Draft VOR Specification FAA-E-37012_v0.22.docx
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Appendix A – VOR Frequency Channelization
FAA-E-37012
DRAFT, January 19, 2022
U.S. Department of Transportation Federal Aviation Administration
PERFORMANCE SPECIFICATION
VERY HIGH FREQUENCY (VHF) OMNIDIRECTIONAL RADIO RANGE (VOR) SYSTEM – CONVENTIONAL (CVOR) AND DOPPLER (DVOR)
FOREWORD
| 1. | This specification is approved for use by all Departments of the Federal Aviation Administration (FAA). |
| 2. | This specification defines the minimum requirements for the Very High Frequency (VHF) Omnidirectional Radio Range (VOR) System, Conventional VOR (CVOR) and Doppler VOR (DVOR) configurations. |
| Draft | Draft | Draft | ||
| Draft | FAA-E-37012 | Draft |
DRAFT ii 01/19/2022 Table of Contents
| 1. | Introduction | 1 |
| 1.1 | Scope | 1 |
| 1.2 | Overview | 1 |
| 2. | Applicable Documents | 2 |
| 2.1 | General | 2 |
| 2.2 | Government Documents | 2 |
| 2.2.1 | FAA Specifications, Standards and Handbooks | 2 |
| 2.2.2 | Other Government Documents, Drawings and Publications | 2 |
| 2.3 | Non-Government publications | 3 |
| 2.4 | Order of Precedence | 6 |
| 3. | Requirements | 7 |
| 3.1 | General Requirements | 7 |
| 3.1.1 | System Characteristics | 7 |
| 3.1.2 | VOR Antenna Compatibility | 7 |
| 3.1.3 | Integrity of Signal | 9 |
| 3.1.4 | Accuracy | 10 |
| 3.1.5 | Environmental Operating Conditions | 10 |
| 3.1.5.1 | Non-Operating Conditions | 10 |
| 3.1.5.2 | Operating Conditions | 10 |
| 3.1.5.3 | Lightning Protection | 11 |
| 3.1.6 | Electromagnetic Interference (EMI) / Electromagnetic Compatibility (EMC) | 11 |
| 3.2 | Transmitter Requirements | 11 |
| 3.2.1 | Operating Channels | 11 |
| 3.2.1.1 | Channel Frequency and Stability | 12 |
| 3.2.1.2 | RF Tuning | 12 |
| 3.2.2 | Carrier Transmitter | 12 |
| 3.2.2.1 | Transmitter Power Output | 12 |
| 3.2.2.2 | Carrier Output Level and Control | 12 |
| 3.2.2.3 | Carrier Power Stabilization | 12 |
| 3.2.2.4 | Carrier Modulation | 12 |
| 3.2.3 | Sideband Output Characteristics | 17 |
| 3.2.3.1 | Conventional Sideband Characteristics | 17 |
| 3.2.3.2 | Doppler Sideband Characteristics | 19 |
| 3.2.4 | Doppler VOR Distributor Assembly | 21 |
| 3.2.4.1 | Distributor Function | 21 |
| 3.2.4.2 | Insertion Loss | 22 |
| 3.2.4.3 | RF Phase Shift | 22 |
| 3.2.4.4 | Switching Isolation | 22 |
| 3.2.4.5 | Stray Radiation | 22 |
| 3.2.4.6 | Distributor Mechanical Design | 22 |
| 3.2.5 | CVOR Carrier, DVOR Carrier, and DVOR Sideband Antennas | 22 |
| 3.2.5.1 | CVOR Transmitting Antenna Sets | 22 |
| 3.2.5.2 | DVOR Sideband Antennas | 23 |
| 3.2.5.3 | DVOR Carrier Antenna | 23 |
| 3.2.5.4 | Fastener Materials | 23 |
| 3.2.5.5 | RF Connectors | 23 |
| 3.2.5.6 | Balance-to-Unbalance Transformers | 24 |
| 3.2.5.7 | Antenna Nameplate | 24 |
| 3.2.5.8 | Antenna Insulators | 24 |
| 3.2.5.9 | Capacitor Plates | 24 |
| 3.2.5.10 | DVOR Antenna Pedestal Cover | 24 |
| 3.2.5.11 | Antenna Finishes | 24 |
| 3.2.5.12 | Mechanical Tolerances | 25 |
| 3.2.5.13 | Electrical Performance | 26 |
| 3.2.5.14 | Insulation Resistance | 26 |
| 3.2.5.15 | CVOR Antenna Shelter | 26 |
| 3.2.6 | Thermal Overload Protection | 27 |
| 3.2.7 | Performance Upon a Fault Condition of RF Equipment Output Circuit | 27 |
| 3.3 | Monitor | 28 |
| 3.3.1 | Operating Channels | 28 |
| 3.3.1.1 | Broadband Operation | 28 |
| 3.3.1.2 | RF Tuning | 28 |
| 3.3.1.3 | Frequency and Accuracy Stability | 28 |
| 3.3.1.4 | RF Input Levels | 29 |
| 3.3.1.5 | Input Interference Immunity | 29 |
| 3.3.1.6 | RF Input Connections | 29 |
| 3.3.1.7 | Detected Audio Output Channel | 29 |
| 3.3.2 | VOR Monitor Operation | 30 |
| 3.3.2.1 | Monitor Alarm Action | 30 |
| 3.3.2.2 | Monitored Parameters | 31 |
| 3.3.2.3 | Test Signals and Monitoring Activities | 34 |
| 3.3.2.4 | Monitor Failsafe | 36 |
| 3.3.2.5 | VOR Test Generator | 36 |
| 3.3.2.6 | CVOR Ground Check System | 37 |
| 3.3.2.7 | DVOR Field Monitoring | 40 |
| 3.3.2.8 | Transmission Line Directional Coupler | 40 |
| 3.4 | Control, Status and Indicator Functions | 40 |
| 3.4.1 | Front Panel | 40 |
| 3.4.1.1 | Controls | 40 |
| 3.4.1.2 | Status and Indicators | 41 |
| 3.4.2 | Maintenance Data Terminal (MDT) | 41 |
| 3.4.3 | Remote Control | 42 |
| 3.4.4 | Fault History | 42 |
| 3.4.5 | Fault Diagnostics | 42 |
| 3.4.6 | Trend Analysis Data Collection and Storage | 42 |
| 3.4.7 | Automatic Reset Function | 43 |
| 3.5 | Remote Maintenance Monitoring (RMM) | 43 |
| 3.5.1 | Remote Monitoring Subsystem (RMS) | 43 |
| 3.5.1.1 | RMS Functions | 43 |
| 3.5.2 | Alarm and Alert Messages | 44 |
| 3.5.2.1 | Alarms | 44 |
| 3.5.2.2 | Maintenance Alerts | 44 |
| 3.5.3 | Non-Volatile Data Storage | 44 |
| 3.5.4 | RMS Data Sampling Rate | 44 |
| 3.5.5 | Spare Input/Output Capacity | 44 |
| 3.5.6 | Environmental Monitoring | 45 |
| 3.5.6.1 | Intrusion Detector | 45 |
| 3.5.6.2 | Smoke Detector | 45 |
| 3.5.6.3 | Obstruction Light Sensor | 46 |
| 3.5.6.4 | AC Power Sensor | 46 |
| 3.5.6.5 | Temperature Sensors | 46 |
| 3.5.7 | RMS Security | 46 |
| 3.5.7.1 | Security Implementation | 46 |
| 3.5.7.2 | Security Level Definitions | 47 |
| 3.5.8 | RMS Data and Control Filtering | 47 |
| 3.5.9 | RMS Failure Protection | 47 |
