTK data, it is possible to use post processing tocompute the position of SmartStation.

Carry out the survey work as outlinedin section 4. However, instead of usingRTK, record the satellite data collectedby SmartStation/SmartAntenna.

Use Leica Geo Office software todownload data via the Internet fromany distant reference stations that areavailable.

Afterwards, use Leica Geo Office todetermine the coordinates ofSmartStation by post processing thebaselines from the reference stations.

Leica Geo Office will now re-computethe coordinates of all detail and topopoints surveyed with SmartStation.

In order to be sure that you can compute the coordinates of SmartStation to centimeter-level accuracy -i.e. resolve the ambiguities in postprocessing - always measure for a sufficient length of time.

It is advisable to mark the points overwhich SmartStation is set up. You willthen be able to re-occupy and collectmore satellite data should this benecessary.

Most SmartStation users will neverneed to use post processing.

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Although both SmartStation andSmartPole combine RTK with total station surveying, the techniques arequite different.

With SmartPole, the entire survey orstake out process is carried out by andcontrolled by the surveyor at the pole.He or she can switch between RTK andtotal station measurements as requiredand use whichever is the most suitable. The total station is remotecontrolled.

SmartPole consists of a hardlock, light-weight, telescopic pole, a precise 360°EDM reflector, a Smart Antenna, and anRX1250T / RX1250Tc Controller. TheRX1250T communicates with theSmartAntenna via BluetoothR and theremote TPS1200 total station via aradio link.

SmartPole is the complete one-mansurvey system, combining all-on-the-pole RTK with robotic total stationmeasurements. All GPS, RTK and totalstation software, as well as all surveyand stakeout application software reside in the RX1250T / RX1250Tc.

7. SmartPole and how it is used

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With SmartPole, conventional controlpoints are not required. Simply set upthe total station wherever it is convenient and begin surveyingimmediately with SmartPole. Take RTKor total station measurements. Switchfrom one to the other, depending onwhich is most convenient for the pointsand detail to be surveyed.

At any time during the survey, setup SmartPole where both RTK andtotal station measurements arepossible. With the pole held steady,determine the coordinates with RTK and also measure angles anddistance to the reflector with thetotal station. Such a point, withboth RTK and total station measurements, is called a“SmartPole Control Point”.

As soon as two or more “SmartPoleControl Points” are available, theresection routine computes thecoordinates of the total station andorients the circle. The coordinates of all other points surveyed up until this time are re-computedautomatically.

SmartPole does everything and haseverything you need.

The examples 7.2 and 7.3 illustratehow SmartPole is used and the advantages that it provides..

RTK fix

Total station measurement

“SmartPole Control Point“

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The coordinates and orientation of thetotal station are determined by measuring angles and distances to atleast two “SmartPole Control Points”.Keep the pole vertical and steady whentaking RTK and total station measurements.

Adding more “SmartPole ControlPoints” will improve the coordinatesand orientation of the total station.The “SmartPole Control Points” shouldbe evenly distributed and at a reasonable distance from the total station.

The position coordinates (E, N) of thetotal station are based on RTK, i.e. onthe RTK coordinates of SmartPole.

Similarly, the height (H) of the totalstation is also based on RTK.

Note, however, that the resectioncomputation gives you the option ofdetermining the height (H) of the totalstation from an independent heightcontrol point (e.g. a benchmark). Thiscan be advantageous when heightshave to be based on a specific heightdatum.

7.1 SmartPole: position, orientation and height

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The taskProperty boundaries and all detail haveto be surveyed. It is convenient to usea total station to measure to buildingcorners, as well as to boundary marksand detail near hedges and trees.Where the area is relatively open, it iseasier and faster to survey with RTK.There are no control points close by,but RTK data can be received from aGPS reference station.

Using a conventional total stationBring in control by running a traversefrom distant control points. Traversearound the area. Coordinate the boundary marks and detail from thetraverse stations. Traversing is awkwardand time consuming. Many temporarypoints have to be established.

Using a conventional RTK roverDetail and boundary marks can be surveyed directly with RTK when thearea is open. But RTK measurementscan be difficult or even impossible atbuilding corners and at points close tohedges and trees. Hidden point

methods using offset measurementscan be used, but are often cumbersomeand inaccurate. The other solution is toestablish temporary control points withRTK and then to survey from them witha total station.

Using SmartPoleSet up the robotic total station fromwhere detail and boundary marks arevisible. Start surveying with SmartPole.

