GPS Block IIIF

Engineering efforts for Block IIIF satellites began upon contract award in 2016—a full 16 years after the government approved entry into the initial modernization efforts for GPS III in 2000.{{Cite web |date=1 December 2019 |title=GPS III Selective Acquisition Report |url=https://www.esd.whs.mil/Portals/54/Documents/FOID/Reading%20Room/Selected_Acquisition_Reports/FY_2019_SARS/20-F-0568_DOC_35_GPS_III_SAR_Dec_2019_Full.pdf |access-date=22 January 2023 |publisher=U.S. Space Force}} As a result, GPS Block IIIF introduces a number of improvements and novel capabilities compared to all previous GPS satellite blocks.

Block IIIF satellites host a redesigned U.S. Nuclear Detonation Detection System (USNDS) capability that is both smaller and lighter than previous systems.

The USNDS is a worldwide system of space-based sensors and ground processing equipment designed to detect, identify, locate, characterize, and report nuclear detonations in the Earth's atmosphere and in space.{{Cite web |date=28 September 2018 |title=(U) Evaluation of the Space-Based Segment of the U.S. Nuclear Detonation Detection System |url=https://media.defense.gov/2019/Nov/12/2002209615/-1/-1/1/DODIG-2018-160.PDF |access-date=22 January 2023 |publisher=U.S. Department of Defense Inspector General}}

GPS IIIF satellites are the first to feature a 100% digital navigation payload.{{Cite web |date=23 February 2021 |title=Four More Digital Mission Data Units for GPS IIIF Satellites to Come from L3Harris |url=https://insidegnss.com/four-more-digital-mission-data-units-for-gps-iiif-satellites-to-come-from-l3harris/ |access-date=22 January 2023 |publisher=InsideGNSS.com}}

The fully-digital navigation payload introduced by Block IIIF (SV11+) produces improved accuracy, better reliability, and stronger signals compared to the 70% digital navigation payload used by GPS Block III (SV01-SV10).{{Cite web |date=11 February 2020 |title=L3Harris Technologies passes Critical Design Review For New Fully Digital GPS IIIF Satellite Navigation Payload |url=https://www.l3harris.com/newsroom/press-release/2020/02/l3harris-technologies-passes-critical-design-review-new-fully |access-date=22 January 2023 |publisher=L3Harris Technologies}}{{Cite web |last=Strout |first=Nathan |date=12 February 2020 |title=The next GPS payload will be fully digital |url=https://www.c4isrnet.com/battlefield-tech/space/2020/02/12/the-next-gps-payload-will-be-fully-digital/ |access-date=22 January 2023 |publisher=C4ISRNet.com}}

GPS IIIF-03 and beyond (GPS III SV13+) will incorporate the Lockheed Martin LM2100 Combat Bus, an improvement on the LM2100M bus used in GPS III SV01 through SV12. The LM2100 Combat Bus provides improved resilience to cyber attacks, as well as improved spacecraft power, propulsion, and electronics.

GPS IIIF satellites will be the first GPS satellites to host an Energetic Charged Particle (ECP) sensor payload.

In March 2015, the U.S. Secretary of the Air Force enacted policy mandating all new Air Force satellite programs must include ECP sensors.{{Cite web |last=Starks |first=Michael |date=2 December 2016 |title=White Paper on ECP Energy Range and Flux Requirements |url=https://apps.dtic.mil/sti/pdfs/AD1120231.pdf |access-date=22 January 2023 |publisher=Air Force Research Laboratory Space Vehicles Directorate}} Aggregating ECP data from multiple satellites allows for enhanced space domain awareness, enabling improved detection of space weather effects as well as differentiation between anomalies induced by hostile activity, the natural environment, or other non-hostile causes.{{Cite web |last=U.S. Air Force |date=30 November 2016 |title=Automatic Exploitation of Energetic Charged Particle Sensor Data |url=https://www.sbir.gov/node/1208177 |access-date=22 January 2023 |publisher=SBIR.gov}}{{Cite web |last=Erwin |first=Sandra |date=14 November 2019 |title=Air Force: SSA is no more; it's 'Space Domain Awareness' |url=https://spacenews.com/air-force-ssa-is-no-more-its-space-domain-awareness/ |access-date=22 January 2023 |publisher=SpaceNews.com}}