| 3.5.10 | Interface with RMM Subsystems | 47 |
| 3.6 | Data Security | 48 |
| 3.6.1 | Access Control | 48 |
| 3.6.2 | Logging | 48 |
| 3.7 | VOR System Design Characteristics | 48 |
| 3.7.1 | Maintainability | 48 |
| 3.7.1.1 | Real Time Clock/Calendar | 49 |
| 3.7.2 | Reliability | 49 |
| 3.7.3 | Modular Construction | 49 |
| 3.7.3.1 | Equipment Mounting | 49 |
| 3.7.4 | Test Points | 50 |
| 3.7.5 | Interchangeability | 50 |
| 3.7.6 | Corrective Maintenance | 50 |
| 3.7.7 | Preventative Maintenance | 50 |
| 3.7.8 | Software/Firmware Updates | 51 |
| 3.7.9 | Electrical Interfaces Between VOR, Monitor Antennas, and Distributor | 51 |
| 3.7.10 | RF Input/Output Connectors | 51 |
| 3.7.11 | Grounding and Bonding | 51 |
| 3.7.12 | Input Power | 51 |
| 3.7.12.1 | AC Power | 51 |
| 3.7.12.2 | Equipment Directly Connected To Line Power | 52 |
| 3.7.12.3 | Power Plugs, Cords, and Outlets | 52 |
| 3.7.12.4 | Leakage Currents | 52 |
| 3.7.12.5 | Power Factor | 52 |
| 3.7.12.6 | Inrush Current | 52 |
| 3.7.12.7 | Harmonic Distortion | 53 |
| 3.7.12.8 | Circuit Overload Protection | 53 |
| 3.7.12.9 | Input Power Conditions | 54 |
| 3.7.13 | DC Power | 54 |
| 3.7.13.1 | Transformer Isolation of Non-Switching DC Power Supplies | 54 |
| 3.7.14 | Removable Parts and Mating Connectors | 54 |
| 3.7.15 | Electronic Equipment Assembly Requirements | 54 |
| 3.7.15.1 | Component Mounting | 55 |
| 3.7.15.2 | Printed Circuit Boards | 55 |
| 3.7.15.3 | Assembly | 55 |
| 3.7.15.4 | Wire Wrap | 55 |
| 3.7.16 | Shelf Life | 55 |
| 3.7.17 | Accessibility | 55 |
| 3.7.17.1 | General | 55 |
| 3.7.17.2 | Enclosures | 55 |
| 3.7.17.3 | Maintenance Access | 56 |
| 3.7.18 | Thermal Design | 56 |
| 3.7.19 | Materials Processes and Parts | 56 |
| 3.7.19.1 | Dissimilar Metals | 56 |
| 3.7.19.2 | Metals, Corrosion Resistance | 56 |
| 3.7.19.3 | Corrosion-Resisting Ferrous Alloys | 56 |
| 3.7.19.4 | Flammable Materials | 57 |
| 3.7.20 | Equipment Manufacturing Processes | 57 |
| 3.7.20.1 | Strain Relief | 57 |
| 3.7.20.2 | Painted Finish | 57 |
| 3.7.21 | Electrical Parts | 57 |
| 3.7.21.1 | Batteries | 57 |
| 3.7.21.2 | Overcurrent Devices | 58 |
| 3.7.21.3 | Connectors with Thermocouple Contacts | 59 |
| 3.7.21.4 | Electrical Power Connectors | 59 |
| 3.7.21.5 | Switches | 59 |
| 3.7.21.6 | Wiring | 59 |
| 3.7.22 | Toxic Products | 61 |
| 3.7.23 | Nameplates and Markings | 61 |
| 3.7.23.1 | Nameplates | 61 |
| 3.7.23.2 | Markings | 64 |
| 3.7.24 | Workmanship | 64 |
| 3.7.24.1 | Cleaning | 64 |
| 3.7.24.2 | Threaded Parts or Devices | 64 |
| 3.7.24.3 | Shielding | 64 |
| 3.7.24.4 | Containment | 64 |
| 3.7.24.5 | Insulation | 65 |
| 3.7.24.6 | Clearance | 65 |
| 3.7.25 | Personnel Safety | 65 |
| 3.7.25.1 | Electrical Safety | 65 |
| 3.7.25.2 | Ground potential | 66 |
| 3.7.25.3 | Shielding | 66 |
| 3.7.25.4 | Guarding of RF Voltages | 66 |
| 3.7.25.5 | Interlocks | 66 |
| 3.7.25.6 | High Voltage Protection | 66 |
| 3.7.25.7 | High Current Protection | 67 |
| 3.7.25.8 | Electrical Connectors | 67 |
| 3.7.25.9 | Mechanical Hazards | 67 |
| 3.7.25.10 | Mechanical Interconnection | 67 |
| 3.7.25.11 | Glass Fibers | 67 |
| 3.7.25.12 | Safety Markings, Signs, Tags, and Symbols | 67 |
| 3.7.25.13 | Display Warnings | 69 |
| 3.7.26 | Mechanical Parts | 70 |
| 3.7.26.1 | Controls and Switches | 70 |
| 3.7.26.2 | Fastener Hardware | 71 |
| 3.7.26.3 | Ventilating Fan Motors | 71 |
| 3.7.26.4 | Bearings | 71 |
| 3.7.27 | Human Engineering | 71 |
| 3.7.27.1 | Noise Criteria | 71 |
| 3.7.27.2 | Identification of Noise Hazard Areas and Equipment | 71 |
| 3.7.27.3 | Display Information | 72 |
| 3.7.27.4 | Virtual Displays - Flash | 72 |
| 3.8 | Installation | 72 |
| 4. | VERIFICATION | 73 |
| 4.1 | Methods Of Verification | 73 |
| 4.1.1 | Inspection (I) | 73 |
| 4.1.2 | Analysis (A) | 73 |
| 4.1.3 | Demonstration (D) | 73 |
| 4.1.4 | Test (T) | 73 |
| 4.2 | Test Allocation | 73 |
| 4.2.1 | Development Test (DT) | 73 |
| 4.2.2 | Operational Test (OT) | 73 |
| 4.3 | General Procedures | 74 |
| 4.3.1 | Test Tools | 74 |
| 4.3.1.1 | Electronic Test Equipment | 74 |
| 4.3.1.2 | Test Simulators | 74 |
| 4.3.1.3 | Antenna Test Range | 74 |
| 4.3.2 | Electrical Grounding | 74 |
| 4.4 | Specific Procedures | 74 |
| 4.4.1 | Environmental Conditions | 74 |
| 4.4.1.1 | Non-Operating Conditions | 74 |
| 4.4.1.2 | Operating Conditions | 75 |
| 4.4.2 | Electromagnetic Compatibility (EMC) | 78 |
| 4.4.3 | DVOR 30 Hz Amplitude Modulation | 80 |
| 4.4.4 | COVR Output Signal Spectrum | 80 |
| 4.4.5 | Antennas | 80 |
| 4.4.5.1 | CVOR Antenna Input Impedance | 80 |
| 4.4.5.2 | DVOR Antenna Input Impedance | 80 |
| 4.4.5.3 | Insulation Resistance | 81 |
| 4.4.5.4 | DVOR Field Monitor Antenna | 81 |
| 4.4.6 | Power Factor | 81 |
| 4.4.7 | Inrush Currents | 82 |
| 4.5 | Verification Requirements Traceability Matrix | 84 |
| 5. | Packaging | 208 |
| 6. | Notes | 209 |
| 6.1 | Definitions | 209 |
| 6.1.1 | 30 Hz AM Signal | 209 |
| 6.1.2 | 30 Hz FM Signal | 209 |
| 6.1.3 | Carrier Power | 209 |
| 6.1.4 | Continuous Wave (CW) | 209 |
| 6.1.5 | Control | 209 |
| 6.1.6 | Duantal Error | 209 |
| 6.1.7 | Electromagnetic Interference (EMI) | 209 |
| 6.1.8 | Executive Monitor | 209 |
| 6.1.9 | Failure | 209 |
| 6.1.10 | Fault Condition | 210 |
