1

GPS Receivers Use-Case Information

GPS Adjacent Band Compatibility Assessment WorkshopHadi Wassaf, Ph.D. Stephen Mackey  George Dimos

The National Transportation Systems Center

Advancing transportation innovation for the public good

U.S. Department of TransportationOffice of the Secretary of TransportationJohn A. Volpe National Transportation Systems Center

September 18, 2014 

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Topics

1. Background2. Use Case Template3. Description of Submitted Use‐Cases from 

DOT Extended Pos/Nav Working Group4. Utilization of Use‐Case Information 5. Request of Information for Additional Use‐

Cases from GPS Receiver Manufacturers6. Future Steps 

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Background June 2014 : DOT Extended Pos/Nav WG meeting in 

Washington DC to discuss the technical approach of the OST‐R portion of the GPS Adjacent Band Compatibility Program including the need for use case information.

July 2014 : GPS use‐case template sent out to DOT Extended Pos/Nav WG  participating  civil departments and agencies 

August 15, 2014 : Extended Pos/Nav WG responses were due September 04, 2014: Presented initial data gathering results 

to the WG for data received up till August 15th

Today: Updated results to reflect data received up through September 5, 2014

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Use Case Template

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Extended Pos/Nav WG Submitted Use Cases

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Agencies That Provided Use Case Responses

DHS(CBP, ICE, TSA, USSS) DOC(NIST, NOAA)  DOI(BLM, FWS) DOT(FAA, FRA, MARAD) NASA  DOT‐CA USDA

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Description of Submitted Use-Cases (Up Till 08\15\2014)

RECEIVER CATEGORIES, RESPONSES, Number of Units

Summary of Use‐Case Information from Pos/Nav responses

Receiver Category Responses Total Known Number of Units/Future

Cellular (CEL) 1 375

General Aviation (GAV) 23 UNKGeneral Location/Navigation (GLN)  42 45,279/22,000High Precision (HPR)  32 4,293/300

Timing (TIM)  28 133/45,100Networks (NET)  3 38

Space Based (SPB)  1 16/7

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Summary of Received Use-Case Information Sorted by Manufacturer (1/2)

*Unknown**To be deployed in the future***Trimble, Ashtech, Novatel, Javad Septentrio, etc

8 10

429

4 1 32

1850

13 2 39 6 8

260

2

1610

3 12 2

300

670

380 32 1

1968

192

0

500

1000

1500

2000

2500

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Summary of Received Use-Case Information Sorted by Manufacturer (2/2)

5 2

3674

2006 11

21450 25 2

30027 47 2 77 3 15 10 9

16524814 30 8 15

0

500

1000

1500

2000

2500

3000

3500

4000

4500

500024000 67100 6471

*Unknown**To be deployed in the future****TBD

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Some Caveats

There are a number of ambiguities on the classifications of receivers that need to be resolved: For example: 22,000 receivers classified as GLN and Timing. We need to go back and get clarification

The make/models are shown mostly as reported. We will need to validate each of the make and model and probably verify them with the reporting agencies to minimize assumptions on our side.  

We have reclassified some of the responses: One response was reclassified from GLN to GAV One response was reclassified from HPR to GAV One response was reclassified from HPR to SPB

A lot of TBD and Unknown receivers: Unless we get clarifications, they will clearly not be part of the pool of receivers to consider for testing although any other relevant use‐case information will be considered

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General Location/Navigation (GLN)

12

10000

1

1850

1 39 6 260 21609

3 670 1 105 191

3674

200

24000

77

22000

1

2570

00

5000

10000

15000

20000

25000

30000

General Location/Navigation (GLN)by Manufacturer

*No Manufacturer available**22,000 GPS receivers to be deployed in the Future/Note that those are double counted under Timing***In release process

Receiver by Manufacturer

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High Precision (HPR)

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High Precision (HPR)by Manufacturer

*Trimble, Ashtech, Novatel, Javad, Septentrio, etc** To be launched in the future 

8 10

428

4 16 12 0 12 2300

80 32

1863

1 2 6 11214

2 27 2 9164 248

7

3863

0

500

1000

1500

2000

2500

3000

3500

4000

4500 Receiver by Manufacturer

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Networks (NET), Space Based (SPB), Cellular (CEL)

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Networks (NET), Space Based (SPB), Cellular (CEL)by Manufacturer

NET

SPB

Receiver by Manufacturer

CEL

*Launched in the Future

38

167 3

25

300

47

0

50

100

150

200

250

300

350

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Timing (TIM)

18

1 2 8 1 5

50

315 10 2

288

0

50

100

150

200

250

300

350

400

450

50045,100

Timing (TIM)by Manufacturer

*Unknown**45,100 GPS receivers to be deployed in the future will be deployed/22000 of which are double‐counted under GLN

