Argos Satellite Tracking - User Guide

Old manual but the principals apply.

The following application is written in Powerhouse.

Please submit any application development enquiries using the feedback form.

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Contents

• The application

• Creating a profile of a PTT
  • Data selection criteria
  • Mapping control
  • Comments on the listing file
• Creating a plot from multiple profiles

• Reference Points
• Maps
• Getting data direct from Argos
• Batch downloading of data
• Putting maps/lists on the web

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The application, back to Contents

The ARGOS application allows users to manipulate ARGOS PTT data and produce maps and listings.

Check for details on this local ARGOS system document or go to the ARGOS home page. You may wish to see the Wildlife Telemetry Clearinghouse for related applications.

To start the application, typing ARGOS once logged onto Marvin and the first screen looks similar to this. There may be slight differences as the application evolves ahead of this manual.

To activate any of the options, just type the number on the left in the action box.

Screen 10 Programs and batch reporting allows the user to cluster multiple PTT profiles together as one logical unit that can be reported via one action. The following example displays the program 973 and lines 4 to 13 display several PTTs and some of the data from the profile.

Investigator and details are for storing the chief invstigator of the program and details of its purpose. Please enter these if missing so the maintainer of the application can sort out any problems with particular ptts/programs.

Batch name is a name that the user can assign to this program and is used by the VAX to name the batch job that gets created. The options at the bottom allow the user to control this job.

• START allow the user to start this program at the specified time of day (most likely before arriving at work so as to get the latest data possible). Simply type START in the action box. If the batch already exists then nothing happens. If that is the case type STOP to kill any ones that are already running.

• STOP kills the batch if running.

• SP (acronynm for Show Progress) displays any jobs (both batch and print) that are active.

• NOW is a special case of doing an immediate one-off run of the program. A useful method of testing that you are getting the types of profile and reports that you want.

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Creating a profile of a PTT, back to Contents

Screen 11 allows the user to create a profile of a PTT that can be used repeatedly to plot maps and/or produce a list of positions and distances from specified reference points.

A profile is a set of parameters that control the extraction of data from the Argos data sets and then the mapping of that subset of data.

Each profile has a unique computer generated number starting from 1. By using this to identify the profile, instead of the PTT number, you can change the PTT number without casuing problems with profiles linked to multi-profile plots. Screen 11 has multiple keys. It will ask for a record via

• Which profile number? If not entered then
• Which program? If not entered then
• Which reference location? If not entered then
• Which PTT number?

The above example requires data about PTT number 1398 from 13-Nov-1994 to 30-Nov-1994 excluding data with quality below 1 and using Edmondson Point in the Ross Sea as the reference point. A map is constructed using the set map limits and not the bounds of the data. When first plotting some data, it is useful just to let the data control the map plot bounds so that all data is visible. After selecting some suitable map limits then set the flag Autoscale map to N.

Once you have a profile then use the following commands

• LIST - will produce list of hits whilst EDIT allows you to edit this listing and finally PRINT will print it on your chosen printer.

• MAP - will produce a map and then print it on your chosen printer. This command invokes IDL which is only available on Alpha.

• GIF - will create a gif file called ARGOS.GIF

  Unfortunately it cannot be directed to the Mac file server so they stay in your login area on the vax. Do the following

  • on a PC just use pathworks to get to them or an FTP program.
  • on a Mac, use Fetch (FTP) to get them to your Mac.

• GIS - export lats/lons into a file for imprting into a GIS.

• EXCEL - export the LIST file with commas so you can import into an Excel spreadsheet.

• VIEW - displays on a second screen all records for the PTT within the date bounds. It wont show you lats/longs nor a sensible date format. The dates are stored as Modified Julian Days (MJD). It will at least indicate if you have any data.

• HIST - produces several histogram plots, including speed, direction, a polar plot of directions, speed versus range and histogram of local time of day the tracker was seen.

• AN - produces an annuli plot - ie time spent at a radial distance or bearing from a reference pt.

• Q - produces a plot versus time of the quality of the PTTs - useful for checking if the battery is dying.

