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Axis

3

Operation

Chapter 4

Axis

3™

33

4.6

DGPS Performance

The OmniSTAR receiver provides both a lock LED and a bit
error rate, monitored through the data collector, to describe the
lock status and reception quality.

*

Note:

Both of these features depend on line-of-sight access

between the Axis

3

antenna and the geostationary

communications satellite broadcasting OmniSTAR
correction information.

The bit error rate has a default, no-lock value of 500. As the
receiver begins to acquire the signal, it will result in a lower bit
error rate. Optimal performance is achieved when this value is
less than 150 and ideally, less than 20.

7 to 10

Intermittent

Low data throughput

<7

No Lock

No data throughput

SNR

Reception

Description

Appx. Data Throughput

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38
39
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42
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Summary of Contents for Axis 3

Page 1: ... Axis 3 TM Operations Manual Part Number 750 1 0060 Rev 2 GPS Receiver System ...

Page 2: ...pt any interference received including interference that may cause undesired operation These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment The equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interfer...

Page 3: ... 2 2 Real Time DGPS 7 2 3 OmniSTAR Worldwide DGPS Service 7 2 3 1 OmniSTAR signal information 8 2 3 2 OmniSTAR Reception and DGPS 8 2 3 2 1 Activating the OmniSTAR Service 9 2 3 2 2 Over Air Subscription Activation 10 2 4 Radio Beacon Service 11 2 4 1 Radiobeacon Range 11 2 4 2 Radiobeacon Messages 12 2 4 3 Radiobeacon Coverage 13 2 5 Radio Beacon Position Accuracy 14 2 5 1 Proximity 14 2 5 2 Late...

Page 4: ...2 3 3 1 Placing Antenna for Optimal Reception 23 3 3 2 Routing and Securing the Antenna Cable 23 3 3 3 Connecting the Axis 3 Antenna 24 3 4 Installing the Data Collector 24 3 5 Preparing for Operation 24 Chapter 4 Axis 3 Operation 27 4 1 Locating Satellites 27 4 2 Interpreting LED Indicators 28 4 2 1 Other LED Conditions OmniSTAR 29 4 3 Understanding Settings 29 4 3 1 Default Configuration 30 4 4 ...

Page 5: ...Contents Axis 3 iii Appendix A Troubleshooting 35 Appendix B Specifications 36 Appendix C Frequently Asked Questions 41 ...

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Page 7: ...pact lightweight yet rugged the Axis 3 receiver will provide you with years of reliable operation 1 1 Ports and Icons This icon is the symbol for power and identifies the power port which is located on the rear panel of the Axis receiver The power port is also referred to in this docu ment as PWR This icon is the symbol for communications and identifies the communications port which is located on ...

Page 8: ...re 1 3 Obtaining Technical Support When contacting customer support please ensure the following information is available the product model serial number and a concise description of the problem CAUTION Cautions inform of possible sources of difficulty or situations that may cause damage to the product WARNING Warnings inform of situations that may cause you harm ...

Page 9: ...lmere The Netherlands Phone 31 36 53 22 880 Fax 31 36 53 26 241 New Zealand Sokkia New Zealand 20 Constellation Drive Mairangi Bay C P O Box 4464 Auckland 10 New Zealand Phone 64 9 479 3064 Fax 64 9 479 3066 USA Sokkia Corporation 16900 W 118th Terrace P O Box 726 Olathe KS 66061 Phone 1 913 492 4900 Fax 1 913 492 0188 Asia Sokkia Singapore Pte Ltd 401 Commonwealth Drive 06 01 Haw Par Technocentre...

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Page 11: ...Welcome Chapter 1 Axis 3 5 ...

Page 12: ...e Selective Availability SA was turned off in May 2000 The initial intent of the Department of Defense was to have the ability to degrade the quality of the GPS signal for all non military users The resulting positioning accuracy with SA on is from a few meters to 100 meters however with SA off the positioning accuracy is approximately two to five meters If there is an immediate danger perceived t...

Page 13: ...rtners The DoD provides the SPS free of charge worldwide to all civilian users For many positioning and navigation applications stand alone or autonomous accuracy is insufficient and differential positioning techniques must be employed 2 1 3 DGPS Format GPS Standard For manufacturers of GPS equipment commonality is essential to maximize the utility and compatibility of a product The governing stan...

