Timothy J Cash

Career Portfolio

The early years 1980-1998

• NASA: HP41C Calculator flight units first Space Shuttle missions. • Sony 8 mm Camcorder: Nighttime Daytime Orbital Survey of Lightning • Trace Gas Analyzer: Spacelab Gas Chromatograph/Mass Spectrometer • Mark Products/Custom Cable: Cable Design Engineer • First optical fiber land seismic cable, harsh environment undersea cables • Litton Resource Systems: Coaxial cable: Cable TV • Western Instruments: Undersea umbilical/neutral tether/video system for Hydra-2500 • ROV, first deep diving ROV in search for Oil 100 miles off Cape May, NJ at 2500 m depths • Western Geophysical/Guidance & Controls Liaison Officer: All Optical Towed Array (AOTA) • First all optical marine streamer for geophysical exploration in industry • Successful sea trial of five sensor streamer, 1985 • Bendix Oceanics: Expert System for Cable Design, SPICE model, 50,000 lines FORTRAN • McDonnell Douglas : Lab Engineer: Sensors, FOG, Polarization Fading White Paper, • Mast Mounted Site Helicopter Electro-Optic Day/Night Vision System • Commonwealth Edison: Analyzed optical fiber network architecture, developed RFP • for private TBON fiber optic network using ComEd right-of-way, towers, road access, • and legacy electronics-nuclear, fossil and commercial real estate facilities. • Engineered/overbuilt 13 sites, 200 route miles of inside/outside plant engineering. • Consultant: Installed fiber optic networks for East Coast cities, design/lay out architecture using configuration spreadsheets based on vendor specifications. • PTII: Built/debugged working prototype Impedance Test Set for Telco Copper in the Loop, tested subscriber pair verifier replacement due to metallic test unit discontinuance.

The latter years 1998-2016 • Boeing: Designed/Installed Delta-4 Optical Fiber Comms on Launch Complexes SLC-37/SLC-6 • Environmental Tests FO Tool Kit: OFM1020 OTDR/28VDC Pwr Module/Flight Test Adapters • FO Tool Kit Payload flown on ISS mission 6A (4/19/01) with de-orbit (6/12/01) • Performed thermal analysis DNA Bioreactor as NASA Spinoff, written into NIH paper. • Consultant: Designed orbital hypersonic tether systems for multiple purposes. • Honeywell: Deployed TASS System as Field Engineer-US AOR, Air Bases, Iraq • NG Consultant: Scrubbed cable/connector drawings ASDS mini submarine. • SFO: Analyzed requirements for 300 man space station concept, 2004 Space Congress. • Consultant: Analyzed optical test set LabView, tested passive optical fiber components. • Consultant: Designed Star Tracker for satellite payload using Blackfin DSP. • Wrote chapter in book: Liftport Opening Space to Everyone-Space elevator deployment . • SEB Tech: Developed Test Metrics-active RFID Tag/Reader migration to open standards. • Ultra Electronics ATS: Engineer Microwave Network (L Band, X Band, Ku Band) Bahrain, • verified microwave path, loss budget, antenna radiation patterns, & sub contractor work. • Designed wireless microwave link Oil & Gas customer Northern Canada production site, reverse engineered IED threat, design & test of NASA Ground Station antennas (2x20m, 1x5.5m) • Supported TDRS Ground Station, Blossom Point, MD (2) 20 m SGL (1) 5.5 m EET Antenna. • Analyzed LTE user equipment, determined power distribution, created interference model LTE user equipment onto GOES/GOES-R GEO/NPOES Polar satellite down links in 1675-1695 MHz band. Analyzed I/N=-10 dB ratios: multiple sites, determined exclusion zone radii. • Perform Field Strength Gap Coverage Analyses at FAA for Distance Measuring Equipment,VHF OmniDirectional Range over continental USA. Generated graphics (KML) and data file

export(DBF/CSV), post-processed large data files using MATLAB script to quantify Signal in Spaceredundancy and follow-on capacity analyses.

