Beacon Receiver Research Articles

Dynamic Range Improvements for Beacon Receivers Using Noise Power Measurements

Dynamic Range Improvements for Beacon Receivers Using Noise Power Measurements

Twelve years of rain attenuation statistics of Earth–space propagation experiment at Ka band in Toulouse

SummarySince 2009, ONERA has been running Ka band propagation experiments in Toulouse (France, latitude 43.57°N, longitude 1.47°E). A rain gauge was also deployed on site to collect rainfall rate measurements concurrently to beacon data. Since April 2011, the beacon receiver has been recording the 20.2 GHz (vertical polarisation) Astra 3B beacon signal along a slant path of 35.1° of elevation angle. All years of the experiment had excellent data availability, hence giving 12 years of data at Ka band. First, the propagation experiment and the data processing methodology are described. Second, a statistical analysis of rain attenuation and rainfall rate is conducted. Comparisons are then performed with the prediction methods of Recommendations ITU‐R P.837‐7 (rainfall rate), P.618‐13 (rain attenuation) and P.678‐3 (variability of propagation phenomena).

A tri-band terrestrial beacon digital receiver system for TEC measurements

The ionosphere is an important component of near-Earth space that has a significant impact on communication and navigation. Furthermore, the total electron content (TEC) of the ionosphere is a widely used parameter in near-Earth plasma environment studies. A design of a digital beacon receiver system for automatically measuring TEC is presented. Universal Software Radio Peripheral (USRP) hardware equipment with software-defined radio technology was used in the tri-band beacon digital receiver to receive and rapidly preprocess beacon signals from satellites in different frequency bands. A software system is built to implement the automatic control of the receiver and to enable data processing of the preprocessed data in order to obtain its phase information and derive the TEC. The tri-band digital beacon receiver system is experimentally proven to automatically detect and archive transit satellites in real time, automatically receive and process satellite beacon signals with recording, and automatically generate TEC measurement results.

Ground-based infrastructure for monitoring and characterizing intermediate-scale ionospheric irregularities at mid-latitudes

We discuss potential science investigations at mid-latitudes enabled by a modern, space-weather-grade, ground-based Radio-Frequency network of scintillation receivers which encompasses Global Navigation Satellite Systems and Beacon receivers, along with coherent radars, and leveraging radio astronomy infrastructure for space weather application. The primary scientific research addresses the controlling space weather drivers for the structuring of mid-latitude ionospheric plasma at intermediate scales (10s of meters—10s of kilometers), their relationship with larger density structures, and their impacts on the trans-ionospheric radio links. These irregularities scintillate the signals impairing the radio link integrity and the underpinning services. The suggested science investigations are currently unable to be fully accomplished because of missing high-fidelity and long-term observations at satisfactory spatial coverage. We discuss the physics responsible for the radio wave disturbances and their impacts, review the current state of knowledge based on available observations, and outline a plan for developing the necessary infrastructure by leveraging existing ground-based distributed observatories that will enable novel scientific investigations and will be synergistic with other geoscience divisions such as seismology, geology, and meteorology.

Ka-Band Satellite Propagation Experiment at the Guiana Space Centre

From January 2017 to December 2021, Office National d’Etudes et de Recherches Aérospatiales (ONERA) and Centre National d’Etudes Spatiales (CNES) operated a beacon receiver able to record the 20.1995 GHz beacon signal of the Amazonas-3 satellite at the Guiana Space Centre in Kourou, French Guiana. A rain gauge was also deployed on site to collect rainfall rate measurements concurrently to beacon data. All years of the experiment, except 2019, had excellent data availability, hence giving four full years of data (2017, 2018, 2020, and 2021). First, the climatic characteristics of French Guiana are shown. Second, the propagation experiment and the data processing methodology are described. Third, the results of the statistical analysis are highlighted and commented. Comparisons are performed with the prediction methods of Recommendation ITU-R P.837-7 (rainfall rate), Recommendation ITU-R P.618-13 (rain attenuation), Recommendation ITU-R P.678-3 (variability of propagation phenomena), and Recommendation ITU-R P.1623-1 (fade dynamics).

