GPS World

Tag: GPS IIF-11

  • System of Systems: New BeiDou TMBOC signal tracked

    New BeiDou TMBOC signal tracked

    Similar structure to future GPS L1C

    China’s new third-generation BeiDou satellites are broadcasting some new signals in space. The newest signal, which just began broadcasting from a satellite launched on Sept. 30, is similar to the future GPS L1C signal with time-division BOC(1,1) and BOC(6,1) signals. Such a type of modulation is called time-multiplexed binary offset carrier (TMBOC).

    Researchers at JAVAD GNSS have been tracking the new signals, particularly those from BeiDou-3 I2S, an inclined geosynchronous orbit (IGSO) spacecraft, NORAD number 40938. I2S is transmitting on three frequency bands.

    The JAVAD researchers used the decoding approach described in their February 2013 GPS World article, “Signal Decoding with Conventional Receiver and Antenna: A Case History Using the New Galileo E6-B/C Signal” by Sergei Yudanov. As a result, the signal’s structure was decoded and L1C TMBOC tracking has been successfully tested on the JAVAD GNSS TRE-3 receiver.

    In addition, new signals on 1575.42+1.023*14 MHz (B1-2), 1176.45 MHz (E5A) and 1207.14 (E5B) frequencies for three satellites (PRN 32, 33, 34) also have been decoded and tested. Figures 1–4 illustrate the experiment.

    Figure 1: BeiDou TMBOC: correlation intensity (l) of BOC(1,1) (red), BOC(6,1) (green) and their sum (blue) versus code chips.
    Figure 1: BeiDou TMBOC: correlation intensity (l) of BOC(1,1) (red), BOC(6,1) (green) and their sum (blue) versus code chips.
    Figure 2: BeiDou TMBOC: Output of “early-late” correlator (dI or derivative of I) of BOC(1,1) (red), BOC(6,1) (green) and their sum (blue) versus code chips.
    Figure 2: BeiDou TMBOC: Output of “early-late” correlator (dI or derivative of I) of BOC(1,1) (red), BOC(6,1) (green) and their sum (blue) versus code chips.
    Figure 3: BeiDou TMBOC Signal: Horizontal axis: 0 – minus one chip shift; 327 – zero shift; 655 – plus one chip shift. C/NO and iono-free “range minus phase.” Slot – BeiDou signal: C/A – B1; P1 – B1-2; P2 – E5B; L2C – B3; L5 – E5A; L1C – L1C.
    Figure 3: BeiDou TMBOC Signal: Horizontal axis: 0 – minus one chip shift; 327 – zero shift;
    655 – plus one chip shift. C/NO and iono-free “range minus phase.” Slot – BeiDou signal: C/A – B1; P1 – B1-2; P2 – E5B; L2C – B3; L5 – E5A; L1C – L1C.
    Figure 4 (right): BeiDou TMBOC Signal: Horizontal axis: 0 – minus one chip shift; 327 – zero shift; 655 – plus one chip shift. C/NO and iono-free “range minus phase.” Slot – BeiDou signal: C/A – B1; P1 – B1-2; P2 – E5B; L2C – B3; L5 – E5A; L1C – L1C.
    Figure 4 (right): BeiDou TMBOC Signal: Horizontal axis: 0 – minus one chip shift; 327 – zero shift;
    655 – plus one chip shift. C/NO and iono-free “range minus phase.” Slot – BeiDou signal: C/A – B1; P1 – B1-2; P2 – E5B; L2C – B3; L5 – E5A; L1C – L1C.

    Researchers Steffen Thoelert and Michael Meurer from the Deutsches Zentrum für Luf t- und Raumfahrt (DLR, German Aerospace Center) have also been busy tracking the newest BeiDou IGSO satellite. Figure 5 shows a spectral measurement of the complete GNSS L-band frequency range, which shows the signal transmissions on B1, B2 and B3 band. The signal was captured with DLR’s high-gain antenna in Weilheim, operated by the DLR German Space Operations Center in Oberpfaffenhofen.

    Figure 5: BeiDou Signal: Complete GNSS L-band frequency range, which shows the signal transmissions on B1, B2 and B3 band.
    Figure 5: BeiDou Signal: Complete GNSS L-band frequency range, which shows the signal transmissions on B1, B2 and B3 band.

    In comparison to the two latest BeiDou-3 MEO satellites, launched on July 25, the IGSO has an additional signal on the B3 band. The MEO satellites transmit only the QPSK(10) while  the new IGSO also transmits an additional BOC(15,2.5) signal. Figure 6 shows the B3 frequency band separately including a combined theoretical signal (QPSK(10)+BOC(15,2.5)). 

    Figure 6: BeiDou Signal: the B3 frequency band separately include a combined theoretical signal PSK(10)+BOC(15,2.5)).
    Figure 6: BeiDou Signal: the B3 frequency band separately include a combined theoretical signal PSK(10)+BOC(15,2.5)).

    IIF-11 up: penultimate GPS Block IIF satellite

    A United Launch Alliance Atlas V 401 launched the GPS IIF-11 mission for the U.S. Air Force on Oct. 31.

    GPS IIF-11 is the second to last of the Block IIF satellites, delivering a second civil signal (L2C) for dual-frequency equipment, and a new third civil signal (L5) to support commercial aviation and safety-of-life applications. The next generation of GPS satellites is GPS III.

    GPS IIF-11 is the third GPS mission to rise this year. GPS IIF-9 launched in March, and GPS IIF-10 in July. The next satellite, GPS-IIF-12, the last of its generation, is destined for space in early February 2016.

