Novatel OM-20000077 user manual Appendix C, Antenna Specifications, Cable Selection

Page 56

Appendix C

Antenna Specifications

The GPS antenna is an important part of the total system performance and its selection should be based on your application. The L1 GPS receivers include a Low Noise Amplifier (LNA) before the RF ASIC. This +20 dB LNA permits reasonable performances with a passive GPS antenna. But depending on the cable loss between the antenna element and the L1 GPS receiver, and position accuracy requirements, a +12 dB up to +36 dB active GPS antenna may be needed.

This appendix is divided into characteristics for high end active geodetic antennas and passive antennas.

We also offer the coaxial cables required between the GPS antenna and the SUPERSTAR II. You will also find in this section, different coaxial cables required in your GPS system. The end of this section includes detailed antenna drawings.

C.1 Cable Selection

The interconnecting cable between the GPS antenna and the receiver is of prime importance for the proper performance of the system. Three parameters should be considered:

1.Loss

2.Isolation

3.Outer diameter

The bigger the outer diameter, the lower the loss. The loss increases with the length of the cable and decreases with extra isolation. If the highest accuracy possible is not required, receivers can accept a total cable loss of 3 dB. Depending on the cable type, this could represent a cable run from 2 m up to 10 m.

Table 11 on Page 56 details the specifications of the RG-58 Low Loss Cable (RG-58/U LLDS80) used in the GPS antenna cable 217-601730-XXX. The RG-58/U LLDS80 is a custom-made low loss noise coaxial cable. It is a double-shielded cable similar to Belden Type 9310 but with the improvement of having 85% minimum coverage of the second shield versus the Belden at 55% coverage. The electrical characteristics are included in Table 11.

Table 11: Coaxial Cable Specifications

Center Conductor

#20 Bare Copper wire, Resistance - 33.1 ohms per Km

 

 

Insulation

Polyethylene

 

 

Inner Shield

Aluminium Foil - 100% coverage

 

 

Outer Shield

Tinned copper braid - 85% coverage, Resistance 45.9 ohms per Km

 

 

Jacket

Black PVC

 

 

Nominal Impedance

50 ohms

 

 

Nominal Vel. of propagation

66%

 

 

Nominal Capacity

101.7 pf per meter

 

 

Attenuation

@ 1000 MHz: 44.3 dB per 100 m (or 54 dB @ 1575 MHz)

 

 

Table 12 shows the minimum and maximum cable length when using GPS antenna cable (drawing 217- 601730-XXX) normally required between the receiver and the chassis case of your system. Please see Page 60 for the cable drawing.

56

SUPERSTAR II User Manual Rev 3

Image 56
Contents Superstar Proprietary Notice Table of Contents Appendices Tables Figures Software License Software License Firmware Updates Contact InformationElectrostatic Discharge CE Notice Warranty Policy Related Publications Congratulations ScopeRelated Publications Introduction Superstar II GPS CardFlexPak-SSII Introduction ChapterChapter Introduction Receiver Specifications Physical CharacteristicsSystem Architecture Radio Frequency RF SectionEnclosure and Wiring Harness Principal Power SupplyOptional LNA Power Supply GPS AntennaInstallation Typical System Configuration Reference DescriptionChapter Installation Electrostatic DischargeEquipment Interconnection Serial ConnectionInstallation Considerations Power ConnectionInstallation Chapter Antenna LocationConnectors and Connector Pins Assignment 1 J1 Interface and Power ConnectorData Link Base Station and Rover Units SeparationRF Connector J2 Serial Data InterfacePreamplifier Power Pass-Through Antenna Supply Protocol Selection and Non Volatile MemoryMemory Back-Up RF InputUse of Discretes Discretes IP2 and IP3 functionsNon-Volatile Memory Data Default ConfigurationNon Volatile Memory Installation Overview Description ReferenceTypical Operational Configuration Reference Description OperationSerial Port Default Settings Communications with the ReceiverGetting Started Operation ChapterPower-Up Information Boot InformationOperational Information Chapter OperationReceiver States Configurable ParametersData Requests Self-Test Mode Dead-Reckoning Mode Built-In Status TestsDatum Support RTCM1 Differential GPS Corrections Fixed Message FormatsRTCM-Format Messages Chapter Message Formats RTCM2 Delta Differential GPS Corrections FixedRTCM9 Partial Satellite Set Differential Corrections Nmea Format Data Messages Message Formats ChapterSingle-Point or Autonomous GPS System ErrorsPositioning Modes of Operation Satellite-Based Augmentation System Sbas Positioning Modes of Operation ChapterChapter Positioning Modes of Operation Sbas ReceiverSbas Messages Positioning Modes of Operation Chapter Troubleshooting Cable Lengths Vs. GainTroubleshooting Chapter Superstar II Family Performance Technical SpecificationsAppendix a Technical Specifications Appendix a Output MessagesAppendix a Technical Specifications Mechanical DrawingConnector Pin Assignment J1 Interfaces and Power Connector Pin Assignment3 I/O Electrical Characteristics O Signals Voltage LimitsFlexPak-SSII Specifications Appendix BStatus Indicators Appendix B FlexPak-SSII SpecificationsFlexPak Status Indicators Port Pin-OutsCables FlexPak-SSII Specifications Appendix BAutomobile Power Adapter Cable NovAtel part number 3.2 13-Pin Deutsch to DB9 Serial Cable NovAtel part number FlexPak 13-Pin Serial CableSetup and Operation Normal SetupDevelopment Kit DescriptionDgps Setup with the FlexPak-SSII Differential GPS SetupStarView Software Installation Antenna Specifications Coaxial Cable SpecificationsAppendix C Cable SelectionAntenna Specifications Appendix C Geodetic Active AntennaAntenna Gain Depending on Cable Length Required Typical Current Consumption Versus Antenna GainAppendix C Antenna Specifications Active AntennaPassive Antenna Recommended Geodetic Active AntennasPassive Antenna Specifications Patch Element GPS Antenna 201-990146-716 MCX, +12 dBGPS Antenna 201-990147-606 +26 dB Antenna Specifications Appendix C Appendix D Standards/ReferencesAppendix E Ttff and Satellite AcquisitionTime-To-First-Fix Ttff Re-AcquisitionUtility Installation Appendix FUpdating Receiver Firmware System RequirementsUpdating Receiver Firmware Appendix F Starting Software and Options UpdateRegistration Key Accepted Programming Success Appendix F Updating Receiver FirmwareAppendix G GPS OverviewGPS System Design Space SegmentHeight Relationships Control SegmentUser Segment Appendix G GPS OverviewGPS Positioning GPS Overview Appendix GSingle-Point vs. Relative Positioning Accuracy versus Precision1Real-time vs. Post-mission Data Processing MultipathStatic vs. Kinematic Positioning Why Does Multipath Occur? Consequences of Multipath ReceptionHardware Solutions For Multipath Reduction Antenna Site SelectionGPS Signal Multipath vs. Increased Antenna Height Antenna DesignsGPS Overview Appendix G Appendix H Glossary of TermsGlossary of Terms Appendix H Appendix H Glossary of Terms Glossary of Terms Appendix H Appendix AcronymsAcronyms Appendix Appendix Acronyms Index GEO, Sbas IndexIndex Index OM-20000077 Rev 2004/03/11