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ashtech Z-Xtreme, System Manual

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12

Real-Time Kinematic Surveying

receiver. Figure 2.5 shows a typical rover receiver.       

The UHF and VHF radios offered in the ZX SuperStation are manufactured by Pacific 
Crest Corporation.

Spread Spectrum

RTK surveys conducted on small project sites not exceeding 2 km between base and 
rover systems can utilize spread-spectrum radios.  An advantage of spread-spectrum 
radios is the license-free operation.  No FCC license is required to operate them since 
spread-spectrum radios are limited in power output to only 1 watt.  In addition, areas 
with a great deal of radio traffic in the UHF or VHF frequencies can make it difficult to 
perform RTK surveys if the radios being used are close to the same frequency.  Since 
spread-spectrum radios function at a much higher frequency and utilize a frequency 
hopping scheme, they are not affected by the traffic. Figure 2.6 shows a spread-spec-

 Figure 2.5   

Pacific Crest UHF/VHF Rover Receiver

Summary of Contents for Z-Xtreme

Page 1: ...4300 Phone and Fax Numbers Main Voice 408 615 5100 Fax 408 615 5200 Sales US 800 922 2401 International 408 615 3970 Fax 408 615 5200 Europe Voice 44 0118 931 9600 Fax 44 0118 931 9601 Support US 800 229 2400 International 408 615 3980 Fax 408 615 5200 Internet support ashtech com http www ashtech com http www magellangps com ...

Page 2: ...egard to this publication and the computer programs are subject to the restrictions and limitations imposed by the copyright laws of the United States of America U S A and or the jurisdiction in which you are located Printed in the United States of America Part Number 630844 01 Revision A November 2000 Trademarks Z XtremeTM Instant RTKTM Z TrackingTM SSRadioTM and the Ashtech logo are trademarks o...

Page 3: ...computer at a time You may not operate the Program in a time sharing or service bureau operation or rent lease sublease sell assign pledge transfer transmit electronically or otherwise dispose of the Program or Documentation on a temporary or permanent basis without the prior written consent of LICENSOR You agree not to translate modify adapt disassemble decompile or reverse engineer the Program o...

Page 4: ...lusion of limitation of implied warranties or liability for incidental or consequential damages so the above limitations or exclusions may not apply to you MANUAL DISCLAIMER THIS MANUAL IS PROVIDED AS IS MAGELLAN MAKES NO WARRANTIES TO ANY PERSON OR ENTITY WITH RESPECT TO THE SUBJECT MATTER OR USE OF INFORMATION CONTAINED HEREIN OR ANY DERIVATIVES THEREOF OR ANY SERVICES OR LICENSES MAGELLAN DISCL...

Page 5: ...00 15 Power System 16 Internal Power 16 External Power 16 Software 17 Field Application Software 17 GPS FieldMate Mine Surveyor II Seismark II 17 Survey Pro with GPS 18 Office Support Software 18 Handheld Transfer Mconvert 18 Survey Link 18 Post Processing Software 19 Ashtech Solutions 19 Ashtech Office Suite 19 Hardware Connectivity 21 Base System 21 GPS Receiver GPS Antenna 21 Radio Radio Antenn...

Page 6: ...lect Appropriate Base System Site 50 Position GPS Antenna Over Base Point 51 Mount the Base Radio Antenna 52 Measure and Record Instrument Height HI of GPS Antenna 52 Connect System Components 53 Power Up Base System 54 Configure Base GPS Receiver to Function as an RTK Base 54 Enter Base Point ID Coordinates and HI Into Base Receiver 55 Verify Function 55 Rover System Setup 57 Mount Receiver Anten...

Page 7: ...the base system transmitting data 80 Step 4 Is the base radio antenna connected to the base radio 80 Step 5 Is the rover radio set to the same frequency as the base 80 Step 6 Is line of sight between base and rover antennae obstructed 81 Step 7 Are you within range specifications of your radio system 81 Step 8 Are you being jammed 82 Step 9 You may have a malfunctioning component in your system 83...

Page 8: ...viii ...