| 6.1.11 | FM Subcarrier Signal | 210 |
| 6.1.12 | Ground Check | 210 |
| 6.1.13 | Inrush Current | 210 |
| 6.1.14 | Line Replaceable Unit (LRU) | 210 |
| 6.1.15 | Mean Frequency | 210 |
| 6.1.16 | Mean Time Between Failures (MTBF) | 210 |
| 6.1.17 | Monitor Antenna | 210 |
| 6.1.18 | Monitor Delay Time | 210 |
| 6.1.19 | Octantal Error | 211 |
| 6.1.20 | Positive Attachment | 211 |
| 6.1.21 | Quadrantal Error | 211 |
| 6.1.22 | Reference Ground Check | 211 |
| 6.1.23 | Remote Monitoring and Logging System (RMLS) | 211 |
| 6.1.24 | Remote Maintenance Monitoring | 212 |
| 6.1.25 | Spurious Radiation | 212 |
| 6.1.26 | Stray Radiation | 212 |
| 6.1.27 | Transistor-Transistor Logic (TTL) | 212 |
| 6.2 | Acronyms, Abbreviations, and Initializations | 212 |
| APPENDIX A - VOR FREQUENCY CHANNELIZATION | 214 |
LIST OF FIGURES
| FIGURE 31. VOR Block Diagram With CVOR Antenna System | 8 |
| FIGURE 32. VOR Block Diagram With DVOR Antenna System | 9 |
| FIGURE 33. Inrush Current Limit Ratios | 53 |
| FIGURE 34. Nameplates | 63 |
| FIGURE 35. Personnel Safety Sign Layout | 68 |
| FIGURE 41. Inrush Current Limit Measurements | 83 |
LIST OF TABLES
TABLE 41. Applicable Requirements From MIL-STD-461G 78
DRAFT FAA-E-37012 DRAFT
ix Introduction Scope This specification establishes the performance, design, test, manufacture, and acceptance requirements for the Conventional and Doppler configurations of the Very High Frequency (VHF) Omnidirectional Radio Range (VOR) System. The Conventional VOR (CVOR) and Doppler VOR (DVOR) systems described within this specification are intended to be separate, complete solutions without the use of conversion kits.
Overview The VOR system described herein is a radio frequency (RF) transmitter navigation system used for the transmission of signals to determine aircraft bearing from a ground station. The VOR system provides facility identification information and azimuth information to properly equipped users within a defined service volume.
Applicable Documents General The documents listed in this section are specified in sections 3 and 4 of this specification. This section does not include documents cited in other sections of this specification, or recommended for additional information, or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in sections 3 and 4 of this specification, whether or not they are listed in this section.
Government Documents FAA Specifications, Standards and Handbooks The following specifications, standards, and handbooks of the exact revision level shown below form a part of this document to the extent specified herein.
| FAA-C-1217H, Chg. 1 |
| Electrical Work, Premises Wiring (2021) |
FAA-E-3039A
Protocol Specification, Common Message Handling Protocol (CMHP) (2018)
| FAA-G-2100H |
| Electronic Equipment, General Requirements (2005) |
| FAA-STD-001B |
| Color and Texture of Finishes for NAS Equipment (1976) |
| FAA-STD-019F, Chg. 3 |
| Lightning And Surge Protection, Grounding, Bonding And Shielding Requirements For Facilities And Electronic Equipment (2020) |
| FAA-STD-032 |
| Design Standards for National Airspace System Facilities (1996) |
| FAA-STD-049 |
| Standard, Fiber Optic Telecommunication, Systems and Equipment (1994) |
Other Government Documents, Drawings and Publications The following other Government documents, drawings, and publications of the exact revision level shown below form a part of this document to the extent specified herein.
| MIL-DTL-5541F |
| Detail Specification Chemical Conversion Coatings On Aluminum And Aluminum Alloys (2006) |
| MIL-HDBK-454B |
| General Guidelines for Electronic Equipment (2007) |
| MIL-STD-461G |
| Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment (2015) |
| MIL-STD-810H |
| Test Method Standard, Environmental Engineering Considerations and Laboratory Tests (2019) |
| MIL-STD-889C |
| Standard Practice, Dissimilar Metals (2016) |
| NAS-IC-51015108-01, v0.92 |
| FAA Interface Control Document, Remote Monitoring and Logging System (RMLS) To Remote Monitoring Subsystem (RMS) Using Common Message Handling Protocol (CMHP) (2014) |
Non-Government publications The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)
| ASHRAE Standard 52.2 |
| Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size (2020) |
(Copies of this document are available online at www.ashrae.org.)
American Society of Mechanical Engineers (ASME)
| ASME Y14.44 |
| Reference Designations for Electrical and Electronics Parts and Equipment (2008) |
(Copies of this document are available online at www.asme.org) Electronic Components Industry Association (ECIA)
| EIA/ECA-310E |
| Standard, Cabinets, Racks, Panels and Associated Equipment (2005) |
(Copies of this document are available online at www.ecianow.org) European Civil Aviation Equipment (EUROCAE)
| ED-137/1C |
| Interoperability Standards for VoIP ATM Components, Volume 1: Radio (2017) |
| ED-137/1C, Chg. 1 |
| Interoperability Standards for VoIP ATM Components, Volume 1: Radio, Change 1 (2020) |
(Copies of these documents are available online at www.eurocae.net) Health Physics Society (HPS)
| N2.1-2011 |
| Radiation Symbol (2011) |
(Copies of this document are available online at www.hps.org.)