GPS IIIF will be the first GPS satellite block to have all space vehicles participate in the Cospas-Sarsat system. The Cospas-Sarsat system is an international collection of satellites spanning low-earth, medium-earth, and geostationary orbit satellites which all listen for 406 MHz distress signals generated by beacons on earth. Satellites relay distress signals to ground stations to initiate timely emergency response efforts.{{Cite web |title=Search and Rescue Satellites |url=https://www.sarsat.noaa.gov/search-and-rescue-satellites/ |access-date=22 January 2023 |publisher=U.S. National Oceanic and Atmospheric Administration}}

Adding laser retro-reflector arrays (LRAs) to all GPS IIIF Space Vehicles allows GPS monitoring stations on earth equipped with laser rangefinding equipment to determine much more precise 3D locations for every GPS IIIF satellite. This improves the ability of the GPS system to provide more accurate time/position fixes to GPS receivers. Estimates are that as more GPS satellites host LRAs, the location accuracy will improve from one meter achievable today to one centimeter accuracy, an improvement of several orders of magnitude.{{Cite web |last=GPS World Staff |date=1 September 2013 |title=Expert Advice: Laser Reflectors to Ride on Board GPS III |url=https://www.gpsworld.com/expert-advice-laser-reflectors-to-ride-on-board-gps-iii/ |access-date=22 January 2023 |publisher=GPSWorld.com}}

Block IIIF will be compliant with the Unified S-Band (USB) capabilities, allowing for consolidation of radio frequencies used for telemetry, tracking, and commanding of Block IIIF satellites.{{Cite web |date=1 January 2011 |title=GPS Future and Evolutions |url=https://gssc.esa.int/navipedia/index.php/GPS_Future_and_Evolutions#New_GPS_satellites |access-date=22 January 2023 |publisher=European Space Agency}}

Regional Military Protection (RMP) is an anti-jamming technology for military GPS consumers. RMP involves directing a massively-amplified spot beam which only includes military GPS signals over a small geographic area. US/allied military GPS receivers located within the RMP spot beam's signal footprint are significantly more difficult for adversaries to jam due to the extremely-amplified signal strength in the area.{{Cite web |date=18 January 2023 |title=GPS III/IIIF: The New Generation Of Positioning, Navigation and Timing |url=https://www.lockheedmartin.com/en-us/products/gps.html |access-date=22 January 2023 |publisher=Lockheed Martin}}

GPS IIIF-03 and newer satellites (GPS III SV13+) will incorporate Lockheed-Martin's LM2100 Combat Bus. Satellites based on the Combat Bus are capable of hosting the "Augmentation System Port Interface" (ASPIN), an interface that allows for future on-orbit servicing and upgrade opportunities.{{Cite web |date=15 November 2021 |title=Lockheed Martin Contracted To Build Three GPS III Follow On Satellites By USSF |url=https://news.satnews.com/2021/11/15/lockheed-martin-contracted-to-build-three-gps-iii-follow-on-satellites-by-ussf/ |access-date=22 January 2023 |publisher=satnews.com}}

The first GPS Block IIIF satellite is planned to launch in 2027.{{Cite web |date=5 November 2023 |title=Final GPS III Missions, First GPS IIIF Satellites Part of SSC's Latest Launch Assignments |url=https://insidegnss.com/final-gps-iii-missions-first-gps-iiif-satellites-part-of-sscs-latest-launch-assignments/ |access-date=21 November 2023 |publisher=Inside GNSS}} The first three launches have been contracted.

{{Main|GPS signals}}

Note: none of the navigation signals that GPS Block IIIF satellites transmit are new in Block IIIF; all signals were first supported in previous generation (Block I, Block II, or Block III) GPS satellites.

GPS IIIF is an evolution of GPS III, which uses the A2100 bus as its core. The new models use the modernized LM2100 bus along with a fully digital navigation payload from L3Harris, a significant upgrade from the previous 70% digital payload used in GPS III.{{Cite web |date=24 February 2021 |title=L3Harris Contracted for 4 Mission Data Units for GPS IIIF Satellites |url=https://www.satellitetoday.com/government-military/2021/02/24/l3harris-contracted-for-4-mission-data-units-for-gps-iiif-satellites/ |access-date=14 June 2021 |website=Via Satellite |language=en}}{{Cite web |last=GNSS |first=Inside |date=23 February 2021 |title=Four More Digital Mission Data Units for GPS IIIF Satellites to Come from L3Harris |url=https://insidegnss.com/four-more-digital-mission-data-units-for-gps-iiif-satellites-to-come-from-l3harris/ |access-date=14 June 2021 |website=Inside GNSS – Global Navigation Satellite Systems Engineering, Policy, and Design |language=en-US}}{{Cite web |title=Most Advanced SBIRS Missile Warning Satellite Ready For 2021 Launch |url=https://news.lockheedmartin.com/SBIRS_GEO_5_Completed |access-date=14 June 2021 |website=Media – Lockheed Martin |language=en-us}}