Page 9: ...er 29 Figure 3 10 Power Cable Connecting Z Xtreme and External Battery 29 Figure 3 11 Pacific Crest Radio Power Communication Cable 30 Figure 3 12 Cable Connecting Pacific Crest to External Battery 31 Figure 3 13 Z Xtreme Base Receiver with all Cable Connections 32 Figure 3 14 Pacific Crest Radio with all Cable Connections 33 Figure 3 15 Handheld Computer with all Cables Connected 34 Figure 3 16 P...

Page 10: ...rvey 56 Figure 4 7 Rover Transport Case 57 Figure 4 8 Geodetic IV GPS Antenna on Rover Pole 58 Figure 4 9 Rover Antenna and Pacific Crest PDL Radios on Backpack 59 Figure 4 10 Radio Antenna Mounted On Pole and on Back of Receiver 59 Figure 4 11 Rubber Duck Antenna Mounted to Z Xtreme 60 Figure 4 12 TDS Ranger Handheld Mounted on Rover Pole 61 Figure 4 13 Receiver Mounted on Pole 62 Figure 4 14 Bac...

Page 11: ...s truly magical task would be carried by one person all day and the price of the entire system would be under 40 000 including both sets of equipment What you ve just read is the difference between GPS surveying in the early 1980s and GPS surveying today Early GPS surveying was static in nature A user sat on a point for an extended period of time 1 3 hours or more If time permitted this user would...

Page 12: ...lity and accuracy of a GPS survey GPS receivers function exactly as the name implies they receive and store transmis sions from the GPS satellites This is their primary function and for some receivers this is their only function In addition to reception and storage of satellite transmis sions some receivers perform additional functions such as compute and display receiver position in various datum...

Page 13: ...e rover GPS receiver are processed by the rover receiver and the centimeter level vec tor horizontal angle vertical angle and distance between the base and rover receiv ers is computed Finally the rover receiver computes the rover position using the known base position and the computed vector This is the basic function of the rover receiver in an RTK system With the base and rover functioning as d...

Page 14: ...rrect location through observing the rod person s current location and directing the amount of movement to the correct location With RTK the rover operator can determine his her current location by observing the handheld computer screen The coordinates of the point of interest are also known by the handheld computer With the RTK system knowing its current location and the location of the point to ...

Page 15: ...i ble and available for use in RTK surveying The RTK system does not require this many satellites to function Accurate and reliable positions can be determined with 5 satellites properly distributed throughout the sky Therefore an obstructed location can be surveyed if at least 5 satellites can be observed This makes RTK use possi ble along a tree line or against the face of a building but only if...

Page 16: ...6 Real Time Kinematic Surveying ...

Page 17: ...ghtfor ward Hardware An RTK system includes a number of hardware components each with a specific function The ZX SuperStation offers options for many of the components each with specific advantages Choosing the right component will depend on the requirements and environment in which the system is to be used In this section each of the major components of the ZX SuperStation is presented If options...

Page 18: ...ctual collection point of the satellite signals It is also the point for which the position of the rover system is computed Therefore to determine the location of a feature the GPS receiver antenna must be placed over this feature The horizontal position of the feature is determined by the location of the center of the antenna The vertical position of the feature is determined by the loca tion of ...

Page 19: ...t reducing the effects of multipath the groundplane attachment significantly increases the size and weight of the antenna For this reason the groundplane attachment is only recommended for use at the base station If the base system is to be located in an area where obstructions such as metal buildings may cause multipath the groundplane attachment is a good option Choke Ring Antenna The choke ring...

Page 20: ...e two since it must have transmit capabilities It also consumes much more power The rover receiver needs only to receive the transmission This requires much less capability and power consumption In some RTK systems the rover radio is so small that it is embedded inside the rover GPS receiver Two distinctly different radio types are available with the ZX SuperStation one working in the UHF VHF freq...

Page 21: ...tioning at higher frequencies i e spread spectrum Because of the power levels at which these radios function and the fre quency they utilize a license must be obtained from FCC to operate them The radio in the rover system is available as a stand alone component or embedded in the Z Xtreme receiver The advantage of the embedded option is the simplicity of not having another component with attendan...

Page 22: ...rum radios is the license free operation No FCC license is required to operate them since spread spectrum radios are limited in power output to only 1 watt In addition areas with a great deal of radio traffic in the UHF or VHF frequencies can make it difficult to perform RTK surveys if the radios being used are close to the same frequency Since spread spectrum radios function at a much higher freq...