Page 14: ... each satellite is the range error This error is the amount that needs to be removed from each satellite distance measurement in order to correct for errors present in the system 2 2 2 Real Time DGPS The base station transmits the range error corrections to remote receivers in real time The remote receiver corrects its satellite range measurements using these differential corrections yielding a mu...

Page 15: ...he OmniSTAR network functions as a wide area DGPS service The information broadcast by the service is based on a network of strategic reference stations The reference stations communicate GPS correction data to control centers where it is decoded checked and repackaged into a proprietary format for transmission to a geostationary L band communications satellite This correction data is rebroadcast ...

Page 16: ...uracy levels across the coverage area Note The GPS receiver inside the Axis 3 provides position information to the L Band receiver for VBS calculations 2 3 2 1 Activating the OmniSTAR Service To use OmniSTAR you must know your receiver s internal L band receiver number This number can be found on the silver tag located on the bottom of the receiver You can contact the OmniSTAR office closest to yo...

Page 17: ...if your subscription has not been activated however it is of no use to you until your subscription is activated When you power on the receiver you must have the antenna in a location with an unobstructed view of the sky The subscription activation will be transmitted over the air and received by the internal L band DGPS receiver To confirm you have a valid and active OmniSTAR subscription refer to...

Page 18: ...acon is dependent upon a number of factors including transmission power free space loss ionospheric state surface conductivity ambient noise and atmospheric losses The strength of a signal decreases with distance from the transmitting station due in large part to spreading loss This loss is a result of the signal s power being distributed over an increasing surface area as the signal radiates away...

Page 19: ...tion of the ground wave to fade Fading occurs when the ground and sky waves interfere with each other The effect of fading is that reception may fade in and out However this problem usually occurs in the evening when the ionosphere becomes more reflective and usually on the edge of coverage areas Fading is not usually an issue with overlapping coverage areas of beacons and their large overall rang...

Page 20: ... current coverage with beacon stations symbolized as white circles Figure 1 World DGPS Radiobeacon Coverage April 1999 The world beacon networks continue to expand and coverage areas are growing The online listing provides the following information about each beacon Station name Frequency MSK rate Location Transmitting ID Reference station ID Field Strength Operating notes ...

Page 21: ... 1 Proximity The distance between a remote user and the reference station is often considerable when using 300 kHz DGPS radiobeacons Broadcast ranges may be as great as 450 km 280 miles or more depending primarily upon transmission power and surface conductivity Consequently some of the errors associated with GPS at the base station differ somewhat from those at the remote user s location This spa...

Page 22: ... Latency can become a concern if lock on the differential signal is lost for ten seconds or more To account for latency a GPS receiver can calculate approximate corrections until new corrections are available Calculating the differential correction for a new epoch using old corrections leads to inaccuracy that grows with time Accuracy is restored when new corrections become available 2 5 3 Ionosph...

Page 23: ...ived by the GPS receiver by a reflection from an object can decrease positioning accuracy These multipath signals increase the measured range to a satellite as the signal takes a longer route to the GPS antenna Certain precautions will minimize GPS antenna sensitivity to these reflected signals Operating away from large reflective structures such as buildings can help to reduce the impact of multi...

Page 24: ...t coverage area are able to use this signal for position determination 2 7 Axis 3 Receiver The Axis 3 receiver is designed for multiple applications especially GIS data collection It includes the following features High Performance 12 channel GPS receiver L Band differential receiver for use with OmniSTAR network subscription Dual channel beacon receiver Dual channel WAAS functionality Provides di...

Page 25: ...s to all internal receivers The enclosure houses an L band antenna for GPS and L Band satellite signals and anH field beacon loop antenna for beacon signal reception Both antenna elements are active during operation and draw power from the Axis 3 receiver All three signals are transmitted from the TNC connector on the antenna to the receiver s antenna RF port The Axis 3 automatically routes these ...

Page 26: ...Cable connecting the receiver to camcorder batteries included Note Using the OmniSTAR satellite corrections requires that a subscription be purchased from OmniSTAR For more information refer to Chapter 2 Section 2 3 2 2 A data collector is required to communicate with the receiver Use the Axis 3 receiver with IMap or other software compatible with the receiver Communication with the receiver requi...

