S-band Signal Research Articles

Estimation and Evaluation of Ionospheric Scintillations at Various NavIC Signal Frequencies using Real Time Data

The ionospheric scintillations affect radio waves from the NavIC satellites through the ionosphere. The ionospheric scintillations lower receiver tracking accuracy, integrity, and continuity. This paper presents the computation of ionosphere parameters such as TEC, ROTI and scintillation index (S) using pseudo range and Carrier to Noise density ratio (C/No) measurements of NavIC L5 and S-band signals. Also, investigates the ionospheric scintillations, which are common in the equatorial and low latitude region. The correlation between the amplitude scintillation index S4 and ROTI is investigated using real data of NavIC receiver at Osmania University, Hyderabad. The results obtained confirm that the scintillations impact varies with radio signal frequency and it is severe on low frequencies during post sunset hours at low latitude regions.

Transmission of signal and idler using optical parametric amplifier based on PPLN waveguide

In this study, we attempted the repeated transmission of S-band signals by compensating for the loss of the transmission fiber using an optical parametric amplifier (OPA) based on a periodically poled LiNbO3 waveguide. We examined and compared the two configurations. The first method involved wavelength conversion of the signal to an idler, while the second method amplified the signal itself. In the latter case, we demonstrated repeated transmissions using external dispersion compensation. In the former case, we demonstrated that it was possible not only to compensate for fiber loss but also to reduce the accumulation of dispersion in transmission fibers by utilizing spectral inversion.

Partial response continuous phase modulation with a prolate spheroidal wave function for compass system in the S-band

Continuous phase modulation (CPM) has the characteristics of high power efficiency, spectral efficiency, and less out-of-band radiation, which is very suitable for the Compass S-band (2483.5–2500 MHz) with limited power and bandwidth. However, as more and more navigation systems share the S-band, the mutual interference between different systems is gradually increasing, and the compatibility of CPM signals with rectangular or raised cosine pulses needs to be further improved. To enhance the navigation performance and compatibility of current CPM candidate signals, we propose to apply continuous phase modulation with prolate spheroidal wave function (CPM-PSWF) to S-band navigation. The proposed modulation scheme selects PSWF with excellent time-frequency energy aggregation and flexible time-bandwidth product as the frequency pulse function of CPM. Then, the influence of key modulation parameters such as M, L, h, and C on CPM-PSWF power spectral density is analyzed, and a specific partial-response CPM-PSWF signal is proposed as the S-band candidate navigation signal. Finally, the navigation performance evaluation criteria are derived, and the proposed signal scheme and existing candidate schemes are comprehensively evaluated. Theoretical analysis and simulation results indicate that compared with CPM with BM2RC(8), cos-phase binary offset carrier (BOCc(4,4)), sin-phase binary offset carrier (BOCs(4,4)), minimum shift keying-BOCs (MSK-BOCs(4,4)) and binary offset carrier (BPSK(8)), the proposed signal scheme not only delivers exceptional spectral performance but also exhibits superior performance in code tracking accuracy and multipath suppression. In addition, in the acquisition and tracking phase, compared with other candidate signals except for BOCc(4,4), the mutual interference between the proposed signal scheme and most S-band signals is the lowest, which is easier to realize the compatibility of the Compass system with IRNSS, Galileo, and Globalstar systems.

Ionospheric correction of S-band tracking radar data using NavIC S-band signals in missile test range applications

AbstractIn missile test ranges, complex missions demand precise trajectory generated by radar. Both the radar and Global Navigation Satellite System (GNSS) signals are affected by atmospheric effects, degrading their accuracy and performance. The Indian Regional Navigation Satellite System/Navigation with Indian Constellation (IRNSS/NavIC) transmits signals in the S-band together with the L-band. This paper presents a novel experimental technique to improve the tracking accuracy of S-band radars using the concurrent NavIC S-band signal. The ionospheric delay using the NavIC S-band signal is calculated first, and the results are used to improve the trajectory data of simultaneously operating S-band radars. This is a unique application of the NavIC S-band signals apart from its conventional usage. During a launch mission, for low elevation angles, the ionospheric error is found to be ~130 m while at higher elevation angles the error values are found to be ~1–3 m. The concept is validated using data from a missile test mission. This report on the use of S-band GNSS signals for the correction of S-band radar range data offers a clear advantage of simplicity and accuracy.

Ultra-wideband discrete Raman amplifier optimization for single-span S-C-L-band coherent transmission systems.

