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What was Northrop Grumman’s GPS Origin Story?

Northrop Grumman’s involvement with GPS has its origins during the mid-1980s, when we became an early adopter. We applied our prior decades of technical expertise in defense and commercial navigation solutions to recognize the significance of GPS as an emerging technology to optimize our inertial navigation products. The first GPS receiver was integrated with the LN-33, our main product for military aircraft, in 1987.

Around the same time, our engineers began to develop an indigenous civil GPS receiver to complement our inertial navigator for use in commercial airliners. This resulted in the certification and fielding of the LTN-2001 product, an eight channel C/A Code GPS receiver. This receiver, in concert with our Autonomous Integrity Monitored Extrapolation (AIME) algorithm, provided our customers a first-ever sole means navigation system using GPS/inertial for non-precision approach.

By the early 1990s, advancements in the semiconductor industry facilitated the reduction of the GPS receiver from a 1,000 cu in stand-alone box to a roughly 6-in by 6-in circuit card. This critical milestone allowed GPS to be embedded into an inertial navigation system (INS) without a significant increase in its size or power consumption and thereby the ubiquitous Embedded GPS INS (EGI) was born. Our first inertial navigation system with embedded military GPS capability was the LN-100G in 1991. This standard form factor was produced across the industry with installations on virtually all the front-line tactical aircraft and rotorcraft for the U.S. Department of Defense (DOD) and many of our allies.

Can you share a breakthrough?

Inspired by accomplishments in the survey community, our team conducted early location accuracy experiments to demonstrate a few decimeters of accuracy between our Woodland Hills, California, location and a facility in San Jose, California, about 500 km away. Leveraging this experience and the same signal processing, our teams became a broader solution provider for adjacent mission applications including precise formation flying for in-flight automated refueling, precision approach and landing, and decimeter-level positioning for the intelligence, surveillance and reconnaissance (ISR) community.

In parallel with these developments, Northrop Grumman, in partnership with the Defense Advanced Research Projects Agency (DARPA), improved the resilience of embedded GPS receivers with a more intimate coupling of INS and GPS. The DARPA GPS Guidance Package (GGP) program demonstrated a Navigation Grade Fiber Optic Gyro (FOG), greatly improved GPS tracking performance under extreme vehicle dynamics, and the ability to track at lower signal-to-noise levels. Our success on this program reinforced our reputation as a GPS integration leader and led to the introduction of Northrop Grumman’s current LN-251 product line, which is broadly used in tactical military aircraft.

In the early 2000s, Northrop Grumman initiated research into the feasibility of a Global Navigation Satellite System (GNSS) software-defined radio and started development of what we now call SERGEANT (Software Enabled Reconfigurable GNSS Embedded Architecture for Navigation and Timing). The company used Spirent signal simulators to evaluate proper GPS M-code tracking over a wide range of test cases in a controlled laboratory environment. Together with the Air Force Research Laboratory (AFRL), Northrop Grumman demonstrated advanced receiver capabilities using SERGEANT starting in 2010. In 2018, AFRL used SERGEANT for the first real-time flight demonstration of a GPS M-code SDR.

How is your company preparing for the next 50 years of PNT with GPS and beyond?

Northrop Grumman foresees the world of GNSS being dramatically influenced by the emergence of alternative radio navigation sources as augmentations to traditional GNSS constellations to provide additional robustness and resilience. Our PNT SDR technology is a foundational tool to integrate these emerging radio navigation signals quickly and accelerate deployment to our customers.

Northrop Grumman has led medium-Earth orbit (MEO) and low-Earth orbit (LEO) PNT technology studies through the DARPA Blackjack proliferated LEO (pLEO) program, starting in 2017. Northrop Grumman’s SERGEANT SDR transceiver is currently being integrated for use in emerging pLEO constellations. We anticipate that these capabilities, as well as emerging cooperative radio navigation signals, will become a critical part of the next 50 years of PNT with GPS.

What is Spirent’s GPS origin story?

Spirent’s GPS genesis began on a rooftop in the middle of the night in the early 1980s. Engineers were attempting to acquire the new GPS signals with their receivers, scheduling their lives around the times when satellites would pass overhead, angling antennas off a roof in the dark, and hoping for favorable conditions. Those difficulties inspired an idea: since real-world conditions are never the same twice, simulating the signals in a lab would control variables and provide repeatable and trustworthy results.