Electro-Optic Umbilical Cable Hydra-2500 ROV

Optical Fiber Video Camera, neutral tether plus umbilical optical cables to surface ship Discoverer Seven Seas control shack

Optical Fiber Sensor Visibility Equation 7 as function (temperature, pressure)

Polarization Fading Analysis Optical Fiber Tow Cable: McDonnell Douglas

RF Test Station for Mast Mounted Site Electro-Optic Sensor

Commonwealth Edison (Chicago, IL), Telecommunications Backbone Optical Network (TBON) Dual OC-12 Ring with OC-3 Shelf DS1 Drop/Inserts:1992-1995 Designed/Installed outside plant, inside plant, and SONET OC-3/OC-12 ADM’s, TM’s, CSU/DSU, OLIU cards, 1/0 DACS, and ICB for a SONET OC-12 network. Configured plug-in cards for channel banks, CSU/DSU, and DACS equipment. Familiar with DS0, DS1, and DS3 test set, telephone butt set, and break-out box to certify DS0 and DS1 circuits for operation on the network through loop-back, continuity, BER, and optical testing (bi-directional OTDR and insertion loss). Provisioned voice switches for cross connect DACS onto a dual SONET ring. Provisioned legacy PBX phone switches down to the punch block, verified wiring Pin-outs using the Fireberd BERT circuit analyzer.

DDM-2000 OC-3 Shelf

Dual Inner/Outer OC-12 Ring Interconnect Telco Systems Route-24 ICB I/F to DDM-2000 OC-3 Shelf

Commonwealth Edison (Exelon, Chicago, IL) Telecommunications Backbone Optical Network (TBON) Eleven Analog/Digital/Voice Circuit Test Methods were executed using Fireberd Bit Error Rate Test Sets, Hand Held TIMS, Butt Sets, RJ11, RJ45, V.24 cables, ABAM DS1 cables, and cross-connect panel interfaces. The circuits were a mix of half-duplex/full-duplex, legacy analog data, digital data, and voice. Some circuits were tested one direction ONLY, while other circuits were tested in BOTH directions. The requirement for a second DS0 Test Set and a second TIMS Test Set drove the tests, so we did not need to Loop the circuit back on itself at Far End “B” and test with a single Fireberd 6000 BER test set from end “A” only. This proved the SONET Network circuit paths end-to-end but did NOT accommodate latency concerns. The tests were written in one day, and executed over a period of several weeks for several hundred mixed analog/digital circuits with circuit test slides available in back-up section.

MFS East Coast Optical Fiber Network Builds: White Plains, Albany, Buffalo, Boston, NYC, Newark, Philadelphia, Washington DC ICG Optical Fiber Network Builds: Nashville, Birmingham, Charlotte

PT Industries International: Advanced Pair Test System Test Head Copper in the Loop Central Office Impedance Test Set

Subscriber Pair Verifier (SPV) Functional Diagram

Type Connection: Single Function Test Head

Type Connection: Multi-Function Test Set

I designed the HASTOL Orbital Hypersonic Tether for Dr. Robert Forward, Tethers Unlimited

Boeing Delta-4 Delta Operations Center (DOC), Space Launch Complex SLC-37

144 Count Single Mode Optical Fiber Cable Cross-Section I installed this cable between DOC and SLC-37 CSB (9,000+ Ft)

144 Count Single-Mode Fiber (SMF) Cable route: Delta Operations Center to SLC-37 Common Support Building (CSB)

I installed optical fiber termination racks in DOC and SLC-37 CSB

Common Support Building (CSB) Communications Room, Location of Optical Fiber Cable Terminations

Space Launch Complex-6, Vandenberg AFB Delta-4 Launch Complex

Two 72 Count Single Mode Optical Fiber Cables were installed into existing roadbed between DOC and SLC-6 according to my recommendations using a diamond saw to defer disturbance of Native American Hallowed Ground

Remote Launch Control Center (RLCC) Building 8510 North VAFB to SLC-6 Delta-4 Launch Complex South VAFB. Two 72 Count SMF Cables were cut and placed into existing road bed route using diamond saw (T Cash recommendation)