Use RTK when there is good satellitereception and the pole can be placedon the markers or at the detail points.Trigger total station measurements topoints at which RTK cannot be used.Take RTK fixes when the total stationcannot be seen.

Whenever it is convenient, determine a “SmartPole ControlPoint” with RTK and total stationmeasurements. Once two or moresuch “SmartPole Control Points” areavailable, the on-board resectionroutine computes the coordinatesof the total station, orients thehorizontal circle, and re-computes

7.2 Property and detail surveythe coordinates of all surveyedpoints.

Additional “SmartPole ControlPoints” can be included and the re-computation updated at any time.

Survey in this way. Switch from RTK tototal station measurements accordingto the points to be surveyed. Re-position the total station whenevernecessary.

The advantages• One-man surveying• TPS and GPS perfectly combined• Switch easily from one to the other• Use whichever is the most suitable• Re-computation made automatically• Saves time and manpower• Provides uniform high accuracy• Conventional control points not

required.• No traversing.

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RTK fix

Total station

Total station measurement

“SmartPole Control Point“

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Staking out with SmartPole is similar to surveying with SmartPole in that youcan switch between total station andRTK measurements. Note, however,that the coordinates and orientation of the robotic total station have first to be determined.

Staking out for a new road junctionA major road junction has to be modified. The roads have to be widened, the alignments improved, andnew slip roads built. There are highbuildings close to some roads and thelarge trees in the area are under protection and cannot be cut. Oncework begins, the site will be clutteredwith equipment, machines, vehicles,material dumps etc. RTK data can bereceived from a reference station.

The usual wayThe standard approach would be totraverse with a total station to bring incontrol and to establish temporary control points from which to set outthroughout the area. Due to the everchanging obstructions and the

complexity of the site, many setupswould be needed. The stakeout strategy would have to be revised frequently.

With SmartPoleSet up the robotic total station wheresections of the site are visible andpoints can be staked out. Determinethe coordinates and orientation of thetotal station by fixing at least two“SmartPole Control Points” with RTKand taking measurements to them withthe total station.

Now start the stakeout work. Use totalstation measurements to stakeoutpoints where RTK cannot be used.Stakeout with RTK where there is goodsatellite reception and where the totalstation cannot be seen.

Whenever necessary, move the robotictotal station to a new position and,again, determine the coordinates andorientation by taking measurements toat least two “SmartPole Control Points”.

7.3 Staking out The advantages• Very flexible• Switch easily from TPS to GPS• Use whichever is most suitable• Fewer setups needed• One-man operation• All control by RTK• Uniform high accuracy• Less downtime due to obstructions• Speeds up stakeout work

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RTK fix

Total station

Total station measurement

“SmartPole Control Point“

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8. GNSS Positioning

GNSS stands for Global NavigationSatellite System.

Each GNSS satellite transmits on twofrequencies. The signals are carrier(sine) waves on which codes aremodulated.

GNSS satellites include the US GPSsatellites, Russian GLONASS satellites,and also satellites from several space-based augmentation systems such asEGNOS and WAAS.

When a GNSS receiver of any typereceives signals from 4 or more satellites, it will calculate and display its position. This is the navigation position. Uncertainties in the satelliteorbits, disturbances to the signals asthey pass through the ionosphere andtroposphere, and other errors limit theaccuracy of the navigation position toabout 5m.

The errors can be reduced and theposition accuracy improved if measurements on the satellite signalsare taken simultaneously at two stations and differenced (subtractedfrom each other). One of the receiversis set up at a known point and is termed the reference; the other receiver is set up at an unknown pointand is termed the rover. The positionof the rover is obtained relative to theposition of the reference.

If only code measurements are used,the position accuracy will usually beabout 30cm to 1m. This is termedDGPS or differential code.

If phase and code measurements areused, the position accuracy will usuallybe about 1cm to 5cm. This is termeddifferential phase.

8.2 Differential GPS8.1 Navigation position

Navigation position

28

Dual frequency receivers are used forsurveying. The two frequencies helpto minimize error influences related todisturbances in the ionosphere.

Dual frequency receivers take phasemeasurements on both frequencies inaddition to code measurements. The reference receiver transmits itsphase and code measurements to the

rover. The rover uses the phase andcode measurements from the reference together with its own phaseand code measurements and computes its position relative to theposition of the reference receiver.With dual frequency phase and codemeasurements from at least

5 satellites, an RTK rover will compute its RTK (differential phase)position to an accuracy of about 1cmto 5cm.

8.3 RTK, differential phase

Rover

RTK differential phase

RoverReference

29

SmartCheck is the Leica GeosystemsRTK technique used for SmartStationand SmartPole.

