The data contained in GEONETCast and the European Space Agency Data Dissemination System (DDS) is delivered via communication satellites. For Africa, the Atlantic Bird 3 (situated at 5 degrees west) has been selected to disseminate these services. A low cost ground reception infrastructure, basically a C-band parabolic antenna with LNB, pointed to the Atlantic Bird and connected to a computer containing a digital video broadcasting (DVB) board, enables one receive and store locally both data streams. Since both data streams originate from the same communication satellite, a single antenna can be used to receive both data streams. The coaxial cable that originates from the antenna simply has to be split and from there they have to be connected to each of the ground receiving stations. The DVB board in each of these systems ensures that the data is captured and stored.

Currently the GEONETCast data stream is a one way system, therfore only reception is possible. This is a continuous data stream. Data is broadcasted on a 24 hour – 7 days basis. Non operation of a ground receiving system results in a data gap, as data is broadcasted only once. The ESA DDS, however, can be configured as a two way data dissemination system, allowing one to receive broadcast data as well. The DDS is operated during specific periods on a daily basis for reception of the data. The data packages actually received are monitored using the ground receiving station's fixed IP address and in case of reception failure the data is re-broadcasted.

GEONETCast is currently disseminating images derived from various geostationary and polar orbiting sensors/platforms, as well as, derived products. As the dissemination system started, it provided the European and African national meteorological centres with relevant and timely information mainly focussing on meteorological applications. Currently, the system is rapidly expanding and is disseminating environmental data from various third party data providers as well. The system is furthermore seen as the data delivery backbone by the Group on Earth Observation (GEO) to provide in-situ, airborne and space borne data as part of the Global Earth Observation System of Systems (GEOSS) to the user community. Further details on the images and products the so called “Product Navigator” can be consulted, are available at EUMETSAT.

By means of the ESA Data Dissemination System (DDS) within 24 hours after sensing the ENVISAT orbits acquired over Africa are transmitted, allowing the user to receive (pre-processed) images and derived products from MERIS, AATSR and ASAR such as calibrated TOA radiances, reflectance’s, brightness temperatures, cloud thickness, water vapour and other geophysical products. Next to this, a set of other products, like the ones produced in the framework of the Global Monitoring for Food Security (GMFS) project for early warning, agricultural mapping and crop yield assessment, covering eastern and western Africa and the 10 days maximum value composites derived from the SPOT-Vegetation instrument, like the normalized difference vegetation index (NDVI) and the normalized difference water index (NDWI), are disseminated when produced. Being able to receive both data streams therefore offers the user near real-time complementary data highly relevant for various applications related to weather, atmosphere, oceans, land, vegetation, water and environment. The data comes free of charge and without internet connectivity.

A single reception station can potentially receive all the data being transmitted from one communications satellite independent of the data provider. A typical reception station comprises a standard PC with DVB card inserted and a satellite off-set antenna fitted with a digital universal V/H LNB for Ku-band, or fitted with a circular polarisation feedhorn, bandpass filter and special LNB for C-band. To decode and decrypt the DVB signal, e.g. for GEONETCast, EUMETCast Client Software and in some instances, EUMETCast Key Unit (EKU) are also required.

The cost of reception stations is kept to a minimum by utilising industry open standards to the maximum extent possible thus resulting in an adaptable front-end solution to users' applications.

In addition to the front-end equipment, data processing software will be required. These software applications are provided as free and open source utilities here. Links to other providers can be obtained from EUMETSAT.