An upgraded version known as the LM2100 Combat Bus will be used starting with the third service vehicle. It will enable on-orbit servicing at a later date, which may include hardware upgrades, component replacement, or refuelling.{{Cite press release |title=Lockheed Martin's First Modernized SBIRS Missile Warning Satellite Now Under U.S. Space Force Control |url=https://www.prnewswire.com/news-releases/lockheed-martins-first-modernized-sbirs-missile-warning-satellite-now-under-us-space-force-control-301294245.html |language=en |last1=Martin |first1=Lockheed |access-date=14 June 2021 |website=www.prnewswire.com}}{{Cite web |date=26 February 2021 |title=Lockheed Martin to upgrade GPS satellites for in-orbit servicing |url=https://spacenews.com/lockheed-martin-to-upgrade-gps-satellites-for-in-orbit-servicing/ |access-date=18 June 2021 |website=SpaceNews |language=en-US}}

Medium Earth Orbit Search and Rescue (MEOSAR) payloads are being provided by the Canadian government on behalf of the Canadian Armed Forces. The time it takes to detect and locate a distress signal will be reduced from an hour to five minutes, along with greatly improved accuracy in locating a distress beacon.{{Cite web |date=13 May 2019 |title=MDA to build search-and-rescue repeaters for GPS 3F satellites |url=https://spacenews.com/mda-to-build-search-and-rescue-repeaters-for-gps-3f-satellites/ |access-date=14 June 2021 |website=SpaceNews |language=en-US}}{{Cite web |last=Canada |first=Public Services and Procurement |title=Government of Canada awards contract for new space-based search and rescue technology |url=https://www.newswire.ca/news-releases/government-of-canada-awards-contract-for-new-space-based-search-and-rescue-technology-832448437.html |access-date=14 June 2021 |website=www.newswire.ca |language=en}}

Laser Retroreflector Arrays (LRAs) will be built by the United States Naval Research Lab. This is a passive reflector system that improves accuracy and provides better ephemeris data. The National Geospatial-Intelligence Agency (NGA) will fund the integration costs of the LRA.

Other significant enhancements include: unified S-Band (USB) interface compliance, integration of hosted payloads including a redesigned United States Nuclear Detonation (NUDET) Detection System (USNDS) payload, Energetic Charged Particles (ECP) sensor, and Regional Military Protection (RMP) capabilities that provide the ability to deliver high-power regional Military Code (M-Code) signals in specific areas of intended effect.{{Cite web |date=May 2021 |title=Department of Defense Fiscal Year 2022 Budget Estimates |url=https://www.saffm.hq.af.mil/Portals/84/documents/FY22/PROCUREMENT_/FY22%20DAF%20J-Book%20-%203022%20-%20SF%20Proc.pdf?ver=NEFQ6zdjfeGcJFeAdv_97g%3d%3d#page=49 |website=Assistant Secretary of the Air Force, Financial Management and Comptroller}}

The U.S. Air Force has identified four "technology insertion points" for GPS Block IIIF. These four points are the only four times during the block's lifecycle where new capabilities will be allowed to be introduced to Block IIIF satellites.

• First Space Vehicle: GPS IIIF-01
• Proposed/possible new functionality:
• On Orbit Reprogrammable Digital Payload{{Cite web |date=26 February 2021 |title=Lockheed Martin to upgrade GPS satellites for in-orbit servicing |url=https://spacenews.com/lockheed-martin-to-upgrade-gps-satellites-for-in-orbit-servicing/ |access-date=27 February 2021 |publisher=SpaceNews}}{{Cite web |date=8 January 2014 |title=On-Orbit Reprogrammable Digital Waveform Generator (ORDWG) for the GPS Spaceccraft Navigation Payload |url=https://govtribe.com/opportunity/federal-contract-opportunity/on-orbit-reprogrammable-digital-waveform-generator-ordwg-for-the-gps-spaceccraft-navigation-payload-baarvkv20140004 |access-date=10 November 2018 |website=govtribe.com |publisher=US Air Force Research Lab}} {{PD-notice}}{{Cite web |date=1 May 2015 |title=Advanced GPS Technologies |url=https://www.gps.gov/multimedia/presentations/2015/04/partnership/slimak.pdf |access-date=10 November 2018 |website=gps.gov |publisher=US Air Force Research Lab}} {{PD-notice}}
• High Power Amplifiers (SSPA's)
• Regional Military Protection (RMP){{Cite web |date=June 2016 |title=Military GPS Receiver Advances Could Help Trim Satellite Costs |url=http://insidegnss.com/auto/mayjune16-WASHVIEW.pdf |access-date=10 November 2018 |publisher=Inside GNSS}}