Page 27: ...red to operate and communicate with the Axis 3 receiver a controller cable and an antenna cable Both cables are provided with the purchase of a new receiver In some systems a null modem adapter is required included Table 1 1 2 3 4 RF PWR ON OFF COM DB9F 2 4 1 3 Figure 1 Back panel ...

Page 28: ...connected directly to the system CPU 3 1 2 Communication Receiver communication with a data collector is handled through Port A GPS Port or an Auxiliary Port The following data parameters are the same for each port and cannot be changed Data bits 8 Parity None Stop bits 1 Figure 3 Power Cable Figure 4 Antenna Cable ...

Page 29: ...8 F and relative humidity is less than 95 The receiver should always be stored between 40 C and 80 C 40 F to 168 F Note The Axis 3 antenna cannot operate in an enclosed environment 3 2 2 Connecting Power To power the Axis 3 receiver connect the single end of the power cable to the PWR port on the rear panel of the Axis 3 receiver and connect the double end of the Y power cable to the camcorder bat...

Page 30: ... Ensure that the antenna is as far as possible from all other equipment that emits Electromagnetic Interference EMI including DC motors alternators solenoids radios power cables display units and other electronic devices If a radar is present mount the antenna outside the path of the radar beam 3 3 2 Routing and Securing the Antenna Cable The Axis 3 antenna should be used with the TNC male to TNC ...

Page 31: ...ee your Axis 3 Jump Start Guide 3 4 Installing the Data Collector To establish communications between the Axis 3 receiver and your data collector connect the data collector to the receiver s COM port with the data collector s supplied cable Note For successful communications the baud rate of the Axis 3 must be set to match that of the data collector Refer to your data collector manual for instruct...

Page 32: ... using 300 khz beacon capability make sure you are operating in an area where beacon service is available When powering on the receiver wait for the system to locate at least four GPS satellites and to acquire a DGPS solution Note When using the receiver for the first time or in a new area it may take up to 30 minutes to establish satellite communication and DGPS solutions ...

Page 33: ......

Page 34: ...mensional position will be calculated after four satellites are located This is called GPS Lock DGPS Lock Under normal conditions the Axis 3 receiver will establish a differential lock in about 10 minutes based on the DGPS source L Band WAAS or 300 khz beacon The initial DGPS position will be accurate to about one meter and will gradually improve during the first few minutes after DGPS is establis...

Page 35: ...ot connected Red Power connected to the receiver GPS Lock Off No GPS lock Yellow GPS lock about one minute after power on Blinking Yellow Differential processor verification will blink three to four times at power up If it does not blink possible differential processor failure Repeated blinking indicates GPS processor failure L Band Beacon WAAS Lock Off No L band differential signal Flickering Yel...

Page 36: ...onfiguration settings required for correct operation Many configuration parameters are preset at the factory prior to shipment Basic settings that can be changed are Baud Rate Message Output Differential Source Mask Angle Frequency and bit rate selection Note Receiver parameters can be changed with a connected data collector Refer to your data collector reference manual for more information Refer ...

Page 37: ... to the station providing the strongest DGPS signal Table 3 Adjustable Settings Parameter Settings Options Baud Rate A B 4800 9600 19200 NMEA Message Output GGA GLL VTG GSV RMC GSA GST Differential GPS source Beacon L Band WAAS Mask Angle 10 degrees recommended Frequency Bit rate Auto Manual Differential Age Time Out 60 seconds Parameter Default Setting Baud Rate Port A 9600 8 N 1 Msg Off Differen...

Page 38: ...tes a Global Search examining each available DGPS beacon frequency and recording Signal Strength SS measurements The receiver uses these measured values to compute an average SS and noise floor to sort the frequencies in descending order of SS The two channels cooperatively examine the frequencies with the highest SS measurements above the computed noise floor to determine the station providing th...

Page 39: ...n its own which is useful when working in an area where you know the frequency but not the MSK bit rate of the closest beacon 4 5 Beacon Performance SNR Reading The Signal to Noise Ratio SNR best describes the beacon receiver performance The SNR is the height of the signal above the noise floor The higher the SNR the better the reception The SNR can be monitored with your data collector refer to y...