Page 23: ...rchangeable The spread spectrum solution for the ZX SuperStation is manufactured by Ashtech and called the SSRadio The rover SSRadio has the option of being embedded into the rover receiver The base SSRadio must be external to the base receiver Radio Antenna The base and rover radios cannot function without antennas The transmission and reception point of the radio signal is the antenna The base r...

Page 24: ...r rover systems Only the choice in radio type will affect which antennas are included in the system There are no options in radio antennas for the UHF VHF radio There is only one set of UHF VHF antennae available The UHF VHF radio antenna for the base and rover systems are identical and interchangeable Figure 2 7 Spread Spectrum and UHF Radio Antennas ...

Page 25: ...ion offers a choice of two handheld computers The choice of field application software will dictate the choice in handheld computers since one com puter is DOS based and the other is Windows CE based A ZX SuperStation includes one handheld computer TDS Ranger The TDS Ranger is a rugged handheld computer developed especially for surveying applications It is designed to withstand harsh environments ...

Page 26: ...se radio must be high consuming a great deal more power Figure 2 9 shows an internal battery power source and the same battery configured as an external power source A number of options are available for powering the ZX SuperStation Each is described below Internal Power Each Z Xtreme receiver in the ZX SuperStation includes one internal battery for power Each battery will operate the receiver for...

Page 27: ...of software components used both in the office and in the field The ZX SuperStation offers options for some of the software components Each component is discussed below Field Application Software The field application software resides in the handheld computer data collector used with the rover system As with a conventional total station this software is the user s interface to the base and rover s...

Page 28: ...d These are the primary tasks of the office support software In addition this software may perform other tasks such as storing survey results in different formats for use in other software transforming results into other datums or grid systems and supporting the ability to check the data The choice of field application software will dictate which office support software will be included in the ZX ...

Page 29: ...ed to support post processing of data collected using receivers in the ZX SuperStation Using Solutions the user can examine satellite availability prior to field operations Mission Planning utility transfer data between the GPS receivers and office computer process raw data to produce vectors between surveyed sights adjust vectors to produce accurate and reliable positions export and create report...

Page 30: ...20 Real Time Kinematic Surveying ...

Page 31: ...nectivity requirements they will be presented separately In addition the rover system is available in two configurations backpack configuration and an optional pole mounted configuration Each of these configurations will be presented separately below Base System Below is presented a list of all connections required to make the base RTK system function GPS Receiver GPS Antenna The GPS receiver requ...

Page 32: ... The GPS antenna can be connected to the receiver at any time before or after the receiver is powered on Make sure the connection at both the receiver and antenna is tight and not cross threaded Radio Radio Antenna The base radio requires the use of an antenna to transmit GPS receiver raw data Therefore the radio antenna must be connected to the radio This connection is also accomplished with a co...

Page 33: ...e ensures that the radio antenna cable is not used for the GPS antenna and visa versa The antenna connector for the Pacific Crest radio is on the back panel labeled ANTENNA The Ashtech SSRadio has its antenna connector located on the front panel labeled ANT The other end of the cable connects to a connector embedded into a bracket designed to facilitate the mounting of the base antenna onto the tr...

Page 34: ...s shown in Figure 3 4 Figure 3 4 Cable Connected to Pacific Crest Radio and Base Radio Antenna CAUTION It is important that the radio antenna be connected to the radio prior to apply ing power to the radio Failing to due so may result in damage to the radio ...

Page 35: ...rts will accept the connection to the radio it is recommended that the radio be connected to the port labeled B The radio communication power cable connection to the radio will be via either a 7 pin Fischer connector or a 5 pin Lemo connector depending on which radio is being used The Pacific Crest UHF VHF uses a Lemo connector with the connection being made on the rear panel of the radio This ser...

Page 36: ...e receiver supplies power to the radio through this connection Handheld Computer GPS Receiver Although the base system does not have a dedicated handheld computer the rover system handheld computer may need to be connected to the base to configure the base GPS receiver This is done by connecting the handheld computer to the GPS Figure 3 6 Communication Cable Connecting Z Xtreme Receiver and Pacifi...