    Galileos chirp

    Shortly after the Galileo satellite using the E24 PRN code started transmitting on Oct. 10, its sibling began transmitting using code E30. Several stations participating in the International GNSS Service Multi-GNSS Experiment are tracking the new satellites; first among those reporting was the University of Liege, Belgium, using its Septentrio PolaRx4 and PolaRxS receivers to download signals.

    The two satellites were launched on Sept. 11. A team of engineers from ESA and France’s CNES space agency are preparing for the next launch, scheduled for December.

  • Next-to-last GPS IIF satellite launched into orbit

    Next-to-last GPS IIF satellite launched into orbit

    GPS IIF-11 Heads for space on Halloween.
    GPS IIF-11 Heads for space on Halloween.

    The U.S. Air Force successfully launched its 11th and next-to-last Boeing-built Global Positioning System GPS IIF series satellite aboard a United Launch Alliance Atlas V 401 launch vehicle from Space Launch Complex 41, Cape Canaveral Air Force Station, Fla., on Oct. 31 at 12:13 p.m. EDT (9:13 a.m. PDT).

    GPS IIF satellites provide improved signals to support both the warfighter and the growing civilian needs of a global economy. Featuring a new operational third civil signal — L5 — that benefits commercial aviation and safety-of-life applications, the GPS IIF series provides improved accuracy through advanced atomic clocks, a longer design life than previous GPS satellites on orbit.The GPS constellation is healthy, stable and robust with two GPS IIAs, 12 GPS IIRs, seven GPS IIR-Ms and 10 GPS IIF satellites on orbit providing precise global positioning, navigation, and timing services to users around the globe.

    Colonel Steven P. Whitney.
    Colonel Steven P. Whitney.

    “The successful outcome of today’s mission is due to the tremendous commitment of a world class team focused on mission success,” said Col. Steve Whitney, director of the Space and Missile Systems Center’s (SMC) GPS Directorate. “I am pleased to say it’s truly an honor and privilege to be part of a mission that plays such a critical role in our nation’s infrastructure. To the men and women of SMC, the 45th, 50th, 310th Space Wings, Boeing, United Launch Alliance, The Aerospace Corporation, GPS IIF and the Atlas V launch teams, thank you!”

    “The GPS IIF satellites play a key role in our modernization effort to provide new space-based capabilities for users around the globe and for decades to come,” said Lt. Gen. Samuel Greaves, SMC commander and Air Force Program Officer for Space. “The successful outcome of today’s mission is due to the tremendous commitment of a world-class team focused on mission success.”

    “As the nation’s premier gateway to space, we are proud to be part of the team providing GPS and its capabilities to the world,” said Brig. Gen. Wayne Monteith, 45th Space Wing (Patrick Air Force Base, Fla.) commander, who served as the Launch Decision Authority. “GPS IIF-11 was the 16th launch this year for the wing. Our team diligently prepared for this important mission through a series of rigorous rehearsals, readiness reviews and pre-operational checkouts. Together, with the Space and Missile Systems Center and our industry partners, we make up one team delivering assured space launch and combat capabilities for the nation.”

    The integrated team is now preparing GPS IIF-12, the last model of the series, scheduled for launch on Feb. 3, 2016. An airmen-led processing team at Cape Canaveral has processed every launch of the series since GPS IIF-1 launched there in May 2010.

    Operated by Air Force Space Command’s 50th Space Wing at Schriever Air Force Base, east of Colorado Springs, Colo., the GPS constellation provides precise positioning, navigation and timing services worldwide as a free service provided by the U.S. Air Force, seven days a week, 24-hours a day.

  • GPS IIF-11 Launch Delayed until Saturday

    GPS IIF-11 Launch Delayed until Saturday

    Major General David Thompson announces a 24-hour delay for the launch of the eleventh GPS-IIF satellite.
    Major General David Thompson announces a 24-hour delay for the launch of the eleventh GPS-IIF satellite.

    Major General David Thompson, Vice Commander, U.S. Air Force Space Command, announced this morning that the GPS IIF launch scheduled for today will be delayed for 24 hours due to a water deluge suppression system at the launch site. Launch should only be delayed for 24 hours.

    The water deluge suppression system is a launch site safety issue. Officials made the call on Thursday evening to postpone the launch to correct a leak discovered in a ground support equipment valve for the launch pad water suppression system. The valve will require repair or replacement.

    The 19-minute launch window on Saturday extends from 12:13 to 12:32 p.m. EDT (1613-1632 GMT).

    A United Launch Alliance Atlas V 401 will launch the GPS IIF-11 mission for the U.S. Air Force on Saturday, Oct. 31, from Space Launch Complex-41 at Cape Canaveral Air Force Station, Fla.

    GPS IIF-11 is the second to last of the Block IIF satellites, incorporating improvements to provide greater accuracy, increased signals, and enhanced performance for users.

    The GPS IIF satellites deliver second civil signal (L2C) for dual-frequency equipment, and a new third civil signal (L5) to support commercial aviation and safety-of-life applications. The next generation of GPS satellites is GPS III.

    GPS IIF-11 will be the third GPS mission ULA launches in 2015. GPS IIF-9 launched on a Delta IV in March, and GPS IIF-10 launched in July. This mission will be ULA’s 11th in 2015 and 102nd since the company was founded in 2006.

    To keep up to speed with updates to the launch countdown, dial the ULA launch hotline at 1-877-852-4321 or join the conversation at www.facebook.com/ulalaunch, twitter.com/ulalaunch and instagram.com/ulalaunch; hashtags #GPSIIF11, #AtlasV.