ISS FO Tool Kit OTDR Primary Fault Isolation

OTDR/Reel Patch Cable Flight Test Adapters

OTDR Signature: FO I/F

Terminated Flight Links

Crew Bench Review 3/20/01 KSC T Cash present in photo

Tactical Automated Security System TASS System installed by T Cash at US AOR on Air Bases in Iraq

Advanced SEAL Delivery System Submarine US Navy Scrub of cable/connector pinouts for production drawings

PM J-AIT STS Overview

Movement Tracking System

• Provides automatic detection of RFID Tags on board MTS trucks • Low-powered RF interrogator integrated into MTS transceiver • Read data will be provided to RF-ITV-I Server

MTS Hub

RF-ITV-I Server

XML-based Feed • Position Reports • Text Messages • RFID Tag Reads

Embedded RFID in MTS System Interoperability

Savi ANSI-256 Active RFID Tags

654 Tag 656-I Tag

ISO Container Tag ISO Container

Tag with sensors

675-I Tag

Portable Deployment

Kit

650 Reader

SMR 650-210

673 Tag Engine

Container Sensor Tag

Intermec 751G/A With 650P

Docking station

with 654 adapter sleeve

T Cash was SME for PM J-AIT RFID-II Contract Products

Field Test Configuration:

Test ID Application Reader Height

Polling Cycle 50' (14 tags)

150' (14 tags)

300' (22 tags)

Rest 654 | 674 |410

654 | 674 |410

654 | 674 |410

8 | 4 | 2 8 | 4 | 2 12 | 6 | 4

1A

Percent Tags Collected

Average Tags Collected

TIPS Read 20' Contnuous 97.14% 87.86% 71.36% 13.6 12.3 15.7 TIPS Read 20' Contnuous 99.29% 83.71% 70.91% 13.9 11.72 15.6 TIPS Read 20' Contnuous 98.57% 87.14% 69.09% 13.8 12.2 15.2 TIPS Read 20' Contnuous 98.57% 88.57% 70.00% 13.8 12.4 15.4 TIPS Read 20' Contnuous 97.86% 85.71% 71.36% 13.7 12 15.7

Average 98.29% 86.60% 70.55% 13.76 12.124 15.52

1B

Percent Tags Collected

Average Tags Collected

SM Read 20' Contnuous 97.86% 90.00% 81.36% 13.7 12.6 17.9 SM Read 20' Contnuous 99.29% 90.00% 80.45% 13.9 12.6 17.7 SM Read 20' Contnuous 97.86% 93.57% 80.91% 13.7 13.1 17.8 SM Read 20' Contnuous 100.00% 92.14% 81.82% 14 12.9 18 SM Read 20' Contnuous 97.86% 94.29% 81.36% 13.7 13.2 17.9

Average 98.57% 92.00% 81.18% 13.8 12.88 17.86

Tag Read Performance Distance from Reader

Comments Tag Type: 654/674/410 Qty: 50 Reader: SR-650 Orientation: Vertical\Horizontal\Orthogonal

ANSI Read Test – Tags at Rest

Field Test Configuration:

Test ID Application Reader Height Polling Cycle

# of Tags Collected @ 15 MPH

# of Tags Collected @ 25 MPH

# of Tags Collected @ 40 MPH

410 |654 |674 410 |654 |674 410 |654 |674 ISO & ANSI

2F Percent Tags Collected

Average Tags Collected

TIPS Read 20' Contnuous 80.00% 100.00% 40.00% 4 5 2 TIPS Read 20' Contnuous 80.00% 100.00% 60.00% 4 5 3 TIPS Read 20' Contnuous 80.00% 100.00% 80.00% 4 5 4 TIPS Read 20' Contnuous 100.00% 80.00% 100.00% 5 4 5 TIPS Read 20' Contnuous 100.00% 60.00% 100.00% 5 3 5