Page 37: ...is recommended that you keep one of them with your base receiver for field use and the other with your PC in the office for data download The computer communication cable connects to the Z Xtreme via one of the three serial ports on the back panel of the receiver These three ports are grouped together and labeled SERIAL PORTS Although any one of the three ports will accept the connection to the ha...

Page 38: ...iver Receiver Power System Power can be supplied to the base GPS receiver in two ways The Z Xtreme receiver has a battery integrated into the receiver for power This con nection does not require a cable The battery is simply inserted into the receiver If a base station is to function unattended and for a period of time not supported by the internal battery an external battery can be used The exter...

Page 39: ...onnector is labeled Power The other end of the external power cable connects to the pouch holding the battery Figure 3 10 Obviously connection of the battery to the receiver is required prior to powering up the receiver The external power source can be connected at any time without concern of Figure 3 9 Z Xtreme Power Cable and Pouch for External Power Figure 3 10 Power Cable Connecting Z Xtreme a...

Page 40: ...ound on the rear panel of the radio The cable supplying power to the radio also serves as the RS232 cable which connects to the GPS receiver Therefore the cable is shaped like a Y with the base of the Y con necting to the radio and the two remaining ends connecting to the power source and the receiver The battery end of the cable is fitted with alligator clips allowing the flexibility to con nect ...

Page 41: ... each Base System component individ ually let s examine each primary component fully connected beginning with the Z Xtreme receiver Fully Connected Z Xtreme Receiver A fully connected Z Xtreme Base receiver will have up to four cable connections as shown in Figure 3 13 Figure 3 12 Radio Communication Power Cable Connecting Pacific Crest to External Battery ...

Page 42: ...receiver In most cases the handheld will need to be connected to the base receiver for configuration Once configured the handheld computer connection can be removed during operation 3 Radio communication power cable plugged into the port labeled SERIAL PORTS B This cable connects the Z Xtreme receiver to the radio This is a mandatory connection that will remain thoughout operation 4 GPS antenna ca...

Page 43: ...port is labeled DATA PWR on the Pacific Crest radio and SERIAL on the SSRa dio This cable connects the radio to the Z Xtreme receiver and in the case of the Pacific Crest also connects the radio to an external power source 2 Radio antenna cable plugged into the antenna port On the Pacific Crest radio this port is labeled ANTENNA and on the SSRadio this port is labeled ANT This cable connects the r...

Page 44: ...y the port is on the right when viewed as shown in Figure 3 15 This cable con nects the Z Xtreme receiver to the handheld computer Only when the handheld com puter is being used to configure the receiver does this connection have to be made Backpack Rover System The backpack rover system places the GPS receiver radio and optional external power supply in a backpack GPS antenna and handheld compute...

Page 45: ...na The rover radio requires an antenna to receive transmissions from the base radio This is accomplished by connecting the radio antenna to the radio through a coaxial cable Figure 3 16 The radio antenna cable for the rover is specially designed to function at the rover therefore it is not interchangeable with the base radio antenna cable The radio antenna cable connects to the radio via either a ...

Page 46: ...signed for use on the rover backpack This adaptor serves as both a connector to the antenna and a mount for the antenna onto the backpack frame Note If the rover radio being used is a Pacific Crest PDL no radio to radio antenna cable is required Rather the radio antenna connects directly to the radio as seen in Figure 3 17 Rover Antenna Connected to Internal Radio ...

Page 47: ...r must be connected to the rover radio in order to get the raw data from the base system Figure 3 19 shows the cable used for this purpose Depending on the radio type used this cable may be identical to the cable used to connect the base GPS receiver to the base radio In addition to supplying received raw data from the base to the rover receiver this cable also supplies power to the Figure 3 18 Pa...

Page 48: ...s recommended that the radio be connected to port B The radio communication power cable connection to the radio is made via either a 7 pin Fischer connector or a 5 pin Lemo connector depending on which radio is being used The Pacific Crest UHF VHF uses a Lemo connector with the connection being made on the front panel of the radio as shown in Figure 3 20 This is the only con nector on the front pa...

