PROPOSAL FOR A GPS RECEIVER RUNWAY INCURSION OPERATIONAL SCENARIO FOR ASSESSING INTERFERENCE FROM ULTRAWIDEBAND TRANSMISSION SYSTEMS
Ed Drocella/National Telecommunications and Information Administration
September 27, 2000
SOURCE OF INFORMATION
- The information used in the development of the GPS receiver runway incursion operational scenario was taken from Document
No. RTCA/DO-247 The Role of the Global Navigation Satellite System (GNSS) in Supporting Airport Surface Operations.
- The following slides will examine parameters to be considered in the link budget analysis for the GPS receiver operational scenario.
FROM PAGE 64 OF DO-247:
UWB TRANSMISSION SYSTEM ASSUMPTIONS
- The UWB transmission system is located just off of the runway beyond the Object Free Area (OFA). The OFA is the region that is kept clear of objects.
- The UWB transmission systems will be located below the GPS receiver antenna.
- What are the UWB applications that should be considered?
FROM PAGE 65 OF DO-247:
Minimum Separation Distances According to
Airport/Aircraft Codes
| Airport/Aircraft
Code |
Taxiway
Width
(m) |
Max Outer Main
Gear Wheel
Span
(m) |
Margin Between
Main Gear and
Taxiway Edge
(m) |
Distance
Between
Centerline and
Object
(m) |
| A/I | 7.5 | 4.3 | 1.5 | 16.25 |
| B/II | 10.5 | 6.0 | 2.25 | 21.5 |
| C/III | 18 | 9.0 | 4.5 | 26.0 |
| C/III | 15 | 6.0 | 3.0 | 26.0 |
| D/IV | 23 | 14.0 | 4.5 | 40.5 |
| D/IV | 18 | 9.0 | 4.5 | 40.5 |
| E/V | 23 | 14.0 | 4.5 | 47.5 |
Note: Based on ICAO Airport Design Manual, Part 2, Taxiways, Aprons and Holding Bays, Doc 9157-AN/901, 1991.
MINIMUM DISTANCE SEPARATION
The minimum distance separation (Dsep) between the UWB transmission system and the GPS receiver can be determined from:
Dsep = [(DOFA)2 + (ha/c)2]1/2
where
DOFA is the object free area distance (m);
ha/c is the aircraft height (m).
GPS RECEIVER ANTENNA COUPLING
Based on the GPS antenna model shown below, the GPS receiver antenna gain in the direction of the UWB transmission system is -4.5 dBic.
GPS RECEIVER PERFORMANCE
- The performance and interference protection requirements for the GPS receiver used for runway incursion applications are not defined at this time.
- For precision approach landing applications, the GPS receiver performance is accuracy. However, for runway incursion applications, continuity may be more important than accuracy.
- Should tracking or acquisition modes of the GPS receiver be considered?
ADDITIONAL LINK BUDGET PARAMETERS
- Free space propagation will be assumed:
LFS = 36.4 + 20 Log (Dsep)
where Dsep is in meters
- A 6 dB safety margin will be included.
SUMMARY OF LINK BUDGET PARAMETERS FOR THE RUNWAY INCURSION OPERATIONAL SCENARIO
- Minimum distance separation (Dsep): Defined by the Object Free Area;
- Propagation Loss: Free space for the minimum distance separation (Dsep);
- GPS Receiver Antenna Gain: -4.5 dBic;
- Safety Margin: 6 dB