The observations of localize ionospheric scintillation structure by FORMOSAT-7/COSMIC-2 Tri-band Beacon network

The preliminary results of FORMOSAT-7/COSMIC-2 beacon data are presented in this paper, and the localized scintillation structure where the radio signals are affected by irregularities is recognized. Irregularities in the ionosphere will affect a radio transmission traveling through it. This study looked at a case of beacon satellite scintillation measurement from three stations in Chung-li (25.136N, 121.539E), Tsao-tun (23.981N, 120.697E), and Che-cheng (25.136N, 121.539E) (22.725N, 120.544E). The open-source coherent beacon receiver may receive beacon signals from beacon satellite systems such as the FORMOSAT-3/COSMIC Tri-band Beacon Transmitter (150, 400, 1066.7 MHz) or the FORMOSAT-7/COSMIC-2 Tri-band Beacon Transmitter (150, 400, 1066.7 MHz) (400, 965, and 2200 MHz). In Taiwan, the three stations were located around 360 km apart in a north–south direction. We can recognize the localize scintillation position where the radio signals are affected by abnormalities by projecting the course of the satellite’s orbit. Because the maximum potential height in the F2 layer is 350 km, the height was previously believed to be 350 km. We apply a project method to approximate the realistic height and length from the 3 stations by a scintillation case near midnight in order to improve on this assumption. As a result, the height of scintillation would be confirmed using the project approach, whether in the F layer or the E layer.

Low-Cost Ka-Band Satellite Receiver Data Preprocessing for Tropospheric Propagation Studies.

Satellite tropospheric propagation studies strongly rely on beacon receiver measurements. We were interested in performing a measurement campaign to characterize rain attenuation statistics. In this article, we outline some of the characteristics and drawbacks one faces when trying to perform a radio wave satellite beacon propagation experiment at the Ka-band with low-cost measurement equipment. We used an affordable beacon receiver consisting of a commercial low-noise block down-converter, an outdoor dual-reflector antenna, and a software-defined radio unit. To measure rain attenuation events, we needed to work out where the reference signal level was at all times. However, as we did not have a radiometer to remove the impact of gases and clouds, since it is a very expensive device, we used a procedure that involved the subtraction of a stable and reliable reference level (template) from the raw received beacon level. This template was extracted from observations during non-rainy periods. The procedure implemented for extracting the template was based on the same data processing methodology used by other authors in this field. Here, we describe through specific examples the main characteristics of the templates extracted on non-rainy days, as well as the impact of some meteorological parameters and unavoidable, but small antenna pointing errors.

Fuzzy Guided Autonomous Nursing Robot through Wireless Beacon Network.