• CELL - computes time spent in hours in a lat/lon cell assuming continous speed from location to location.

Some parameters and how they control the data.

• Put on Web Flag to put data on web, see here for more details.

Data selection

• Minimum Quality - each Argos message has a quality flag associated with it. The ranking order from best to worst is 3, 2, 1, 0, A, B and Z.

• Delta time between fix (hrs) - Each fix has a time recorded to within seconds. However successive close fixes do not give any sensible movement information as the best fix (class 3) has an error of 150 metres. Fixes within this time of the last fix are ignored.

• Maximum allowed speed (kph) - this filters out any fixes that give speeds greater than this value. Penguins might not be able to travel at 50 kmh. A note of caution. Error circles are large (see next parameter for values) and may give rise to spurious large speeds. To cancel this filtering option, set it to zero.

  The method used is

  1. assume all data points are 'good'.
  2. Take the data point in question and calculate the 4 speeds to the previous 2 and the next 2 'good' points.
  3. Average this speed by taking the root mean square of the 4 speeds.
  4. Assign this to this data point and repeat for all 'good' data points from the 3rd point to the 3rd last point. The assumption is that the first 2 and last 2 data points are always 'good'.
  5. If there is one 'bad' point then it is likely that the RMS speed for points surounding this data point will exceed the required maximum speed. Find the point with the highest speed, mark it as 'bad' and keep the the other points as 'good'.
  6. Repeat from (2) until no more points lie above the maximum speed.

  The following graph show the original RMS speeds for 78 data points (in black). After filtering for speeds above 5 km/hr, the red line is the result. Note that removing one 'bad' point can significantly lower the RMS velocity for surrounding points. In this case only 7 points were filtered out

  

  This method has the advantage of excluding bad points no matter what class.

• Date control - has several values. -1 forces plotting program to use the start/end dates as specified, 0 uses all data in the file and a value greater than 0 means plot the last so many days data.

• Start date and end date - if date control is set to -1, then programs uses these dates/times to limit what data is used.

• Tiris Tag / Band - enter if bird as a Tiris tag or Band attached. Then can associate Argos data to APM weighbridge / nest data. If the animal has an attachment, enter its weight so that it can be subtracted off weighbridge records. (Not yet properly implemented so dont panic)

• Include Ref pt - this one letter code allows the user to include the reference point in the analysis. For example if a penguin is deployed then there is an obvious start time and position. If he/she is nabbed after returning, then that time can be used for speed calculations from the last PTT fix. This code has 4 possible values
  • B = Both include the ref point and start and end times in the list of PTT fixes.

  • S = Start - only include start point as the end of the deployment was not possible (seal went to sea!) or the end time could not be accurately established.

  • E = End - only include end point as the start of the deployment was not recorded.

  • N = None - do not use start or end points at all.

Mapping control

• Require day marks on plot - set to Y if marks on plot at the beginning of the solar day are required.

• will plot day marks ONLY - computes day marks and plots them and NOT the indiovidual points. Good for seeing overall movements per day for a long trip.

• Require day marks on plot - set to Y if marks on plot at the beginning of the solar day are required.

• Connect points - set to Y if require points to be connected. If N then an asterisk is placed at each location.

• Require error circles on fixes - set to Y will cause the plots to have error circles drawn. The radius are
  • class 3   150 m
  • class 2   350 m
  • class 1  1000 m

  Class 0 or worse have no guaranteed position nor error radius. Class 0 hits have been known to appear on the other side of the world. Giving it an error radius is meaningless.

• Annotate points with fix no - set to Y if the fix number is written on the map.

• Include Gebco data - enter Y if you wish to superimpose the GEBCO bathymetry data.

• Autoscale map - set to Y means the data points define the plot bounds whilst N means the plotting program uses the user entered map limits.

• Map Name - use a dot <return> to view a list of maps that can be used. Ensure the map will be visiible within the boundaries you have selected.

• Map projection - the list of available projections are
  • O - orthographic (the default and only one that is used for now)
  • L - Lambert Equal Area
  • M - Mercator
  • A - Azimuthal
  • G - Gnomic

• Map limits - Set required mapping limits provided Autoscale is N. Be careful that southern lats need a minus and be careful of the order.