We experimentally compare the performance of two key ultra-wideband discrete Raman amplifier structures, a cascaded dual-stage structure and an in-parallel dual-band structure, in fully loaded S-C-L band coherent transmission systems over 70 km of single-mode fiber. Our results show that dual-band discrete Raman amplifier with minimized backreflections can effectively avoid unstable random distributed feedback lasing, reduce the noise figure, and therefore improve the transmission performance for signals at shorter wavelengths, versus the cascaded dual-stage structure. The average noise figure for S-band signals is 6.8 dB and 7.2 dB for the dual-band structure and cascaded dual-stage structure, respectively, while the average S-band Q2 factor is similarly improved by 0.6 dB. Moreover, the cascaded dual-stage discrete Raman amplifier requires guard bands around the 1485-nm and 1508-nm pumps as the signal and pump wavelengths overlap, which results in a bandwidth loss of ∼10 nm and reduces the potential net data throughput to 28.6 Tb/s for 30-GBaud DP-16QAM signals. However, the dual-band structure can utilize the bandwidth more effectively, which leads to a higher estimated net data throughput of 31.2 Tb/s.

Advantage of IRNSS S-band signal for GBAS applications in adverse ionospheric storm conditions

Advantage of IRNSS S-band signal for GBAS applications in adverse ionospheric storm conditions

A Comprehensive Evaluation of Possible RNSS Signals in the S-Band for the KPS.

Recently, the Korean government has announced a plan to develop a satellite-based navigation system called the Korean Positioning System (KPS). When designing a new Radio Navigation Satellite Service (RNSS) signal, the use of the S-band has emerged as an alternative to avoiding signal congestion in the L-bands, and South Korea is considering using the S-band with the L-bands. Therefore, this study proposed possible S-band signal candidates and evaluated their performance, such as the radio frequency (RF) compatibility, spectral efficiency, ranging performance, and receiver complexity. Several figures-of-merit (FoMs) were introduced for quantitative performance evaluation for each candidate. Each FoM was calculated using an analytical equation by considering the signal design parameters, such as the center frequency, modulation scheme, and chip rate. The results showed that the outstanding candidate signal was different depending on the signal performance of interest and the reception environments. Therefore, we discuss and summarize the signal performance analysis results considering the whole FoMs together. Under the assumptions given in this paper, the binary phase shift keying (BPSK)(1), sine-phased binary offset carrier (BOCs)(5,2), and BPSK signals were superior for the spectral efficiency, ranging performance, and receiver complexity, respectively.

Photon‐to‐photon polarization modulation using Mxene thin film as modulator

In this work, photon-to-photon polarization modulation is experimentally demonstrated using a Mxene material, Ti2C thin film as a modulator. S-band signal (1500 nm) polarization state is modulated by a control pump (1400 nm) in the Ti2C thin film based on the thermo-optic effect. A total of 34.67˚ of polarization rotation is achieved with the variation of pump power from 0 to 223 mW. From the regression analysis, the system is operated in highly linear condition, with R2 value of 0.991 and an efficiency of 0.1589˚/mW. Throughout the polarization rotational range, the variation of ellipticity is less than 5˚ while the variation of output power is less than 3.5 dB.

Carrier-Aided Dual-Frequency Vectorized Tracking Architecture for NavIC Signals

A new carrier-aided dual-frequency vectorized tracking (CA-DFVT) architecture for the Navigation with Indian Constellation (NavIC) is presented. CA-DFVT tracks both NavIC L5 (1176.45 MHz) and S-band (2492.028 MHz) signals concurrently. It uses the precise carrier phase measurements from the S-band signal and the unambiguous code phase measurements from the L5 signal to form a new measurement model for the extended Kalman filter (EKF) to estimate the position, velocity, and time (PVT) solutions. The new measurement model takes advantage of the benefits of the higher frequency S-band signal, i.e., less ionospheric delay and carrier phase noise, as well as the L5 signal’s inherent noise mitigation capabilities. Compared to the single-frequency approach, the dual-frequency approach in CA-DFVT eliminates the ionospheric effect and minimizes other errors, resulting in better navigation solutions. The proposed CA-DFVT enhances the reliability and robustness of NavIC signal tracking and position estimation in interference and high dynamics environments. We used static and dynamic field tests to validate the performance and robustness of the proposed CA-DFVT receiver architecture. In comparison to single-frequency (L5/S-band) vector tracking, the CA-DFVT receiver demonstrated consistent signal tracking and position estimation with higher position accuracy. In the static case, the mean horizontal position accuracy of CA-DFVT improves by approximately 2–4 and 9–14 m compared to L5-only VT and S-only VT, respectively, while, in the dynamic case, it improves by approximately 2–5 and 25–42 m, respectively.