Robotics is one of the most emerging technologies today, and are used in a variety of applications, ranging from complex rocket technology to monitoring of crops in agriculture. Robots can be exceptionally useful in a smart hospital environment provided that they are equipped with improved vision capabilities for detection and avoidance of obstacles present in their path, thus allowing robots to perform their tasks without any disturbance. In the particular case of Autonomous Nursing Robots, major essential issues are effective robot path planning for the delivery of medicines to patients, measuring the patient body parameters through sensors, interacting with and informing the patient, by means of voice-based modules, about the doctors visiting schedule, his/her body parameter details, etc. This paper presents an approach of a complete Autonomous Nursing Robot which supports all the aforementioned tasks. In this paper, we present a new Autonomous Nursing Robot system capable of operating in a smart hospital environment area. The objective of the system is to identify the patient room, perform robot path planning for the delivery of medicines to a patient, and measure the patient body parameters, through a wireless BLE (Bluetooth Low Energy) beacon receiver and the BLE beacon transmitter at the respective patient rooms. Assuming that a wireless beacon is kept at the patient room, the robot follows the beacon’s signal, identifies the respective room and delivers the needed medicine to the patient. A new fuzzy controller system which consists of three ultrasonic sensors and one camera is developed to detect the optimal robot path and to avoid the robot collision with stable and moving obstacles. The fuzzy controller effectively detects obstacles in the robot’s vicinity and makes proper decisions for avoiding them. The navigation of the robot is implemented on a BLE tag module by using the AOA (Angle of Arrival) method. The robot uses sensors to measure the patient body parameters and updates these data to the hospital patient database system in a private cloud mode. It also makes uses of a Google assistant to interact with the patients. The robotic system was implemented on the Raspberry Pi using Matlab 2018b. The system performance was evaluated on a PC with an Intel Core i5 processor, while the solar power was used to power the system. Several sensors, namely HC-SR04 ultrasonic sensor, Logitech HD 720p image sensor, a temperature sensor and a heart rate sensor are used together with a camera to generate datasets for testing the proposed system. In particular, the system was tested on operations taking place in the context of a private hospital in Tirunelveli, Tamilnadu, India. A detailed comparison is performed, through some performance metrics, such as Correlation, Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE), against the related works of Deepu et al., Huh and Seo, Chinmayi et al., Alli et al., Xu, Ran et al., and Lee et al. The experimental system validation showed that the fuzzy controller achieves very high accuracy in obstacle detection and avoidance, with a very low computational time for taking directional decisions. Moreover, the experimental results demonstrated that the robotic system achieves superior accuracy in detecting/avoiding obstacles compared to other systems of similar purposes presented in the related works.

Analysis of rain fade characteristics from experimental satellite measurements at Ka/Q bands for a temperate location Vigo, Spain

Rain is one of the most dominant factors for satellite communication systems link performance at frequencies above 10 GHz, increasing rapidly at higher frequencies. The prediction of time dynamics of the rain attenuation is required to improve the efficiency of various fade mitigation techniques (FMTs) to reduce signal fading. Fade duration and fade slope statistics are used to describe the dynamic behavior of attenuation experienced by radio communication links. The present study is based on experimental measurements from a Ka band (KaSAT) and Q band (AlphaSAT) beacon receiver at the frequencies 19. 7 GHz and 39. 4 GHz respectively. In this paper, annual and monthly variation of rain attenuation statistics for a temperate location Vigo, Spain is presented. Monthly variation of rain attenuation statistics is much larger than the yearly variation for the present location. This paper also analyzes the fade duration and fade slope statistics for both the bands. The conditional probability density function (PDF) of fade slope shows general symmetry between positive and negative slope values for both Ka and Q bands. All the measured statistics (1st order and 2nd order) are compared with the existing ITU-R and COST-205 models. Predictions of rain attenuation by both the models are close to the measured data. For fade duration statistics, as attenuation threshold increases, performance of both ITU-R and COST-205 models improves for Ka band. For Q band, COST model performs better compared to ITU-R model. Measured probability density function of fade slope fits with the ITU-R model more closely for Q band compared to Ka band.

Quasi-Coherent Phase-Based Localization and Tracking of Incoherently Transmitting Radio Beacons