Page 49: ...ter must communicate with the rover GPS receiver in order for the computer to control certain operations in the receiver and for the receiver to send computed positions to the computer This is accomplished using an RS232 computer communication cable as shown in Figure 3 21 The rover computer communication cable is coiled for convenience in rover operation The cable functions the same as the comput...

Page 50: ... power source is available for use on the rover system if extended operation is required without interruption The external power source is connected to the GPS receiver via a dedicated external power cable The external power source and cable is identical for the base and rover system For details on the connection please refer to the GPS Receiver Receiver Power Sys tem section under Base System abo...

Page 51: ...mputer to the Z Xtreme receiver This is a mandatory connection that will remain throughout operation 3 Radio communication power cable plugged into the port labeled Serial Ports B This cable connects the Z Xtreme receiver to the radio If using an external radio this is a mandatory connection that will remain thoughout operation If using a radio internal to the GPS receiver this connection is not r...

Page 52: ... different as seen in Figure 3 23 With the internal radio the Radio Communication Power cable is no longer present In its place a radio antenna cable is added connecting to the port labeled RADIO Figure 3 23 Cable Connections for Z Xtreme Rover with Internal Radio ...

Page 53: ...n the Pacific Crest PDL radio and labeled Serial on the SSRadio This cable connects the radio to the Z Xtreme receiver and in the case of the Pacific Crest also connects the radio to an external power source 2 Radio antenna cable plugged into the antenna port On the SSRadio this port is labeled ANT This cable connects the radio to the radio antenna On the Pacific Crest PDL radio the antenna is mou...

Page 54: ... pole along with the other components All components are pole mounted eliminating the need for a backpack Below is presented a list of all connections required to make the pole mounted rover RTK system function GPS Receiver GPS Antenna As with the base system and backpack rover system the pole mounted rover GPS receiver requires an antenna to receive satellite signals The same type of cable is use...

Page 55: ...GPS receiver via a coaxial cable Figure 3 26 The radio antenna cable for the base and rover are not interchangeable The radio antenna cable connects to the internal radio via either a TNC or BNC type connector depending on which type of radio used If the remote radio is a Pacific Crest UHF VHF radio the connector will be BNC If the remote is utilizing an Ashtech SSRadio the connector will be a TNC...

Page 56: ...e computer This is accomplished using an RS232 computer communication cable Figure 3 28 The rover computer communication cable is coiled for convenience in rover operation The cable functions the same as the com puter communication cable at the base system so they can be interchanged if needed The handheld computer GPS receiver connection particulars are identical for the base and rover systems Pl...

Page 57: ... a mandatory connection that will remain throughout operation 2 Radio antenna cable plugged into the port labeled Radio This cable connects the radio internal to the Z Xtreme receiver to the radio antenna This is a mandatory connection that will remain throughout operation 3 GPS antenna cable plugged into the port labeled GPS This cable connects the Z Xtreme receiver to the GPS antenna This is a m...

Page 58: ... the serial port On the TDS Ranger the RS232 port is on the left when viewed as shown in Figure 3 30 On the Husky the port is on the right when viewed as shown in Figure 3 30 This cable con nects the Z Xtreme receiver to the handheld computer This concludes our review of the hardware component connectivity for the ZX Super Station We are now ready to examine the setup procedures for performing an ...

Page 59: ...ood use In this chapter we will go through the steps required to set up the base and rover sys tems to perform an RTK survey Base System Setup Prior to your discussion on setup of the base system let s examine how the base sys tem is packaged All components of the Z Xtreme RTK base system reside in a transport case Figure 4 1 with the exception of two items These items are the tripod and base radi...

Page 60: ...to access the base station site Prior to departing for field work it is recommended that the base system is examined to ensure that all required components are indeed in the transport case Now that we have confirmed that all required base system components are accounted for let s take the system out into the field Below are the steps required to success fully set up your RTK base system Select App...

Page 61: ...of post processed static mode of satellite surveying assuming the site is not too heavily obstructed Position GPS Antenna Over Base Point In most cases the base receiver antenna will be positioned over a point with known coordinates In some cases the coordinates of the base GPS antenna will be assumed computed by the base receiver to an accuracy of approximately 20 meters In either case a physical...

