The national network of Continuously Operating Reference Stations, abbreviated as VNGEONET use the global navigation satellite system (GNSS) to provide positioning and navigation data information for agencies and organizations, individuals in surveying, mapping and other related fields.

VNGEONET network structure includes 3 main components: Continuously Operating Reference Stations (CORS), central processing control station and users.

VNGEONET network structure diagram

1. Continuously Operating Reference Stations (CORS)

The VNGEONET network started construction in 2016 and completed by the end of 2019, including 65 Continuously Operating Reference Stations (CORS) spread throughout the territory of Vietnam icluding:

- 24 Geodetic CORS stations are designed with concrete landmarks drilled deep to stable layer, evenly distributed across the country with a density of about 200km/station to be used as the national terrestrial reference frame.

- 41 NRTK CORS stations combined with 24 Geodetic CORS stations are used to provide data for real-time dynamic GNSS measurement with cm-scale accuracy distributed at a density about 50km-80km/station located in Nothern Delta,  the Central Coastal, and the Southern Delta.

Location map of 65 CORS stations installed evenly throughout Vietnam territory

2. VNGEONET network equipment and software

The VNGEONET network includes 65 CORS stations and a central processing control station located in Ha Noi.

a. At 65 CORS stations

The equipment at the CORS station is designed specifically for Leica CORS stations (AR25 antenna and GR50 GNSS receiver) and Met 4A meteorological sensors.

b. At the central processing control station

The central processing control station is designed according to national standards for server systems and computer room infrastructure. Including Dell servers, CISCO devices, data storage and data backup systems supporting up to 100TB, with a multi-layer security system (by account, software, hardware). The central processing control station has a stable mains power source and high-speed internet connection to ensure network continuity. The central processing control station to calculate, process and provide services of the VNGEONET network.

The software system includes:

- Spider Net software system from Leica

- Long edge mesh processing software achieves Bernese millimeter accuracy

- Meteorological software RTMon GPS Solution

3. Data provided by VNGEONET network

a. Real-time kinematic data in the VN-2000 national coordinate system, national altitude system (VRS, iMAX, Single base).

- Real-time kinematic (RTK) solutions provided by VNGEONET network include: Network RTK (VRS, iMAX) and Single base RTK. In which the Network RTK solution has higher stability and reliability than the traditional Single base RTK solution because it is calculated from a network of CORS station points (at least 3 CORS stations), the Network RTK solution is recommended.

b. 24-hour static GNSS data acquired from CORS stations in RINEX format with signal acquisition intervals of 1 second, 15 seconds, 30 seconds.

- Provide GNSS data 24-hour static data received from CORS stations serves for post processing and calculation.

* References:

1.   Thông tư số 03/2020/TT-BTNMT: Quy định kỹ thuật về mạng lưới trạm định vị vệ tinh quốc gia

2.   Quyết định số 2537/QĐ-BTNMT: Ban hành quy định về vận hành, bảo trì mạng lưới trạm định vị vệ tinh quốc gia.