Average 88.00% 88.00% 76.00% 4.4 4.4 3.8

2G Percent Tags Collected

Average Tags Collected

SM Read 20' Contnuous 100.00% 40.00% 40.00% 5 2 2 SM Read 20' Contnuous 100.00% 100.00% 20.00% 5 5 1 SM Read 20' Contnuous 80.00% 40.00% 20.00% 4 2 1 SM Read 20' Contnuous 100.00% 80.00% 60.00% 5 4 3 SM Read 20' Contnuous 80.00% 80.00% 60.00% 4 4 3

Average 92.00% 68.00% 40.00% 4.6 3.4 2

Dual Mode Read Test - Tags in motion

Comments

Speed (MPH)

Tag Type: 410\654\674\ Qty: 1 \ 3 \ 1 Reader: Dual Mode SR-650 Orientation: Vertical\Horizontal\Orthogonal

Bahrain Microwave Network: Seven Sites Across Island

NERA MW Radio: Multiple Sites (7) PTP Links

MW Tower, each site varies

T Cash Microwave Network Consultant MW Network Path Loss Analysis MW Antenna Pattern Analysis Access (Voice/Data) Channelization MW Test Requirements Analysis Verified status and quality of microwave sub contractor work progress

Enter your System Information in Blue Boxes Only, do not change formula in Red Boxes.

INPUT DATA

Site Name Transmitter Receiver Antenna Gain (dBi) 36.8 36.8 Frequency (MHz) 15000

Losses (Misc,Conn,TX,RX) 6.8 6.8 Path Length, PL (km) 5 Loss/100 ft. 1.137 1.137 Path Length, PL (miles) 3

Cable Length (ft) 147.64 288.71 Cable Loss 1.6786668 3.2826327

Antenna Height (Meters) 35 47.5 Modulation Receiver Sensitivity (dBm) -76.5

Transmit Power (milliwatts) 2000 DBPSK 9.6kb/s -85.5 Transmit Power (dBm) 22 DQPSK 19.2kb/s -82.5

Effective Radiated Power (dBm) 50.3 8PSK 28.8kb/s -79.5 Receive Threshold Criteria 1X10-8 16QAM 38.4kb/s -76.5

Calculation Free Space Path Loss = 36.575 + 20Log (D) + 20 Log (F) System Gain (dB) 156.8 Availability = 100%*(1-C * T * F* D3 * 10-f/10 * 10-4)

Free Space Path Loss (dB) 130.33 Maximum Radio Distance = 4*(Tx^0.5 + Rx^0.5) Fade Margin 26.49 dB Where:

Climate Factor (0.1 to 0.5) 0.30 D is Distance in between the antennas in miles Topology Factor (0.25 to 4.0) 0.25 F is Frequency in MHz

Availability (%) 99.999133% C is Climatic Factor ranging from 0.1 (mild & dry) to 0.5 (severe, humid) T is Topology Factor (ranging from 0.25 (mountainous) to 4.0 (flat land)

The Maximum Radio Distance Tx is Transmitter Height in Meters (MRD) between two sites based 51.23 km Rx is Receiver Height in meters upon the above data is:

How to use Path Calc Chart Enter the INPUT DATA - antenna gain, cable loss, cable length - etc, Enter the required Path Length (distance) into Cell F7

NB: The above figures are guidelines only Review Fade Margin (Cell C20) below 20 dB is unacceptable ArWest cannot be held responsible for accuracy Increase/Decrease PL until Fade Margin is acceptable

Compare PL with MRD (Cell C26) Increase/Decrease Antenna Heights until MRD > PL

Typical Bahrain Microwave Network Free Space Path Loss Calculation

Parabolic Antenna Analysis Bold

Frequency = 1500.0 MHz; 20.0 cm

Reflector Diameter = 2.44 meters = 8.0 ft

Reflector Depth = 2.64 meters = 8.7 ft

Focal length = 0.14 meters = 0.5 ft; F/D = 0.06

Feed Illumination Angle = -0.91 radian = -52 degrees

Illumination Efficiency = 50 %

Computed Antenna Gain = 7.3E+02 Ap = 28.7 dBi

Antenna Half Power Beamwidth = 8.4E-02 radian = 4.84 degrees

Minimum Drift Scan time = 1.9E+01 min = 1160.6 sec

Link Antenna Model Gain (dBi) Kay Height (m)