Page 62: ...Alternatively the radio antenna can be mounted on its own Some users will mount the radio antenna on a tall pole to give more range between the base and rover systems Measure and Record Instrument Height HI of GPS Antenna Remember that measurements of satellite data are made at the center horizontally and vertically of the GPS antenna Yet the location of the base point monument is not at the cente...

Page 63: ...ase field case connect all components as listed below Some of these connections will already be made Check these connections to ensure the connectors are seated properly Refer to the previous chapter on how to establish these connections GPS antenna GPS receiver Radio antenna Radio Radio GPS receiver Radio power Radio GPS receiver power GPS receiver Handheld computer GPS receiver Figure 4 5 Measur...

Page 64: ...B of the receiver 3 Set the frequency on which the base radio will transmit data In most cases this will not change but it is recommended that the current frequency is checked This is accomplished using the handheld computer If using the spread spectrum radio you are not required to select a frequency 4 Inform the receiver if you want to collect raw data for post processing In most cases these are...

Page 65: ...will produce 2 ppm 0 002m per 1 kilometer or 0 010ft per mile of error in the vector between the base and rover If the rover is 5 kilometers 3 miles from the base this will produce 0 010m 0 030ft of error in the vector In most cases the base receiver will estimate it s position to better than 30 meters probably closer to 10 20 meters but an error of 50 meters is possible If you plan to use an esti...

Page 66: ...spective bags during operation The lid of the transport case can also be par tially closed to ward off rain Be extremely careful not to pinch the cables coming out of the base In hot environments the base radio may need to be operated out of the case The radio is very resistant to rain therefore do not worry about leaving it out Figure 4 6 Base System Ready to Survey ...

Page 67: ... cables The Accessories bag will hold miscellaneous items such as handheld pole bracket and HI measurement device The Kit bag includes shoulder straps to allow it to be used as the rover backpack If you prefer to have the rover system pole mounted all components on the rover pole removing the need for a backpack an optional kit can be purchased for this purpose As with the base system it is recomm...

Page 68: ...enter to be transferred to the ground It s critical that the HI of the antenna above the ground is measured accurately It can be physically measured or the HI can be calculated based on the known fixed length of the pole plus the thickness of the antenna from the base to the data measurement point An HI measurement device is included with the rover system Mount Radio Antenna In the backpack config...

Page 69: ... the antenna onto the pole directly below the GPS antenna Figure 4 10 An option for the pole mount configuration is to use the included rubber duck antenna and connect it directly to the radio antenna connector on the back of the GPS Figure 4 9 Rover Radio Antenna and Pacific Crest PDL Radios on Backpack Figure 4 10 Radio Antenna Mounted On Pole and on Back of Receiver ...

Page 70: ...ntenna The disadvantage is the adverse affect on radio range This configu ration is good for small project sites Mount Handheld Computer The handheld computer is mounted onto the pole along with the GPS antenna A special mounting bracket for the handheld is included in the rover system as shown in Figure 4 12 Figure 4 11 Rubber Duck Antenna Mounted to Z Xtreme ...

Page 71: ... Receiver Pole mount Only For the pole mounted configuration the GPS receiver must be mounted onto the pole A special mounting bracket is supplied for this purpose Figure 4 13 Figure 4 12 TDS Ranger Handheld Mounted on Rover Pole ...

Page 72: ...r on back of GPS receiver if radio is internal Radio GPS receiver not required if radio is internal to GPS receiver GPS receiver power GPS receiver optional if internal battery is used for GPS receiver Power up Rover System Power up by pressing the power button on the GPS receiver Turn on the handheld computer using the power button on the keyboard Check that all components are powered up The GPS ...

Page 73: ...t can be changed but normally the default values for these parameters are sufficient Following is a list of some of these more advanced parameters Raw data format Sets the format in which raw data is being transmitted by the base Options are RTCM and PBEN Ashtech proprietary Default is PBEN Confidence level of RTK initialization Sets the statistical confidence level for RTK initialization Options ...

Page 74: ...dy to perform a survey Figure 4 14 shows the backpack rover system fully configured and ready to survey With the backpack rover configuration the GPS receiver rover radio if internal radio is not used and optional external power source remain in the backpack The back pack is carried on the users back during field operation Figure 4 15 shows the pole mounted configuration Figure 4 14 Backpack Rover...

