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GPS-Base Manual

Revision: 180928

25

restored from the GPS-Base, it can be entered by the user or the GPS-Base can average its

position for a period of time to find an approximate location for the antenna.

There is some discussion at the end of the manual describing the benefits of each technique.

In general it is sufficient to average for three minutes. For repeatable work, save the averaged

location, and then restore this location using the 

Restore from file

 feature. To be accurate to

a map it will be necessary to average for a long period of time (and hope that the person who

made the map did this too, which they may not have).

Figure 7. 

NAVbase Settings page

Averaging time

Use this option to let the GPS-Base find its own position using GPS measurements. This is

the most common option to use. For temporary installations, a three minute period is

sufficient. Longer periods can be used to find the location of the antenna more precisely.

Note: if you average for three minutes then all the data for this average will be accurate to

2 cm compared to other data obtained during this average. If you re-average you will end up

in a different location and the data from the new location will not overlay the old location.

Use the Save/Restore features so that future data will overlay the current data.

Summary of Contents for GPS-Base series

Page 1: ...Confidently Accurately User Manual GPS Base GNSS aided inertial navigation system ...

Page 2: ...respective holders Any redistribution of the software must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution Environmental protection Waste electrical products should not be disposed of with household waste Please recycle where facilities exist Check with your Local Authority or OxTS ...

Page 3: ...t holders or contributors be liable for any direct indirect incidental special exemplary or consequential damages including but not limited to procurement of substitute goods or services loss of use data or profits or business interruption however caused and on any theory of liability whether in contract strict liability or tort including negligence or otherwise arising in any way out of the use o...

Page 4: ...ir at an authorised location only Determination of replacement or repair will be made by Oxford Technical Solutions Limited personnel or by personnel expressly authorised by Oxford Technical Solutions Limited for this purpose In no event will Oxford Technical Solutions Limited be liable for any indirect incidental special or consequential damages whether through tort contract or otherwise This war...

Page 5: ...Setting up the tripod and antenna 17 Connecting the GNSS antenna and radio modem cables 18 Powering up and monitoring the GPS Base 19 Communicating with the product 22 The NAVbase interface 23 Product Selection 23 Connection 24 Remember portselection 24 Settings 24 Averaging time 25 Restore position from file 26 Enter antenna position 26 Leave unchanged 26 Advanced 26 Status 27 Communication 28 La...

Page 6: ...Oxford Technical Solutions 6 SATEL radio status 31 Freewave radio status 31 Differential correction message format 33 Message output and frequency 33 Repeatability 35 Index 38 Specifications 37 ...

Page 7: ...avigation System LED Light Emitting Diode MFDD Mean Fully Developed Deceleration MSAS MTSAT Satellite Augmentation System NMEA National Marine Electronics Association NTRIP Networked Transport of RTCM via Internet Protocol PPS Pulse s Per Second RD Raw Data an OxTS file format RINEX Receiver INdependent EXchange format RTK Real Time Kinematics SBAS Satellite Based Augmentation System SDCM System f...

Page 8: ...e is a difference however the base station calculates the length of time each satellite signal would need to be delayed by in order to cause the difference between the surveyed location and the GNSS measurement being produced Introduction Thank you for choosing Oxford Technical Solutions The GPS Base is a highly portable GPS base station that transmits differential corrections to one or more diffe...

Page 9: ...eal Time Kinematic carrier phase measurements the principle is the same but the remote GNSS receiver also has to figure out the difference in the number of carrier phase cycles between the GPS Base and itself To do this the GPS Base measures the carrier phase of the signals from each satellite and transmits it to the remote system Figure 1 Differential GNSS overview The base station is either plac...

Page 10: ... settings for the radios supplied with your GPS Base and in which countries they can be used While the GPS Base will work seamlessly with our own GNSS aided INS products it is not limited to them in any way The GPS Base can also serve as a general base station for other products To help achieve this the GPS Base transmits corrections inthree common formats RTCA RTCA2 RTCMv3 Table 2 Overview of dif...

Page 11: ...for GLONASS RTCA2 The RTCA2 format is suitable for GPS and GLONASS differential corrections RTCMv3 The RTCMv3 format is suitable for GPS and GLONASS differential corrections Table 4 RTCA message output Message Standard frequency Limited frequencya a Used when the Limit output corrections message rate ETSI EN 300 220 1 option is enabled RTCAOBS L1 L2 pseudo range and carrier phase 1 Hz 0 25 Hz RTCA...