SmartCheck computes at least twoindependent RTK fixes before theposition coordinates are first available.The coordinates are then updatedcontinuously as long asSmartStation/SmartPole receives therequired phase and code data fromSmartAntenna and the reference.

SmartCheck continuously computesindependent position fixes in order toensure that the coordinates are correct. This continuous process ensures the highest possible RTK reliability, 99.99% for RTK fixes at upto 30km to 50km from a referencestation.

SmartCheck needs only a few secondsto compute an RTK position. The horizontal accuracy is 10mm + 1ppm.The vertical accuracy is 20mm + 1ppm.

The maximum range at which an RTKrover can calculate centimeter-levelaccuracy positions depends on errorinfluences related to the ionosphere,troposphere and satellite orbits.Depending on the prevailing atmospheric conditions, the rangelimit for RTK can vary from about30km to 50km or more.

RTK is extremely reliable and is unlikely to fail. In spite of this, theuser should be aware that:

• If obstructions block some of the satellite signals, or if the distance tothe reference is too long for the prevailing conditions, an RTK rover may only be able to compute a DGPS (code) position and not an RTK (phase) position.

• If the reference receiver stops working, or if the communication link between the reference and rover fails, the rover will not receive data from the reference and will only compute a navigation position.

SmartStation and SmartPole haveaccuracy status icons and a coordinatequality indicator. These show the typeof position and the accuracy achieved.

8.4 SmartCheck for total RTK reliability 8.5 The range of RTK

SmartCheck Reliability99.99%

Range about 30km to 50km

Accuracy10mm + 1ppm

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9. Before using SmartStation and/or SmartPole

SmartStation/SmartPole will probablyhave been configured for you so thatyou can start using RTK immediately.

This may have been done by your Leicarepresentative or by your own technicalsupport personnel.

If the equipment has not been configured for RTK, the following have to be considered:

• Reference stations, • Communication link • Coordinate system • Configuration set

Reference stations can transmit data in various ways and in various formats.SmartStation/SmartPole has to be configured to receive the data in thetransmitted format.

Depending on how the data are transmitted, it may or may not benecessary to enter the following: identification number of reference station, type of receiver at referencestation, type of antenna at referencestation.

Data can be transmitted from thereference to SmartStation/SmartPoleby radio, phone or Internet.

SmartStation/SmartPole has to beequipped with the appropriatecommunication device and configuredfor it. Various parameters have to beset.

INTERNET

9.1 Reference stations 9.2 Communication link

GNSS reference station,Florence, Italy

GPS coordinates are in the WGS84system. This is a three dimensionalCartesian coordinate system. WGS84coordinates are given as X, Y, ZCartesian coordinates, or latitude, longitude and height (above theWGS84 ellipsoid).

Conventional surveying is carried outin grid coordinates: Eastings,Northings and Height (above adatum).

SmartStation and SmartPole use RTK to determine position. For conventional surveying, the RTKWGS84 coordinates have to be converted to the required grid coordinates.

Your technical support personnel, orpossibly your Leica representative, willusually have entered a so-called coordinate system into SmartStation/SmartPole for the area, region or evencountry in which you are working. Theequipment uses the coordinate systemto transform RTK WGS84 coordinatesinstantly into the required N, E, H gridcoordinates.

If the required coordinate system hasnot been entered, you will have todetermine and enter it. If you move to a new area that has a differentsystem of grid coordinates, you willhave to determine and enter a newcoordinate system for that area.

See the System 1200 TechnicalReference Manuals.

X

P Z

Y

Yp

O

Xp

Zp

Ht

Long

Lat

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9.3 Coordinate system

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Different people, all over the world,use SmartStation and SmartPole in different ways and for different applications. To satisfy these requirements, SmartStation andSmartPole have many functions,options, routines and programs.

SmartStation and SmartPole can beset to work in exactly the way thatthe individual user wants them towork.

Your technical support personnel, oryour Leica representative, will normallyhave defined a so-called configurationset that includes the correct settingsfor the reference stations (9.1) andthe communication link (9.2) that youuse.

The configuration set makes theequipment work and display in exactlythe way that you want it to do.

If your needs change, or you havenew applications, or you move toanother area with different referencestations, you may have to modify theconfiguration set or define a new configuration set.

See the System 1200 TechnicalReference Manuals.

9.4 Configuration set

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10. What the operator needs to know about RTK

Due to its ease-of-use, versatility, cm-level accuracy and high reliability, RTKhas become a standard survey tool.