Institute of Electrical and Electronics Engineers (IEEE)
| IEEE 149-1979 |
| Test Procedures for Antennas (1979) |
| IEEE C62.41.2-2002 |
| IEEE Recommended Practice on Characterization of Surges in Low Voltage (1000 V and Less) AC Power Circuits (2002) |
| IEEE 519-2014 |
| IEEE Recommended Practice and Requirements for Harmonic Control in Electric Power Systems (2014) |
| IEEE C95.1-2019 |
| Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic, and Electromagnetic Fields, 0 Hz to 300 GHz (2019) |
| IEEE C95.2-2018 |
| Standard for Radio-Frequency Energy and Current-Flow Symbols (2018) |
| IEEE 1100-2005 |
| Recommended Practice for Powering and Grounding Electronic Equipment (2005) |
(Copies of these documents are available online at www.ieee.org) Institute for Printed Circuits (IPC)
| IPC-CC-830C |
| Qualification and Performance of Electrical Insulating Compound for Printed Wiring Assemblies (2018) |
| IPC J-STD-001H |
| Requirements for Soldered Electrical and Electronic Assemblies (2020) |
| IPC-CM-770E |
| Guidelines for Printed Board Component Mounting (2004) |
| IPC-SM-780 |
| Component Packaging and Interconnecting with Emphasis on Surface Mounting (1988) |
| IPC-A-600K |
| Acceptability of Printed Boards (2020) |
(Copies of these documents are available online at www.ipc.org) International Electrotechnical Commission (IEC)
| IEC 61000-3-2 |
| Electromagnetic compatibility (EMC) – Part 3-2: Limits for harmonic current emissions (equipment input current ≤ 16 A per phase) (2018) |
(Copies of this document are available online at www.iec.ch) National Electrical Manufacturers Association (NEMA)
| NEMA 250-2018 |
| Enclosures for Electrical Equipment (1000 Volts Maximum) (2018) |
| NEMA C18.1M, Part 1-2015 |
| American National Standard for Portable Primary Cells and Batteries with Aqueous Electrolyte – General and Specifications (2015) |
| NEMA C18.1M, Part 2-2019 |
| American National Standard for Portable Primary Cells and Batteries with Aqueous Electrolyte – Safety Standard (2019) |
| NEMA C18.2M, Part 1-2013 |
| American National Standard for Portable Rechargeable Cell and Batteries – General Specifications (2013) |
| NEMA C18.2M, Part 2-2014 |
| American National Standard for Portable Rechargeable Cell and Batteries – Safety Standard (2014) |
| NEMA C18.3M, Part 1-2019 |
| American National Standard for Portable Lithium Primary Cell and Batteries – General Specifications (2019) |
| NEMA C18.3M, Part 2-2019 |
| American National Standard for Portable Lithium Primary Cell and Batteries – Safety Standard (2019) |
| NEMA WD 6-2016 |
| Wiring Devices – Dimensional Specifications (2016) |
| NEMA Z535.1-2017 |
| American National Standard for Safety Colors (2017) |
| NEMA Z535.2-2011 |
| American National Standard for Environmental and Facility Safety Signs (2017) |
(Copies of these documents are available online at www.nema.org) National Fire Protection Association (NFPA)
| NFPA 70 |
| National Electric Code 2020 Edition (2019) |
(Copies of this document are available online at www.nfpa.org.)
SAE International
| AMS-STD-595 |
| Colors Used in Government Procurement (2017) |
(Copies of this document are available at http://www.sae.org.)
Underwriters Laboratories Inc. (UL)
| UL 268 |
| Standard for Smoke Detectors for Fire Alarm Systems (2016) |
| UL 489A |
| Standard for Circuit Breakers for Use in Communications Equipment (2018) |
| UL 900 |
| Standard for Safety Air Filter Units, Edition 8 (2015) |
(Copies of this document are available online at www.ul.com) Order of Precedence In the event of a conflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.
Requirements The requirements of this specification are applicable to both the CVOR and DVOR configurations unless explicitly stated otherwise.
General Requirements System Characteristics The CVOR system shall provide:
1. Amplitude modulation (AM) of the carrier signal by 9960 Hz ±480 Hz;
2. A 1020 Hz AM signal with identification keying to produce alphabetic characters;
3. Voice modulation in the range of 300 Hz through 3000 Hz;
4. Two RF double sideband outputs that are 30 Hz removed from (30 Hz above and below) the carrier reference input; and,
5. A 9960 Hz frequency modulated (FM) subcarrier signal for purposes of amplitude modulating the carrier output.
6. A system configuration with four Alford loop antennas.
The DVOR system shall provide:
7. AM of the carrier signal by 30 Hz;
8. A 1020 Hz AM signal with identification keying to produce alphabetic characters;
9. Voice modulation in the range of 300 Hz through 3000 Hz;
10. Two RF sideband outputs that are 9960 Hz above, and two RF sideband outputs that are 9960 Hz below the carrier reference input; and,
11. A distributor function that is synchronized to the 30 Hz AM and switches the sideband signals to the appropriate antennas.
12. A system configuration with either 48 or 50 sideband antennas (3.2.5.2).
VOR Antenna Compatibility The VOR shall operate with the CVOR or DVOR antenna systems using interconnecting cables up to a maximum length of 500 ft. See Figure 31 below for the CVOR block diagram and Figure 32 for the DVOR block diagram.
FIGURE 31. VOR Block Diagram With CVOR Antenna System
FIGURE 32. VOR Block Diagram With DVOR Antenna System Integrity of Signal
a. The integrity of the signal, expressed as a probability of not transmitting false guidance signals, shall be equal to or greater than 0.999999999, which is equivalent to 1-(1 x 10‑9).
b. The implemented system design shall ensure that no single event or failure causes an out-of-tolerance azimuth condition to occur and persist beyond the monitor response time.
c. The implemented system design shall provide mechanisms that prevent unintended changes to parameters that cause an out-of-tolerance azimuth condition and/or unintended outage.
Accuracy The ground station contribution to the error in the bearing information conveyed by the horizontally polarized radiation from the VOR for all elevation angles between 0 degrees and 60 degrees, measured from the center of the VOR antenna system, shall be within ±2 degrees.
Environmental Operating Conditions Unless otherwise stated, all requirements of this specification shall be met over the full range of service conditions appropriate for the equipment described. The following VOR operating and non-operating environmental condition requirements were derived from MIL-STD-810.
Non-Operating Conditions Non-Operating Temperature Range The VOR system packaged for storage, shipping, or transporting (non-operating) shall withstand a temperature range of 46°C to +71°C.
Non-Operating Altitude The VOR system packaged for storage, shipping, or transporting (non-operating) shall withstand atmospheric pressure of 575 to 1025 mbar (equivalent to approximately 15 000 ft above sea level in a standard atmosphere down to approximately 300 ft below sea level).
Vibration The VOR system shall not be damaged when subjected to the vibrations listed in Table 514.8C-I, Method 514.8 Annex C of MIL-STD-810, and the exposure duration provided in Annex C paragraph 2.1.4.
Shock The VOR system shall not be damaged when subjected to the mechanically induced shock as specified in Method 516.8, Procedure II of MIL-STD-810.
Operating Conditions Outdoor Temperature All outdoor equipment shall operate in the temperature range of -46°C to +50°C.
Indoor Temperature All indoor equipment shall operate in the temperature range of 10°C to +50°C.
Rain All outdoor equipment shall operate while exposed to wind-blown rain, at a rate of 1.7 mm/minute (4 inches/hour), and up to 18 m/s (40 mph) blowing wind.
