GNSS at Geodetic Observatory Pecny

Global Navigation Satellite Systems (GNSS) have revolutionized positioning, navigation, and timing, becoming a common part of our everyday life. GNSS have also supported the development of scientific applications and services. From 90th, the Geodetic Observatory Pecny (GOP) contributes to variety of them in these domains:

• collecting and disseminating high-accuracy GNSS data from reverence stations,
• developing strategies and systems for precise GNSS analyses,
• developing software tools for precise GNSS data analysis, quality check and dissemination.

Observations

First observations of GPS NAVSTAR system has been performed at GOP in 1992. More then 100 stations are operated today by GOP and provides continuous GPS, GLONASS, Galileo, QZS observations in real-time streams in RTCM format, high-rate data, hourly and daily files in RINEX 2.xx/3.xx format.

Dissemination and monitoring

Since 2002, GOP has operated the EUREF local data center with a particular focus on hourly data dissemination for near real-time GNSS analysis (e.g. troposphere monitoring, ultra-rapid orbit determination). Today, GOP data center also collects and disseminates precise models and products useful for GNSS analyses (orbits, clocks, meta data, supporting information etc). Since 2003, GOP has run a local NTRIP broadcaster for real-time GNSS data streams from many stations of the EUREF Permanent Network (EPN) and other selected from the global network of the International GNSS Service (IGS). Recently, a quality check (QC) monitoring was added to various data sources (EUREF historical archive, MGEX-campaign etc).

Analysis and monitoring

GOP has a long-term experience in high accuracy GPS processing. Originally, all analyses were based on advanced use of the Bernese GNSS software. GOP produces a variety of solutions contributing to several international services or projects - IGS, EUREF, E-GVAP, EPOS. Products extend from real-time, near-real time (hourly/ultra-fast) to long-term homogeneous re-analyses. Just mentioning some of them (for more details follow our web-pages):

• ultra-rapid GNSS orbits (since 2004 for IGS),
• near real-time troposphere monitoring in support of numerical weather forecasting (since 2000 in COST-716, TOUGH, E-GVAP, COST-ES1206),
• rapid and final estimates of EUREF subnetwork (since 1996 for EUREF),
• real-time GNSS data processing for coordinate and troposphere monitoring (since 2012),
• homogeneous re-processing of EUREF Permanent network in support of the reference frame maintenance (1996-present) within Repro1/2 campaigns (2008, 2014),
• long-term GNSS combinations in support of velocity field estimation (EUREF network, 2004, 2012),
• monitoring of the Czech Positioning Service (CZEPOS, since 2006),

Software development

Since 2011, we have been developing the G-Nut library for precise GNSS analyses and data/product monitoring. In 2014, the G-Nut-based applications became important tools in support of new services and developments at GOP. The following end-user applications were successfully derived and used from the G-Nut core library:

• Anubis - for multi-GNSS data quality check
• Geb - for real-time and offline coordinate estimation using Precise Point Positioning method
• Tefnut - for real-time, near real-time and offline troposphere estimation
• Shu - for generation of tropospheric correction models based on numerical weather data fields
• Apep - for various parameter time-series analysis (troposphere, coordinates etc.)