• First Space Vehicle: GPS IIIF-07
• Proposed/possible new functionality:
• M-Code Space Service Volume{{Cite web |last=Bauer |first=Frank |date=11 June 2015 |title=GPS Space Service Volume (SSV) Ensuring Consistent Utility Across GPS Design Builds for Space Users |url=https://www.gps.gov/governance/advisory/meetings/2015-06/bauer.pdf |access-date=10 November 2018 |website=gps.gov}} {{PD-notice}}

• First Space Vehicle: GPS IIIF-13
• Proposed/possible new functionality:
• Near Real-Time Commanding
• Advanced Clocks

• First Space Vehicle: GPS IIIF-19
• Proposed/possible new functionality:
• TBD

The U.S. Air Force employed a two-phase competitive bid acquisition process for the GPS Block IIIF satellites.

On 5 May 2016, the U.S. Air Force awarded three Phase One Production Readiness Feasibility Assessment contracts for GPS III Space Vehicles (SV's) 11+, one each to Boeing Network and Space Systems, Lockheed Martin Space Systems Company, and Northrop Grumman Aerospace Systems.{{Cite web |last=U.S. Air Force Space and Missile Systems Center, Public Affairs |date=8 January 2016 |title=SMC releases RFP for GPS III Space Vehicles 11+ Phase 1 Production Readiness Feasibility Assessment |url=https://www.losangeles.spaceforce.mil/ |access-date=2 December 2017}} {{PD-notice}} The phase one contracts were worth up to six million dollars each. During the phase one effort, both Boeing and Northrop Grumman demonstrated working navigation payloads.{{Cite web |last=Capaccio |first=Anthony |date=2 November 2017 |title=Air Force Plans US$10 Billion GPS III Contest Amid Lockheed Delays |url=https://www.bloomberg.com/news/articles/2017-11-02/lockheed-s-latest-delays-on-satellites-may-open-door-to-boeing |access-date=2 December 2017 |website=bloomberg.com |publisher=Bloomberg}}

On 19 April 2017, the U.S. Air Force Space Command announced the start of the second phase of its acquisition strategy with the publication of a special notice for an "Industry Day" for companies planning on bidding for the contract to manufacture GPS III vehicles 11+.{{Cite web |last=Divis |first=Dee Ann |date=27 April 2017 |title=Door Open to New Bidders as Air Force Moves Closer to GPS III Buy |url=http://www.insidegnss.com/node/5448 |url-status=dead |archive-url=https://web.archive.org/web/20171202102753/http://www.insidegnss.com/node/5448 |archive-date=2 December 2017 |access-date=3 May 2017 |website=insidegnss.com |publisher=Gibbons Media & Research}} During the Industry Day event, the Air Force shared the tentative acquisition strategy which it will use to evaluate proposals, then solicited feedback from potential bidders.

In July 2017, the Deputy Director of the U.S. Air Force GPS Directorate stated the acquisition strategy for GPS Block IIIF would be to award the manufacturing contracts for all 22 Block IIIF satellites to the same contractor.{{Cite web |last=Divis |first=Dee Ann |date=17 July 2017 |title=GPS Official: Expect One Follow-on GPS III Contractor, Tech Insertion Points |url=http://www.insidegnss.com/node/5546 |url-status=dead |archive-url=https://web.archive.org/web/20180218031238/http://insidegnss.com/node/5546 |archive-date=18 February 2018 |access-date=15 August 2017 |website=insidegnss.com |publisher=Gibbons Media & Research}}

In November 2017, the Deputy Director of the U.S. Air Force's GPS Directorate announced the name of the second tranche of GPS III satellites was "GPS Block IIIF".{{Cite web |last=Divis |first=Dee Ann |date=22 November 2017 |title=Next Tranche of GPS Satellites to be called GPS IIIFs |url=http://insidegnss.com/node/5695 |url-status=dead |archive-url=https://web.archive.org/web/20171202102800/http://insidegnss.com/node/5695 |archive-date=2 December 2017 |access-date=1 December 2017 |website=insidegnss.com |publisher=Gibbons Media & Research}}

