Rover Receiver Research Articles

Multi-sensor Attitude Estimation using Quaternion Constrained GNSS Ambiguity Resolution and Dynamics-Based Observation Synchronization

Recently, high accuracy and low-cost navigation hardware is becoming increasingly available that can be efficiently used for the control of autonomous vehicles. We present a sensor fusion method providing tightly coupled integration of pseudorange, carrier phase, and Doppler satellite measurements taken at multiple vehicle-mounted GNSS antennas with onboard inertial sensor observations. The key of accurate GNSS position and orientation estimation is the successful integer ambiguity resolution. We propose a method that uses the quaternion states as constraints to improve ambiguity resolution and to increase the accuracy of the GNSS based attitude determination. Generally, the low-cost hardware neither allows a hardware-level time synchronization between the GNSS receivers due to a lack of a common external oscillator nor provides the clock steering function available in geodetic GNSS receivers. The lack of observation synchronization causes several degrees of error in attitude estimation. To eliminate this effect, a dynamics-based solution is presented that synchronizes the observations by taking the dynamics of the moving platform into account. Compared to common external oscillator based sensor setups, our solution allows to increase both the number of rover receivers on the platform and the baselines between them easily, thus it opens up new possibilities in the attitude determination of large vehicles. We validate our approach against a tactical grade inertial navigation system. The results show that our approach using low-cost sensors provides the ambiguity success rate of 100% for the moving baselines, and the positioning and attitude error reached the centimeter and half a degree level, respectively.

On the GPS signal multipath at ASG-EUPOS stations

Abstract The accuracy of the results of satellite measurements is influenced by many factors. One of them is the multipath phenomenon resulting from reflections of the satellite signal, mainly from objects in the vicinity of the GNSS antenna. The multipath remains a domain source of ranging errors in satellite positioning. Despite the groups of multipath mitigation methods, it is impossible to totally eliminate the influence of this error on the measurement results. This error has two main effects in the case of carrier phase differential positioning. First, the multipath increases the initial search space for correct ambiguities. Secondly, the accuracy of the vector solution between the reference station and the rover receiver is affected. The authors of this article analyzed the presence of multipath in the Polish network of permanent GNSS stations ASG-EUPOS. Data from the year 2021 were used for the analysis. Two computational strategies were adopted to determine the multipath. The pseudorange multipath observable combination (MP) for L1, L2 and L5 signals was used for code measurements. In the case of the carrier phase, multipath analyses of double-differenced L1, L2, and L5 carriers between neighbouring stations were performed. Based on the research, the average multipath level for the Polish GNSS reference stations network was determined. Stations where the levels of particular combinations exceed the assumed values were successively determined. Finally, multipath models in the form of sidereal maps were created. Based on these models, six stations were identified and recommended for further analysis concerning the impact of multipath on GNSS measurements.

The Implementation of Precise Point Positioning (PPP): A Comprehensive Review.

High-precision positioning from Global Navigation Satellite Systems (GNSS) has garnered increased interest due to growing demand in various applications, like autonomous car navigation and precision agriculture. Precise Point Positioning (PPP) offers a distinct advantage over differential techniques by enabling precise position determination of a GNSS rover receiver through the use of external corrections sourced from either the Internet or dedicated correction satellites. However, PPP's implementation has been challenging due to the need to mitigate numerous GNSS error sources, many of which are eliminated in differential techniques such as Real-Time Kinematics (RTK) or overlooked in Standard Point Positioning (SPP). This paper extensively reviews PPP's error sources, such as ionospheric delays, tropospheric delays, satellite orbit and clock errors, phase and code biases, and site displacement effects. Additionally, this article examines various PPP models and correction sources that can be employed to address these errors. A detailed discussion is provided on implementing the standard dual-frequency (DF)-PPP to achieve centimeter- or millimeter-level positioning accuracy. This paper includes experimental examples of PPP implementation results using static data from the International GNSS Service (IGS) station network and a kinematic road test based on the actual trajectory to showcase DF-PPP development for practical applications. By providing a fusion of theoretical insights with practical demonstrations, this comprehensive review offers readers a pragmatic perspective on the evolving field of Precise Point Positioning.

