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    Archived pages: 311 . Archive date: 2014-01.

  • Title: Argos User's Manual
    Original link path: /manual/index.html
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  • Title: Tracking - Argos
    Descriptive info: Home.. System.. How it works.. Tracking.. How does Argos track mobile platforms?.. How does Argos monitoring work?.. Transmitters can be tracked two separate ways:.. Conventional Argos tracking: The Argos centers calculate your transmitter locations by measuring the Doppler Shift on its transmit frequency.. GPS positioning: if a GPS receiver is integrated into your Argos transmitter, a dedicated processing module at the Argos center 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.. The reference system is the World Geodetic System (WGS 84).. Doppler Shift.. Argos locations are calculated by measuring the Doppler shift on the transmitter signals.. This is the change in frequency of a wave when a source of transmission and an observer are in motion relative to each other.. The classic case is when an observer notices a change in the sound when a train approaches and moves away.. Similarly, when the satellite "approaches" a transmitter, the frequency of the transmitted signal measured by the onboard receiver is higher than the actual transmitted frequency, and  ...   between the frequency measured on board the satellite and the transmitter frequency.. The processing center calculates an initial estimate of the transmitter's position from the first and last messages collected during the pass and the most recent calculated frequency.. The intersection of the cones for these two messages with the terrestrial radius plus the height declared for the transmitter (altitude sphere) gives two possible positions.. For each position, least-squares analysis is used on the equations to refine the estimate of the transmitter's position and transmit frequency.. The position with the better frequency continuity is chosen, and its plausibility checked.. Four checks validate the location calculation:.. Minimum residual error,.. Transmission frequency continuity,.. Shortest distance covered since latest location,.. Plausibility of velocity between locations.. For the location to be validated at least two must test positive.. GPS positioning.. GPS positions are recorded in the transmitter and sent via the Argos system.. Using GPS in addition to Argos allows you to:.. Have two location systems in one,.. Acquire positions as often as you want,.. Obtain highest accuracy (10 meters) without influence from transmitter quality,.. Spread positions evenly throughout the day..

    Original link path: /web/en/93-tracking.php
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  • Title: Monitoring - Argos
    Descriptive info: Monitoring.. Argos platforms can be linked to sensors that collect observations such as: water salinity, atmospheric pressure, wind direction, GPS positions, animal heart rates, etc.. These data are processed by the Argos centers and quality controled observations are delivered..