Page 75: ...65 RTK Preparation With the pole mounted configuration all components of the rover system are mounted on the pole removing the need for a backpack Figure 4 15 Pole mounted Rover System Ready to Survey ...

Page 76: ...66 Real Time Kinematic Surveying ...

Page 77: ...racy prior to initialization could be anywhere from 0 15 meters 0 5 ft to a couple meters The initialization process is required to fine tune the rover sys tem Once initialized the rover system will function at it s specified level of accuracy until initialization is lost Your field application software running on the handheld com puter will inform you of the current state of initialization and wh...

Page 78: ... survey certain aspects of the system are affected It s important to be aware of the affect on system performance as the separation between the base and rover increases Communication The RTK rover system must remain in constant communication with the base system in order to determine accurate positions As the rover system approaches the range of the radio system used communication will begin to ge...

Page 79: ...e could become 60 seconds or more when the rover is 10 km 6 miles from the base Accuracy The accuracy at which the rover system can position is adversely affected as the base rover separation increases The accuracy of the rover system degrades at a rate of about 1 2 parts per million of base rover separation This amounts to about an additional 0 001 m to 0 002 m per kilometer 0 005 ft to 0 010 ft ...

Page 80: ...70 Real Time Kinematic Surveying ...

Page 81: ...uses of the effect are presented along with a remedy Barring a component failure the reme dies presented in this troubleshooting section should resolve any problems encoun tered in preparing the ZX SuperStation system to perform a survey If the steps outlined in this troubleshooting section fail to get you up and running there is a good chance that a component in your system has failed In such an ...

Page 82: ... this problem Step 1 Is the GPS receiver powered up To determine if the receiver is powered up examine the power LED on the front panel of the receiver If the LED is on red or green the receiver is on Receiver not powered up 1 Turn on the receiver Press and hold the power switch on the left side of the Z Xtreme front panel The button must be held for a few seconds since there is a delay in power o...

Page 83: ...o the antenna Ensure the connection is snug and not cross threaded b Once connected give the GPS receiver a few seconds to lock onto satellites Antenna connected to receiver 1 Ensure proper connection The GPS antenna must be connected to the port on the back of the receiver labeled GPS Antenna Ensure this is the case 2 Ensure the connection at the receiver and the antenna is tight and not cross th...

Page 84: ...Turn on the radio The Ashtech SSRadio has a power switch on its front panel Other radio types automatically turn on once power is applied Press the radio power switch to turn on the radio 2 Go to 3 if the problem is not yet resolved 3 Check the power source a If using a UHF VHF radio power is supplied by an external power source b Check to ensure that the power cable is connected to both the radio...

Page 85: ...f the radio powers up there is a problem with the base radio Call your local dealer or Ashtech customer support for assistance Base radio powered up Go to step 2 below Step 2 Is the Base Radio Connected to the GPS Receiver In order for the base radio to transmit data it must receive the data from the base receiver To determine if the radio is connected to the receiver look for a cable con necting ...

Page 86: ... base radio is connected The base radio should currently be connected to the RS232 port labeled B on the back of the Z Xtreme Use the field application soft ware or the front panel of the receiver to verify that port B is set as the output port for RTK base data Receiver not set 1 Set the receiver to output RTK base data on port B 2 Using either the field application software or the front panel of...

Page 87: ...ponent that is malfunctioning You may have a malfunctioning radio or radio communication cable If using Pacific Crest UHF VHF radios it is not possible to further isolate the problem Contact your local dealer or Ashtech customer support for assistance If using the external Ashtech SSRadio follow these steps to isolate the problem com ponent 1 Replace the radio cable with the one from the rover sys...

Page 88: ...cal to that on the base system Refer to the base system troubleshooting section above for details Radio Not Receiving Data Transmitted By Base The base GPS receiver by default is set to send data to the base radio once every second The base radio will transmit this data immediately upon receiving it There fore the rover radio should be receiving data from the base once every second The receive LED...

Page 89: ...he problem is not yet resolved c You may have a malfunctioning radio or radio power cable If using Pacific Crest UHF VHF radios it is not possible to further isolate the problem Contact your local dealer or Ashtech customer support If using the external Ashtech SSRadio follow these steps to isolate the problem component i Replace the radio cable with the one from the base system If the radio power...