Improving ambiguity resolution with common-antenna-based dual-board receiver for low-cost real-time kinematic positioning

Ambiguity resolution is of critical importance to the carrier phase-based real-time kinematic (RTK) positioning method. Improving the accuracy of float ambiguities is beneficial for achieving ambiguity resolution. However, the large measurement noise from low-cost receivers will worsen the estimation accuracy of float ambiguities, which affects the ambiguity resolution performance. In this contribution, to reduce the influence of large measurement noise on ambiguity resolution for low-cost receivers, an improved RTK method for ambiguity resolution is proposed to enhance the accuracy of float ambiguities by equipping the rover receiver with common-antenna-based dual global navigation satellite system (GNSS) boards instead of only one GNSS board. First, the dual-board design can increase the measurement redundancy of the same frequency to suppress the measurement noise. Second, because the common-antenna design can form a moving zero-baseline between the dual GNSS boards, the ambiguities between them can be easily fixed. Known fixed ambiguities can be used as constraints to strengthen the positioning model. Simulation and real-world static and kinematic experiments were conducted to test the proposed method. The results demonstrate that the proposed method can improve the accuracy of float ambiguities by increasing the redundancy of the measurements and introducing the constraints of the ambiguities, and the improved accuracy is about 20%. Compared with the traditional single-board RTK method, better ambiguity resolution performance can be achieved by taking advantage of the proposed common-antenna-based RTK method.

GNSS rover receivers’ horizontal positioning accuracy assessments based on NRTK-VRS surveying

This research investigates a horizontal positioning accuracy obtained from the NRTK-VRS GNSS positioning technique. Measured and computed RMSEs are compared based on the data obtained from 2122 test points within the GNSS CORS network. Rover controllers and receivers have been applied for positioning solutions at every designed test point and their corresponding RMSE measurements. This work compares the measured and computed RMSEs based on this network real-time positioning. Result shows that the 1.5 cm of measured RMSE from the controller is equivalent to 3.4 cm of the computed horizontal positioning accuracy; therefore, the scale factor is 2.27.

Comparative analysis of regression algorithms for the prediction of NavIC differential corrections

Abstract Indian Regional Navigation Satellite System (IRNSS) or Navigation with Indian Constellation (NavIC) provides positioning, navigation and timing information services to various users in Indian region. Standalone NavIC may not meet the position accuracies for certain application such as civil aviation. Differential NavIC is used for improving the position accuracy of rover receiver, which make use of differential corrections (transmitted from reference station). However, if the satellite signals are temporarily lost due to abruptly changing atmosphere, satellite health issues or if the satellite signals are attenuated due to city infrastructures in urban areas, tree canopies, the accuracy of NavIC will be degraded. This article compares regression tree and bagging tree based differential corrections prediction algorithm with the actual differential corrections, by considering the NavIC satellite signal strength (C/No) and elevation angle (El), to improve the NavIC positioning accuracy. The improvement in the position accuracy is obtained by utilizing predicted differential corrections. The position accuracy of rover using actual differential corrections (2DRMS – 3.09 m), regression tree predicted differential corrections (2DRMS – 5.96 m) and bagged tree predicted differential corrections (2DRMS – 3.06 m) are compared. Here, the rover accuracy using actual differential corrections and bagged tree predicted differential corrections are approximately equal. So, the position accuracy using bagged tree predicted differential corrections are accurate when compared to regression tree predicted differential corrections.

METHODOLOGY TO IMPROVE THE ACCURACY OF DETERMINING THE POSITION OF UAVS EQUIPPED WITH SINGLE-FREQUENCY RECEIVERS FOR THE PURPOSES OF GATHERING DATA ON AVIATION OBSTACLES

Low-altitude photogrammetric studies are often applied in detection of aviation obstacles. The low altitude of the Unmanned Aerial Vehicle (UAV) flight guarantees high spatial resolution (X, Y) of the obtained data. At the same time, due to high temporal resolution, UAVs have become an appropriate tool for gathering data about such obstacles. In order to ensure the required accuracy of orientation of the photogrammetric block, Ground Control Points (GCPs) are measured. The recently introduced UAV positioning solutions that are based on Post-Processing Kinematic (PPK) and Real Time Kinematic (RTK) are known to effectively reduce, or, according to other sources, even completely eliminate the necessity to conduct GCP measurements. However, the RTK method involves multiple limitations that result from the need to ensure continuous communication between the reference station and the rover receiver. The main challenge lies in achieving accurate orientation of the block without the need to conduct time-consuming ground measurements that are connected to signalling and measuring the GCPs. Such solution is required if the SPP code method is applied to designation the position of the UAV. The paper presents a research experiment aimed at improving the accuracy of the determination of the coordinates of UAV for the SPP method, in real time. The algorithm of the SPP method was improved with the use of IGS products.

