ARGOS SYSTEM
Why choose Argos? Worldwide tracking and environmental monitoring by satellite 30 YEARS OF E X P ER I E N C E 22000 ACTIVE T R A N S M I TT ER S PER M O N T H 8 000 ANIMALS TAGGED AND T R AC K E D Argos is a unique worldwide location and data collection system dedicated to studying and protecting the environment. Argos is a unique worldwide location and data collection system dedicated to studying and protecting the environment. Argos helps the scientific community to better monitor and understand our
environment, but also helps industry to comply with environmental protection regulations implemented by various governments. To meet system use requirements, all programs using Argos have to be related in some way or form to environmental protection, awareness or study, or to protecting human life. Applications for which a clear governmental interest prevail are also approved. Pioneer satellite system Argos is a satellite-based system operating since 1978. The Argos system collects data from Pl a t f or m Terminal Transmitters, PTTs, and delivers this telemetry data to the users desktop. It was established under an agreement between: French Space Agency (CNES) National Oceanic and Atmospheric Administration (NOAA, USA) National Aeronautics and Space Administration (NASA , USA) Argos is operated and managed by Collecte, Localisation, Satellites (CLS), a CNES subsidiary near Toulouse, France and CLS America, a CLS subsidiary based in Washington, USA. The Argos instruments are housing on board of satellites of different organizations the NOAA, the Japanese space agency (NASDA) and the European Meteorological Satellite organization (Eumetel). Two satellites are operational at any time. The message of the PTTs are received on board of the satellites and relayed in real time to the ground. Additional the messages are stored and transmitted every time they pass over one of the 3 ground stations, located at Wallops Island (USA), Fairbanks (USA) and Lannion (France). The data are sending directly onto the Global Telecommunication System (GTS). Argos services offers the possibility your transmitters in the field, you'll be able to send messages to the PTT in the field. Messages sent by PTT’s ca n be processed for location or data collection or both. A robust system The Argos system is: 6 satellites, which follow polar orbits at an altitude of about 850km (530 miles), 60 terrestrial receiving stations 2 data processing centers. Unlike the Global Positioning System (GPS) that needs a minimum of three satellites to be in range to pinpoint an object's location, Argos is still so attractive and working so well after 30 years, the Argos system was designed as a very simple and robust system.
As a satellite passes overhead, it picks up data from a transmitter, which is continuously sending out messages in short pulses. During the 10 minutes or so that the satellite is in range, it will measure the frequency of each message it receives. However, an effect known as the Doppler shift means that each frequency the satellite receives is slightly different - as it moves towards a transmitter, it records a higher frequency, as it moves past it, it records a lower frequency. Using these frequency changes, together with the satellite's speed, position and the original frequency that the transmitter beamed out, the transmitter's position can be calculated. Argos users are able to pick up the results via email, websites or via a "Google Earth". System advantages CLS operates Argos system and are constantly in contact with Argos users and try always to make sure the Argos system fits with their needs. Argos is constantly evolving: Polar orbits Worldwide coverage, by increasing the number of satellites More data, by increasing the amount of data sent on each satellite pass Optimization of transmitter power consumption Reduction in the size of transmitters ( 4,5g smaller) The three main capabilities in which Argos is evolving are: Doppler location capability The Argos processing centers use the Doppler effect to locate transmitters. The advantages of Doppler location are low transmitter power consumption and instant location opportunities throughout satellite passes (useful for marine animals for example). GPS p o s i t i o n i ng The Argos processing system uses the GPS receiver as a sensor and sends users their GPS positions as if they were sensor data. The processing system has been modified to make the GPS positions available in the same format as regular Doppler-derived locations. User can choose whichever form of location best suits their needs. H i gh s e n s i t i v i t y of sa t e lli te r e c e i v er t o t ra n s m i tter m essages That means transmitters can be miniaturized and be operated on low radiated power, achieving good results with just 250 mW and using very low power, so that animals can be tracked over long distances.
GPS positions via Argos Why GPS and ARGOS are different? There are two separate ways of location or tracking your transmitter: Argos location: the Argos centers calculate your transmitter locations by measuring the Doppler shift on its transmit frequency. Even if you do not send sensor or other data, the minimum message length is 32 bits. GPS positioning: if a GPS receiver is interfaced or built into your Argos transmitter, a dedicated processing module at the Argos centers can extract the GPS positions from your Argos messages, validate them, and output them as regular Argos positions. The coordinates in both cases are in latitude and longitude, in thousandths of degrees. The reference system is the World Geodetic System (WGS 84). With Argos, keep your data accurate and up to date T h e ad v a n t ages of s e n d i ng GPS p o s i t i ons v i a t he A r g o s s y stem : having two location system s is more reliable than just one GPS positions can be generated as often as you want Accuracy is higher (within 100 meters) and does not depend on the transmitter quality Positions can be spread evenly through the day Providing the GPS positions in the Argos messages are in the format defined by CLS, they are output in latitude and longitude, and made available just like Argos locations.
How Argos works? Powered by batteries or solar energy, the Argos transmitters send messages at regular intervals of short duration (less than one second) at Argos instruments on satellites that pass at 850 km altitude. The collected information is sent to sixty ground receiving stations that calculate the position of the argos beacons or buoys and retransmit all the two treatment centers in France (Toulouse) and United States (Washington). CLS centers data analyze and retransmit qualified data to Argos users (scientists, governments, industry, etc.) Argos is a unique worldwide location and data collection system dedicated to studying and protecting the environment. Argos transmitter A platform refers to any equipment integrating an Argos-certified transmitter. Each platform is characterized by an identification number specific to its transmission electronics. A platform transmits periodic messages characterized by the following parameters: Transmission Frequency (401.650 M Hz ± 30 k Hz), which must be stable as the location is computed on the basis of Doppler effect measurement. Repetition period, which is the interval of time between two consecutive message dispatches, varying between 90 and 200 seconds according to the use of the platform, platform identification number, all collected data. The transmission duration of each message is less than one second. Platforms: - Argos transmitters and packaging dedicated to wildlife tracking - Drifting buoys - Ice buoys - Subsurface Floats - Moored buoys Argos satellites Polar orbiting satellites collecting data: flying at an orbit of 850 km above the earth pick up the signals and store them on-board and relay them in real-time back to earth.
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