The direct measurement of distance-dependent information between wireless units represents a challenge for wireless locating systems, because it requires the exact time synchronization of separate wireless units. To avoid these synchronization efforts, many wireless locating systems only evaluate phase difference of arrival (PDOA) measurements. While simple PDOA localization techniques rely on multiangulation, advanced PDOA concepts like the holographic extended Kalman filter (HEKF) directly evaluate the measured phases without non-linear preprocessing. However, these differential phase measurement approaches are less sensitive than systems that can measure absolute phase variations, which allow the tracking of much smaller position changes than the signal’s carrier wavelength. This paper proposes to extend the HEKF by the evaluation of absolute phases in an incoherent measurement setup, which consists of a continuous wave (CW) beacon and several receivers. The developed quasi-coherent holographic extended Kalman filter (QCHEKF) uses the overdetermined PDOA measurements to estimate the phase–frequency relation between each beacon–receiver pair. Then, the established phase–frequency relations allow the evaluation of absolute phase measurements and, thus, the accurate localization and tracking of a simple, unsynchronized, narrowband CW beacon, even under severe multipath conditions. This novel concept is experimentally validated via 3D localization results in a challenging indoor scenario using a 24 GHz CW measurement setup. Here, the QCHEKF improves the achieved localization accuracy in comparison to the HEKF by 35 % from 0.78 cm to 0.51 cm, while the maximum deviation from the trajectory reduces by 68 % from 5 cm to 1.6 cm. Furthermore, the QCHEKF enables the exact tracking of fast changes in direction, which is usually a significant challenge for standard wireless target tracking systems.

A Semi-2D Synthetic Storm Technique for Orbital Diversity on Earth-Space Propagation Paths

In this article, new assumptions are introduced into the well-known synthetic storm technique (SST) proposed by Drufuca and further developed by Matricciani, to address the orbital diversity in satellite links. The new approach receives as input information on collocated rain rate recordings and instantaneous estimates of the storm direction and speed; and assumes that the rain event is transversely constant to the storm movement. The achieved improvements are evaluated by analyzing two example measured rain attenuation events “seen” by two Ka -band beacon receivers looking at two different satellites spaced around in azimuth. A study is made of the cross correlation coefficient between rain attenuation series for these two links. Moreover, a methodology is sketched as to how multiple non-GEO satellite constellation availability (for global Internet access at Ka -band) could be evaluated in the frame of the SST.

A Low-Cost On-Street Parking Management System Based on Bluetooth Beacons.

In recent years, many city governments around the world have begun to use information and communication technology to increase the management efficiency of on-street parking. Among various experimental smart parking projects, deployment of wireless magnetic sensors and smart parking meters are quite common. However, using wireless magnetic sensors can only detect the occupancy of parking spaces without the knowledge of who are currently using these parking spaces; human labor is still needed to issue the parking bills. In contrast, smart parking meters based on image recognition can detect the occupancy of parking spaces along with the license plate numbers, but the cost of deploying smart parking meters is relatively high. In this research, we investigate the feasibility of building an on-street parking management system mainly based on low-cost Bluetooth beacons. Specifically, beacon transmitters are installed in the vehicles, and beacon receivers are deployed along the roadside parking spaces. By processing the received beacon signals using Kalman filter, our system can detect the occupancy of parking spaces as well as the identification of the vehicles. Although distance estimation using the received signal strength is not accurate, our experiments show that it suffices for correct detection of parking occupancy.

Preliminary analysis of rain attenuation and frequency scaling method for satellite communication

Rain attenuation plays a significant role in satellite communications in the Ka band. The paper studied the rain attenuation using empirical formulations of the prominent models like ITU-R P.618-13, ITU-R P.838-3, Moupfouma, and Garcia Lopez. At a rain rate of 47.6 mm/hr, measured by Indian Meteorological Department for 2018 for Gadanki, near Tirupati, India, the attenuation values were calculated. The measured data, acquired by Ka band digital beacon receiver, is compared with the calculated data at the frequency of 20.2 GHz for both horizontal and vertical polarizations. The value of parameters viz. relative error, root-mean-square error, standard deviation error, and Chi-square error were calculated. Frequency scaling for the frequency of 30.5 GHz was calculated with the help of ITU-R P.618-13 method.