Integrated High-Accuracy Correction Technology of Radio-Wave Refraction for Deep-Space (High-Orbit) Targets

The radio-wave refraction error caused by the troposphere and ionosphere badly affects accuracy in terms of the navigation, positioning, measurement, and control of a target; it is the main source of errors in high-accuracy measurement and control systems. The high-accuracy technology needed for radio-wave refraction error correction (mainly in the troposphere and ionosphere) has been the focus of research for a long time. At present, the correction methods used for radio-wave refraction errors have a low accuracy. For an S-band radio-wave signal, the accuracy of refraction error correction can generally only reach m-level (elevation angle of 15° and above), and thus has difficulty meeting the requirements of dm-level accuracy refraction error correction for deep-space and high-orbit targets. To improve the accuracy of radio-wave refraction error correction for deep-space and high-orbit targets, a novel correction method for tropospheric and ionospheric range error due to refraction is proposed in this study, on the basis of the measured data from a water vapor radiometer and dual-frequency Global Navigation Satellite System (GNSS). The comprehensive calibration test is conducted in combination with the Chinese Area Positioning System (CAPS) in Kunming. Results show that this method can effectively correct the range error due to refraction that is caused by the troposphere and ionosphere. For an S-band radio-wave signal, the accuracy of refraction error correction can reach dm-level accuracy (elevation angle of 15° and above), which is 50% higher than that achieved with traditional methods. This work provides an effective support system for major projects, such as lunar exploration and Mars exploration.

Feasibility of using an S-band GNSS carrier by comparing with L and C bands

Global navigation satellite systems (GNSSs) play an important role in both military and civilian industries, but most of the existing GNSS carriers are crowded in the L band. Although some modulations, such as binary-offset-carrier (BOC) and its modifications, can reduce the mutual interference of one GNSS signal to others, the exhausted L-band frequencies are still the bottleneck to improve GNSS performance further. The problem can be solved if the GNSS carriers can be allocated to other bands, such as S band (2483.5–2500 MHz) and C band (5010–5030 MHz), which adjoin L band. In this paper, the feasibility of using an S-band GNSS carrier is evaluated systematically. The transmission path loss, the transmission errors, and the signal reception performance of an S-band carrier are analyzed by comparison with an existing L-band carrier and a potential C-band one. The impacts of the S-band carrier both on the satellite payload and on the receiver are discussed. The compatibility of the S-band signal with the existing signals in the adjacent band is also addressed. The conclusive remarks presented will be helpful to implement an S-band carrier.

Estimation and Analysis of Scintillations Induced Tracking Jitter for NavIC L5-band(1176.45MHz) and S-band(2492.028MHz) Signals

Estimation and Analysis of Scintillations Induced Tracking Jitter for NavIC L5-band(1176.45MHz) and S-band(2492.028MHz) Signals

Case Study: Performance Observation of NavIC Ionodelay and Positioning Accuracy

The NavIC is an Indian satellite based navigation system uses the L5 and S-band signals to provide 10 m (metres) and 0.1 m positioning accuracy services for civilian and military users respectively. The positioning accuracy of the NavIC system is affected by many sources of error, and the ionospheric delay (Ionodelay) error is the dominant error in all. We observed the NavIC L5 band Iono delay and positioning accuracy under the influence of the intense geomagnetic storm (D st = −124, KP = 8) that occurred on 8 September 2017 at various geographical locations. Here, the NavIC S band is explored to observe the impact of geomagnetic storm (8 September 2017) and the performance is compare with NavIC L5 band at the low-latitude SVNIT Surat station (21.16° N, 72.78° E) for the second week of September 2016, 2017 and 2018. To observe the impacts of seasonal variation on the NavIC L5 and S band Ionodelay is also measured for the days of June 2016 to May 2017. It has been observed that in the days of the Summer season and an intense geomagnetic stormy day (8 September 2017) NavIC performance has faced challenges for positioning accuracy. It has been also observed the compare to NavIC L5 band S band faced more challenges for positioning accuracy. After correcting the ionosphere, troposphere, clock, and other deviations, the average ∼70% NavIC positioning accuracy is improved for the overall observed duration, conditions, and locations.

Design of a GNSS Antenna to Prevent LNA Saturation and Intermodulation Caused by S-Band Signals

In this paper, a Global Navigation Satellite System (GNSS) antenna design which prevents low-noise amplifier (LNA) saturation (compression) and intermodulation caused by S-band signals is proposed to improve the reception of GNSS signals. A simulation was conducted to determine which method can more efficiently decrease the S-band signal while maintaining the noise figure and the antenna gain concurrently. Considering the simulation results, an LNA is manufactured and an LNA performance test is conducted. System-level tests are performed to verify the new GNSS antenna function and to assess the performance improvement. The test results showed that the proposed antenna with the new LNA operates robustly without being affected by signals radiated from nearby S-band antennas while also meeting the required specifications.