Page 12: ...Used when the Limit output corrections message rate ETSI EN 300 220 1 option is enabled RTCM1004 extended L1 L2 GNSS pseudo range and carrier phase 1 Hz 0 25 Hz RTCM1012 extended L1 L2 GLONASS pseudo range and carrier phase 1 Hz 0 25 Hz RTCM1005 base station antenna position 0 2 Hz 0 14 Hz RTCM1007 extended antenna descriptor and set up information The base station firmware always configures the b...

Page 13: ...ional components delivered with your product Please note the customer must check that the supplied radio can be used without a license or obtain a suitable license before using the GPS Base Oxford Technical Solutions cannot be held responsible for using this equipment illegally without the correct radio license Figure 2 Example of GPS Base system Table 7 Summary GPS Base components common to all v...

Page 14: ...420 magnetic antenna with TNC connector Table 9 Additional components supplied with SATEL 869 MHz radios Qty Description 2 SATEL SATELLINE EASy with display radio modem 869 MHz 2 3 m Satel 869 magnetic antenna with TNC connector Table 10 Additional components with Freewave radios Qty Description 2 Freewave FGR2 900 MHz radio modem 2 3 m Satel 869 magnetic antenna with TNC connector 2 Freewave FGR2...

Page 15: ...frequency energy and if not installed and used in accordance with the instructions may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to t...

Page 16: ...le is carefully matched to the GPS Base and lengthening or shortening the cable will reduce the performance of the system Never connect the GNSS antenna to the radio aerial connector which uses the same connector The use of two TNC connectors is required since they have much better ground properties compared to BNC connectors The radio aerial output has a high power signal that may damage the GNSS...

Page 17: ... away overnight it is important to mark the location of the GNSS antenna It will need to be placed in precisely the same location on each day If possible mount the antenna on a pole that has been fixed in the ground and can be left behind until the test has finished Setting up the tripod and antenna 1 The tripod legs use a friction lock to maintain their position To extend each leg twist each leg ...

Page 18: ...able Figure 4 GPS Base cable connections As shown above the GNSS antenna connects to the left of the handle and the radio modem connects to the right Do not swap the connectors over or damage may occur If radio modems are being used to transmit and receive DGNSS corrections one of the supplied antennas should be connected to the Radio connector The radio modem antenna should be placed as high up a...

Page 19: ... used The first thing the GPS Base loads as part of the boot process is a configuration file which is held in its internal memory The configuration file controls how the GPS Base behaves The first time an GPS Base is powered up after delivery the default settings are used The default settings tell the GPS Base to average its position over a three minute period once it computes a GNSS position and ...

Page 20: ...w solid No solution Yellow blink User Accuracy Level UAL out of bounds STEADYLINE If PwrPak7 configured as Base Green solid Fixed position Yellow solid Pending fixed position Yellow blink Invalid fix Hardware LED descriptions INS LED Description LED Label LED State Description INS indicates the INS status of the receiver PwrPak7 E1 or PwrPak7 using an external IMU only Off INS inactive Green solid...

Page 21: ... blink for 3 seconds then Red solid Stick mount error Stick plugged in but corrupt or unsupported format Off No connection to the TRANSFER port or stick is unmounted LOG LED and Button Description LOG Button with LED LED State Description Logging Green slow blink Logging to Internal lots of memory available Green solid Internal logging stopped lots of memory available Green Yellow alternating blin...

Page 22: ...Monitor the status of the GPS Base Save differential correction data to disk To communicate with the GPS Base the NAVbase software needs to know which port the GPS Base is connected to The GPS Base connects using USB but the USB drivers makes the GPS Base appear as a serial COM port Normally the driver will install three COM ports for the GPS Base COM5 COM6 and COM7 Any of these can be used If the...

Page 23: ...h screen is shown in Figure 5 Product Selection As NAVbase is our universal base station configuration tool the first task is to tell the software which base station is about to configured Simply select GPS Base and click the Next button You will notice that different options are available depending on the product selected Figure 5 The initial screen presented by NAVbase Select the GPS Base and cl...

Page 24: ...t selection option is checked then in future the software will skip the port scan Normally the GPS Base will remain on the same port so it is not necessary to visit this page each time If the GPS Base cannot be found on the saved port NAVbase will scan all the ports which can take time It is best to have the GPS Base on and connected before starting the software Settings Before the GPS Base will o...

Page 25: ...me and hope that the person who made the map did this too which they may not have Figure 7 NAVbase Settings page Averaging time Use this option to let the GPS Base find its own position using GPS measurements This is the most common option to use For temporary installations a three minute period is sufficient Longer periods can be used to find the location of the antenna more precisely Note if you...

