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Logan Scott

15 November 2017

1

Presentation to PNT Advisory Board

15 November 2017, Redondo Beach

Technical Working Group "TWG"

Roberson Report "Roberson"

Adjacent Band Compatibility "ABC"

National Advanced Spectrum and

Communications Test Network "NASCTN"

Where they overlap, the data generally agree

BUT NOT the conclusions

15 November 2017

2

15 November 2017 3

The stated objective of the

NASCTN testing was to

"develop a test method" and "validate the test method".

Adjacent-band LTE activity was represented

through emulated, modulating LTE waveforms Down Link 1526MHz - 1536 MHz, "DL" 1585 Watts EIRP Uplink 1627.5 MHz - 1637.5 MHz "UL1" 200 mWatt EIRP Uplink 1646.5 MHz - 1656.5 MHz "UL2" 200 mWatt EIRP

15 November 2017

4

NASCTN

Presentation

Focus

15 November 2017 5

Network

Reference

Receiver Survey Receiver Pair

RTK Rover RTK Base

15 November 2017 6

Rover

Station in

RTK Mode

Rover

Station in

DGPS Mode

15 November 2017

7

Reference

Station at

a Precisely Known

Location

Differential Corrections

(e.g. PRN23 is Off by 5.31 meters) Rover

Station in

DGPS Mode Rover

Station in

RTK Mode

Carrier Phase Data

Position

Based On

Corrected

Pseudoranges

Position=

Reference

Position +

Relative

Location

8 From:

NIST Technical Note 1952

LTE Impacts on GPS Final

Report

February 2017

available at: https://doi.org/10.6028/NIS

T.TN.1952

National Advanced Spectrum

and Communications Test

Network (NASCTN)

High OOB

Reject

Antenna

NASCTN

High Precision Position (HPP) Receivers

15 November 2017

High OOB

Reject

Antenna

15 November 2017

9

NASCTN

High OOB

Reject

Antenna

High OOB

Reject

Antenna

10

NASCTN

Real Time Kinematic (RTK) Receivers

15 November 2017

Receiver (Mode)

Antenna Type KILL Threshold

(dBm Isotropic) IMPAIR Threshold (dBm Isotropic)

DUT7 (HPP)

DUT8 (HPP)

DUT9(HPP)

DUT10(HPP)

DUT11(RTK)

DUT12(RTK) Normal

Normal

Normal

Normal

Normal

Normal -35

46
45
38
54

40 -70

70
60
70
70
60

DUT9(HPP)

DUT11(RTK)

DUT12(RTK) High OOBE Reject

High OOBE Reject

High OOBE Reject >0

>5 3 0 >5 5

15 November 2017

11 † NASCTN test results provide very coarse information on where C/No degradation occurs since large step sizes in LTE power were used at lower powers. ABC tests show ~-65 dBm lower power bound for 1dB C/No degradation for HPR

15 November 2017 12

Received Signal Strength from

a 1500 Watt EIRP Transmitter

Chart From Appendix H.1.2,

TWG Page 13 of 20

Rural TWG

Received Strength

Above Free Space

Propagation

Prediction

15 November 2017 13

Received Signal Strength from

a 1500 Watt EIRP Transmitter

Chart From Appendix H.1.2,

TWG Page 13 of 20

HPP & RTK Receivers without High OOB Reject Lose Lock In this Range

HPP & RTK Without High

OOB Reject Antenna

Can't Track at All

Rural

NASCTN / TWG

15 November 2017 14

Received Signal Strength from

a 1500 Watt EIRP Transmitter

Chart From Appendix H.1.2,

TWG Page 13 of 20

HPP & RTK Receivers without High OOB Reject Lose Lock In this Range

HPP & RTK Without High

OOB Reject Antenna

Can't Track at All

HPP & RTK Receivers without High OOB Reject Can Have

Degraded C/No in this Range of Received Power

Rural

NASCTN / TWG/ABC

Received Signal Strength

from a 1500Watt EIRP Transmitter

Chart From Appendix H.1.2,

TWG Page 11 of 20

Suburban

15 November 2017

15 12 November 2017 15

HPP & RTK Receivers without High OOB Reject Lose Lock In this Range

HPP & RTK Without High

OOB Reject Antenna

Can't Track at All

HPP & RTK Receivers without High OOB Reject Can Have

Degraded C/No in this Range of Received Power

NASCTN / TWG/ABC

15 November 2017 16

Received Signal Strength from

a 1500Watt EIRP Transmitter

Chart From Appendix H.1.2,

TWG Page 8 of 20

Urban

12 November 2017

16 HPP & RTK Receivers without High OOB Reject Lose Lock In this Range

HPP & RTK Without High

OOB Reject Antenna

Can't Track at All

HPP & RTK Receivers without High OOB Reject Can Have

Degraded C/No in this Range of Received Power

NASCTN / TWG/ABC

15 November 2017 17

15 November 2017 18

Time to First Fix (sec)