On the variability of the Equatorial Ionization Anomaly Trough over Indian region: A novel analysis using Beacon TEC measurements

A novel method using single station beacon Relative Slant Total Electron Content (RSTEC) measurements is proposed to estimate the location of Equatorial Ionization Anomaly Trough (EAT). The feasibility of this method is established based on simulations of RSTEC using (International Reference Ionosphere) IRI model electron densities.Using the RSTEC measured by the Coherent Radio Beacon Receiver at Thiruvananthapuram (8.5° N geographic North, 77° geographic E, 0.5° N dip north), the spatial variability of the EAT location during 2006–2007 over the Indian region has been analyzed. The differential phase of signals emitted by beacons at 150 MHz and 400 MHz on board low earth orbiting satellites (LEOS) has been used to estimate the RSTEC. This study shows that EAT exhibits local time (morning – afternoon) variation as large as 7 degrees on either side of the dip equator. Further the trough location exhibits a systematic latitudinal change with seasons. The combined control of trans-hemispheric winds as well as magnetic field aligned diffusion is found to be the reason for the observed properties of trough location.

Integrity Concept for Maritime Autonomous Surface Ships' Position Sensors.

The primary means for electronic position fixing currently in use in majority of contemporary merchant ships are shipborne GPS (Global Positioning System) receivers or DGPS (Differential GPS) and IALA (International Association of Lighthouse Authorities) radio beacon receivers. More advanced GNSS (Global Navigation Satellite System) receivers able to process signals from GPS, Russian GLONASS, Chinese Beidou, European Galileo, Indian IRNSS, Japan QZSS, and satellite-based augmentation systems (SBAS), are still relatively rare in maritime domain. However, it is expected that such combined or multi-system receivers will soon become more common in maritime transport and integrated with gyro, inertial, radar, laser, and optical sensors, and they will become indispensable onboard maritime autonomous surface ships (MASS). To be prepared for a malfunction of any position sensors, their state-of-the-art integrity monitoring should be developed and standardized, taking into account the specificity of MASS and e-navigation safety. The issues of existing requirements, performance standards, and future concepts of integrity monitoring for maritime position sensors are discussed and presented in this paper.

Evening time multi-instrumental verification of ionospheric irregularity in East Africa, Ethiopia

This study verifies ionospheric irregularity and its associated scintillation using five independent observations during June solstice and September equinox, 2014 over the understudied and data scarce East African longitude sector. Simultaneous measurements of ionospheric irregularity through Communication and Navigation Outage Forcasting System (C/NOFS), Scintillation Networks and Decision Aid (SCINDA) GPS receivers, Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC), GNSS GPS, VHF dedicated beacon receivers as well as ionosonde were carried out in the region. C/NOFS has detected prereversal enhancement (PRE, the most accepted trigger of equatorial spread F (ESF)) at ~19:00 LT during September equinox and at ~20:00 LT for June solstice. The PRE detection during June is further confirmed by the ionosonde derived uplift movement of hmF2 over the region. Rate of change of TEC index (ROTI) is also found to be capable of capturing the evening time ionospheric irregularities in a way consistent to the dedicated scintillation measuring instruments regardless of the spatial difference between the two GNSS GPS sites in East Africa. Overall, throughout the in situ and ground-based ionospheric irregularity measurements, extreme scintillation starts to occur at around 19:00 LT and continued until midnight. Besides, the power spectral density (PSD) was computed using the Fast Fourier Transform (FFT) algorithm for S4 data measured while receiving L-band and VHF signals as well as while measuring C/NOFS ion density. Upon the captured strength of ionospheric irregularity, the noisy portion of frequency on PSD is wider in VHF and C/NOFS driven irregularity index than the corresponding L-band irregularity observation. Most importantly the calculated slope (m) and the strength of irregularity (β) using the power spectral law has enabled us to produce a model which better fits the observed spectrum. It was also found that the PSD theoretical modeling better matches for L-band than VHF and Ni spectral observation.