Single-Baseline Long-Distance RTK using a CLS GNSS Module and Open-Source Software: A Case Study from India

For GNSS Real-Time Kinematic (RTK), the reference Base receiver operating at a precise location together with the wirelessly connected Rover receiver(s) provide(s) high-quality real-time position solutions. This work shows the potential of compact, low-cost, single-frequency (CLS) GNSS modules as the RTK Rover up to large baseline distances. A combination of the uBLOX M8T CLS module and the Tallysman TW2710 patch antenna is used in single and hybrid GNSS combinations for short-to-long single-baseline lengths with the open-source RTKLib as the processing software. The results show that, for up to 288 km baseline distance, GPS, GLONASS and Galileo standalone operation provides below 1, 3 and 2 m precisions, respectively and sub-0.5 m precision is achieved for GPS+GLONASS+Galileo and GPS+Galileo+QZSS operations. The work shows the advantages of CLS modules as Rover those exploits the multi-constellation signal availability from India using open-source RTK processing software for reduction of the overall RTK infrastructure cost.

Improving the Position Accuracy of Rover Receiver using Differential Positioning in Indian Regional Navigation Satellite System

Navigation with Indian Constellation (NavIC) is the Indian Regional Navigation Satellite System (IRNSS) developed by Indian Space Research Organization (ISRO) to provide the position and navigation services for Indian region. NavIC or IRNSS is individual satellite constellation which has seven satellites covering the Indian subcontinent. Accuracy of NavIC standalone is insufficient in certain applications such as civil aviation. To improve the position accuracy performance of NavIC system, differential positioning technique is utilized. In this paper, differential positioning is carried out, considering two IGS (IRNSS-GPS-SBAS) receivers (one as reference station and the other as rover), which are capable of receiving IRNSS signals from 7 satellites, GPS signals from 12 satellites, SBAS signals from 2 satellites. Here, NavIC constellation alone is considered for the analysis. The differential positioning is carried out using the pseudorange measurements on L5 (1176.45 MHz), S1 (2492.028 MHz) and dual (L5 and S1 both) and accuracies are compared in terms of the statistical parameters Circular Error Probability (CEP), Distance Root Mean Square (DRMS), 2DRMS (twice the DRMS). The improvement in the horizontal accuracy (2DRMS) of the rover using pseudorange measurements on L5 is observed to be 78.81%, on S1 it is 69.14 % and using dual frequency (L5 and S1 both) it is 80.73% when compared to NavIC standalone.

Global Navigation Satellite System Real-Time Kinematic Positioning Framework for Precise Operation of a Swarm of Moving Vehicles.

The global navigation satellite system (GNSS) real-time kinematic (RTK) technique is used to achieve relative positioning centimeter levels among multiple agents on the move. A typical GNSS RTK estimates the relative positions of multiple rover receivers with respect to a single-base receiver. In a fleet of rover GNSS receivers, this approach is inefficient because each rover receiver only uses GNSS measurements of its own and those sent from a single-base receiver. In this study, we propose a novel GNSS RTK framework that facilitates the precise positioning of a swarm of moving vehicles through the GNSS measurements of multiple receivers and broadcasts fixed-integer ambiguities of GNSS carrier phases. The proposed framework not only provides efficient RTK positioning but also reliable performance with a limited number of GNSS satellites in view. Our experimental flight tests with six GNSS receivers showed that the systematic procedure of the proposed framework could maintain lower than 6 cm of 3D RMS positioning errors, whereas the conventional RTK failed to resolve the correct integer ambiguities of double difference carrier phase measurements more than 13% in five out of nine total baselines.

Performance Evaluation of Different GNSS Positioning Modes

This paper gives a comparison of different GPS positioning modes using RTKLIB which is free and open-source software. The modes tested in this work are Single point positioning ( SPP), precise point positioning (PPP), Satellite-based augmentation system ( SBAS), Differential GPS (DGPS), and Real-Time Kinematic (RTK). The data for tests were obtained from NetR9 receivers, these types of receivers are multi-frequencies and multi-constellation receivers that provide carrier and phase measurements. The SPP mode is the very simplest mode, it can be used for applications where accuracy is not less than 5m, and it can be improved to achieve 1m by using SBAS corrections but only in the coverage area of the system. The DGPS can also provide 1m accuracy using a second receiver as a base station which can increase the cost of the operation. For applications that need very high accuracy, RTK and PPP can be used to reach centimeter-level accuracy. RTK needs a base station in addition to the rover receiver used for the positioning; PPP uses precise orbital and clock solutions which are not available in real time for all users.

