Signal analysis of the first GPS III satellite

Abstract

The signal-in-space of the first GPS Block III spacecraft is analyzed based on radio-frequency measurements collected with a 30 m high-gain dish antenna as well as data from geodetic GPS receivers. The spectral properties and modulation characteristics are discussed with focus on the L1 band, which employs a novel interlaced majority voting technique for combination of the C/A, P(Y), and L1C data+pilot signal components. Compared to the preceding generation of Block IIF satellites, a modified shaping of the L1 transmit antenna gain pattern is found, which results in lower carrier-to-noise density ratios at mid to high elevations. Along with this, use of a separate transmission chain for the military M-code signal is evidenced through the analysis of in-phase/quadrature signal components and the derived transmit antenna gain variations. A high level of signal purity is demonstrated on all frequencies, which can be attributed to the use of a new, mostly digital, signal generation unit. Maps of code bias variations for selected signals are presented to quantify the achievable user tracking performance as a function of user receiver parameters. For the L5 signal, a notable reduction of digital distortions is obtained with respect to the Block IIF satellites, whereas analog distortions are found to be of similar magnitude. Thermally induced L5 phase variations found in the Block IIF satellites are no longer observed in GPS III. Using triple-frequency phase observations, a sub-centimeter consistency of the L1, L2, and L5 carriers is demonstrated.

Global Navigation Satellite Systems as State-of-the-Art Solutions in Precision Agriculture: A Review of Studies Indexed in the Web of Science

“…Recent Major Upgrades Impacts on PA References GPS GPS III satellites Improved signal strength [28] L5 civil signal Increased resistance to multipath interference and signal blockages [29,30] GLONASS GLONASS-K satellites Increased satellite availability and improved signal strength [31,32] Galileo Full operational capability Global coverage and constant and reliable signal reception [33] High Accuracy Service An experimental service aiming to provide centimeter-level positioning accuracy [34] BeiDou BeiDou-3 satellites Global coverage and constant and reliable signal reception [35,36] New signals (B1C, B2a, and B2b)…”

GNSS visibility and performance implications for the GENESIS mission

“…Where required, actual power sharing ratios for specific satellite types and signal modulations were obtained from in-phase-quadrature signal samples or signal spectra collected with the high-gain antenna (Thoelert et al 2018). In the case of GPS III, it may be noted that the military M-code contributes to the received L1 and L2 signal powers but is transmitted from a separate antenna (Thoelert et al 2019). For these satellites, the M-code contribution to the total power was separated using a modeled gain pattern of the M-band antenna and a least-squares fit of the modeled and observed effective isotropic radiation power (EIRP) variation over off-boresight angle.…”

“…In the case of GPS III, it may be noted that the military M-code contributes to the received L1 and L2 signal powers but is transmitted from a separate antenna (Thoelert et al. 2019 ). For these satellites, the M-code contribution to the total power was separated using a modeled gain pattern of the M-band antenna and a least-squares fit of the modeled and observed effective isotropic radiation power (EIRP) variation over off-boresight angle.…”

Latest GNSS signal in space developments – GPS, QZSS & the new Beidou 3 under examination

“…Other differences are present in the L5 and L6 band. More details can be found in [11] and [5]. Summarizing the new facts, within L5 an additional L5S signal has been transmitted by QZS-2 and the following spacecrafts, while in the L6 band a new component has been transmitted on the Q-component.…”