JOC Height (m)

Aperture (m) f (MHz) Depth (m)

KAY-JOC SP8-1.3NS (TR) 29.2 27.0 57.0 2.4 1500.0 2.6

Typical Bahrain Microwave Network Antenna Pattern Calculation

NASA TDRS Ground Station, Blossom Point, MD (2) 20 mtr SGL, (1) 5.5 mtr EET Antennas

SCNS Contract Principal Engineer (Orbital) RF Design, Test, Installation Factory Acceptance Test Site Acceptance Test Site Construction and engineering support Assured quality of RF engineering work

NASA TDRS Ground Station, Blossom Point, MD (Assembly of 20 meter SGL Reflector Antenna

NASA TDRS Ground Station, Blossom Point, MD SGL 20 meter S-Band Feed

NASA TDRS Ground Station, Blossom Point, MD SGL 20 meter Ku-Band Feed

NASA TDRS Ground Station, Blossom Point, MD SGL 20 meter Subreflector

Determined LTE user equipment transmission power distribution,Urban/Suburban and Rural

NOAA GEO/Polar Sat D/L Interference Analysis from LTE Cellular U/L

NOAA Facilities

WALLOPS COMMAND AND DATA ACQUISITION STATION (WCDAS)

New GOES-R Site WALLOPS COMMAND AND DATA ACQUISITION STATION WCDAS

CONSOLIDATED BACKUP (CBU) FACILITY Fairmont, West Virginia

GOES-R satellite, launch: November 2016

Conclusions

OverloadThe distance to mitigate potential overload effects of gain compression, LNA damage, and IM were analyzed, and a result of 6.4 meters for GOES-R and 64 meters for GOES legacy was found with full power UE’s assumed.

RFIThe LTE UEs have the potential to cause interference to NOAA receiving systems. The aggregate effect of UE systems includes the impact of numerous UEs operating outside the required separation distance.

OverloadThe LTE UE systems have the potential to cause IM, gain compression, and physical damage to the NOAA earth stations.

Interference ThresholdsRFI Threshold ranges between -146.6 to -195.1 dBW, while 10% RFI Threshold ranges between -156.6 to -205.1 dBW.

Conclusions (Continued)

Overload AnalysisGain CompressionRequired Distance to Mitigate (m) ranges between 1.9 to 68.1 m

Distance to mitigate potential for physical damage to LNARequired Distance to Mitigate (m) ranges between .61 to 21.5 m

IntermodulationThe minimum power to cause IM (the “RF IM Threshold”) at the LNA input is -53.1 dBm (-83.1 dBW). The calculated distances to mitigate potential 3rd order IM in the receiving systems were found to be:Required Distance to Mitigate ranges between 97.2 to 465.1 mThe IM threshold is the minimum power to cause IM at the LNA input.

Recommendations

It is recommended that due to the inherent safety of life functions of the GOES-R (and other meteorological or earth exploration satellite systems), and recognizing the economic benefits of these systems, the distances to mitigate potential RFI be enforced by regulation. UE unwanted emissions limits, as specified by industry, be codified in FCC regulations in force for the auctions.UE power levels should be codified to match CDF submitted by industry.NOAA should improve front-end filtering (pre-LNA to extent possible) to provide increased attenuation to adjacent band interfering signals. It is expected that this will reduce the already tight link margins.Testing and coordination should be performed prior to-LTE deployment. Any test program should be designed to ensure that low percentage propagation events would be observed, given the GOES-R requirements for 99.99% availability and 10-10 BER.Allow zones to be developed for a few additional sites of importance to NOAA. Several sites identified but not analyzed in this study including White Sands, NM, Anderson AFB, Guam, and Norman, OK.

Distance Measuring Equipment (DME)

DME is used by commercial aircraft to determine distance from a ground-based transponder, using pulse pairs – two pulses of fixed duration and separation. Aircraft interrogates ground transponder, after a precise time delay (typically 50 microseconds), ground station replies with an identical sequence of pulse-pairs on a different “paired” frequency. DME receiver in aircraft searches for reply pulse-pairs with correct interval and reply pattern to original interrogation pattern and interrogator locks onto DME ground station. The Time difference between interrogation and reply, minus 50 microsecond transponder delay is translated into distance (n.mi) based on 12.36 microseconds = travel time for 1 nautical mile (1,852 m).