Page 40: ...ess between the Axis 3 antenna and the geostationary communications satellite broadcasting OmniSTAR correction information The bit error rate has a default no lock value of 500 As the receiver begins to acquire the signal it will result in a lower bit error rate Optimal performance is achieved when this value is less than 150 and ideally less than 20 7 to 10 Intermittent Low data throughput 7 No L...

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Page 42: ...lid correction source DGPS LED Illuminated Verify that Axis receiver is locked to GPS satellites GPS LED illuminated Check integrity and connectivity of power and data cable connections Random data from Axis 3 receiver Verify baud rate settings of Axis receiver and data collector No GPS lock Check integrity of antenna cable Verify Axis antenna unobstructed view of the sky Verify antenna cable leng...

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Page 44: ...ions Item Specification Frequency 1 575 GHz Channels 12 Horizontal Accuracy 1m 95 confidence DGPS Internal Beacon Engine Operational Specifications Item Specification Frequency Range 283 5 325 kHz Channels 2 Input Sensitivity 1 5 mV m for 10 dB SNR 100 bps MSK Rate Reacquisition Time 2 Seconds Typical MSK Bit Rate 50 100 and 200 bps Frequency Selection Manual or Automatic Frequency Offset 10 Hz Dy...

Page 45: ... 48 VDC Power Consumption 6 5 W Power Connector Circular 2 pin Locking Plug Mechanical Characteristics Item Specification Enclosure Powder coated aluminum extrusion with powder coated aluminum front and end plates Length 190 mm 7 48 in Width 125 mm 4 9 in Height 51 mm 2 0 in Weight 0 76 kg 1 68 lb Antenna Connector TNC Socket Environmental Specifications Item Specification Storage Temperature 40 º...

Page 46: ...MHz 10 MHz LNA Gain GPS 28 dB Power Specifications Item Specification Input Voltage 4 85 to 15 0 VDC Input Current 50 60 mA Mechanical Characteristics Item Specification Enclosure Powder coated aluminum base polycarbonate dome Mounting Thread 1 14 UNS 2B Length 129 mm Width 129 mm Height 98 mm Weight 450 g 1 0 lb Antenna Connector TNC Socket Antenna Extension Cable RG 58U 10 m 33 ft in Length Envi...

Page 47: ...40 Axis 3 Appendix B Specifications Operating Temperature 40 ºC to 85 ºC Humidity 100 Condensing Environmental Specifications ...

Page 48: ......

Page 49: ... for more information Question Where is the 300 khz signal available Answer The beacon signal is broadcast from transmission stations around the world Refer to section 2 4 3 for further information Question What is WAAS Answer WAAS Wide Area Augmentation System is a free differential source WAAS is a network of GPS stations throughout the United States These stations collect GPS data and solve for...

Page 50: ...ormation refer to Specifications in Appendix B of the manual GPS DGPS Question How do I know when my Axis 3 receiver has located a GPS signal Answer The easiest way is to look at the LED status indicators on the receiver See Section 4 2 Interpreting LED Indicators page 27 for more information Question How long does it take to get a DGPS lock Answer On normal power up you should have DGPS lock with...

Page 51: ...43 Axis 3 Appendix C Frequently Asked Questions ...

Page 52: ... differential corrections 7 G global search 31 32 gps beacon service 11 dgps format 6 H humidity 22 L LED 28 M multipath 16 R radiobeacon background search 31 coverage 13 global search 31 range 11 reception 12 range 14 range rate 15 receiver front panel 28 specifications 36 RTCM SC 104 6 S selective availability sa 15 signal to noise ratio snr 32 35 specifications antenna 38 receiver 36 T technica...

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Page 54: ...640 Fax 33 4 72 492 646 SOKKIA S R L Via Alserio 22 20159 Milano Italy Phone 39 02 66 803 803 Fax 39 02 66 803 804 SOKKIA N V S A Doornveld Asse 3 Nr 11 B1 1731 Zellik Brussels Belgium Phone 32 2 466 82 30 Fax 32 2 466 83 00 SOKKIA KFT Légszeszgyár u 17 7622 Pécs Hungary Phone 36 72 226 636 Fax 36 72 324 636 SOKKIA KOREA CO LTD 2Fl Chungam Bldg 129 11 Chungdam dong Kangnam ku Seoul Republic of Kor...

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