Provided that you set up SmartStationor SmartPole where there is a reasonably clear view of the sky and reliable communication with the reference station, determining the coordinates with RTK will usually be a matter of a few seconds only.

Although RTK is very easy to use, theSmartStation or SmartPole operator (as any other RTK rover operator)should have a basic understanding ofthe technique.

In order for SmartStation or SmartPoleto compute its position using RTK: • The equipment has to track at least

5 satellites.• The reference has to track at least

the same 5 satellites.• The reference has to transmit the

data to SmartStation and/or SmartPole.

The status icons in the display showthe number of satellites above thecut-off angle and the number of satellites being tracked. The cut-offangle is usually set to 10° in the configuration set. With the presentconstellation of more than 30 GNSSsatellites, there will almost always beat least 5 satellites available providedthat you set up the equipment wherethere is a reasonably clear view of thesky. In most cases there will be morethan 5 satellites.

10.1 Number of satellites

34

10.2 Obstructions

Buildings, large trees with heavy foliage and other obstructions canblock the signals from one or moresatellites. Although the signals canpass through trees with light foliage,the strength of the signals will bereduced.

Whenever possible, set upSmartStation or SmartPole in clearareas or where there are few obstructions.

When surveying in or around wooded or developed areas, it is usually impossible to avoidobstructions completely.

With experience you will soon be ableto judge where you can set up the equipment and acquire sufficientsatellites.

O.K.

No

35

10.3 Multipath

The satellite signals reflect off buildings and similar objects.

If SmartStation or SmartPole is set upclose to a tall building or next to atruck or other vehicle, theSmartAntenna may receive both direct and reflected signals. This is termed multipath.

As the SmartAntenna and the processing algorithms are designed to suppress the influence of reflectedsignals as much as possible, multipathwill usually have little influence.

Note, however, that if a building orobject has a very smooth reflectivesurface, multipath may be severe. Insuch a case, the equipment (as anyother RTK rover) may take somewhatlonger than usual to compute an RTKposition fix.

36

10.4 Range and accuracy of RTK

Various error influences, particularlythose relating to ionospheric delays,tropospheric delays and satellite orbits,affect the satellite signals. If the rover is close to the reference,the errors will be similar at both therover and reference and will be largelyeliminated by the differential RTK technique. The greater the distance between rover and reference, the morethe errors will differ and the more diffi-cult it becomes to eliminate them. It follows that, as the distance increases,a range will be reached at which RTKcan no longer determine the position to centimeter-level accuracy.

As the troposphere and ionosphere varyconsiderably from place to place, withthe time of day, time of year, and fromyear to year, it is impossible to specifyan exact maximum range. RTK range willoften be somewhat longer during thecool of the night than during the heatof the day. RTK range also tends to belonger in mid latitudes than at low andhigh latitudes.

The RTK range for a moving RTK roveris usually quoted as about 30km inmid latitudes in favorable conditions.The RTK accuracy is usually given as10mm + 1ppm. A handheld SmartPoleis usually used in a moving mode.

As SmartStation is static (on a tripod),movements do not affect the data.SmartStation's RTK algorithms areoptimized for static mode and willcompute position fixes at about 50kmfrom a reference station in mid latitudes in favorable conditions. The RTK accuracy of 10mm + 1ppm ismaintained, even at maximum range.

Satellite orbits

Ionosphere

Troposphere

10.5 Standard reference stations and networks of reference stations

10.5.2 Networks of reference stations

If RTK could be carried out in a perfectenvironment, there would be no ppmaccuracy component and no restrictionto range. Unfortunately, however, theenvironment is not perfect and it alsochanges continuously. Various influences lead to distance-dependenterrors and restrict the range at whicha rover can compute an RTK positionfix.

By combining reference stations into anetwork and continuously analyzingthe data, it is possible to model thedistance-dependent errors and compute corrections.

Measurement data and correctionparameters, or corrected referencestation measurement data, can betransmitted to the rovers. The roverscan then compute RTK position fixesat longer ranges and with higher accuracy.

10.5.3 SmartStation and SmartPole

SmartStation and SmartPole acceptdata from standard reference stationsand from networks of reference stations. The appropriate settings haveto be made in the configuration set.

10.5.1 Standard reference stations

A standard GPS reference stationtransmits data directly toSmartStation, SmartPole and otherGPS rovers. The RTK range and accuracy quoted in 10.4 are for standard reference stations.