Operating Altitude All indoor and outdoor equipment shall operate over the atmospheric pressure range of 700 to 1025 mbar (equivalent to approximately 10 000 ft above sea level in a standard atmosphere down to approximately 300 ft below sea level).
Wind Velocity The VOR antenna system shall operate in wind conditions up to 100 mph velocity.
Ice Loading The VOR antenna system shall withstand up to 0.5 inches accumulation of clear ice on all outdoor components.
Humidity
a. Equipment shall operate within a relative humidity range from 5% to 100% when the temperature is 40°C or less.
b. Above 40°C, the equipment shall operate with a relative humidity based upon a dew point of 40°C.
Fine Sand (Dust) The outdoor equipment shall be impervious to sand and dust intrusion, as described in 4.4.1.2.7.
Lightning Protection The electronic equipment shall be provided with devices that protect against atmospheric electricity and transients from nearby lightning strikes in accordance with FAA-STD-019.
Electromagnetic Interference (EMI) / Electromagnetic Compatibility (EMC)
a. The system shall be successfully tested in accordance with the requirements in 4.4.2.
b. The equipment manufacturer or supplier shall ensure the system meets the requirements of Federal Communication Commission (FCC) Rules and Regulations, Code of Federal Regulations (CFR) Title 47, Chapter 1: Subchapter A, Part 2 and Part 15; and, Subchapter D, Part 87.
c. All components of the Remote Maintenance Monitoring (RMM) subsystem and any other computing devices shall meet the requirements for Class A computing devices in accordance with FCC Rules and Regulations, CFR Title 47, Chapter 1, Subchapter A, Part 2, subpart J, (Frequency Allocations and Radio Treaty Matters; General Rules and Regulations).
Transmitter Requirements Operating Channels
a. The system shall operate without modifications within the frequency band from 108 MHz to 118 MHz.
b. The transmitter shall transmit on the frequency that corresponds to the assigned channel without physical equipment modification or special test equipment. See Appendix A for current channelization.
c. Tuning of the antenna and CVOR bridge (Government Furnished Equipment (GFE)) shall be exempt from the requirement in b. above.
Channel Frequency and Stability
a. The transmitted frequency shall not vary by more than ±0.0005% from the assigned frequency under the initial (room temperature) conditions.
b. Over the service conditions listed in 3.1.5.2, the transmitted frequency shall not vary by more than ±0.001% from the assigned frequency.
c. A sample of the unmodulated transmitter output signal shall be provided on a front panel Sub-Miniature version-A (SMA) female connector with a 50 Ω removable termination.
d. The output level for the required signals in c. above shall be 0 ±3 dBm.
RF Tuning
a. The transmitter shall be capable of operating on any channel assignment within its design range without the need for adjustments or tuning beyond the change of system parameter values.
b. RF circuit components shall not be damaged as the result of deliberate or inadvertent maladjustment of tuning and level controls over their full range of adjustment.
Carrier Transmitter Transmitter Power Output
a. The transmitter shall be capable of providing at least 150 W carrier power output into a 50 Ω load as measured at the output of the transmitter cabinet.
b. Power requirements shall be met with amplitude modulation of not less than 80% (total) of those signals specified in 3.2.2.4.
Carrier Output Level and Control
a. The power output shall be adjustable throughout a range of at least 25 W through 150 W with the output automatically maintained within ±0.5 dB.
b. The transmitter shall require no mechanical/hardware change to operate in the specified settings in a. above.
Carrier Power Stabilization After 1 minute of power being applied to the transmitter, and within 6 s of being switched to operational mode, the transmitter output power shall be at least 90% of the nominal output.
Carrier Modulation Modulation Levels The following AM levels for the radiated signal shall be established and maintained within ±1%:
a. CVOR modulation levels:
1. 9960 Hz – 30%
2. Voice peak 300 Hz – 3000 Hz – 30%
3. 1020 Hz identification – 5%
b. DVOR modulation levels:
1. 30 Hz AM signal – 30%
2. Voice peak 300 Hz – 3000 Hz – 30%
3. 1020 Hz identification – 5% Output Signal Spectrum Spurious radiation components within the specified frequency bands on both sides of the carrier signal frequency shall not exceed the levels tabulated in the following paragraphs for the modulation type and levels indicated. Except as noted below, all harmonics and spurious radiation greater than 63 kHz removed from the assigned frequency shall not exceed 50 mW.
Reference Modulation The transmitter shall be capable of amplitude modulation to a depth of 80%.
CVOR 9960 Hz Amplitude Modulation
a. The transmitter shall be capable of amplitude modulation by the 9960 Hz FM subcarrier to a depth of 30 ±1%.
b. Provision shall be provided such that the 9960 Hz FM can be adjusted to achieve amplitude modulation from 20% to 40%.
c. With the modulation level above in a., the levels of the harmonics of the 9960 Hz shall not exceed the values indicated:
| Frequency Band |
| Level Below Fundamental |
| 1. |
| 9960 Hz (reference) |
| 0 dB |
| 2. |
| 15 kHz through 18 kHz |
| 15 dB |
| 3. |
| 18 kHz through 27 kHz |
| 32 dB |
| 4. |
| 27 kHz through 37 kHz |
| 52 dB |
| 5. |
| Above 37 kHz |
| 62 dB |
9960 Hz Mean Frequency Stability The mean frequency (see 6.1.15) of the 9960 Hz FM subcarrier signal shall be 9960 Hz ±0.1%.
Subcarrier Phase Control and Stability
a. A phase shift control shall be provided in the 30 Hz reference signal of the 9960 Hz FM subcarrier generator.
b. This control shall provide a range of 0.00 degrees to 359.99 degrees of phase shift between the 30 Hz reference signal and the 30 Hz zero crossover(s) of the RF sideband(s).
c. The phase shift control shall be in increments of 0.01 degrees or less.
d. Once the phase shift control is set, the phase stability between the 30 Hz reference signal and the 30 Hz zero crossover point(s) of the RF sideband(s) shall remain constant within ±0.1 electrical degrees of the 30 Hz signal.
9960 Hz Frequency Modulation
a. The 9960 Hz generator shall be frequency modulated by the 30 Hz audio signal (30 Hz reference signal).
b. The 30 Hz reference signal shall cause the 9960 Hz generator to deviate by ±480 Hz (deviation ratio of 16).
c. This deviation (b.) shall be constant within ±15 Hz.
9960 Hz Level and Stability The level and stability of the 9960 Hz signal shall fulfill the requirements of subparagraph 3.2.2.4.1.
9960 Hz Amplitude Modulation Amplitude modulation of the 9960 Hz signal due to frequency deviation shall not exceed a value of 2.0%.