The Pioneer Effect: A New Physics with a New Principle

Radiometric data from the Pioneer 10/11, Galileo and Ulysses spacecraft indicated an anomalous constant acceleration acting on them, directed toward the Sun, and a gradual growth of the radio signal frequency emitted by the receding transmitter. The reported odd acceleration of Pioneer 10 with a magnitude ∼8.5 × 10−10 m/s2 can be explained by an induced gravitational interaction on the S-band signals traveling between the probe and the Earth, arising from the electromagnetic properties of the outer Solar System vacuum zero-point radiation interacting with matter. Their nature is of quantum vacuum origin, and these induced forces act in addition to ordinary gravitational forces, violating the principle of Equivalence. We suggest a new physical theory based on a new principle called “Compensation” as a thinkable explanation for the non-conventional Pioneer effect. The theory of Relation, which is an alternative to the inflationist model, postulates that our universe is made of two antagonistic but complementary structures. The principle of Compensation contradicts Relativity theory, predicts such acceleration and is for the electromagnetic spacetime metric what the principle of Equivalence is for the gravific spacetime metric.

Disturbed Flows in the Inner Solar Wind and Near Earth’s Orbit

Coronal mass ejections from active regions on the Sun can be observed as series of individual events separated in time in the inner solar wind and near-Earth plasma. To find such events we have analyzed experimental data of dual-frequency solar wind radio sounding by the Rosetta and Mars Express spacecraft. The cycles of experiments performed in 2010 and 2011 measured the frequency fluctuations of X- and S-band signals. The temporal variations in the level of frequency fluctuations measured in the inner solar wind have been compared with the time variations in average plasma parameters recorded near Earth’s orbit. Since radio-sounding cycles were sufficiently long, we have managed to record events where significant amplifications of frequency fluctuations in the inner solar wind and increases in the plasma concentration near Earth’s orbit are associated with flare processes in the same active region on the Sun. Here, the amplifications of frequency fluctuations on the east limb occur earlier than near Earth’s orbit, and those on the west limb occur later. The time shift for the west limb turns out to be less than for the east limb. The sign of the time shift and the ratios between its numerical values depend on active region displacement relative to the central meridian due to the rotation of the Sun.

Application of Navigation with Indian Constellation (NavIC) Signals for Ionosphere Irregularities Measurement

Soon Indian’s mobile phones and cars are to be installed with new and indigenous satellite technology, i.e. Navigation with Indian Constellation (NavIC) developed by ISRO. After successful completion of NavIC, India has become fifth nation in the sequence of countries with independent navigation technology/system. The NavIC technology will be used mainly for terrestrial, aerial and marine navigation along with tracking and disaster management. Here we are proposing the application of NavIC signals for measuring and montoring ionosphere layer behaviour leading accuracy degradation of satellite based navigation and communication systems. This paper presents the computation of ionosphere parameters such as TEC, ROTI and scintillation index (S4) using pseudo range and Carrier to Noise density ratio (C/No) measurements of NavIC L5 and S-band signals. ROTI and S4 results revealed that the impact of ionosphere irregularity is more on L5 than that of S-band signals.

Estimation and Analysis of IRNSS Satellites Differential Code Biases using Real Data

IRNSS is a regional navigation system developed by the Indian Space Research Organization (ISRO) for precise position and navigation services over the Indian sub-continent. However, the IRNSS measurements are being affected by the many residuals or biases. Differential Code Biases (DCB) are very significant in the precise measurement of ionosphere Total Electron Content (TEC). In this paper, DCB of all available IRNSS satellites and receiver is derived from the pseudorange measurements of IRNSS on L5 and S-band signals. Results show that the estimated daily mean DCB of IRNSS satellites is in the range between -0.60 nanoseconds(ns) and 0.606 ns. Further, the receiver DCB is obtained as 7.904 ns.

Acquisition and Tracking of S-Band Signals of Navigation with Indian Constellation (NavIC)

The IRNSS satellite network covers a large area of the India with 7 satellites, 3 geostationary and 4 that are geosynchronous. IRNSS signals are transmitted in the L5 and S-Bands. The L5 band frequencies range from 1164.45-1188.45 MHz and the S band frequencies range from 2483.5-2500 MHz.NavIC is the IRNSS satellite constellation network that can be employed to a variety of applications. In order to achieve this signal must be acquired and tracked. IRNSS signals have PRN sequences unique for each satellite. These sequences are used to scramble and encrypt the signal, in order for a receiver to acquire the signal, it needs to have the same PRN sequence as that of the sending satellite, this is achieved in acquisition using an efficient search method. Once the PRN sequence is generated at the receiver it has to be tracked continuously to ensure that there is no loss of signal at a later point, which is achieved in the tracking phase. Several factors can lead to noise generation in the satellite signal; this can lead to either a Doppler shift in carrier or shift in PRN both leading to loss of signal, thus a correctional loop is also implemented in the tracking phase to correct the effect of noise.

S 대역 신호에 의한 위성항법수신기의 RF 신호간섭

S 대역 신호에 의한 위성항법수신기의 RF 신호간섭