37

Standard reference station

Network of reference stations

38

Reference stations, or control centersof networks, transmit data to RTKrovers. Radios, phones or the Internetcan be used.

In order to receive the data,SmartStation and SmartPole have tobe equipped with the appropriatecommunication device. Various settings have to be made in the configuration set.

10.6.1 Radio modems

The advantages:• No running costs (charges).• Any number of RTK rovers can

obtain the data.The disadvantages:• The range at which a rover, or

SmartStation or SmartPole, can operate is usually less than if phones are used.

• Obstructions, particularly at longer ranges, can cause loss of reception.

• Interference on adjacent frequenciesmay also lead to poor reception.

10.6.2 Phone modems

The advantages:• Reliable connection.• No interference.• Little loss of reception due to

obstructions.• Few restrictions to the range at

which reliable communication is possible.

The disadvantages:• Rovers, i.e. SmartStation and

SmartPole, incur call charges.

10.6.3 The Internet

The Internet is being used more andmore for transmitting data from reference stations to RTK rovers.The advantages:• Charges should be less than with

mobile phones.• Few restrictions to range at which

communication is possible.The disadvantages:• The reliability of connections may

not always be as high as with phones.

10.6 Communication between the reference and SmartStation/SmartPole

INTERNET

39

RTK is extremely reliable. Provided thatSmartStation/SmartPole is configuredcorrectly, is receiving data from thereference, and is set up in a reasonablyopen area, RTK is unlikely to fail.Position icons and the coordinate quality indicator show the type of position.

RTK position CQ quality indicator - about 0.01m to 0.05m

If there are 5 or more satellites, and ifthe distance to the reference is not toogreat for the prevailing atmosphericconditions, SmartStation/SmartPole willcompute an RTK position. This will bethe usual case.

The two ticks indicate that SmartCheckis computing independent position fixesto ensure that the RTK position is correct (see 8.4).

DGPS Differential code position CQ quality indicator - about 0.3m to 2m

If only 4 satellites are used, or if thedistance to the reference is too greatfor the prevailing atmospheric conditions, SmartStation/SmartPole will compute a differential code position.

Navigation positionCQ quality indicator - about 3m to 20m

If there is no communication betweenthe reference and SmartStation/SmartPole, the communication arrow in the display will notmove/blink. As no data is received fromthe reference, the equipment can onlycompute a navigation position.

A maximum value for the CQ qualitycontrol can be specified in the configuration set. If the value isexceeded, a warning appears whenyou try to STORE the computed coordinates.

If you set a maximum value of0.05m for CQ, you can be sure thatonly centimeter level RTK positionfixes will be accepted and stored.

10.7 Type of position and coordinate quality indicator

40

11. SmartStation and SmartPole - new ways to survey

SmartStation and SmartPole are revolutionary tools that combine LeicaGPS1200 RTK surveying with LeicaTPS1200 total station surveying.

SmartStation and SmartPole are quitedifferent and are used in differentways.

SmartStation uses RTK to determinethe position of the total stationdirectly. All survey and stakeout workis then carried out by the TPS1200total station.

SmartPole is a GPS1200 RTK roverthat also fully controls a remoteTPS1200 total station. SmartPole canswitch from RTK measurements tototal station measurements dependingon the area and the points to be measured. With SmartPole, one mancontrols the entire survey and stakeout process.

As RTK provides the control forSmartStation and SmartPole surveys,conventional control points and traversing are not needed.

With SmartStation or SmartPole, youcan go straight to the site and startworking immediately.

Both SmartStation and SmartPole areincredibly versatile:

• Survey and stakeout are faster.

• Fewer total station setups are needed.

• They can be used for any type of job.

• They save time and manpower.

• They increase productivity and profits.

• And RTK ensures uniform high accuracy throughout the entire workarea.

Leica GRX1200 Product brochureut labore et.

Leica GPS SpiderProduct brochureut labore et.

Leica GPS1200 Product brochure

Leica SmartStationTotal Stationwith integrated GPS

Leica SmartPoleProduct brochure

Leica TPS1200 SeriesHigh performance Total Station

LeicaSmartStationProduct brochure

Leica TPS1200Product brochure

Leica System 1200 SoftwareIntegrated Software for GPS1200 and TPS1200

Leica System1200 SoftwareProduct brochure

Illustrations, descriptions and technical specifications are not binding and may change. Printed in Switzerland – Copyright Leica Geosystems AG, Heerbrugg, Switzerland, 2007. 757677en – IV.07 – RVA

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www.leica-geosystems.com

Leica GPS1200 SeriesHigh performance GPS System

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