GNSS Issues, Opportunities and

AccoladesBrad Parkinson Stanford

Frank van Diggelen Google

Bottom Lines Up Front• Ligado now proposes 9.8 watt transmitters. The

PNTAB strongly recommends disapproval of this proposal• Unknown, but probably very close tower spacing• Many other organizations have filed opposition

• FCC reportedly to approve Galileo use in November meeting

• Latest cell phone GNSS chips have amazing Capabilities

• We have some largely-unheralded GNSS Heroes in our midst…

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ClashAssured PNT for All 3

Underlying cause of the Clash:How much received power does a communications system need?•  

Assured PNT for All 4

Energy per Received Bit

Ambient Noise in Receiver Antenna

A little HandwavingBy the Prof

Greatly Simplified Communication Theory•  

Assured PNT for All 5

Not Startling: To send larger amounts of Data, need to spray the user with proportionally more power

Qualcom predicts 490 Mbit/s median speeds for a common configuration of 3.5 GHz 5G 

Assured PNT for All 6

• A certain company (Lxxx) had License for transmitting Satellite to Ground for

CommunicationsBut the received power was very low and

did not support a large D (Data Rate)

But Lxxx saw a great opportunity• Convert the License to high power terrestrial transmissions (Asked for 15.8 Kw)• Tower Spacing at about ¼ mile • Would support broadband – sending movies etc. = 5G?

• Spectrum Value would jump: $2B ➜ $10B+• Tried to get the FCC to slip this through just before

Thanksgiving 2010 – while everyone was digesting turkey• PNT community found out and slowed the process down• But*But apparently a predecessor Lxxx company had

already found a significant Clash with GPS…• According to Harbinger lawsuit

Assured PNT for All 7

Summary of the latest Ligado Proposal:1. Completely abandons terrestrial use of the 1545-55 MHz band2. Reduces Power from 1.5kW to 9.8 Watts in 1526-36 MHz band3. Unspecified distance between Transmitters4. Monitoring up to users, who must use a call-in number5. Allege proposal resolves all aviation issues (Evidently Aviation community

disputes this) 6. Does not directly address most sensitive receivers – High Performance -

but say “Ligado’s co-existence agreements with major GPS manufacturers and thousands of hours of empirical testing assure protection for all other classes of GPS devices”. • Thus statement is not true. Top three manufacturers support international

standard of 1 dB degradation, equivalent to a 25% drop in GPS signal power. • “New” Ligado 10W proposal violated noise standard by factors of 2500 or more

at 400m spacing. Note: High-Performance receivers create over $30B per year in identified benefits to the US.

7. Proof of “assured protection” is ascribed to Ligado sponsored tests that were found inadequate and incomplete by an independent review board. Thus, “proof” is an erroneous statement.

8. Completely ignores ABC testing which clearly shows proposal is unacceptable.9. Continue to totally ignore effects on new GPS signals (L1C) and complementary

GNSS systems (e.g. Galileo)10. Military receiver impacts – i.e. M-code must be discussed by USAF who

apparently oppose the proposal8

Adjacent band interference concern

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“Upper” band is apparently off the table. Is this forever?

Assured PNT for All

“Lower” band Power reduced to 9.8 Watts. Spacing not specified but original was ~400 meters. To meet broadband requirements it is possible

that this will be less. Perhaps about 100 to 200 meters. Plausibly, perhaps Micro or Femtocells. Microcells typically are a watt at 500 Meters coverage

(~1 km spacing). Femto cells are 100 milliwatts at 30 Meters.

The 5G Revolution – The Ligado Target?

• “Frequencies from 600 MHz to 14 GHz”•Received power must increase: “wireless radiation from 5G network will be 30 times stronger than 4G LTE systems. “

•Expect much greater tower density and higher power to accommodate data rates

50% Area Protected –

spacing = 2.4 * Degradation Limit Radius

90% Area Protected –

spacing = 6.0 * Degradation Limit Radius

20% Area Protected –

spacing = 2.1* Degradation Limit Radius

Green – Un-degraded

Degradation Limit

Radius and Circle

A visual Example:To insure additional GPS interference noise does not exceed 25% International Standard either:• Limit minimum Transmitter

Spacing for a given power Or• Constrain Power for a given

spacing (Reduce Degradation Radius)

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Summary Rationale for Disapproval• PNTAB believes use of GPS should be protected everywhere and for all current and future

uses as directed by EXCOM letter in 2011. The “G” in “GPS” should really be Global.

• At “new” ~10 watt power, tower spacing would have to be at least 18 kilometers to protect High Performance Receivers, even if only protected over 90% of coverage area

• Viewed another way, with 400 meter spacing, Ligado power would have to be further reduced from ~10 watts to 0.036 watts (2500 times lower) to protect tested High Performance Receivers, even if only protected over 90% of coverage area.

• Asking the High Performance GPS Users to monitor the interference is totally unrealistic – they would not know how to do it, and would have no means to trace the problem to Ligado.

• Ligado continues to ignore emerging use of modernized GPS and GNSS signals. Impacts to receivers tracking these wider bandwidth signals could be worse than for current GPS signals

• If Ligado’s current license is approved, their spokesperson implied that over time they would expect to be allowed power increases. Temporary power reductions offered only to gain regulatory approval must be recognized as such and rejected.

• Proposal is deliberately vague on geometry and spacing of towers. Ligado has repeatedly declined to provide these critical technical details to PNTAB to enable full and accurate assessment of interference. They have addressed Aviation (433m) and ignored High Performance Uses that have shown to be much more sensitive to degradation.