This distance is referred to as “slant range”, straight-line distance from the aircraft to the ground station, and is slightly more than the actual horizontal distance because of the difference in elevation between the aircraft and the station. The accuracy of DME ground stations is 185 m (±0.1 nmi).

DME Traffic Load A typical DME transponder can provide distance information to 100 to 200

aircraft at a time. Above this limit, the transponder avoids overload by limiting the sensitivity of the receiver. This results in shorter-than-normal DME range, particularly for small aircraft with their low-powered DME units.

Coverage Gap Analysis Purpose and Methodology

FAA Spectrum Engineering requested an analysis be performed to evaluate the Network of High DMEs for insufficient field strength levels to provide full coverage to the Standard Service Volume (SSV) 130-n.mi regions (Coverage Gap Analysis).

The purpose was to perform a DME-DME signal coverage analysis, create a working baseline and recommend candidate DME sites, if needed, that both resolve any coverage deficiency and maximize the signal redundancy for as many DME-DME pairs within the adjoining deficient area.

DME Frequency band 962 - 1213 MHZDME Error (95% Prob.) 0.1 n.miThis frequency range is in UHF Band and characterized by line of sight (LOS), direct wave propagation.Use Automation Frequency Manager (AFM) to export all relevant (High) DME sites (947) from the Government Master File (GMF) database, Terminal (25 n.mi), Low (40 n.mi), and High (130 n.mi) DME.Use Terrain Analysis Package (TAP) to build a link budget model of each High DME Site (947) in the NAS.

Let R be the radius of the Earth and h be the altitude of a telecommunication station.The line of sight distance d of this station is given by the Pythagorean theorem:

Since the altitude of the station is much less than the radius of the Earth,The approximate range can be estimated by the formula:

Where d is distance in nautical miles and h is altitude in feet above the ground level. For an altitude of 20,000 feet the approximate range will be 155 NM.

Sequence of events:Aircraft interrogates the ground station by transmitting a series of pulse-pairs (interrogations) on the RX frequency of the ground station.Pulse-pairs have a constant time interval (T1 = 12µsec or 36µsec) between pulses.The interrogator randomly varies the time interval between pulse-pairs (Jitter)Ground station receives the series of pulses-pairs, after a precise time delay (50 µsec), ground station replies with an identical sequence of reply pulse-pairs at a frequency 63 MHZ above or bellow the interrogator frequency.Aircraft DME receives reply and measures elapsed time from when it sent the interrogation until it received the reply, subtracts 50 microsecond delay, and calculates exact distance from ground station, given the fact that Distance = Velocity x Time.

DME Link Budget Parameters

Range of Coverage 160 nautical miles over 360 degrees.Five (5) flight altitudes, 5,000, 14,500, 18,000, 24,000 and 45,000-Ft MSL.LAT, LON, and altitude above ground level (AGL in Feet) for each High DME site.Transmit power greater than or equal to 1,000 Watts.DME transmit frequency within 962 to 1213 MHz L Band, excluding 978, 1030 and 1090 MHz, choice of Mid-Band frequency 1088 MHz for ease of use.Exclude all DME sites engineered in conjunction with Instrument Landing Systems (ILS) and those DME sites co-located with VHF Omni-directional Range (VOR).DB Systems 5100A DME Ground (Omni) Antenna, Gain 9.5 dBiBendix King Air Model KN-62A Approved DME Receiver was assumed.RF signal defined at the tip of the Aircraft DME Receive Antenna

DME transponder antenna

DME aircraft ¼ wave antenna

DME distance and VOR/ADF cockpit display instruments

DME Run for Record Strategy

Locate all points in the NAS where DME interrogator field strength level at tip of aircraft receive antenna falls to a minimum level of 54 dBμV (-114.5 dBW) or less in a timely and affordable manner.