Accounting for BDS-2/BDS-3 inter-system biases in PPP and RTK models

Inter-system Biases (ISBs) between BDS-2 and BDS-3 is of great importance for BDS-2/BDS-3 joint processing, which is meaningful to make full use of BDS observations and improves PNT (positioning, navigation, timing) performance. In this contribution, we derive ISBs models with undifferenced ionospheric-free (IF) combination and double-differenced model, corresponding to the IF-PPP and RTK technologies respectively. To analyze code ISB in PPP, we processed data from 55 multi-GNSS experimental (MGEX) stations including 7 receiver types and conduct a detailed analysis on the effect of frequency, receiver types and precise products from 4 IGS Analysis Centers (ACs). It is concluded that both the overlapping frequency and the non-overlapping frequency of BDS-2/BDS-3 exist code ISB. The code ISB of overlapping frequency is within 10 ns, and that of the non-overlapping frequency can reach 100 ns. Moreover, code ISB is influenced by receiver types as well as satellite geometry. The average ISB of stations with the same manufactures tend to be the same while that of stations from different manufactures are different. Affected by the satellite geometry, the ISB characteristics exhibit periodicity and correlation with the location of stations. By comparing ISB calculated by different precise clock products from the GeoForschungsZentrum (GFZ), European Space Agency (ESA), Center for Orbit Determination in Europe (CODE) and Wuhan University (WHU), the results show that the daily STD of ISBCOD, ISBWHU,ISBESA and ISBGFZ is about 0.2 ns, which means that ISB can be calibrated by constant estimation when these products are used. As for Differential Inter-system Biases (DISBs) in RTK, it is discovered that the BDS-2/BDS-3 joint differenced system has a Differential Inter-system Code Bias (DISCB) that exceeds 3.4 ns when the rover and base receivers are made by different manufactures and the hardware delay characteristics for BDS-2 and BDS-3 are different. However, the Differential Inter-system Phase Bias (DISPB) doesn’t exist and can be neglected in RTK.

RTK positioning based on the phase-only differential corrections

Multi-GNSS multi-frequency observations improve the accuracy, availability and reliability of the single-site RTK positioning but also simultaneously raise the communication bandwidth needed for the transmission of differential corrections. A RTK positioning algorithm is proposed that transmit the phase-only differential corrections to achieve the ambiguity-fixed RTK positioning, significantly reducing the communication bandwidth requirements. The essence of the presented method is that the code differential positioning solution implied in the conventional RTK positioning procedure can be replaced by the single point positioning solution of the rover receiver to realize RTK positioning. For typical application scenarios, the transmitted bits in a single epoch can be reduced by more than 25% when the corrections are sent with the RTCM protocol. The experiments by the GPS dual-frequency data over the 10 km and 180 km baselines shown that the performance of the presented RTK algorithm are comparable to that of the conventional RTK positioning, which verifies its feasibility and effectiveness.

High-Accuracy Real-Time Kinematic Positioning with Multiple Rover Receivers Sharing Common Clock

Since the traditional real-time kinematic positioning method is limited by the reduced satellite visibility from the deprived navigational environments, we, therefore, propose an improved RTK method with multiple rover receivers sharing a common clock. The proposed method can enhance observational redundancy by blending the observations from each rover receiver together so that the model strength will be improved. Integer ambiguity resolution of the proposed method is challenged in the presence of several inter-receiver biases (IRB). The IRB including inter-receiver code bias (IRCB) and inter-receiver phase bias (IRPB) is calibrated by the pre-estimation method because of their temporal stability. Multiple BeiDou Navigation Satellite System (BDS) dual-frequency datasets are collected to test the proposed method. The experimental results have shown that the IRCB and IRPB under the common clock mode are sufficiently stable for the ambiguity resolution. Compared with the traditional method, the ambiguity resolution success rate and positioning accuracy of the proposed method can be improved by 19.5% and 46.4% in the restricted satellite visibility environments.