That idea grew to be Spirent’s positioning division — a team of experts whose sole focus is to partner with customers to accelerate the deployment of robust PNT technology. In 1985, one of the first groundbreaking simulators provided to a customer generated six GPS L1/L2 signals. Soon after, we developed the world’s first simulator with SA-A/S capability, establishing our reputation for innovation. Today, simulation is for much more than convenience. The further upstream testing starts, the better for R&D and investment decisions. Because of that, we work across the spectrum in close partnership with constellation developers, receiver manufacturers, and OEM application integrators.

Can you share a recent breakthrough?

GPS regional military protection (RMP) is a nascent anti-jamming capability that uses a steerable, narrow-beam M-code signal, allowing U.S. and allied forces to operate much closer to interference without losing connection. Spirent supports RMP, so modernized GPS user equipment (MGUE) can be tested and integrated with RMP long before live-sky signals are available.
Another major breakthrough is in AltNav, a catch-all term that includes non-GNSS sources of RF and other complementary PNT, with recent attention focused on low-Earth orbit (LEO) constellations. Spirent has developed LEO AltNav simulators for both the military and commercial sectors that seamlessly integrate with Spirent’s extensive testbed for GNSS, threat simulation, inertial navigation systems, and additional complementary PNT.

How is your company preparing for the next 50 years of PNT with GPS and beyond?

As a trusted industry test partner, one of Spirent’s guiding principles over the past five decades has been to support PNT developers and early adopters by being first-to-market with new signals and constellations. Enabled by our flexible solutions, our dedication to that tenet will continue across the next five decades.

NAVWAR resilience testing is an area where emerging test needs will continue to demand more from the test environment. Layered PNT positioning engines — including GNSS, secure military signals, CRPA systems, multi-orbit architectures, and sensor fusion — are driving complexity in the test regimes that support them. Spirent’s purpose-built solutions are designed to meet these advancements, with deterministic simulation that delivers definitive validation and accurate test results.

Spirent pioneered the use of software-defined radios for GNSS simulation with the GSS9000, which enabled the same architecture to support new signal types, higher motion rates, user-defined waveforms, and more than double the generated signals. The next generation will extend that flexibility, capacity, and ease of integration to future complementary PNT sources while maintaining system performance across physical and virtual realms.

IBM, a global technology provider, has released its latest geospatial artificial intelligence (AI) initiative to address climate change. These efforts involve collaborations across various regions and uses advanced AI models designed for geospatial applications. 

Central to these initiatives is IBM’s geospatial foundation model, developed jointly with NASA. These models aim to generate environmental insights and solutions related to climate change. Unlike traditional AI models, these use a vast amount of climate-relevant data to accelerate the analysis of various environmental aspects that are affected by climate change. 

“AI foundation models utilizing geospatial data can be a game-changer, allowing us to better understand and address climate-related events with unprecedented speed and efficiency,” said Alessandro Curioni, IBM fellow and vice president of Accelerated Discovery. 

Analyzing urban heat islands in UAE 

IBM and the Mohamed Bin Zayed University of Artificial Intelligence (MBZUAI) have partnered to map urban heat islands in Abu Dhabi using a fine-tuned version of IBM’s geospatial foundation model. The goal of the project is to understand the impact of local landscapes on temperature anomalies, the company said. The initial results show a decrease in heat island effects, which can provide valuable insights for future urban design strategies. 

Reforestation and water sustainability in Kenya 

 In partnership with Kenya’s Special Envoy for Climate Change, Ali Mohamed, IBM is supporting the National Tree Growing and Restoration Campaign. The initiative aims to plant 15 billion trees by 2032, particularly in critical water tower areas affected by deforestation. IBM’s geospatial model powers a digital platform to track tree planting activities, aiding local efforts in restoring forests and measuring carbon sequestration impact.  

Elevating climate resiliency in the UK 

In collaboration with the Science and Technology Facilities Council (STFC) and Royal Haskoning DHV, IBM is developing AI-driven tools for climate risk assessment in the UK. These tools will focus on assessing weather impacts on aviation operations, the company said. Additionally, the TreesAI research project aims to map areas suitable for tree planting to mitigate surface water flooding and offer urban developers a digital planning platform.  

IBM extends collaboration with NASA for weather forecasting 

IBM and NASA have partnered to develop an AI foundation model dedicated to weather and climate applications. The collaboration aims to enhance the accuracy and speed of weather forecasting, predict wildfire conditions and understand meteorological phenomena. IBM researchers will work closely with NASA to train and validate this model, IBM said.  

Maritime Robotics, a Norwegian provider of autonomous technology, and Teledyne Marine have delivered several unmanned surface vessels (USVs) to Ukraine’s Navy for advanced sensor data collection. 

