International Telemetry Consortium

Effects of Diminishing Spectrum Resources on Aeronautical

Telemetry

Jim Rizzo

Greg Strombo

AFFTC/ITC

Edwards AFB CA, 93534

25 October, 2001

DAB Issues

WRC-92 2310 – 2360 MHz» 2320 – 2345 Digital Audio Broadcast

– Affect began Summer 2000– Sirius Satellites First– XM Followed 2 months later– 1 Validated report of interference from Sirius– 2310 – 2320 & 2345 – 2360 Still not occupied

BBA-97 2385 – 2390– Still not occupied– Exasperating problems with DAB re-allocation

Initial Response to DAB

Formed ad hoc group in Aug 00» RCC TG and FMG Members

Discussed ramifications of DAB/TM Presentation by Gene Law of technical

ramifications Wrote policy letter: Strongly Urging all

member ranges to cease operations in 2320-2345 MHz

Predicted InterferenceTelemetry vs. DAB Rcvr

0

3

6

9

12

15

18

21

24

(I+

N)/N

(dB

)

0 200 400 600 800 1000 Range (TM XMTR to DAB RCVR) (km)

TM: 5W 5 Mb/s PCM/FM

Immediate Effects of Reduced Spectrum

Mission Profile Changes» Aircraft are routinely placed into standby and has

resulted in lost missions» Aircraft often operate outside of normal working

hours and on weekends – Note: Activity was specifically excluded from this

analysis to better enable comparison to predicted telemetry utilization levels

» Limitations on preflight ground testing» Limitations on Area of Operations

Telemetry Consumers at Edwards AFB

AFFTC Operations» 410th FLTS » 411th FLTS» 416th FLTS» 418th FLTS » 419th FLTS » 452nd FLTS » Test Pilot School

Significant Activities» Contractors

– Lockheed – Boeing– Northrop

» Phillips Laboratory» Miscellaneous

– Missiles– Special Scheduling

» NASA Ops (DFRC)

Spectrum Resources for Availability Analysis

Band DescriptionBand Start

Band End

Hrs/Day

Date Start

Date End

Total Days

MHz-Hrs Per Day

MHz-Hrs for Period

L-Band 1435 1525 8 08/05/01 10/04/01 40 720 28800

S-Band 2200 2290 8 08/06/01 10/05/01 40 720 28800Pre-DAB 2310 2390 8 08/05/01 10/04/01 40 640 25600

Upper S Pre BBA 2360 2390 8 08/05/01 10/04/01 40 240 9600

Upper S Post BBA 2360 2385 8 08/05/01 10/04/01 40 200 8000

83200

67200

65600

Total Pre DAB

Total Pre BBA

Total Post BBA

TM Utilization atEdwards AFB

OrganizationTotal Use MHz-Hrs Pre DAB Post DAB Post BBA

Projected 2001 Post DAB

410 FLTS/DOO 132.50 0.16% 0.20% 0.20% 0.16%411 FLTS/DOO 7255.50 8.72% 10.80% 11.06% 14.27%416 FLTS/DOO 2837.95 3.41% 4.22% 4.33% 1.10%418 FLTS/DOO 1105.50 1.33% 1.65% 1.69% 0.78%419 FLTS/DOO 5732.84 6.89% 8.53% 8.74% 17.88%452 FLTS/DOO 575.00 0.69% 0.86% 0.88% 2.91%LOCKHEED   532.50 0.64% 0.79% 0.81% 0.78%MISCELLANEOUS 15383.00 18.49% 22.89% 23.45% 29.91%NASA FLIGHT OPS 22259.20 26.75% 33.12% 33.93% 3.04%NORTHROP   142.00 0.17% 0.21% 0.22% 0.00%USAF TPS 81.67 0.10% 0.12% 0.12% 0.13%TOTALS 56037.66 67.35% 83.39% 85.42% 70.95%

TM Utilization atEdwards AFB

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

Pre DAB Post DAB Post BBA Projected 2001 PostDAB

Assumes: Full 8 hour flying dayNo other ranges operating100% Spectrum efficency

No Mission Slips

0

2000

4000

6000

8000

10000

12000

1999 2000 2001 2002 2003 2004 2005

MH

z/H

ou

rs p

er

we

ek

Projected Utilization Discrepancies

Delay of aircraft deliveries reduced spectrum consumption rates

Extended aircraft modifications Unanticipated new systems Cancellation of projects

Result; Train Wreck Delayed approximately 18 Months

Telemetry Spectrum Metrics

Use » Provides Actual Amount of Unoccupied Spectrum» Determines Efficiency of Spectrum Reuse

Availability» Characterizes Band Fragmentation» Projects Availability of Unoccupied Spectrum

– Probability that Standard mission types could schedule telemetry on short notice or reschedule after mission slips

» Effectiveness of Automated Tools being Integrated into IFDS Phase III Software Development

Increasing Spectrum Availability

Geographic Separation» Line-of-Sight Analysis» Propagation Analysis» Direction to Receiver Analysis

Operational Constraints» Restriction on pre-flight TM checks» Radio Frequency “Hats”

Temporal Techniques» 15 min Time Increments for Scheduling» Evening and Weekend Missions

Increasing Spectrum Availability

Spectrum Monitoring» Provides Actual Spectrum Utilization» Early Identification of Rogue Emitters

Interference Resolution» Reduction of Spectrum Piracy

Summary

Presence of DAB has increased number of “Lost Missions”

Worst Has Yet to Come Current Mitigation Efforts

» Mission Profile Adjustments» Implementation of IFDS Phase III» Development of IFDS Metrics» Greater Monitoring of Spectrum