Modeling and assessment of real-time precise point positioning timing with multi-GNSS observations

Real-time precise point positioning (PPP) method is of great interest for global navigation satellite systems (GNSS) time application with multi-GNSS observations. In this study, a multi-GNSS precise timing approach using Centre National d’Etudes Spatiales (CNES) real-time products was presented to improve the reliable of precise timing. Users can obtain the difference between the local time (time of rover receiver) and UTC(k) directly using a GNSS receiver, once the CNES products are aligned to UTC(k) by a multi-GNSS PPP approach. In other words, the reference times of the realigned products for GPS, GLONASS, BDS-2 and Galileo are UTC (k). Then, users can obtain the difference between the local time and UTC(k) directly using any single-system or multi-GNSS combination. Note that the receiver hardware delay needs to be calibrated before timing application. Numerical analyses clarify how the multi-GNSS precise timing approach performs. First, the standard deviation (STD) of the difference between the multi-GNSS timing results and the clock difference from the IGS final products is shown to be less than 0.5 ns. The multi-GNSS solutions outperform that of a single system. Furthermore, GPS-only PPP timing solutions perform better than that of GLONASS and Galileo-only. In addition, the maximum reductions of STD values are up to 33.6%, 11.6%, 14.6%, 25.6% for GPS-only, GLONASS-only, Galileo-only and multi-GNSS timing, respectively, using a receiver clock model. Second, the frequency stability of the multi-GNSS scheme is slightly better than GPS-only. For single-system PPP timing, GLONASS-only performs worst, while GPS-only performs best. The maximum improvements of frequency stability are up to 61.9%, 67.1%, 90.6%, 65.8% for GPS-only, GLONASS-only, Galileo-only and multi-GNSS timing, respectively, with a receiver clock model using the realigned products. More interestingly, we found that the performance Galileo-only was improved with the observations on 2019 as compared to Galileo with the observations on 2018.

Red de transporte de datos en formato RTCM, vía protocolo de Internet (Ntrip). Implementación en la región y proyección futura a través de SIRGAS

Las CORS (Estaciones de Referencia de Observación Continua), utilizan los GNSS (Sistemas Satelitales de Posicionamiento Global), para determinar con alta preci- sión una posición, mediante la observación de los satélites de las constelaciones disponibles (GPS, GLONNAS, próximamente Galileo y Compass/BeiDou). 
 Empleando la técnica llamada de Corrección Diferencial, es posible eliminar casi totalmente la influencia de los errores inducidos voluntariamente o producidos por la señal GNSS. El método DGNSS, tanto en modo Post Proceso como en Tiempo Real, son las modalidades más utilizadas. Actualmente están disponibles tam- bién soluciones PPP (Precise Point Positioning - Posicionamiento Puntual Preciso), a partir de desarrollos generados en varias agencias de investigación. Últimamente se han presentado ciertos avances sobre PPP (Posicionamiento de Punto Preciso), particularmente en tiempo real: PPP-RTK. 
 Las Correcciones Diferenciales pueden ser obtenidas directamente a partir de un receptor GNSS, de una CORS o de una red CORS, conectadas a un Servidor-Cáster a través de Internet. 
 El cliente o usuario móvil utilizando tecnología de telefonía móvil (GSM, GPRS, EDGE, UMTS) y un programa Cliente, puede acceder a la dirección IP del Cáster, a través de protocolo Ntrip (Red de Transporte de datos en formato RTCM a través Protocolo de Internet), a fin de obtener los datos de corrección diferencial para el receptor GNSS que está utilizando. 
 Ntrip se basa en HTTP (HyperText Transfer Protocol - Protocolo de Transferencia de Hipertexto), siendo capaz de trasmitir cualquier tipo de datos GNSS a través de mensajes RTCM (Radio Technical Commission for Maritime Services) o datos en formato propietario (raw data). El usuario puede elegir entre una serie de produc- tos, como por ejemplo correcciones de una sola CORS, o corrección de una red CORS. Existen diversas soluciones de red, como ser: VRS (Estación de Referencia Virtual), FKP (Parámetros de Corrección de Planos), MAX (Máster-Auxiliar), iMAX (individual Máster-Auxiliar

A New Asynchronous RTK Method to Mitigate Base Station Observation Outages.