Maritime Robotics’ Otter USV, equipped with the Teledyne RESON SeaBAT T51-R multibeam echosounder, is now being used by Ukraine’s Navy. The USV is designed for critical data collection without endangering human lives, as the sensors are carried by an unmanned vehicle. The data and information collected by the USV aims to strengthen Ukraine’s defense, enhance maritime traffic security and support the safety of civilians in the areas. 

Otter USV is part of Maritime Robotics’ portfolio of autonomous technologies capable of supporting military personnel in mapping and securing marine environments. Controlled and navigated remotely, Maritime Robotics’ USVs are designed to identify, locate and safely neutralize potential threats such as explosive devices and sea mines.  

On Oct. 26, 2023, I participated in an American Society for Photogrammetry and Remote Sensing (ASPRS) Pacific Southwest Region Fall Technical webinar. The webinar provided an overview of the ASPRS Positional Accuracy Standards for Digital Geospatial Data (Edition 2, Version 1.0 – August 2023). The document can be downloaded here.

I also participated — virtually — in the Nov. 2, 2023, California Spatial Reference Center (CSRC) Coordinating Council fall meeting where Dr. Riadh Munjy, California State University, Fresno, discussed the revisions to the ASPRS Positional Accuracy Standards for Geospatial Data.

The most significant changes introduced in this second edition of the standards include:

1. Elimination of references to the 95% confidence level as an accuracy measure.
2. Relaxation of the accuracy requirement for ground control and checkpoints.
3. Consideration of survey checkpoint accuracy when computing final product accuracy.
4. Removal of the pass/fail requirement for Vegetated Vertical Accuracy (VVA) for lidar data.
5. Increase the minimum number of checkpoints required for product accuracy assessment from 20 to 30.
6. Limiting the maximum number of checkpoints for large projects to 120.
7. Introduction of a new term: three-dimensional positional accuracy.
8. Addition of Best Practices and Guidelines Addenda for:
   1. General Best Practices and Guidelines
   2. Field Surveying of Ground Control and Checkpoints
   3. Mapping with Photogrammetry
   4. Mapping with Lidar
   5. Mapping with UAS

As outlined above, Edition 2 contains Best Practices and Guidelines for (1) General Best Practices and Guidelines and (2) Field Surveying of Ground Control and Checkpoints. The three addenda listed in the table of contents: Mapping with Photogrammetry, Mapping with Lidar, and Mapping with UAS will be available for public comment later, and will be added to Edition 2, Version 2.0.

Dr. Abdullah informed me that these addenda are on track to be put out for public comments during December 2023, therefore he believes they will probably be published in January or February 2024. The box titled “Summary of Significant Changes in Edition 2” provides the changes with the reason and justification for each change. The document can be downloaded from ASPRS here.

One of the changes is to relax the accuracy requirement for ground control and checkpoints. At first glance, this seems like the wrong thing to do. However, after understanding the justification, the requirement for ground truth still needs to be at least twice as accurate as the product.

Both Dr. Abdullah and Dr. Munjy’s emphasized in their presentations that the current accuracy requirements for ground controls in photogrammetric work of four-times better than the produced products, and the checkpoint accuracy requirement is three-times better than the assessed product. This makes it difficult, if it is not impossible, to use RTK-based techniques for this type of surveying. This by itself is not the reason for the change. During Dr. Abdullah’s presentation, he provided the following reasons for the change:

1. “Experience taught us that the requirements of four-times and three-times adopted in edition 1 of the standards are excessive and too restrictive, partly due to the reason outlined in (b) below.
2. Today’s sensors, software, and processing methodology are more accurate and the room for errors in the product is diminishing, therefore we do not need a safety factor of 3 or 4 to obtain accurate products.
3. Increasing demand for higher accuracy geospatial products.”

The new standards now factor in the accuracy of the survey checkpoints when determining the accuracy of the product. During Dr. Abdullah’s presentation, he provided the following reason for the change, “As we are producing more accurate products, errors in surveying techniques of the checkpoints used to assess product accuracy, although small, can no longer be neglected and it should be represented in computing the product accuracy.” He also highlighted that, “As product accuracy increases, the impact of error in checkpoints on the computed product accuracy increases.” The document provides equations used to compute the values. See below.

A very significant change, in my opinion, is the removal of the standards for Vegetated Vertical Accuracy (VVA) for lidar data. See below.

I am not sure I agree with the reasoning, but I understand why it was done. GNSS-based surveys do not perform well in vegetated areas, and this is the technology used to validate the non-vegetated vertical accuracies (NVA). That said, there are non-GNSS technologies — sometimes denoted as traditional surveying methods — that could be used to validate VVA, so this seems like an elimination of a requirement based on the limitation of a particular technology.

