Groundstation GS-E

Components

• 400 MHz receiver integrated
• Initialisation cable between GS-E or PC and radiosonde

Overview
The main function of the GS-E groundstation is receiving the radiosonde signal and providing local GPS information. All functions of the GS-E are software-controlled by a standard PC via USB.

SDR (Software Defined Receiver)
The core of the GS-E is a so-called software defined receiver. A Software Defined Receiver (SDR) is such where demodulation and the last IF (intermediate frequency) processing are done entirely in software. Usually this means using a DSP, but in the case of the GS-E, this processing is done on a PC. Most modern PCs are now faster and more powerful than many DSPs were only a few years ago. The radiosonde signal is received by  a software-defined PC-based narrowband receiver (400 MHz to 406 MHz). This PC-based receiver is USB-controlled and compatible with modern desktop and notebook computers with USB interface.

Antenna Switch (Diversity)
The GS-E provides a USB controlled antenna switch. This gives the possibility to connect two 400 MHz antennas at the same time to ensure 100 % coverage. The selection of the right antenna is done completely automatically by the software GRAWMET by continuously checking the signal strength of both inputs.

GPS Module
An integrated GPS module provides exact position information of the groundstation. This GPS information can be used for applying differential GPS mode.

Software
The GS-E is fully controlled by the meteorological software GRAWMET via USB. This includes the tuning of the receiving frequency, control of AFC (Automatic Frequency Control), selecting of the optimal filters, frequency sweeping, selection of the right antenna, etc.

Meteorological Messages (WMO)
TEMP FM35-XI, TEMP SHIP FM36-XI, PILOT FM32-XI, PILOT SHIP FM33-XI, BUFR 3’09’052 (for TEMP data) and BUFR 3’09’051 (for PILOT data)