Generate coverage gap solutions for the 947 DME sites and five flight levels during low usage times (1×1 n.mi granularity, 880,000 records, 33 minutes per run).Several iterations of tile and radial coverage runs were tested within TAP.

Perform field strength analyses and generate image maps of field strength for each DME site at each of five altitudes.

Post-process raw EM solver output data using Matlab custom scripts.Matlab used for creation and Google Earth to view images.Use maps to determine requirements for any new DME sites to be used to support DME-DME Area Navigation (RNAV) for commercial aviation.

Identify locations where field strength deficiencies exist, and propose optimal location(s) (i.e. coordinates) for additional DME site(s) that supplements the required signal coverage for any identified signal deficient regions (SDRs).

Signal in Space Conclusions

5,000-Ft AGL The signal-in-space at 5,000-Ft AGL is more than 90% continuous in the Eastern and Central Service Areas, where there are >= 4 DME signals per square mile.

14,500-Ft AGLWhen 33 candidate sites are added into the Western Service Area, the signal in space continuity exceeds 95%, with over 99% of signal coverage containing at least to or more DME signals per square mile. Of these 33 sites, six in Nevada are mandatory to eliminate SDRs and decrease the odds for RNAV degradation at lower altitudes.

18,000-Ft AGLThe field strength (≥54 dBµV) at 18,000-ft (MSL) is 100.00% continuous in the NAS, which equates to a minimum of one, viable DME signal every square mile.Signal in space continuity with two or more signals exceeding 95%.

24,000-Ft and 45,000-Ft AGLSignal in space is 100%

Further study on air traffic density and airport capacity is required.

VHF Omni-Directional Range (VOR) Minimum Operational Network (MON) Goals and Coverage Gap Analysis

The present age of the Network of VOR Navigational Aids in the United States exceeds 40 years, and is difficult to maintain due to the lack of availability of critical components.

The program of record to reduce the number of VOR sites is referred to as VOR Minimum Operational Network (VOR MON). The goal is to reduce the number of operational VOR sites by ~308, and modify (increase) the service volumes of the Terminal VOR (25 n.mi) and Low VOR (40 n.mi) to a greater distance which would support General Aviation in an emergency situation.

Spectrum Engineering requested an analysis be performed to evaluate the Network of VORs in the GMF for sufficient field strength levels for their own SSV, as well as the potential to overlap neighboring VOR sites. The data generated is used to assess whether a VOR’s field strength extends to overlap the potential coverage gap of any neighboring VOR sites.

VHF omnidirectional range (VOR) Frequency Band: 108-117.95 MHzConventional VOR (CVOR): error component, 95% Prob: 1 n.miDoppler VOR (DVOR): error component, 95% Prob: 1 n.mi

VOR MON Link Budget Model

Use Terrain Analysis Package (TAP) to build a link budget model of each VOR Site to be retained (~588) in the NAS. The number of VOR sites to be decommissioned is ~308 in number.

Use the primary FAA Spectrum Engineering tool, Automation Frequency Manager (AFM) to export all VOR sites to be retained from the GMF database, for all VOR: Terminal (25 n.mi), Low (40 n.mi), and High (130 n.mi).

VOR MON Link Budget Parameters

Minimum FS Criteria: 5 μV, 14 dBμV, -123 dBWRange of Coverage 130 nautical miles over 360 degrees.Five (5) flight altitudes, 5,000, 12,000, 14,500, 18,000 and 45,000-Ft MSL for the Eastern, Central, and Western Service Areas in the continuous forty-eight (48) states, Alaska and Hawaii.LAT, LON, and altitude above ground level (AGL in Feet) for each retained VOR site.Transmit power equal to 100 Watts.VOR transmit frequency within 108 to 117.95 MHz VHF Band.Conventional Alford Loop VOR Antenna with Counterpoise, Gain 2.2 dBiNo special VOR Receiver was assumed.Signal defined at the tip of the Aircraft VOR Receive Antenna