Traditional surveying methods that use geodetic levels, theodolites, and total stations to measure distances, angles, and heights are still used by surveyors to perform certain projects. Since there are other surveying methods that could be used for evaluating the VVA, it does not seem like a valid reason for a change.

The ASPRS standards does state that, “for projects where vegetated terrain is dominant, the data producer and the client may agree on an acceptable threshold for the VVA.” Therefore, the client can require the surveyor to meet a specific accuracy level for vegetated areas. I am sure this was discussed during the working meeting, so I leave it to the experts to make the appropriate decisions and recommendations.

Finally, it should be noted that, as discussed above, the new ASPRS standards eliminated the reference to the 95% confidence level as an accuracy measure. The document provides the following statement about the National Standard for Spatial Data Accuracy (NSSDA):

“The National Standard for Spatial Data Accuracy (NSSDA) documents the equations for the computation of RMSE_X, RMSE_Y, RMSE_R and RMSE_Z, as well as horizontal (radial) and vertical accuracies at the 95% confidence levels — Accuracy_R and Accuracy_Z, respectively. These statistics assume that errors approximate a normal error distribution and that the mean error is small relative to the target accuracy. The ASPRS Positional Accuracy Standards for Digital Geospatial Data reporting methodology is based on RMSE alone, and thus differs from the NSSDA reporting methodology. Additionally, these Standards include error inherited from ground control and checkpoints in the computed final product accuracy.”

Appendix D of the ASPRS document provides the equations with an example for computing the accuracy statistics. The document also has a section with examples for users who wish to relate the ASPRS 2023 Standards to the FGDC National Standard for Spatial Data Accuracy (NSSDA).

Dr. Munjy ended his presentation at the CSRS 2023 fall meeting with the following statements:

“ASPRS Accuracy Standards 2023 have become more aligned with science and statistical theory,” and “These Standards are intended to be a living document which can be updated in future editions to reflect changing technologies and user needs.”

I would encourage all users to download the document to better understand the changes and reasons for the changes. It can be downloaded here.

Hexagon’s Safety, Infrastructure & Geospatial division has partnered with Pitkin County Regional Emergency Dispatch Center to upgrade its digital mapping and response for 911 calls in Colorado’s premier mountain tourist destination. The partnership aims to make the county safer for residents and visitors.

By using HxGN Connect software, Pitkin County can bring modern mapping capabilities to its computer-aided dispatch (CAD) system, as well as incorporate Smart Advisor, Hexagon’s assistive artificial intelligence solution.

Pitkin County, home of Aspen and its four major ski areas, hosts 1.5 million tourists per year. The upgrades will improve emergency response capabilities for major events such as the X Games and JAS Aspen music festival, the company says.

The cloud-based solution, hosted in Microsoft Azure, is designed to map 911 calls and conduct long-term resource planning. Smart Advisor will work in the background to help dispatchers and first responders connect related incidents and provide geofencing to concentrate resources on large events. Officials plan to expand the system to take advantage of its cross-organization collaboration capabilities by potentially linking the county’s CAD system with the fire department’s network of mountaintop smoke detectors and the Department of Public Works’ snowplows.

Pitkin County dispatchers will use HxGN Connect for digital mapping within its CAD system in the mountainous tourist destination.

The Educational Irish Research Satellite, EIRSAT-1, has successfully launched from Vandenberg Space Force Base, California on Dec. 1, 2023. Hitching a ride on a SpaceX Falcon 9 launcher, the small satellite has made history as Ireland’s first satellite.  

 Over the course of six years, EIRSAT-1 was designed, built and tested by students from University College Dublin (UCD) in Dublin, Ireland, participating in the European Space Agency (ESA) Academy’s Fly Your Satellite Program. The program is a hands-on initiative that helps university student teams develop their own satellites according to professional standards. The launch opportunity itself was provided by the ESA. 

 Throughout the development of the satellite, ESA experts provided training and guidance to dozens of UCD students, the ESA said. The students’ learning journey included test campaigns at ESA Education’s CubeSat Support Facility in Belgium, as well as dedicated spacecraft communications sessions at both ESA Academy’s Training and Learning Centre and the European Space Operations Centre in Darmstadt, Germany. These sessions were designed to teach the procedures for operating Ireland’s first spacecraft.  

From low-Earth-orbit (LEO), EIRSAT-1 will carry out three main experiments, which were built from scratch by the students: 

• GMOD, a detector to study gamma ray bursts, which are the most luminous explosions in the universe and occur when a massive star dies or two stars collide. 
• EMOD, an experiment to see how a thermal treatment protects the surface of a satellite when in space. 
• WBC, an experiment to test a new method of using Earth’s magnetic field to change a satellite’s orientation in space. 