Real-time kinematic (RTK) positioning is a satellite navigation technique that is widely used to enhance the precision of position data obtained from global navigation satellite systems (GNSS). This technique can reduce or eliminate significant correlation errors via the enhancement of the base station observation data. However, observations received by the base station are often interrupted, delayed, and/or discontinuous, and in the absence of base station observation data the corresponding positioning accuracy of a rover declines rapidly. With the strategies proposed till date, the positioning accuracy can only be maintained at the centimeter-level for a short span of time, no more than three min. To address this, a novel asynchronous RTK method (that addresses asynchronous errors) that can bridge significant gaps in the observations at the base station is proposed. First, satellite clock and orbital errors are eliminated using the products of the final precise ephemeris during post-processing or the ultra-rapid precise ephemeris during real-time processing. Then the tropospheric error is corrected using the Saastamoinen model and the asynchronous ionospheric delay is corrected using the carrier phase measurements from the rover receiver. Finally, a straightforward first-degree polynomial function is used to predict the residual asynchronous error. Experimental results demonstrate that the proposed approach can achieve centimeter-level accuracy for as long as 15 min during interruptions in both real-time and post-processing scenarios, and that the accuracy of the real-time scheme can be maintained for 15 min even when a large systematic error is projected in the U direction.

Network real-time kinematic data screening by means of multivariate statistical analysis

We introduce a novel approach to the computation of network real-time kinematic (NRTK) data integrity, which can be used to improve the position accuracy for a rover receiver in the field. Our approach is based on multivariate statistical analysis and stochastic generalized linear model (SGLM). The new approach has an important objective of alarming GNSS network RTK carrier-phase users in case of an error by introducing a multi-layered approach. The network average error corrections and the corresponding variance fields are computed from the data, while the squared Mahalanobis distance (SMD) and Mahalanobis depth (MD) are used as test statistics to detect and remove data from satellites that supply inaccurate data. The variance-covariance matrices are also inspected and monitored to avoid the Heywood effect, i.e. negative variance generated by the processing filters. The quality checks were carried out at both the system and user levels in order to reduce the impact of extreme events on the rover position estimates. The SGLM is used to predict the user carrier-phase and code error statistics. Finally, we present analyses of real-world data sets to establish the practical viability of the proposed methods.

Nonlinear Observer for Tightly Coupled Integrated Inertial Navigation Aided by RTK-GNSS Measurements

A modular nonlinear observer is considered for tightly coupled integration of inertial measurements with global satellite measurements. A real-time-kinematic (RTK) approach is utilized where the rover and base station measure pseudoranges, carrier-phase, and carrier-phase derived Doppler, to be used in a dual receiver configuration. The modular observer design consists of a nonlinear attitude observer and a translational motion observer (TMO). The attitude observer represents the vehicle attitude as unit quaternions and estimates the gyro bias. A TMO based on the double-differenced measurements between the rover and base station receiver is proposed. The ambiguities introduced by the carrier-phase measurements are included in the state vector and are initially considered real valued, later to be resolved to integer values. The advantages of the nonlinear observer compared with a Kalman filter are reduced computational load, no linearization requirement of the model, and proven stability. The proposed observer is verified using experimental data from flights with an unmanned aerial vehicle, where the position estimates are shown to be within 2–4 cm of a global positioning system $L_{1}$ -based RTK reference solution.

Development of GNSS Receiver for Mobile CORS with RTK Correction Services Using Cloud Server

Requirements for precise Real Time Kinematic (RTK) positioning have been significantly growing in Indonesia since early 2010, resulting from the national programs on village mapping, land cadastre certification, infrastructure developments, and one map policy. The activities require a sub-decimetre level of positioning accuracy to produce detail maps to the scale of 1:500. RTK positioning with CORS should be the most reliable technique to meet the accuracy level. However, the existing distribution of Indonesia CORS Network, consisting of 150 active stations, is still far from adequate since the inter-station distances are of around 500 km while an ideal range should be less than 50 km. This paper related to an initiative for the development of a GNSS receiver that can be transportable and easily set up in the field as a base station to provide RTK CORS correction services with local contents. The initiative supports national efforts on the densification of Indonesia CORS Network to better distribution. The development was started using the Tersus OEM GNSS board series BX305, including the integration of the board to a mini PC. Further developments have been made covering the following, namely: i) to add a long-term stable power supply in the receiver, ii) customization of receiver command settings, iii) to add a GSM modem and internet protocol for data communication from the receiver to a cloud server, iv) installation of SNIP software in a cloud server to provide CORS corrections with NTRIP caster, and v) testing the NTRIP client performance in the rover receiver. Results from the land cadastre surveys carried out in Bandung, Padang and Tangerang Cities show that the length of time for the fixed positioning with resolved ambiguities could be obtained within less than 5-7 seconds with the rover locations less than 10 km from the base station. A longer time to obtain fixed solutions required for the distance at the range of 10 to 20 km, and it is becoming more difficult to get fixed solutions over 20 km. Further developments would be carried out using affordable price GNSS OEM boards provided by different manufacturers.