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Opposition to Latest Ligado Proposal

• NASA• Dept of Commerce• USAF• PNT ExCom (?)• Alliance of Automobile

Manufacturers• National Weather

Association, • Weather Coalition,

• Aerospace Industries Association

• American Meteorological Society,

• American Weather and Climate Industry Association

• General Aviation Manufacturers Association

• Iridium Communications, Inc.

Woops! - GNSS is not just L1 C/A

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PNTAB: Interference tests or analyses should be for all proposed GNSS signals!

11/3/18 ESA Jan 2017- Dr. Parkinson

Good News: Apparently the FCC is inclined to approve use of Galileo in US (Finally!)

•EC formally requested permission in 2013•Users have exploited Galileo signals for several years – many advantages e.g. ERAIM•May have implications re: allocations in nearby frequencies

“the Commission will vote in November on allowing American devices to access …Galileo. Enabling the

Galileo system to work …with …GPS …should make GPS more precise, reliable, and resilient — a boon to

consumers and businesses alike.” (FCC Chairman Ajit Pai)

Opportunity – new chip capabilities and access

Dr. Frank van Diggelen

Evolution and opportunities in consumer GNSS

Frank van Diggelen

GPS and MooreRF-CMOS

RF and Baseband chip sets Single chip GNSS

Process nodes of GNSS chips over time

2 micron, survey receiver, proprietary GPS chips

.25 micron, GL16000

.18 micron, GL20000.13 micron, Hammerhead

90nm, BCM4750

65nm, BCM4751

40nm, BCM4752

28nm, BCM4775

Data from 2000 onwards courtesy of Broadcom.

GNSS constellations in phones

Benefon Esc!GPS phone

HP iPaq 6915GPS smartphoneFirst:

Samsung Galaxy S,

...+GLO

Galaxy Note

... +QZSS

Galaxy S5...+BDS

Galaxy S6...+GAL

Xiaomi Mi8...+L5

+

+

+

+

Sources: gsmarena.com, samsung.com, xiaomi.com

Access to GNSS data from phones

PVT, satellite az/el, C/No

GPS raw measurements

(Android N “Nougat”)

GNSS raw meas’s + AGC

(Android O “Oreo”)

Continuous Carrier Phase

(Android P “Pie”)

Dual-frequency carrier phase in phones ...

GPS L1 GAL L1GLO L1

GPS L5 GAL L5

Source: “Android GNSS Measurements Inside the BCM47755” ION GNSS+ 2018. S. Shade, P Madhanicourtesy: Broadcom

5 cm

5 cm

RTK was not built in a day: evolution of cm accuracy

Sources: https://www.trimble.com/corporate/about_history.aspx; Trimble Product Firsts presentation.

Photos courtesy of Trimble Navigation Inc.

1988 Static, post-processed.Trimble 4000SLD, “44 lbs (without car battery)”

Rapid-Static, real-time processing

1994 RTK, Real Time Kinematic“on-the-fly initialization”

Kinematic, post processed.

2018“Preliminary Analysis of the RTK Positioning using Android GNSS Raw Measurements”, Sharma et al. ION GNSS+ 2018.

“Positioning with Single and Dual Frequency Smartphones” Warnant et al. ION GNSS+ 2018.

“FLAMINGO – Enhanced Location Accuracy in the Mass-market” Roberts et al. ION GNSS+ 2018.

RTK was not built in a day: evolution of cm accuracy 2017

“On the Path to Precision - Observations with Android GNSS Observables” Riley et al. (Trimble). ION GNSS+ 2017.

“PPP using Low-Cost and Ultra-Low-Cost GNSS Receivers” Gill et al. ION GNSS+ 2017.

“Trends, Innovations and Enhancements for Low-Cost PPP”, Calle et al. ION GNSS+ 2017.

“Smartphone Applications for Precise Point Positioning”, Laurichesse et al. ION GNSS+ 2017.

Celebrating a Few of our AttendeesCan you guess who?

A Few of, the many, little-heralded heroes in the GNSS Community.

Focus on regular attendees in our SCPNT conference

Gaylord Green, Col. USAF Retired• Grew up in very rural area

• Less than 20 in his high school class

• Went to USAFA and Stanford

• Oceanic Salmon Fisherman

• Very competitive at Tennis and Golf

• Major Contributor to GPS Design at “Lonely Halls Meeting” 1973

• Invented Sidereal GPS Orbits

• Organized the first GPS satellite Procurement

• Was head of the GPS Program for USAF

• Program Manager of Minuteman Inertial Guidance Development

• Later Program manager of Gravity Probe-B at Stanford

Tom Langenstein Executive Director of SCPNT• Grandfather was a stone-carver who worked on

the original Stanford Buildings

• Bachelor’s Degree in Industrial Engineering

• Regular Attendee of “The Burning Man” in Black Rock Desert of Nevada

• Has been Program Manager and Deputy Program Manager at Stanford for over 30 years

• Has Lead the organization and operation of this SCPNT Symposium since first event

• Currently also Executive Director:• Fermi Gamma-ray Space Large Area

Telescope (LAT)• Accelerator on a Chip International

Program (ACHIP)

Todd Walter – Leader of FAA technical Program at Stanford• Collegiate Equestrian• PhD Physics• Wife is an Engineer and

accomplished Technical Editor

• Former President of the ION• Distinguished Service Award, Institute of

Navigation (January, 2012)• Fellow of the ION, Institute of Navigation

(June, 2006)• With Per Enge, led major effort to insure

WAAS could be used• International Expert on GNSS

Augmentations

And Also – another Heroine

• Grace Fontanilla

Questions?

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