Receiver by Manufacturer

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General Aviation (GAV) [Non-Precision]

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General Aviation (GAV) [Non-Precision]by Manufacturer

0

0.2

0.4

0.6

0.8

1

1.2 Receiver by Manufacturer

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Description of Submitted Use-Cases ANTENNA TYPESCategory Make Model Integration Orientation

CEL No Response No Response Integrated Fixed

GLN >20 >20 Integrated / Separate

Fixed  / Variable

HPR >20 >20 Integrated / Separate

Fixed  / Variable

TIM Novatel, Ashtech, Symmetricom,TrueTime, Trimble

701/702/703ASH701945G_M58532A

Separate  Fixed(Variable in future,application to support radio networks) 

NET Trimble, Cambium Zephyr,PTP45600 

Separate  Fixed

SPB JPL, Haig‐Farr Separate  Fixed

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Description of Submitted Use-Cases RECEIVER ANTENNA HEIGHT AND SPEEDCategory MIN Height 

(ft. AGL)MAX Height (ft. AGL)

Speed (mph)

Comments

CEL NoResponse

NoResponse

NoResponse

GAV NoResponse

1,00033,000

100300

Aerial surveysAirborne science

GLN 0 – 5

50

2 – 15

100

0 ‐ 1040 ‐ 7015035

Mississippi river, soloforestData collectionProvide constant lat/lon pos.

HPR 0 ‐ 5 2 –33

0 ‐ 100

0 ‐ 100 ‐ 4515 – 60

Cadastral boundary surveysMobile terr. Laser scanningGround networks

TIM 0 ‐ 8 15 ‐ 100 150

0100 Future radio support

NET 0 ‐ 7 7 ‐ 130 0

SPB 1,700,000 4,300,000 16,000

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Description of Submitted Use-Cases URBANIZATION AND TERRAIN

Category Urbanization (mostly) Terrain (mostly)URBAN / SUBURBAN / RURAL FLAT/SLOPED/CANYON – OPEN/IMPEDED – DRY/WET

CEL Urban/Suburban/Rural Flat/Sloped/Canyon – Open/Impeded ‐ Dry

GAV Rural  Flat ‐ Open ‐ Dry

GLN Urban/Rural/Suburban Flat/Sloped/Canyon  ‐ Open/Impeded ‐ Dry/Wet

HPR Urban/Rural/Suburban Flat/Sloped/Canyon ‐ Open/Impeded ‐ Dry/Wet

TIM Urban/Rural/Suburban Flat/Sloped/Canyon ‐ Open/Impeded ‐ Dry

NET Urban/Rural Flat/Sloped ‐ Open ‐ Dry

SPB N/A N/A

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Utilization of Use-Case Information

The use‐cases collected have the following 2 primary purposes:A. Identifying the receiver types and associated applications B. Collecting input to the network aggregation tool

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A. Identifying Receiver Types and Associated Applications (1/2)

An integral part of the current Adjacent Band Compatibility work is the development and implementation of a receiver test plan to assess harmful interference levels in the adjacent band.

The receivers in the use case responses will be considered candidate receivers to be tested.

However, a set of agreed upon criteria must be used to down‐select from a set of “representative” receivers to be tested. 

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A. Identifying Receiver Types and Associated Applications (2/2) What should the down‐selection process entail?  Possible criteria are:

The number of units deployed (must be greater than some threshold)

Type and/or criticality of the application 

Whether a particular receiver model is known to bound the performance of some other receiver models from the same manufacturer , (i.e. representative of other receiver for the same application). 

o This is to eliminate redundant testing o This requires going through receiver specifications and working with manufacturers 

Testing Feasibility:o Whether the receiver hardware and software permit easy access to the relevant 

information (SNR, other spectral information, Pseudorange error, Loss of Lock and other Alarms, etc…)

o In the case of integrated Antenna/Receiver: Accessibility to receiver input port for a wired test.

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B- Collecting Input to the Network Aggregation Model (1/7)

Volpe is in the process of developing and implementing a Network power aggregation tool based on known and established propagation models.

The purpose of this tool is to estimate the RFI power coupled into a GNSS receiver antenna based on a wireless network characteristics with flexible attributes

The use cases determine some of the ranges of inputs to be used when looking at an interaction scenario using the aggregation tool

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B- Collecting Input to the Network Aggregation Model (2/7)

The relevant use‐case information for the aggregation tool are:i. Range of Antenna Heightsii. Antenna Orientation: Fixed or Variableiii. Urbanization Leveliv. Terrain Attributesv. Mobility/Maneuvering Speeds

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B- Collecting Input to the Network Aggregation Model (3/7)

i. The GNSS antenna height (or relative height to transmit antenna) determines the effects of each transmitter antenna pattern on the coupled RFI power level.

