Data are transmitted hourly or half hourly from the memory of the sun photometer microprocessor via the Data Collection Systems (DCS) to either of three geosynchronous satellites GOES, METEOSAT or GMS and then retransmitted to the appropriate ground receiving station. The data can be retrieved for processing by Internet linkage resulting in near real-time acquisition from almost any site on the globe excluding poleward of 80 degrees latitude. The DCS is a governmental system operated for the purpose of transmitting low volume environmental data from remote sites for various institutions and government agencies.
The frequencies, channels and transmission windows are assigned by NOAA NESDIS for GOES, EUMETSAT for METEOSAT and GMS which are broadcast in the 401 to 402 MHz range. The satellite transmitter module used is a Vitel VX1004 which is commercially modified for use with the CE 318 A (The Vitel VX1004/2 is used by the PHOTON group but it is no longer in production). The antenna is conical approximately 40 cm in diameter and 40 cm long. The transmitter system is battery operated and charged by a 10 watt solar panel.
Data may be downloaded automatically from the Cimel sun photometer and stored on the local computer. This computer can run software to automatically transfer K7 files to the AERONET processing system through the Internet. Alternatively, users may download K7 files manually from the instruments using a PC or laptop and manually submit these files to the processing system.