Cume Prob Mean C/No(dB-Hz)

EIRP at DUT(dBm)

Extracted from NASCTN Figures 6.49 and 6.101

TRACK ACQUIRE

Acquires Faster

In Presence of

Interference

Acquires

Below Track

Threshold

Acting Normal?

15 November 2017 19

Time to First Fix (sec)

Cume Prob Mean C/No(dB-Hz)

EIRP at DUT(dBm)

Extracted from NASCTN Figures 6.49 and 6.101

TRACK ACQUIRE

Acquires Faster

In Presence of

Interference

15 November 2017 20

Time to First Fix (sec)

Cume Prob Mean C/No(dB-Hz)

EIRP at DUT(dBm)

Regular Antenna High Out of Band Reject

Acquisition

Threshold 34 dB

Above Track

Threshold EIRP at DUT(dBm)

Data from NASCTN Figures 6.49 and 6.101

Acquisition

Threshold 14 dB

Above Track

Threshold

Time to First Fix (sec)

Figures

6.50,6.51,6.52, 6.53

show no output when

EIRP > -47 dBm

15 November 2017 21

Received Signal Strength from

a 1500 Watt EIRP Transmitter

Chart From Appendix H.1.2,

TWG Page 13 of 20

Rural

TWG/NASCTN

DUT12(RTK) with High OOB

Reject Can't Reliably Acquire

DUT12(RTK) with Regular

Antenna Can't Reliably Acquire

RTK Receivers Lose Signals in

the Course of Normal Operation and Need to Reacquire &

Perform Phase Fix-ups

Multipath Eats Margins in Observables

False Acquisitions Would Complicate or Break Fix-ups High OOB Reject Filters Seem to Make Ambiguity Resolution Harder

15 November 2017

22

RTK Operating

Environments are Complex

NASCTN Does Not Capture

This Complexity

HPP and RTK receivers can expect significant impairment up to and including complete failure at ranges upwards of a mile.

One of the two RTK receivers tested shows symptoms consistent with false acquisition induced by interference.

High OOB reject filters appear to cause acquisition impairments.

Effect needs to be understood

Small sample size and lack of field data in NASCTN provides inadequate basis for a decision

Two RTK receivers

15 November 2017 23

15 November 2017 24

The data does not

support this statement

15 November 2017 25

High Precision and RTK applications are critical

infrastructure and require strong protections Adopt a 1dB Interference Protection Criterion for equipment AS IS

1 dB IPC corresponds to 20% Reduction in SNR

Many fielded RTK and HPP receivers were not

designed or tested for a high interference environment High Out of Band Reject Filter effects on RTK are not well understood

15 November 2017

26
Multi-constellation GNSS is the foundation of high integrity, robust operation. Provides Coverage & Accuracy In Challenged Environments

Enhances RAIM and ARAIM Effectiveness

Makes Spoofing Significantly Harder

Is in Widespread Use NOW

15 November 2017

27

Multi-GNSS

Receivers are in

Widespread Use

15 November 2017 28

EU Requirement for New Equipment starting 13 June 2017 DIRECTIVE 2014/53/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL

Specifies Requirements for Tolerating Out of Band

Interference with No more Than 1 dB C/No Degradation

15 November 2017

29

15 November 2017 30

Figure from: GPS-ABC Radiated

Chamber Testing Overview and

Results, GPS-ABC Workshop VI,

March 30, 2017, Hadi Wassaf,

Pratik Gandhi, George Dimos,

Stephen Mackey

15 November 2017

31

Chart from: Loss of Lock Analysis

GPS -ABC Workshop VI RTCA, Washington, DC

March 30, 2017

Christopher Hegarty and Ali Odeh, The MITRE Corporation

15 November 2017

32

Chart from: Loss of Lock Analysis

GPS -ABC Workshop VI RTCA, Washington, DC

March 30, 2017

Christopher Hegarty and Ali Odeh, The MITRE Corporation

15 November 2017 33

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