Page 90: ...nsmission Base system not transmitting data See Base system does not transmit data under Base System Troubleshooting above to troubleshoot this problem Base system is transmitting data Go to step 4 below Step 4 Is the base radio antenna connected to the base radio The base system will transmit data without a base radio antenna but the range will be severely limited Antenna not connected Connect th...

Page 91: ...t possible move to higher ground or a location where there is less obstruction 3 If after moving the rover radio begins to receive data from the base then the previous location is too obstructed from the base You will need to either raise the base radio antenna higher or move the base to a location with less obstruction between the base and rover radio antennae Go to step 7 below if the problem is...

Page 92: ...tion of the RTK system Interference is more a problem with UHF VHF radios than with spread spectrum radios There are two methods to determine if there is traffic on the frequencies you wish to use The best method is to acquire a handheld scanner and to listen for traffic on the frequency you plan to use The second method is to observe the receive LED on the base or rover radios The base and rover ...

Page 93: ...em Is Not Computing A Position Once the rover GPS receiver is set to function as an RTK rover it will only compute RTK quality positions In order to accomplish this the rover receiver must collect raw satellite data at it s position and also receive base satellite data transmitted by the base system Without these two components the rover receiver will not compute a position To determine if the rov...

Page 94: ...anel of the receiver Ensure the connections at the receiver and the radio are fully seated Go to step 3 if the problem is not yet resolved Step 3 Is the radio connected to the correct port When setting up the rover GPS receiver one of the parameters is the port through which the rover receiver should expect data from the radio If the parameter setting does not match the port to which the radio is ...

Page 95: ...oubleshoot this problem Tracking satellites Go to step 5 below Step 5 Are base and rover tracking at least 4 common satellites In order for the rover system to compute an RTK position using both the base satellite data and rover satellite data the base and rover receivers must observe data from at least 4 common healthy satellites simultaneously Without this common data the rover cannot compute an...

Page 96: ... The rover GPS receiver must be set to function in RTK rover mode in order for it com pute accurate RTK positions If not set in RTK rover mode the receiver will compute autonomous positions which could contain about 10 meters or more of error This is probably the problem if HRMS and VRMS values are in the 10s of meters Use the field application software to determine if the rover GPS receiver is se...

Page 97: ...obstructions exist at the base or rover more the system to an open area Tracking at least 5 satellites Go to step 3 below Step 3 HDOP VDOP Values Too High for Precision Requirements Dilution of Precision DOP values give a quality indication of the satellite geometry at any given time Satellite geometry is important to the precision of an RTK solution In fact the DOP value is used as a multiplier i...

Page 98: ... Precision requirements too stringent for RTK If the RTK system is not delivering the precision requirements you need for your spe cific task it is possible that your precision requirements are too stringent for the RTK system Review your system documentation to determine the precision specifications for the RTK system Precision not beyond capability Go to step 5 below Precision beyond capability ...

Page 99: ... configure base system 54 control establishment 5 control station 2 coordinates of base point 55 D data collection 2 data collector 3 datums 18 default values 63 densification 5 determining traffic 82 different formats 18 DOP 87 DOP values above 4 88 DOS 15 17 DTM 4 E export formats 19 F FCC 11 feature location 4 feature stakeout 4 Fischer 25 38 fix ambiguities 86 float solution 86 frequency hoppi...

Page 100: ... 8 post processing 54 63 power amplifier 11 precise orbits 19 productivity 4 R radio is transmitting data 55 radio license 11 radio range 13 radio traffic 12 random flashing 82 raw data 2 10 19 22 54 63 raw data format 54 raw satellite data 55 receiver is observing satellites 55 receiver position 2 reports 19 reschedule survey 86 87 reverse polarity 23 45 rover pole 57 rover position 3 8 55 RS232 ...

Page 101: ... TNC 45 topographic 4 transmission frequency 55 true base position 55 U UHF 10 V VDOP 87 vector 3 vectors 19 vertical angle 3 vertical position 8 VHF 10 view current DOP 87 volume computations 4 VRMS 86 87 W WGS84 55 Windows CE 15 WPI Husky 16 ...

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