1. Radio Frequency Interference Measurement System
For the
Quarterly Review of the NASA/FAA Joint University
Program for Air Transportation Research
Thursday April 5th, 2001
Douglas Burch, Undergraduate Research Associate
Avionics Engineering Center
Ohio University, Athens
Project Sponsor: FAA

2. Purpose of the RFIMS
Determine and isolate Radio Frequency Interference (RFI) problems with the National Airspace System (NAS) communication and navigation facilities through in-flight analysis of signal data collected on an airborne platform.

3. Radio Frequency Interference (RFI) Team Capabilities
Airport Airspace Analysis Modeling
- Prediction of interference levels within ILS/VOR/VHF
Communication service volumes.
Technical support for international frequency coordination.
Airborne RF data collection
- Characterization of RF environment through
measurement of signal levels and noise floor.
- Mitigation of ILS/VOR/VHF Comm/GPS RF
interference by determining frequency, type, direction and
ultimately location and cause.

4. Airborne Capabilities
Avionic Engineering Center’s Cessna Centurion (C210T) on a Radio Frequency Interference Mission.
Spectrum Analysis
Direction Finding (DF)
Radio Frequency Scanning
GPS Mapping
Signal generation & filtering
Audio & video data recording

5. Breakdown of Airborne Capabilities
Radio Direction Finding
Signal Analysis and Measurement
Audio Comparison & Recording

6. Radio Direction Finding
Audio
To Audio Switching
DF Receiver
ICOM IC-R8500
DF Antenna
Computer #3
DF Bearing Display & Processor Control / RCVR Control
DF Bearing Processor

7. Four-aerial Adcock Antenna

8. DF Receiver ICOM IC-R8500 Communications Receiver
Frequency Range:
– MHz
– MHz
– MHz

9. Software Control for the Receiver
Software Receiver Control in Sequential Search Mode.

10. Software Control for the Receiver
Software Receiver Control in Discrete Search Mode.

11. Portable RFIMS Rack

12. Software Control for DF Hardware

13. Signals Analysis and Measurement Components
RFIMS
Signals Analysis and Measurement Components
Rack Components
External Components
ILS Localizer/VOR Receiver
2-Channel Intercom
16-Channel A/D Converter
2 Embedded Systems
RF Control Unit
Spectrum Analyzer
RF Signal Generator
Digital Video Recorder
Digital Altimeter
GPS Receiver
2 Portable Computers

14. Signal Analysis and Measurement
Control from Data Stream Manager (DSM)
RF Signal Generator
Comm. Antenna
NAV Antenna
From DSM
RF Control and Switching
Digital Video Recorder
Comm RCVR
Spectrum Analyzer
From DSM
To DSM
Analog to Digital Converter
To Audio Switching
NAV RCVR
To DSM

15. Spec A / Sig Gen / Receiver

16. Control for the Spectrum Analyzer

17. Signal Analysis and Measurement Computer Control
RF Signal Generator
GPS Antenna
Computer #2 Moving Map Display
Control & Switching
GPS RCVR
Data Stream Manager (DSM)
Spectrum Analyzer
Computer #1 Master Control Data Logging Real-time Plotting
Spectrum Analyzer
Computer #4 Real-time Simulation Calculations
A/D Converter
Digital Meter

18. Moving Map Display

19. RFIMS Position

20. Audio Comparison & Recording
Scanner Antenna #1
Scanner Antenna #2
Scanner Receiver #1
Aircraft Intercom
Scanner Receiver #2
Two-Channel Audio Recorder
ICOM RCVR
Audio Switching
(Audio I/O)
COMM RCVR
Two-Channel Headphones

21. Airborne Missions Signal Analysis and Measurement Missions:
Simulate Signals to determine if they are a possible RFI threat to NAS communication facilities
Measure localizer signal to insure they are in proper working order.
Fly grid patterns to determine antenna coverage of the VOR.
Direction Finding Missions:
Determine and locate RF interference.

22. Airborne DF Statistics
Direction Finding Missions:
100 % success rate for RF interference missions.
50% resolved by Direction finding.
50% resolved using Audio Comparison.

23. Contact Information
Project Manager: Walter Phipps
Software Engineer: Janet Blazyk
Research Engineer: Kevin Johnson
Undergrad Assistant: Douglas Burch

24. Questions?