Verification of ionospheric perturbation induced L-band frequency scintillation using HF/VHF bands over the African equatorial and low latitude region, Ethiopia

This study verifies the ionospheric perturbation induced scintillation in L-band range of frequency using HF/VHF bands over the African equatorial and low latitude regions with a focus over Ethiopia. The study was conducted using the SCINDA, ionosonde and beacon receivers installed at different regions in Ethiopia. In the F-layer height (hmF2), a reverse decrease of foF2 in combination with significant background TEC reaching up to 10 TECU prior to the depletion was observed during the evening hours. This creates conducive environment for the generation of ionospheric irregularities that can be manifested by Rate of TEC Index (ROTI) and scintillation index (S4) enhancement. Vertical Perturbation Index (PI) was computed using vertically integrated ion density profiles to verify the irregularities from independent source and found that HF inferred PI can potentially identify the existence of ion density irregularity and further verify L-band frequency scintillation. On the other hand, simultaneous observation of S4 in VHF and UHF bands showed excellent agreement despite VHF scintillates more than UHF due the difference of transmitting frequency bands. Besides, Power spectrum density (PSD) was computed using the FFT algorithm for S4 data measured while receiving L-band and VHF signals for selected PRNs observed by the receivers. The calculated slope (m) and the strength of irregularity (beta) using the power spectral law has enabled us to produce a model which better fits the observed spectrum. It shows beta higher for VHF and lower for UHF; while, PSD modelling better matches for UHF than VHF spectral observation.

Affordable Programmed Satellite Pointing System for Propagation Experiments

The development of future communication systems at Q-/V-band requires extensive characterization of the atmospheric propagation channel. The European Space Agency funded the TDP-5 payload that was installed on the Alphasat satellite and is now available for performing propagation measurements in Europe at Ka- and Q-/V-bands. However, as the satellite has an orbit that can reach up to 3° inclination and the antennas have a much smaller half-power beamwidth (HPBW), the received signal amplitude variation along the day would be unacceptably high to perform propagation measurements. A commercial antenna pointing system with adequate specifications represents a severe cost burden on the already expensive beacon receiver hardware. After analyzing the requirements, we describe the detailed project, hardware development, calibration, test, and field measurement performance of a very affordable pointing system for medium-sized parabolic antennas, based on standard linear actuators. An innovative method for fine-tuning the pointing system against the satellite, requiring only equipment that is easily available, is also described in detail. The estimated price is several orders of magnitude less than a commercial one and, upon a careful tuning of the pointing system, the target angular resolution of ±0.026° was achieved in the experimental scenario.

Resolution Enhanced of GRBR Observation-Based Ionospheric Tomography in Indonesia

An ionospheric tomography reconstruction using Algebraic Reconstruction Technique (ART) method has been successfully carried out recently. Data utilized on this work was a campaign-based Gnu-Radio Beacon Receiver (GRBR) observation in West Java during 8-10 November 2016 and 25-29 September 2017 data. Grid resolution of the tomography previously had been increased in the in the latitudinal (0.5o horizontal direction) and altitude (~25 km in vertical direction) scales. Although the quality of the tomography has also met a compatibility level through the correlation analysis (e.g. 85% of correlation coefficient), the computation result should be improved in order to get the best value of bias frequency (i.e. < 1 MHz). Through this opportunity, the result of the tomography within the grid resolution of 0.5o and ~25 km for the latitude and altitude respectively is presented.

Propagation Experiment at <italic>Ka</italic>-Band in French Guiana: First Year of Measurements

ONERA, the French Aerospace Lab, and CNES, the French Space Agency, are currently running a Ka -band propagation experiment at the Guiana Space Centre (CSG) in Kourou (French Guiana). A rain gauge and a beacon receiver able to record the 20.2 GHz beacon signal of the Amazonas 3 satellite have been deployed. The equipment is operational since January 1, 2017, and the duration of the experiment has been set to three years. This letter addresses some results of the first year of measurements (from January 2017 to December 2017). The annual and monthly complementary cumulative distribution functions of rainfall rate and rain attenuation are presented as well as a comparison with the rain attenuation prediction method recommended in ITU-R P.618-13.