    Original link path: /web/en/94-monitoring.php
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  • Title: 3.2 Argos location principle
    Descriptive info: The Argos system calculates locations by measuring the Doppler Effect on transmission frequency.. The Doppler Effect is the change in frequency of a sound wave or electromagnetic wave that occurs when the source of vibration and observer are moving relative to each other.. 3.. 2.. 1 Physics and Measurement: The Doppler Effect.. Similarly, when the satellite approaches a transmitter, the frequency of the transmitted signal measured by the onboard receiver is higher than the actual transmitted frequency, and lower when it moves away.. A major feature of the Doppler location is the existence of two possible positions of the platform that give exactly the same frequency measurements on board the satellite: the nominal ( true ) location and the mirror ( virtual ) location.. They are symmetrical about the sub-satellite track and, unfortunately, they are not a priori distinguishable.. Since 2011, users can choose between two location processing algorithms for Argos.. Both techniques compute the Doppler frequency shift on the transmitters signal.. 2 The positioning algorithm based on Least squares analysis (unchanged since 2007).. If four or more messages are received by the satellite, the location calculation process follows the following steps.. An initial estimate of the platform position is computed from the first and last messages collected during a single satellite pass and the last computed frequency of the transmitter.. The intersection of the cones for these two messages with the terrestrial radius plus the height declared for the transmitter (altitude sphere) gives two possible locations.. For each of the two possible locations, and by using all messages received during the satellite pass over the platform, a least-squares analysis is used to refine the estimates of the transmitter's position.. If this analysis fails, the location calculation process cannot continue and no location is provided.. The location with the minimal residual error is chosen, and its plausibility is tested.. Four plausibility tests are used to validate the location:.. Minimal residual error.. ,.. Transmission frequency continuity.. Minimum displacement.. (shortest distance covered since most recent location),.. Two tests must be positive for the location to be validated.. If the first location fails more than two tests, the second possible location is tested.. If both locations fail more than two tests, then the location is not distributed to users, unless they subscribe to.. Service Plus/Auxiliary Location Processing.. (See.. Chapter 3.. 6.. for more information).. The location algorithm provides the two solutions where the first one is the most plausible and considered as the nominal location.. An estimation of the location accuracy is calculated using the  ...   to be validated.. For all locations, an estimation of the accuracy is provided.. Locations computed with less than 4 messages are distributed to users if they subscribe to.. 4 Error estimation.. Due to the satellite’s polar orbit, the Argos position error is better represented by an ellipse rather than by a circle.. For those users who wish to use it, CLS provides the following values corresponding to the ellipse of error for all locations:.. Error radius.. Length of the semi-major axis.. Length of the semi-minor axis.. Ellipse orientation (.. expressed as an angle with the North, going towards to the East).. GDOP*.. (Geometric Dilution of Precision).. Users can employ this description of the location error for example to assimilate positions into an animal movement model.. Error ellipse is available for all locations with the Kalman filter and for locations computed with more than 4 messages with the Least squares method.. For the Least squares method with 2 and 3 messages, CLS provides only:.. Ellipse orientation.. *Geometric Dilution of Precision (GDOP).. is a measure of the effect of the geometry of the satellite-beacon configuration on location accuracy.. The actual Argos location accuracy depends on both the GDOP value and the quality of the transmitter (frequency stability).. As a general rule, a smaller GDOP value yields a more accurate position.. How to access these parameters.. These values are available as.. Diagnostic Data in ArgosWeb.. and.. distributed in tabular format ONLY via ArgosDirect.. Via ArgosWeb.. Users can access the information via ArgosWeb in the.. Consultation/Data Table.. section (display Diagnostic Data by clicking on this icon.. , then selecting.. ) or from the.. Data Download.. screen (display diagnostic data by clicking on.. ).. These parameters are available in clearly identified table columns (see below).. For additional information, consult ArgosWeb’s online help.. Via ArgosDirect.. These parameters are also available via ArgosDirect.. Users must request them from their User Services.. They are distributed in clearly identified table columns (see below).. Column title.. Semi-major axis.. Semi-minor axis.. GDOP.. Units.. Meters.. Degrees (from North when heading East).. m/Hz.. 5 Altitude estimations.. Location computations are extremely sensitive to altitude variations.. A significant error in altitude can considerably reduce the accuracy of a location, especially if satellite visibility is unfavorable.. To improve location accuracy, a.. digital elevation model (DEM).. is automatically included in all location computations for ground mobiles and birds.. The DEM used is based on the USGS GTOPO30 model.. It is broken down into squares with sides of 30 arc seconds of an arc and is used to estimate platform altitude..

    Original link path: /manual/3-location/32_principle.htm
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  • Title: 3.4 Location classes
    Descriptive info: 4 Location classes.. From the beginning of Argos service, locations have been classified according to the following criteria:.. type of location.. (Argos or GPS),.. estimated error*.. number of messages received.. during the pass.. Regardless of the number of messages received during a satellite pass, an estimated error is calculated.. For classification purposes, the error is assumed to be isotropic and hence characterized by a single number called the radius of error.. It corresponds to one standard deviation (sigma) of the estimated location error.. The location class is attributed based on the radius of error.. The location class and associated error is sufficient for many applications.. Still, the location error is not  ...   error, for example to assimilate positions into an animal movement model, will now have access to this information (see.. 4.. Note however, that the classical error description based on location class and radius of error will remain available to all users.. Class.. Type.. Estimated error*.. Number of messages received per satellite pass.. Least Squares.. Kalman Filter.. G.. GPS.. 100m.. 1 message or more.. Argos.. 250m.. 4 messages or more.. 2.. 250m 500m.. 1.. 500m 1500m.. 0*.. 1500m.. A.. No accuracy estimation.. Unbounded accuracy estimation.. 3 messages.. B.. messages.. 1 or 2 messages.. Z.. Invalid location (available only for Service Plus/Auxiliary Location Processing).. * Class 0 locations.. are available by request only..

    Original link path: /manual/3-location/34_location_classes.htm
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  • Title: Why use Argos-3? - Argos
    Descriptive info: Argos-3 system.. Why use Argos-3?.. Why use Argos-3?.. Argos 3: How it works.. Articles Publications.. Better transmission management.. Rendez-vous with satellite.. Interactive data collection.. Power saving.. Less time on surface for Argo floats.. Greater volume data.. 10 times more messages collected.. High data rate channel.. Two-way communication.. Change mission settings.. Remote management of sensors.. Message reception acknowledgement.. © Copyrights IFREMER..