Following EIRSAT-1’s deployment to orbit, the student team is now working to establish contact with the satellite and start operations from their dedicated ground control facility, also entirely operated by students and located at UCD in Dublin. 

The U.S. Army has awarded Lockheed Martin and Northrop Grumman other transaction agreements (OATs) for the first phase of the Launched Effects (LE) program.

Launched Effects “will provide standoff sense and effect capabilities for soldiers while keeping air and ground forces outside the range of adversary weapon systems,” according to the service’s Program Executive Office for Intelligence, Electronic Warfare and Sensors. It also said LE will also support forces entering and exiting mission areas. 

 Northrop has been awarded for two payloads and Lockheed Martin has been awarded for one, with each award valued at about $100,000, according to the Army. The OTA will total about $37 million over all three phases. 

 The LE program consists of three phases. During that span, the Army aims to mature payloads from a technology readiness level of 6, a prototype system that has been tested in a relevant environment, to TRL 7, a prototype that has been demonstrated in an operational environment. 

 Launched effects have been successfully tested by the Army in the past, including at Project Convergence. In January 2023, General Atomics Aeronautical Systems announced its Eaglet launched-effect flew for the first time, dropping off an Army-owned Gray Eagle Extended Range UAV during a demonstration in Utah. 

Half a century ago, on December 22, 1973, Deputy Secretary of Defense William P. Clements, on the recommendation of the Defense Systems Acquisition and Review Council, directed the entire Department of Defense — through the Navstar GPS Joint Program Office, under the spectacular leadership of  Col. Bradford Parkinson — to proceed with the GPS program. While this magazine mostly focuses on the present and the future, we occasionally pause to remember how it all began.

In the following articles, we are lucky to benefit from the long memories of four gentlemen who were there. Read the full articles.

“Lost in the desert, they demanded GPS” by Gaylord Green

“From ‘We don’t need it’ to ‘We can’t live without it’” by Martin Faga

“They used GPS even before it was fully built” by Dave Zilkoski

“GPS: The birth of the commercial GPS industry and how it changed the world” by Charles R. Trimble

Trimble Navigation, which had started out making Loran receivers, was looking for its next marine project when HP decided to cancel its GPS project. Budget problems in Washington put completion of GPS in doubt. However, encouraging words from Brad Parkinson were enough for Trimble Navigation to buy the canceled project.

The purchase included a stack 14-ft high of unclassified reading material and a breadboard that fit on the table of a mobile home. It was a working GPS receiver that had recorded the mobile home’s position as it was driven around freeways in the San Francisco area. It took 12 months for a team of two engineers and 15 consultants to come up with the seven breakthroughs needed for the block diagram. Trimble was to iterate this block diagram on an 18-month cycle to follow Moore’s Law cost curve to the $100 required for car navigation. It took another year to build six rack-mounted multichannel receivers.

In October 1984, Trimble sold the first receiver for $100,000. Then came the sale of 20 OEM single channel timing receivers. The oil service industry was an important early market. At the time there were only seven GPS satellites in the sky and applications were limited to 3-4 hrs/day of accurate position measurement. Accuracy was a market driver, which led to the development of differential systems. These provided meter accuracies over wide areas. The next and far more difficult step was enabling a 1st order survey — which required accuracies of 1 cm/km.

Meanwhile, next gen GPS was added to Trimble’s marine Loran-C receiver and the company produced aviation receivers for the commercial markets. In January 1986, Trimble licensed its GPS technology for the Japanese car navigation market to Pioneer.
Then came the Shuttle disaster, and a new rocket had to be designed to launch more satellites. With only seven satellites in the sky and an unknowable time for rocket development, GPS use for navigation was off the table. Getting carrier phase 1st order products to work became critical for Trimble’s survival. In May of 1986, Trimble shipped an order of seven survey systems to the California Department of Transportation (Caltrans). Earthquake monitoring was a niche market add-on. Another “bet your company” deal was a Japanese order of 25 dual frequency systems.

During this time Trimble started to realize GPS was more than a device — that time-stamping events and geo-tagging things made it a valuable information technology component. The real value was in the information. By 2000, the Hong Kong price of the GPS function in quantities of a million devices a month was $1. GPS became ubiquitous and a fundamental component of a thriving information technology market.

GPS started out as a real-time worldwide system for navigation. It is now an indispensable part of modern life. GPS has truly changed our world.