Also in November 2017, it was announced that development of the fully digital navigation payload for GPS Block IIIF satellites had completed.{{Cite web |date=9 November 2017 |title=Harris Completes Development of Fully Digital Navigation Payload for Future GPS III Satellites |url=http://www.insidegnss.com/node/5680 |url-status=dead |archive-url=https://web.archive.org/web/20171203013846/http://www.insidegnss.com/node/5680 |archive-date=3 December 2017 |access-date=2 December 2017}} The Block IIIA program schedule was delayed multiple times due to issues with the navigation payload.{{Cite web |date=11 February 2014 |title=GPS III Payload Facing Delays |url=http://gpsworld.com/gps-iii-payload-facing-delays/ |access-date=2 December 2017 |website=gpsworld.com |publisher=North Coast Media}}{{Cite web |last=Gruss |first=Mike |date=14 September 2016 |title=Lockheed Martin says first GPS 3 satellite delayed until December |url=http://spacenews.com/lockheed-martin-says-first-gps-3-satellite-delayed-until-december/ |access-date=2 December 2017 |website=SpaceNews}}

While the Air Force originally expected to publish the formal Request For Proposals (RFP) for GPS Block IIIF production in September 2017, it was not released until 13 February 2018.{{Cite web |last=Divis |first=Dee Ann |date=16 January 2018 |title=Industry Awaits GPS III RFP As Delays Mount |url=http://www.insidegnss.com/node/5746 |url-status=dead |archive-url=https://web.archive.org/web/20180120065627/http://www.insidegnss.com/node/5746 |archive-date=20 January 2018 |access-date=18 January 2018 |website=insidegnss.com |publisher=Gibbons Media & Research}} The RFP was for a firm-fixed price (FFP) contract for a single company to manufacture all 22 space vehicles. All three participants from phase one (Boeing, Lockheed Martin, and Northrop Grumman) were believed to be likely to submit proposals. The government held a pre-proposal conference in El Segundo, California, to be held on 15 March 2018 for potential bidders to ask the Air Force questions about the solicitation. The submission deadline for proposals was 16 April 2018.{{Cite web |date=13 February 2018 |title=GPS IIIF Request For Proposal (RFP) |url=https://www.fbo.gov/spg/USAF/AFSC/SMCSMSC/FA8807-17-R-0009/listing.html |access-date=13 February 2018 |website=fbo.gov}} {{PD-notice}}

The bid status of companies who participated in phase one, in alphabetical order:

• Boeing: declined to submit a proposal{{Cite web |last=Divis |first=Dee Ann |date=18 April 2018 |title=Boeing Declines to Bid on GPS III |url=http://www.insidegnss.com/node/5841 |url-status=dead |archive-url=https://web.archive.org/web/20180419005835/http://insidegnss.com/node/5841 |archive-date=19 April 2018 |access-date=20 April 2018 |website=insidegnss.com |publisher=Gibbons Media & Research}}
• Lockheed Martin: submitted a proposal
• Northrop: declined to submit a proposal

On 14 September 2018, the Air Force awarded a manufacturing contract with options worth up to US$7.2 billion to Lockheed Martin.

GPS Block IIIF's ground control system of record will be the same used for GPS Block III, the Next Generation GPS Operational Control System (OCX).

In order to be able to command and control Block IIIF satellites, in April 2021 the U.S. Space Force awarded a $228 million contract to Raytheon Intelligence and Space called OCX Block 3F, which builds on the existing OCX Block 2 system and adds the ability to perform Launch and Checkout of Block IIIF satellites.{{Cite web |last=Dunn |first=Michael |date=2 May 2022 |title=Directions 2022: GPS positioned for the future |url=https://www.gpsworld.com/directions-2022-positioned-for-the-future/ |access-date=21 January 2023 |publisher=GPSWorld.com}}{{Cite web |date=6 May 2021 |title=Counting 0, 1, 2, 3F: The Long Hello of GPS OCX |url=https://insidegnss.com/counting-0-1-2-3f-the-long-hello-of-gps-ocx/ |access-date=21 January 2023 |publisher=Inside GNSS}}

OCX Block 3F delivery was expected in July 2025, with operational acceptance expected in late 2027.{{Cite web |date=6 November 2022 |title=Military Communications & Positioning, Navigation, and Timing Overview & GPS Enterprise Update |url=https://www.gps.gov/governance/advisory/meetings/2022-11/baker.pdf |access-date=21 January 2023 |publisher=U.S. Space Force Space Systems Command}}

{{Portal|Spaceflight}}

• BeiDou Navigation Satellite System
• BeiDou-2 (COMPASS) navigation system
• Galileo (satellite navigation)
• GLONASS
• Quasi-Zenith Satellite System

{{Reflist}}

{{GPS satellites}}

Category:Global Positioning System