Conventional VOR Rotating Cardoid Antenna Pattern

VORTAC @ Upper Table Rock , Jackson County, Oregon

Aircraft VOR-LOC Blade Antenna

Flight Test Limits of Coverage

Recent flight tests of Conventional (Alford Loop) Antenna and Doppler Antenna VOR sites for Limits of Coverage found that RF propagation is optimal for those facilities which were flight tested:

IRW CVOR Oklahoma City, OK: ~83 n.miDLH DVOR Duluth, MN: ~93 n.mi

The 100W Conventional VOR’s (CVOR) field strength at 5,000-ft AGL represents the worst-case transmit power for establishing a new VOR service volume under the VOR MON. CVOR make up 93% of the VOR infrastructure in the NAS; therefore, a “sufficient” VOR MON coverage directly derives from their signal range capability. For altitudes below 18,000-ft AGL, there is ~7 n.mi difference in radial distance from facility where the 7.5 μV and 5 μV Field Strength exists, yet both should typically exist, as minimum, beyond the frequency protected service volume (FPSV) radial line of sight at altitude. This is the necessary and sufficient criteria to setting a more practical service volume for 100W CVOR (70 n.mi as opposed to 77 n.mi). When signal strength and quality does not satisfy flight test requirements, then the affected portions of the site’s FPSV is restricted from navigational use.

Field Strength-Signal Quality, D/U Ratio

Poor signal quality correlates well when a signal strength <7.5 µV occurs.If a 70 n.mi VOR radius exhibits ≥7.5 µV for 95% of most orbits with 90% or better signal quality compliance, then ~85% of the radials are operationally viable.This potential may be enhanced IF compliant inter-site radials that intersect were to be made mandatory. The caveat remains that flight check at 70 n.mi must be performed; however the Field Strength-Signal Quality correlation resulting from simulation should significantly reduce the amount of restriction flight testing, saving money in tough economic times.

The Desired/Undesired (D/U) ratio is used to establish the minimum geographic separation between two same frequency/adjacent channel sites within the National Airspace System. This assures that aircraft within the FPSV of the VOR can navigate without encountering co-channel radio frequency interference (RFI) caused by another nearby site. The minimum geographical distance between Low FPSVs is 180-NM for same frequency VOR sites. Expanding their FPSV radii to 65 – 77 NM requires these two sites’ critical distance to be at least 230 to 250 NM apart. Additional separation (310 n.mi) is required when increasing their ceiling (45,000-Ft) altitudes for the 77 n.mi FPSV. Co-channel sites not separated by less than critical distance must be re-channeled (minimum of 1, depends on how many sites lie in the RFI cluster.)

Risk/Impact/Mitigation

Risk: The quantity of VORs requiring re-channelization due to co-channel RFI is insufficient, if the final FPSV radius is between 65 – 77 n.mi.

Impact of Risk: NextGen DME frequency assignment plan is a co-stakeholder. Further delay to the VOR MON radius selection undermines the validity and accuracy of the assessment on other Programs of Record at the FAA.

Mitigation: Spectrum Engineering proceeds with co-channel separations based on 77 n.mi for 5,000 to 45,000-ft AGL since VOR re-channeling quantity is insensitive to the proposed range.

High Risk: Any changes to VOR Retain/Decom List after June 1, 2016 requires re-doing the entire VOR & DME spectrum analyses.

Consequence: Each redo further delays finalizing the NextGen DME and VOR MON frequency assignments and implementation schedules for 2025 end-state, and v-v, revisions to other Programs of Record have the same ramifications to the VOR MON efforts.

Signal in Space Flight Test Viability

5,000-Ft AGL The signal-in-space at 5,000-Ft AGL is less than nominal at several locations, with analysis to provide VOR coverage overlap ongoing. This is more the case in the Western Service Area, where there are mountainous areas.

12,000-Ft AGLSignal in space is 95%

14,500-Ft AGLThe field strength (≥5 µV) at 14,500-ft (MSL) is 100.00% continuous in the NAS

18,000-Ft and 45,000-Ft AGLSignal in space is 100%

Further flight testing to support sufficient coverage to retained and neighbor VOR sites is ongoing.