    Original link path: /web/en/251-why-use-argos-3.php
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  • Title: Argos 3: How it works - Argos
    Descriptive info: Argos 3: How it works.. Argos-3 is the new generation of the Argos satellite system.. It offers new capabilities including:.. -.. two-way communication,.. - better transmission management, and.. - platform remote control and programming.. In order for the Argos-3 system to function, user platforms must be equipped with.. a new generation of Argos-3 compatible terminals called Platform Messaging Transceiver (PMT).. The innovative and new PMT is capable of sending and receiving messages to/from satellite, as well as processing commands.. Users equipped with a PMT and subscribed to the downlink service will fully benefit from the new communication capabilities made possible with Argos-3.. The PMT is fully compatible with all satellites of the Argos constellation and can also be used like an Argos-2 transmitter.. • Transmitters send signals to satellites.. Argos-3 instruments will fly on board the three MetOp satellites (2006, 2012.. and 2014) of the European Organization for the Exploitation of Meteorological Satellites (Eumetsat), and SARAL, a satellite of the Indian Space Research Organization (ISRO) in 2012.. Argos-3 transmitters are capable of forecasting when a satellite will pass and can be programmed to send messages only when a satellite is in view.. •Satellites send acknowledgement signals to transmitters.. Thanks to new Argos-3 two-way communication, the satellite sends a signal back to the platform when a message has been correctly received.. Furthermore, the satellite can send messages from users to any Platform Messaging Terminal (PMT).. • Ground antennas relay data from satellites to processing centers.. Nearly 60 antennas located at all points of the globe collect data from satellites in real-time  ...   received, they may be shared with the scientific community, governments or institutions that use the data as important management tools.. Two-way communication: Argos-3 downlink messaging.. Argos-3 makes two-way communication with all platforms equipped with a Platform Messaging Transceiver (PMT) possible.. In addition to satellite acknowledgement of messages received error-free, the downlink makes it possible for users to program their platforms remotely.. • Users send commands to the Downlink Message Management Center (DMMC).. Argos users send commands via a web interface.. Their commands are processed by the DMMC, operated by CLS in Southwestern France.. • DMMC relays messages to master platforms.. The DMMC relays commands to master platforms, located in Toulouse, Fairbanks and Svalbard.. A master platform is a powerful PMT, capable of communicating with the Argos-3 instruments aboard satellites.. • Master platforms upload messages to satellite.. Master platforms automatically upload commands on the next satellite pass.. • Satellites download messages to Platform Messaging Transceivers (PMTs).. When the satellite recognizes its target platform, (platform to which the command is addressed, identified by its ID number), it sends the message, via the downlink, to the PMT.. The satellite also sends system information via the downlink on the pass (system information includes time and orbit information, allowing the PMT to calculate the next satellite pass).. • PMT receives command.. Upon receiving the command, the PMT sends an acknowledgement that it has received the command error free; then processes the information contained in it.. It uses system information to calculate the next satellite pass, then waits for the next satellite pass in energy-saving mode..

    Original link path: /web/en/233-argos-3-how-it-works.php
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  • Title: Articles & Publications - Argos
    Descriptive info: Articles Publications.. Articles & Publications.. Argos-3 in drifters.. Download PDF.. Exciting Results for the Argos-3 DBCP Pilot Project.. -.. Shortly after the first buoy deployment in 2009, the main objectives of the integration of Argos-3 into SVP (Surface Velocity Program) and SVP-Barometric drifters have been reached.. Surface High-Speed Data Transmission.. The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) has achieved the world’s first high-speed data transmission by the ARGOS-3 system, using a transmitter called PMT-HD (Platform Message Transceiver High Data Volume).. The ARGOS-3 compatible transmitter, developed by KENWOOD and exclusively designed for ocean observation, was integrated into an m-TRITON buoy.. Argos-3 for Argo floats.. IFREMER A new generation of ARVOR floats with ARGOS-3 capability.. T.. he Technological Research and Development Department of the French Research Institute for Exploitation of the Sea (IFREMER) is currently working on the integration of Argos PMTs into their ARVOR float.. They plan to deploy these new, improved floats by the end of the year.. Argos in moored buoy.. ARGOS-3  ...   Barrera explain how the Argos-3 system provides the stable and powerful satellite link telemetry required for their work.. How Argos-3 can benefit the data buoy community?.. The benefits of ARGOS-3 for the data buoy community: DBCP Pilot.. Composed of over 1250 drifting buoys and 400 moored buoys, the Data Buoy Cooperation Panel (DBCP) network provides measurements such as sea-surface temperature, surface current velocity, air temperature and wind information.. Argos-3 functions, such as high data rate and downlink messaging capabilities, are important to the community because they promise to enhance buoy performance and improve data collection, as Michel Guigue explains.. Argos-3 in the Arctic.. ARGOS-3 In the North Pole new data collection systems for a changing Arctic environment.. Understanding climate change in the Arctic region is crucial to understanding environmental change on a global level.. But as climate change modifies this region, new observing systems must be developed in order to study it, explains Dr.. Takashi Kikuchi, of the Japan Agency for Marine Science and Technology (JAMSTEC)..