DVOR – 30 Hz Amplitude Modulation
a. The transmitter shall be capable of amplitude modulation by a 30 Hz signal to a depth of 30 ±1%.
b. Provision shall be provided such that the 30 Hz AM can be adjusted to achieve amplitude modulation from 20% to 40%.
c. With this modulation level, the levels of the harmonics of the 30 Hz shall not exceed the values indicated:
| Frequency |
| Level Below Fundamental |
| 1. |
| 30 Hz (reference) |
| 0 dB |
| 2. |
| 60 Hz |
| 32 dB |
| 3. |
| 90 Hz |
| 50 dB |
| 4. |
| 120 Hz |
| 60 dB |
| 5. |
| Beyond 120 Hz |
| 60 dB |
30 Hz Mean Frequency Stability The mean frequency (see 6.1.15) of the 30 Hz AM signal shall be 30 Hz ±0.01%.
DVOR – Phase Control and Stability
a. An adjustable phase control shall be provided to permit setting of the zero crossover of the 30 Hz signal with respect to the center of the interval of time during which the upper sideband (USB) signal is fed to the first antenna output (No. 1) of the distributor.
b. This control shall provide a range of 0.00 degrees to 359.99 degrees of phase shift to the 30 Hz signal.
c. The phase shift shall be in increments of 0.01 degrees or less.
d. For any initial setting of the phase adjust control in a. above, the variation of the zero crossover of the 30 Hz amplitude modulated carrier signal with respect to the distributor switching sequence described in 3.2.4.1 shall not exceed ±0.2 electrical degrees of the 30 Hz signal.
Identification Modulation
a. The identification audio signal generator shall provide a sinusoidal 1020 Hz output signal for keyed or continuous tone to amplitude modulate the carrier output signal.
b. Output for keying a Distance Measuring Equipment (DME) shall be provided that employs an isolated, solid state relay with contact resistance lower than 250 Ω, capable of sinking a current of 20 mA and withstanding an open circuit voltage of 50 VDC.
c. Alternately to the Morse Code keying, the DME keying output shall be selectable to provide a Morse Code synchronization signal to initiate operation of the DME’s internal identification keyer.
1020 Hz Frequency Stability The stability of 1020 Hz frequency shall be within ±0.5%.
Harmonic Distortion The total harmonic distortion of the 1020 Hz audio signal (continuous tone output) shall not exceed 3.0%.
Output Level and Stability
a. The oscillator/keyer shall provide adjustable levels sufficient to amplitude modulate the carrier output from 3 to 8%.
b. The identification amplitude modulation of the carrier output shall be maintained to within ±1%.
Identification Keying Identification Keying Source
a. The keyer shall operate to key the 1020 Hz audio signal into the dot-dash characters of International Morse Code representing any three-letter combination of the alphabet and the four-letter code of “T-E-S-T”.
b. The alphabetic characters shall be programmable through the maintenance data terminal (MDT).
Identification Keying Control The transmitter shall provide controls to:
a. Enable/disable identification keying;
b. Program the keyer to operate in association with Tactical Air Navigation (TACAN)/DME equipment such that:
1. Every fourth identification cycle causes keying pulses to be provided to the TACAN/DME.
2. The other identification cycles shall be for the VOR.
c. Enable/disable continuous transmission of identification signal pulse groups;
d. Select three-letter alphabetic Morse Code characters in normal operation;
e. Select a mode in which the identification code is set to “T-E-S-T”; and,
f. Automatically generate a maintenance alert when the identification code is selected as “T-E-S-T”.
Identification Signal Characteristics
a. The identification signal shall consist of the transmission of the code in dots and dashes (Morse Code).
b. The repetition rate for the three- or four-letter identification code group shall be eight times per minute, except as noted in 3.2.2.4.4.4.2-b above.
c. The maximum key down time shall not exceed 5 s per identification code group.
d. The dots shall have a time duration of 0.1 s to 0.125 s.
e. The dashes shall be three times the duration of the dots ±5%.
f. The duration between dots and/or dashes shall be equal to that of one dot ±5%.
g. The time duration between letters shall be equal to the duration of three dots within ±5%.
Voice Modulation Dry Circuit Input
a. The equipment shall include provisions to accept an alternate voice input from GFE (e.g., Automatic Terminal Information Service (ATIS), Flight Service Station (FSS)) that may be used to continuously modulate the voice channel of the VOR transmitter when it is not being modulated by voice as stated in 3.2.2.4.5.2.
b. The equipment shall incorporate a shielded 600 Ω audio input transformer.
c. The primary winding shall accommodate input levels as high as +6 dBm with a 600 Ω input impedance.
d. The transformer shall incorporate multiple shields for protection against hum pickup due to external magnetic fields.
e. Hum pickup shall not exceed 280 mV.
Voice Over Internet Protocol
a. The equipment shall include provisions to accept a voice over internet protocol (VoIP) input that will be used to continuously modulate the voice channel of the VOR transmitter when it is not being modulated by voice on the dry circuit input (3.2.2.4.5.1).
b. The interface shall be in accordance with EUROCAE ED-137, Volume 1, and selectively, either internet protocol (IP) version 4 (IPv4) or IPv6.
c. This VoIP interface (b.) shall be a separate connection than that described in 3.5.10.
Voice Input and Modulation Circuitry
a. The transmitter shall contain the necessary circuitry to accept voice frequencies in the range of 300 Hz to 3000 Hz, amplify, and provide automatic gain control to achieve amplitude modulation of the carrier output up to 30%.
b. The voice modulation circuitry shall operate over a 20 dB range (3.2.2.4.5.4) given an input signal (3.2.2.4.5.1) range between -30 dBm and +6 dBm.
Automatic Gain Control
a. An automatic gain control circuit shall be incorporated in the voice frequency amplifier circuitry.
b. The gain control shall maintain the output within ±1 dB over a 20 dB range of input signal change.
Audio Response The voice frequencies transmitted by the carrier amplifier shall be limited by the voice amplifier response and filtering techniques to conform to these characteristics:
| Frequency Range |
| Response |
| a. |
| 300 Hz – 3000 Hz |
| The response shall be flat to within 1.5 dB (except 1020 Hz see 3.2.2.4.5.6). |
| b. |
| Below 300 Hz |
| 1. The response shall decrease smoothly. |
2. The response to 30 Hz shall be at least 50 dB below the response at 600 Hz.
| c. |
| Above 3000 Hz |
| 1. The response shall decrease smoothly to 6000 Hz. |
2. Above 6000 Hz the response shall be at least 50 dB below the response at 600 Hz.
Note: These requirements are imposed to ensure non-interference with the navigation signals, 30 Hz, 1020 Hz, and 9960 Hz.
Identification Notch Filter
a. A notch filter shall be incorporated into the voice frequency amplifier to reduce the 1020 Hz component by at least 30 dB below the normal amplifier response, measured at 600 Hz.
b. The rejection band shall be centered at 1020 Hz.
c. At the frequencies of 1000 Hz and 1040 Hz, the response shall be within 6 dB of the 600 Hz response.
d. For frequencies of 990 Hz and less, and 1050 Hz and greater, the requirements of 3.2.2.4.5.5 shall apply.
Amplifier Gain The overall gain of the voice frequency amplifier (including gain control circuitry and any fixed gain circuits) shall be sufficient to provide amplitude modulation of the carrier signal (not to exceed 30%), when the power output is 150 W.
Sideband Output Characteristics Conventional Sideband Characteristics
a. Two RF double sideband outputs shall be provided that are 30 Hz removed from (30 Hz above and below) the carrier center frequency.
b. The two RF sideband outputs shall contain 30 Hz components that are at audio phase quadrature (90 degrees) with each other.
Note: These RF double sidebands are combined in the VOR antenna system in a manner such that a 30 Hz amplitude modulated carrier signal is produced (nominal amplitude modulation is 30%).