Comments on the listing

At the top of the listing is the date range, profile name and comments from the profile, the miminum quality of fixes used and the start reference point.

It contains the following columns

• The PTT number

• the fix number - a sequential number starting from 1 to provide a connection between the ARGOS fix record on the listing and what appears on the plot.

• UT date and time

• Solar or local time - derived from the longitude

• Sun alt and Az - first column is the altitude of the sun above the horizon (negative implies below the horizon) and the next is the azimith from north.

  The final column (marked L for light) is a flag to indicate how dark it is

  • D - implies dark ie sun 18 degrees below horizon
  • A - Astronomical twilight - sun altitude between -18 and -12 degrees
  • N - Nautical twilight - sun altitude between -12 and -6 degrees
  • C - Civil twilight - sun altitude between -6 and 0 degrees
  • nothing - the sun is up.

• the quality of the fix

• latitude and longitude of the fix

• the distance (in kilometres) and bearing to the last fix

• the time in hours from the last fix

• the speed in km/hr from the last fix

• the distance (in kilometres) and bearing to the reference point or if that has not be specified then the first fix for this profile.

• the final column is the accumulated travel distance (in kilometeres) from the start point.

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Creating a plot from multiple profiles, back to Contents

This screen allows the user to associate several profiles together and then plot them on a common map.

Inputs are:

• Profile name - any name is allowed just as a reference to get this multi-profile from the database.

• Plot title - Pretty obvious. This will appear on top of the map.

• Map name - As per standard profile. Use "." to see a list of valid map files.

• Map projection - See the previous described list

• Connect points - Y to connect tracks or N to plot asterisks at locations.

• Autoscale map - enter Y to use the data to limit the size of the map.

• Include Gebco data - enter Y if you wish to superimpose the GEBCO bathymetry data.

• Map limits - Overrides the values in the individual profiles.

To enter a profile, goto to the PTT field and use "." to see a list of profiles. This new screen will ask for either a PTT number or a simple return will then ask for a reference location (easy then to list all profiles at a deployment site). Select the required profile by typing the id number in the action box. This profile and some details will be displayed back on the multi-profile screen.

Finally once a profile is created, do either of the following

• MAP - type MAP in the action box and IDL will create a map and print it directly on your selected printer. See the main menu for what is your current printer.

  Some hints - use a low resolution map such as tas_to_msn until you get the desired result and then use the high resolution map aat_coast.geo for a final output. This later map takes a while to read and plot.

• GIF - will create a gif file called ARGOS.GIF

  Unfortunately it cannot be directed to the Mac file server without corruption so they stay in your login area on the vax. Do the following

  • on a PC just use pathworks to get to them or FTP.
  • on a Mac, use Fetch (FTP) to get them to your Mac.

• HIST - This takes the combined data and produces several histogram plots, including speed, direction, a polar plot of directions, speed versus range and histogram of local time of day the tracker was seen.

• PAIR - This produces a plot over time of the separation in distance of any two profiles. That is it allows the user to see if animals are sticking together. If for example you have three profiles, then there will be three pairs of distance plotted over the common time base of the profiles. Naturally this escalates as you have more profiles. For N profiles, the number of plots will N*(N-1)/2. At the moment NO checks are made for non-overlapping datasets - the program may die.

  The following example plot of 3 profiles shows the two birds are near each other whilst the 3rd bird is typically more than 60 km from them. The index on the right hand side shows which PTTs are paired per plot.

  

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Reference Points, back to Contents

Screen 12 is a maintenance table of reference points and locations that can be used to calculate distance and bearings from as the PTT transmitter wanders about. A three letter code is used to identify the location. Use a sensible code that is easy to remember. Note some locations are ships as this table is used by many other applications so please dont muck it up indescriminately.

If relevant, enter positions as decimal degrees (negative for southern latitudes or western longitudes) and decimal minutes.

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Maps, back to Contents

Screen 13 is maintenance table of known map filenames and associated descriptions that the user can select from for plotting.