- 1 0 0- 5 0

05 0

1 0 0

- 1 0 0

- 5 0

0

5 0

1 0 0- 1

- 0 . 5

0

0 . 5

1

G x ( d B )

3 - D G ( , ) A n t e n n a D i r e c t i v i t y F o r t h e F i r s t T r a n s m i t t e r In S p h e r . C o o r .

G y ( d B )

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- 1 0 0- 5 0

05 0

1 0 0

- 1 0 0

- 5 0

0

5 0

1 0 0- 1

- 0 . 5

0

0 . 5

1

G x ( d B )

3 - D G ( , ) A n t e n n a D i r e c t i v i t y F o r t h e F i r s t T r a n s m i t t e r In S p h e r . C o o r .

G y ( d B )

B- Collecting Input to the Network Aggregation Model (4/7)

ii. GNSS Receiver Orientation: determines the receiver antenna pattern effects on power coupling  

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B- Collecting Input to the Network Aggregation Model (5/7)

iii. Urbanization Level: 

This information is primarily relevant to the electromagnetic propagation. The choice of parameters for these propagation models are based on the urbanization levels among other contributing factors 

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B- Collecting Input to the Network Aggregation Model (6/7)iv. Terrain attributes have two main effects:

Affects Antenna orientation

Blockage for a sector of the interfering network 

0

1000

2000

3000

4000

5000

60

-1800-1600-1400-1200-1000-800-600-400-2000200

0

10

20

30

40

50

X (m)

Transmitters Network 3-D Map

Y (m)

Z (m

)

Blocked Transmitters

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B- Collecting Input to the Network Aggregation Model (7/7)v. Mobility/Maneuvering speeds: 

• This is not an explicit input to the model. The primary utilization of this parameter is to get a feel of how dynamic the scenario is. 

• For example, in a complex terrain the speed can be informative on how long a scenario is expected to be static. That is, how often a scenario can change in the course of one hour (for example).

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Request Use-Cases from GPS Receiver Manufacturers

Although the collected responses from US agencies reveal a wide diversity of specialized applications, the number of receiver units involved is probably not representative of the total number of active GPS receivers in the US.

It is desirable that the DOT Extended Pos/Nav Working Group responses be complemented with additional information from receiver manufacturers, academic institutions, or other sources, regarding the characteristics of prominent applications which involve the bulk of the GPS receiver units in the US.

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Appendix

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General Location/Navigation (GLN)by Manufacturer and Model

Receivers by Model

1

1850

1 39 6120

5585 2 2 2 10 3 1 3 59 6 3

842

8 501050

454

1004 2 3

670

1105

4 2

185

2124

50

1500

20077

1 4 1102100

2035

2 16

209

2 5741 1 0 150

500

1000

1500

2000

2500

300010000

24000 22000

*No Manufacturer available**22,000 GPS receivers to be deployed in the Future/Note that those are double counted under Timing***In release process

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High Precision (HPR) [1/2]by Manufacturer and Model

*Trimble, Ashtech, Novatel, Javad Septentrio, etc**To be launched in the future

6 2 6 4 1 1 2 1672

284

2 3 48 2 2 12 4 12 0 12 2

300

278

101012 8 1 1 1 5104

1672

12 6 2025 8 1 2 2 2 2 3 8 2 2 2 2 412478

0

200

400

600

800

1000

1200

1400

1600

1800Receiver by Model

38

High Precision (HPR) [2/2]by Manufacturer and Model

**To be launched in the future

2 1 26 2 910050 2 4 2 6

248

6 1 31171733 1 1101

1523198

2 1 2 1 1 2

2578

1 3 1 8

300

1115 2

391

3 2 31 1 1534 4 12 2 2 10

500

1000

1500

2000

2500

3000 Receiver by Model

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Networks (NET), Space Based (SPB), Cellular (CEL)by Manufacturer and Model

Receivers by ModelNET

SPB

CEL

16 19

2 1 412 7

100

200

10 153 2

45

0

50

100

150

200

250

*Launched in the Future

40

Timing (TIM)by Manufacturer and Model

Receiver by Model

*Unknown**45,100 GPS receivers will be deployed in the future/22000 of which  are double‐counted under GLN

1 2 4 4 1 5

50

3 15 3 2 5 2 222

1 1 1 1 80

50

100

150

200

250

300

350

400

450

50045,100

41

0

0.2

0.4

0.6

0.8

1

1.2

General Aviation (GAV) [Non-Precision]by Manufacturer and Model

Receiver by Model