Sideband Output Power Control
a. Each sideband output shall be capable of providing a minimum of 0.25 W through 6 W power output when terminated into a 50 Ω resistive load.
b. Each sideband output shall be individually adjustable in increments of 0.001 W.
c. The two sideband signal power levels shall be automatically maintained within 1.0% of each other.
d. Provision shall be provided such that the two sideband outputs can be adjusted simultaneously to achieve amplitude modulations from 20% to 40%.
e. The power outputs specified in a. above shall automatically track the carrier power (3.2.3.2) to provide constant modulation within ±1.0%.
Carrier Frequency Suppression The carrier frequency component present within each sideband RF output shall not exceed a level which is 30 dB below the power level of each sideband output.
30 Hz Harmonic Distortion The total harmonic distortion of the 30 Hz envelope shall not exceed 1.0%.
Output Signal Spectrum
a. Spurious signal components within the bands of frequencies from 300 Hz to 9000 Hz above and below the carrier frequency shall not exceed a level which is 50 dB below the level of either 30 Hz sideband component as measured at the sideband output connector.
b. Signals more than 9000 Hz removed from the carrier signal shall not exceed a level of 60 dB below the level of either 30 Hz sideband component as measured at the sideband output connector.
c. The levels of the harmonics of the 30 Hz shall not exceed the values indicated below:
| Frequency Band |
| Level Below Reference |
| 1. |
| Upper sideband (USB) (fc +30 Hz) |
| 0 dB (reference) |
| 2. |
| Lower sideband (LSB) (fc -30 Hz) |
| 0 dB (±0.1 dB) |
| 3. |
| Carrier (fc) |
| 30 dB (3.2.4.1.2) |
| 4. |
| Second harmonic (fc ±60 Hz) |
| 30 dB (balanced within 1 dB) |
| 5. |
| Third harmonic (fc ±90 Hz) |
| 30 dB (balanced within 2 dB) |
| 6. |
| Fourth harmonic (fc ±120 Hz) |
| 40 dB (balanced within 2 dB) |
| 7. |
| Fifth harmonic (fc ±150 Hz) |
| 40 dB (balanced within 2 dB) |
| 8. |
| All higher order harmonics of 30 Hz |
| 50 dB |
Output Envelope Symmetry The audio phase relationship of the two outputs shall be in phase quadrature, 90 ±2 degrees.
Note: The correct separation of the zero points of both output envelopes will address 3.2.3.1.4 carrier (fc) suppression requirement.
RF Phase
a. The RF phase relationship of the two sideband outputs shall reverse at 90 degree intervals of the 30 Hz audio modulating signal.
b. At the phase reversal in a. above, the phase accuracy shall be alternately 0 ±3 degrees and 180 ±3 degrees, referenced to the carrier output phase in c. below.
c. The RF phase of the two sideband outputs shall be maintained to within ±3 degrees referenced to the carrier output phase.
d. Controls shall be provided to adjust the phase of the two sideband outputs individually, relative to the carrier output phase by at least ±60 degrees in increments of 1 degree.
Deviation from Average Maximum Envelope Amplitude For one complete period of the 30 Hz modulation signal, any individual maximum envelope amplitude, at both the outputs, shall not deviate by more than 0.5% from the average of all such maximums (averaged over a period of at least five complete cycles of 30 Hz).
Output Circuit Loading
a. The sideband output circuitry shall provide the specified performance (3.2.3.1) when connected to a load with any value of voltage standing wave ratio (VSWR) up to 1.5:1.
b. The sideband output transmitter shall not be damaged as the result of any degree of mismatch, including open and short, at any point on the output transmission line(s).
Sideband Power Stabilization After one minute of power being applied to the transmitter, and within 6 s of being switched to operational mode, the sideband output power shall be at least 90% of the nominal output.
Power Output Measurement Directional couplers and detectors shall be incorporated at each sideband output for measurement of forward and reverse power and VSWR, for display locally and remotely.
Doppler Sideband Characteristics The DVOR sideband transmitter shall provide two sideband outputs that are nominally 9960 Hz above and 9960 Hz below the frequency of the VOR carrier transmitter, respectively.
Sideband Output Power Control
a. The sideband transmitter shall be capable of providing at least 10 W of continuous wave (CW) power at each sideband output.
b. The output power shall be adjustable throughout a range of at least 2.5 W to 10 W, in 0.5 W increments.
c. After initial setup, sideband power outputs shall automatically track the carrier output power with an accuracy of within ±0.25 dB for carrier transmitter power changes of +1.0 dB to -3.0 dB.
d. Provision shall be provided such that the four sideband outputs can be adjusted simultaneously to achieve amplitude modulations from 20% to 40%.
Output Frequencies
a. The USB transmitter frequency shall be fc + (9960 Hz ±10.0 Hz).
b. The LSB transmitter frequency shall be fc – (9960 Hz ± 10.0 Hz).
Output Phase
a. The phase of each sideband output signal shall be maintained such that there is no more than 12 degrees difference between the phase of the 9960 Hz beat frequency, produced by mixture of the sideband signal with the carrier reference signal, and the phase of the 9960 Hz reference signal.
b. Controls shall be provided to adjust the phase of the four sideband outputs individually, relative to the carrier output phase by at least +/-60 degrees in increments of 1 degree.
Stabilization and Response Time After one minute of power being applied to the transmitter, and within 6 s of being switched to operational mode:
a. The transmitter output frequency and phase shall meet the requirements in 3.2.3.2.2 and 3.2.3.2.3 above; and,
b. The sideband output power shall be at least 90% of the nominal output.
Sideband Modulation
a. The sideband RF voltage, as referenced to peak sideband power, shall vary as cos0.836(θ) within a tolerance of ±(0.09cos0.836(θ) + 0.009).
b. The LSB zero amplitude point shall be within ± 75 µs from the 0 degree reference point of the 30 Hz waveform.
Note: The modulation may be applied in the sideband transmitters.
Output Signal Spectrum Spurious radiation components within specified frequency bands on either side of the fundamental shall not exceed the following levels:
| Frequency Band |
| Level Below Fundamental |
| a. |
| 15 kHz through 18 kHz |
| 15 dB |
| b. |
| 18 kHz through 27 kHz |
| 32 dB |
| c. |
| 27 kHz through 37 kHz |
| 52 dB |
| d. |
| Above 37 kHz |
| 62 dB |
Carrier to Sideband Isolation The level of the carrier reference frequency in the output of either sideband output signal shall be at least 34 dB below the level of the sideband output signal.
Cross-Channel Isolation
a. The level of the USB signal present in the output of the LSB signal shall be at least 40 dB below the output level of the USB signal.
b. The level of the LSB signal present in the output of the USB signal shall be at least 40 dB below the output level of the LSB signal.
Stray Radiation With the transmitter operating at maximum output power (3.2.3.2.1), stray radiation shall not exceed a level of 14.0 mW effective radiated power. This requirement shall be met with the equipment in or out of its enclosure.
Power Output Measurement Directional couplers and detectors shall be incorporated at each sideband output for measurement of forward and reverse power and VSWR for display locally and remotely.