Page 26: ...n of the GPS antenna Note that the altitude must be entered in EGM96 not WGS 84 Leave unchanged Use this option if the GPS Base already knows its location and you do not want to change it If the GPS Base has a location stored internally or a location has already been acquired during the session this option will be selected automatically Advanced Using Advanced the correction type and the Base Stat...

Page 27: ...ASy 896 firmware version 3 63 4 onwards that comply to the 10 duty cycle restriction imposed by ETSI EN 300 220 1 Status page The Status page is used to monitor the GPS Base The GPS Base does not need the PC software to be running continuously once the GPS Base is configured then the PC can be disconnected unless it is being used to log data Figure 9 shows the Status Page Figure 9 GPS Base status ...

Page 28: ...to the Connection page to select a different port or connect a GPS Base to the computer Averaging The GPS Base is averaging the GPS positions RTCA OK This is the normal mode for the GPS Base when it is working correctly and outputting RTCA corrections RTCA2 OK This is the normal mode for the GPS Base when it is working correctly and outputting RTCA2 corrections RTCMv3 OK This is the normal mode fo...

Page 29: ...ential correction format When using this feature it is necessary to replace the GPS antenna in exactly the same position each time Only one antenna location can be stored on the GPS Base if a new location is stored it will overwrite the old one To find out which antenna location is stored in the GPS Base it must be connected to a computer and the software must be used If there is a location stored...

Page 30: ...option to start logging the raw GPS measurements from the GPS Base Once started the Start Logging button will become Stop Logging which will stop the logging of the raw GPS measurements when pressed While logging it is not possible to change page or quit ...

Page 31: ... Red Transmitting a packet Off Red Off Off Orange Noise or other transmission on this frequency Off Red Off Green Green Receiving a packet Table 13 Freewave radio LED states and meanings Condition Base station modem Mobile modem Carrier Detect CD Transmit TX Clear to Send CTS Carrier Detect CD Transmit TX Clear to Send CTS Powered No link Red Slow red flash Red Off Red flash Linked Sending data Re...

Page 32: ...m a more secure link It can be difficult on the mobile unit to know if data is being received since only a transmit LED is available If differential corrections are not being received by the INS GNSS product then check that the differential correction format on the GPS Base and on the INS GNSS product are the same ...

Page 33: ...equency Limited frequencya a Used when the Limit output corrections message rate ETSI EN 300 220 1 option is enabled RTCA1 pseudo range corrections 1 Hz 0 25 Hz RTCAOBS L1 L2 pseudo range and carrier phase 1 Hz 0 25 Hz RTCAREF base station position 0 2 Hz 0 2 Hz Table 15 RTCAv2 message output Message Standard frequency Limited frequencya a Used when the Limit output corrections message rate ETSI E...

Page 34: ...na as a Novatel GNSS 702 GGL 0 1 Hz 0 1 Hz RTCM1012 extended L1 L2 GLONASS pseudo range and carrier phase 1 Hz 0 25 Hz RTCM1033 base station and antenna descriptor 0 1 Hz 0 1 Hz a Used when the Limit output corrections message rate ETSI EN 300 220 1 option is enabled Table 16 RTCMv3 message output Continued Message Standard update rate Limited update ratea ...

Page 35: ...station gets this position wrong then the remote GNSS receivers will also be wrong They will be correct relative to the base station but they will have the same error on the earth that the base station has This is important when turning the GPS Base off and on again See Figure 11 Figure 10 Shifting base station antenna example The problem of shifting the antenna typically occurs when The tripod is...

Page 36: ...so it is accurate to 2 cm or better However since the timescale for this is long it is not usually practical except for permanent installations Even when you have a permanent installation it is not required since all it does is allows you to relate your measurements to a surveyor s measurements and this is rarely required To overcome the problem of averaging the save restore feature of the GPS Bas...

Page 37: ...l specification for the GPS Base unit is shown below Table 17 Technical specification excluding radio modem Parameter Specification Power 9 36 V dc 2 W Operating temperature Corrections Frequency Format 40 C to 75 C RTCA Differential L1 L2 RTCA2 RTCMv3 1 Hz RS232 ...

Page 38: ...tool 21 custom configurations 19 D Differential GNSS 9 H Harmonised 10 L license 13 M multi path 16 N NAVbase 21 P Pseudo range 10 R Radio modems 9 Repeatability 33 RTCA 10 11 31 RTCA2 10 RTCAv2 11 31 RTCMv3 10 12 31 RTK Real Time Kinematic 9 S save restore 34 Specifications 35 T tripod 17 W Wi Fi 9 ...

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