Map name is the actual VMS filename. The above examples live in the directory pointed to by the logical map:. These maps have a specfic data format. Contact the author for more details.

Filenames ending with GEO are recent and better resolution maps. All new map files will eventually replace the older *.DAT files.

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Getting data direct from Argos, back to Contents

Options 20 and 21 allow direct connection to an ARGOS computer and require a valid ARGOS computer Username and password. The connection to Melbourne needs Telnet whilst the connection to France requires logging into a VAX that has PSI software for access to Austpac. At the moment only BIGEAR has this facility. Connecting to Melbourne should be sufficient for most needs.

Both these options create a log file of the session with the Argos computers, and if the appropriate commands were used, the log file will contain the PTT data amongst other text. See the last section for details of some Argos commands.

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Batch downloading of data, back to Contents

Each day, in the wee small hours, a batch job connects to the Argos computer in Melbourne and downloads the last two days data. After processing and loading into the local Argos data files, a summary message is created and mailed to the mail list ARGOS_USERS. An example of one of these messages is

 Statistics from loading recent PTT data
 Records read                1191
 New records added            833
 Old records updated          357

For file: SCISUP:[ARGOS.SCRATCH]ALL_DISPOSE_DAILY.DAT;2
Program    PTT  Passes  Dates                     Notes
    366   1171      41  1996 01 10 to 1996 01 11
          1172      46  1996 01 10 to 1996 01 11
          1173      37  1996 01 10 to 1996 01 11
    973   1398      21  1996 01 10 to 1996 01 11
         21055      30  1996 01 10 to 1996 01 11
         23358      19  1996 01 10 to 1996 01 11
         23360      19  1996 01 10 to 1996 01 11
         25985      21  1996 01 10 to 1996 01 11
         25986       6  1996 01 10 to 1996 01 10
         25987      33  1996 01 10 to 1996 01 11
         25989      34  1996 01 10 to 1996 01 11
         27169       5  1996 01 11 to 1996 01 11  No calibration file for PTT
   1155   4471      39  1996 01 10 to 1996 01 11
          4473      37  1996 01 10 to 1996 01 11

At the top is the total number of records contained in the download, the number of records that were updated and the number of new ones. Since the load occurs every day and we get two days data, the number of updated records is about the same as the number of new records. A PTT will create at most 28 messages per day, ie a message per pass.

Further down is the PTT and its program along with the number of messages processed. If a calibration file is missing, it is noted in the last column. This file is important as it contains the dates when the PTT is valid along with conversion factors for converting sensor data to real units. For tracking purposes, the conversion factors are not important.

Note that by the time you query the database, the data is between 4 and 24 hours old. If you wish to get the most recent positions (for example retrieving an incoming PTT) then you will need to login directly to the Argos computers.

The Argos computers retain only the last 4 days data online. After that it is purged. About two to three weeks after the end of a month, the Division receives a tape containing the complete records from the last month. It is a superset of the daily downloads. All data in the database is replaced with this set of data. You know when a new set of data has been added when you receive a mesage like...

Date: Tue, 16 Apr 1996 14:17:07 +1000 (EST)
From: "John Morrissy, Antarctic Div." 
To:   ARGOS_USERS@antdiv.gov.au
CC:   JOHN_MOR@antdiv.gov.au
Subject: New monthly Argos tape

These files from the new monthly Argos tape are now in ARGOS_DATA
DS_1996_02.DAT
CZ_1996_02.DAT

This signifies that new Class Zero (CZ) and Dispose (DS) data files for Feburary 1996 have been processed. It has been sent to the email list ARGOS_USERS.

Note that a repeated analysis of the last months data may give rise to a different output. After three months, Argos remove all data and expect the host institute to retain the data. The current online database at the Division goes back to 1991 with tapes going back to 198?. There are notes on how the process for downloading ARGOS data.

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Putting maps/lists on the web, back to Contents

The flag 'Put on Web' can be user set to 'Y' (for yes) so that the data from that profile can be automatically placed on the web after the normal daily download. Note that the maps are not fantastic but it does allow a user to quickly check the data without running the ARGOS program.