Doppler VOR Distributor Assembly The DVOR distributor assembly is used to provide sequential electronic switching of the DVOR sideband transmitter outputs in a counterclockwise direction, when viewed from above, to the circular array of 48 or 50 sideband antennas at the rate of 30 Hz.
Distributor Function
a. The distributor shall operate with two USB signals and two LSB signals from the sideband transmitters.
b. Separate switching channels for each sideband signal shall provide two separate modulated pulse trains of complementary waveforms (E1 and E2), one for subsequent application to odd numbered antennas and the other to even numbered antennas.
c. For a DVOR utilizing 50 sideband antennas in normal operation, each sideband output shall be applied to one antenna at a time by electronic switching for 1/750 second in the following repeating sequence:
1. E1 (USB) Antenna No. 1, 3, 5, 7, 9 --- 47, 49, 1 ---
2. E1 (LSB) Antenna No. 26, 28, 30, 32, 34 --- 22, 24, 26 --- (and 1/1500 second delayed with respect to the above)
3. E2 (USB) Antenna No. 2, 4, 6, 8, 10 --- 48, 50, 2 ---
4. E2 (LSB) Antenna No. 27, 29, 31, 33, 35 --- 23, 25, 27 ---
d. For a DVOR utilizing 48 sideband antennas in normal operation, each sideband output shall be applied to a one antenna at a time by electronic switching for 1/720 second in the following repeating sequence:
1. E1 (USB) Antenna No. 1, 3, 5, 7, 9 --- 45, 47, 1 ---
2. E1 (LSB) Antenna No. 24, 26, 28, 30, 32 --- 20, 22, 24 --- (and 1/1440 second delayed with respect to the above)
3. E2 (USB) Antenna No. 2, 4, 6, 8, 10 --- 46, 48, 2 ---
4. E2 (LSB) Antenna No. 25, 27, 29, 31, 33 --- 21, 23, 25 ---
e. In addition, means shall be provided through the MDT to disable the normal switching sequence and to cause the sideband outputs to be applied continuously to any selected pair of diametrically opposite antennas, or to remove the output to all antennas.
Insertion Loss
a. The insertion loss of the distributor shall not exceed 1.0 dB, as measured at the sideband input terminal relative to the output signal as measured at any of the corresponding sideband antenna output connectors.
b. The insertion loss shall vary by less than ±0.2 dB between each sideband channel, as measured from the distributor input to any of the distributor corresponding sideband antenna output connectors.
c. This requirement (b.) shall be met at all output connections with a VSWR of up to 2.5:1.
RF Phase Shift The RF phase shift shall be within ±5.0 degrees for each sideband channel, as measured from the distributor input to each of the corresponding distributor sideband antenna output connectors.
Switching Isolation
a. The distributor output shall be applied to the designated antennas only during the specified intervals of normal switching or whenever continuous radiation is selected (3.2.4.1-e).
b. During every other interval of the switching cycle, and when in a switched off condition, the level of output to any connector shall be at least 60 dB below the on signal level.
c. When the antennas are switched off, they shall be connected to a 50 Ω load.
Stray Radiation With the equipment operating at maximum sideband transmitter output power, stray radiation shall not exceed a level of 14.0 mW effective radiated power.
Distributor Mechanical Design
a. The distributor shall be designed to operate up to 500 ft away from the DVOR transmitter.
b. The distributor shall be mountable in a stand-alone rack.
c. The distributor shall be powered by a nominal 120 VAC source (backed-up by GFE power source).
d. The distributor shall operate in temperature and humidity ranges specified in 3.1.5.2 for outdoor environment.
Note: An open-design architecture is acceptable for the stand-alone rack in b. above.
CVOR Carrier, DVOR Carrier, and DVOR Sideband Antennas The requirements provided in this section (3.2.5) are applicable to the Alford loop style antennas.
CVOR Transmitting Antenna Sets Each antenna equipment set shall include the following:
a. Left-handed connected VOR loop antenna assembly (qty. 2), per drawing D-50399.
b. Right -handed connected VOR loop antenna assembly (qty. 2), per drawing D-50399.
c. VOR antenna pedestal (qty. 4), per drawing B-50400.
d. VOR polarizer pedestal furnished complete, per drawing B-50401.
e. VOR polarizer furnished complete, per drawing B-21547.
f. Antenna pedestal mounting support, per drawing D-50435.
g. VOR antenna support plate, per drawing B-50402.
h. VOR antenna pedestal mounting support (qty. 7), bonding segments, with screws, per drawing B-50403.
i. Balance-to-unbalance transformer (3.2.5.6) (qty. 4), per drawing DE-B-3428.
j. VOR antenna mounting plate locking wedge per drawing, DE-B-2132.
Note: The VOR Antenna Mounting Plate Locking Wedge is to be inserted into the gap between the 5-inch hole in the antenna support plate and the 4-inch pipe of the polarizer pedestal for the purpose of permanently maintaining the polarizer pedestal centered position and be resilient to the extent that "rattling" cannot occur when the polarizer pedestal is vibrated moderately.
DVOR Sideband Antennas
a. Each DVOR sideband antenna set shall include the following:
1. Doppler VOR sideband antennas (48 or 50), per drawings D-51007-1 and D-51007-2.
2. DVOR pedestals (48 or 50), per drawing B-50400.
3. Balance-to-unbalance transformer (3.2.5.6) (48 or 50), per drawing DE-B-3428.
4. Bracing kit, per drawing D-5615.
b. All antenna feed section jumpers shall be connected in the same manner, either right-handed connected or left-handed connected (see drawing D-50737).
Note: The number of DVOR sideband antennas will be either 48 or 50 depending on the design. Drawing D-5615, bracing kit, is particular to a DVOR with 50 sideband antennas and will be adjusted to accommodate a DVOR design with 48 sideband antennas.
DVOR Carrier Antenna
a. The split carrier DVOR antenna shall be furnished complete as shown on drawings DE-D-2744-1, DE-D-2744-2, DE-D-2744-3, DE-A-2744-4, and DE-D-2744-5.
b. The non-split carrier DVOR antenna shall be furnished complete in accordance with 3.2.5.2.
Fastener Materials Except where otherwise specified, all screws, nuts, and washers shall be stainless steel and comply with 3.7.19.3.
RF Connectors Each antenna assembly shall be provided with 3 type UG-58A/U receptacles for connection of the balance-to-unbalance transformer and the RF input cable.
Balance-to-Unbalance Transformers
a. Balance-to-unbalance transformers shall be fabricated using phase stable swept coaxial cable (e.g., ¼” Heliax).
b. The cable above (a.) shall be terminated at one end with type-N male connector, and include a second uninstalled connector for terminating the opposite cable end during installation.
c. Balance-to-unbalance transformers shall have a measured electrical length greater than a half-wavelength of a 108 MHz signal.
d. Markings shall be in accordance with drawing DE-B-3428D.
Antenna Nameplate
a. An antenna nameplate shall be mounted on the upper surface of the supporting cross and shall be fastened to the cross by means of four machine screws.
b. The equipment title on the nameplate shall be as follows:
1. VOR ANTENNA, 108-118 MHz; or,
2. DOPPLER VOR SIDEBAND ANTENNA; or,
3. DOPPLER VOR CARRIER ANTENNA.
c. The antenna nameplate shall include the FAA Type number.
Antenna…
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