    Original link path: /web/en/257-articles-publications.php
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  • Title: Register with Argos - Argos
    Descriptive info: User Area.. Getting started.. Register with Argos.. Register with Argos.. Please download and fill out the following forms and return them by fax or mail to.. CLS.. :.. System Use Agreement.. ID Number Request Form.. The Argos Operations Committee will check that your program is compatible  ...   then send you:.. a Purchase Order.. Once you have signed and returned your purchase order to us, we will give you:.. your program and platform numbers.. passwords for consulting your results on line.. a form for you to specify the type of data processing you require..

    Original link path: /web/en/114-register-with-argos.php
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  • Title: Manuel Argos
    Original link path: /manuel/
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  • Title: ArgosMonitor - Argos
    Descriptive info: User forms.. ArgosMonitor.. ArgosMonitor.. ArgosMonitor is a platform monitoring service that makes it possible to monitor platforms remotely.. ArgosMonitor automatically sends an alert message to users in certain pre-defined circumstances.. For Biologists.. For Oceanographers/Meteorologists.. For Hydrologists/Users of other fixed stations.. ArgosMonitor for Biologists.. ArgosMonitor allows biologists to answer the following questions about their platforms:.. Is my transmitter still working?.. If it stopped transmitting temporarily, has it started working again?.. Has the animal I am following entered a wintering zone? returned to its nest? crossed a border?.. Is the study animal still alive (are heart rate and/or temperature measurements normal)?.. Is the battery low?.. ArgosMonitor Basic Services.. Keeping an eye on platform performance.. Transmission ArgosMonitor.. Is the transmitter still working?.. Transmission ArgosMonitor sends you an alert when no message has been received from your platform for a pre-defined time period.. An alert message will also be sent if no location has been calculated.. GEO ArgosMonitor.. Has the animal I am tracking entered a wintering zone? returned to its nest? crossed a border?.. GEO ArgosMonitor sends you an alarm message when a platform enters or leaves a customized zone.. Sensor ArgosMonitor:.. Is the animal still alive (are heart rate, temperature measurements normal)? Is the battery low?.. Sensor ArgosMonitor can alert users  ...   my platform performing (battery level, light sensor, etc.. )?.. Sensor ArgosMonitor alerts you if an unusual value for a particular sensor is reported.. ArgosMonitor "Watchdog" Services.. Added security for high-value ocean buoys.. Silent ArgosMonitor.. Has my equipment surfaced inadvertently?.. This service is designed for underwater moorings, (i.. e.. , platforms that only use Argos in case of an emergency ).. It sends an alert (and if possible, a location) if at least two messages have been received via the Argos system.. MBM ArgosMonitor.. Is my moored buoy floating away?.. Designed for Moored Buoys, this service will alert you if a moored buoy leaves its mooring zone.. It also provides you with locations so you can quickly recover your Moored Buoy.. ArgosMonitor for Hydrologists/Users of other fixed stations.. A number of customized ArgosMonitor services help hydrologists, and more generally, all users of fixed stations, answer the following questions about their platforms:.. Is my platform still working?.. Are the batteries weakening? How are my sensors performing? Has something unusual occured: sudden atmospheric pressure drop? has the temperature risen unexpectedly? Has the water level risen or dropped?.. How are my sensors performing? Has something unusual occured: sudden atmospheric pressure drop? has the temperature risen unexpectedly? Has the water level risen or dropped?..

    Original link path: /web/en/115-argosmonitor.php
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  • Archived pages: 311