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<book>
  <title>TeleMetrum</title>
  <subtitle>Owner's Manual for the TeleMetrum System</subtitle>
  <bookinfo>
    <author>
      <firstname>Bdale</firstname>
      <surname>Garbee</surname>
    </author>
    <author>
      <firstname>Keith</firstname>
      <surname>Packard</surname>
    </author>
    <copyright>
      <year>2010</year>
      <holder>Bdale Garbee and Keith Packard</holder>
    </copyright>
    <legalnotice>
      <para>
        This document is released under the terms of the 
        <ulink url="http://creativecommons.org/licenses/by-sa/3.0/">
          Creative Commons ShareAlike 3.0
        </ulink>
        license.
      </para>
    </legalnotice>
    <revhistory>
      <revision>
        <revnumber>0.3</revnumber>
        <date>23 November 2010</date>
        <revremark>New section on AltosUI mostly by Keith</revremark>
      </revision>
      <revision>
        <revnumber>0.2</revnumber>
        <date>18 July 2010</date>
        <revremark>Significant update</revremark>
      </revision>
      <revision>
        <revnumber>0.1</revnumber>
        <date>30 March 2010</date>
        <revremark>Initial content</revremark>
      </revision>
    </revhistory>
  </bookinfo>
  <chapter>
    <title>Introduction and Overview</title>
    <para>
      Welcome to the Altus Metrum community!  Our circuits and software reflect
      our passion for both hobby rocketry and Free Software.  We hope their
      capabilities and performance will delight you in every way, but by
      releasing all of our hardware and software designs under open licenses,
      we also hope to empower you to take as active a role in our collective
      future as you wish!
    </para>
    <para>
      The focal point of our community is TeleMetrum, a dual deploy altimeter 
      with fully integrated GPS and radio telemetry as standard features, and
      a "companion interface" that will support optional capabilities in the 
      future.
    </para>
    <para>    
      Complementing TeleMetrum is TeleDongle, a USB to RF interface for 
      communicating with TeleMetrum.  Combined with your choice of antenna and 
      notebook computer, TeleDongle and our associated user interface software
      form a complete ground station capable of logging and displaying in-flight
      telemetry, aiding rocket recovery, then processing and archiving flight
      data for analysis and review.
    </para>
    <para>
      More products will be added to the Altus Metrum family over time, and
      we currently envision that this will be a single, comprehensive manual
      for the entire product family.
    </para>
  </chapter>
  <chapter>
    <title>Getting Started</title>
    <para>
      This chapter began as "The Mere-Mortals Quick Start/Usage Guide to 
      the Altus Metrum Starter Kit" by Bob Finch, W9YA, NAR 12965, TRA 12350, 
      w9ya@amsat.org.  Bob was one of our first customers for a production
      TeleMetrum, and the enthusiasm that led to his contribution of this
      section is immensely gratifying and highy appreciated!
    </para>
    <para>
      The first thing to do after you check the inventory of parts in your 
      "starter kit" is to charge the battery by plugging it into the 
      corresponding socket of the TeleMetrum and then using the USB A to B 
      cable to plug the Telemetrum into your computer's USB socket. The 
      TeleMetrum circuitry will charge the battery whenever it is plugged 
      into the usb socket. The TeleMetrum's on-off switch does NOT control 
      the charging circuitry.  When the GPS chip is initially searching for
      satellites, the unit will pull more current than it can pull from the
      usb port, so the battery must be plugged in order to get a good 
      satellite lock.  Once GPS is locked the current consumption goes back 
      down enough to enable charging while 
      running. So it's a good idea to fully charge the battery as your 
      first item of business so there is no issue getting and maintaining 
      satellite lock.  The yellow charge indicator led will go out when the 
      battery is nearly full and the charger goes to trickle charge.
    </para>
    <para>
      The other active device in the starter kit is the half-duplex TeleDongle 
      rf link.  If you plug it in to your computer it should "just work",
      showing up as a serial port device.  If you are using Linux and are
      having problems, try moving to a fresher kernel (2.6.33 or newer), as
      there were some ugly USB serial driver bugs in earlier versions.
    </para>
    <para>
      Next you should obtain and install the AltOS utilities.  The first
      generation sofware was written for Linux only.  New software is coming
      soon that will also run on Windows and Mac.  For now, we'll concentrate
      on Linux.  If you are using Debian, an 'altos' package already exists, 
      see http://altusmetrum.org/AltOS for details on how to install it.
      User-contributed directions for building packages on ArchLinux may be 
      found in the contrib/arch-linux directory as PKGBUILD files.
      Between the debian/rules file and the PKGBUILD files in 
      contrib, you should find enough information to learn how to build the 
      software for any other version of Linux.
    </para>
    <para>
      When you have successfully installed the software suite (either from 
      compiled source code or as the pre-built Debian package) you will 
      have 10 or so executable programs all of which have names beginning 
      with 'ao-'.
      ('ao-view' is the lone GUI-based program, the rest are command-line 
      oriented.) You will also have man pages, that give you basic info 
      on each program.
      You will also get this documentation in two file types in the doc/ 
      directory, telemetrum-doc.pdf and telemetrum-doc.html.
      Finally you will have a couple control files that allow the ao-view 
      GUI-based program to appear in your menu of programs (under 
      the 'Internet' category). 
    </para>
    <para>
      Both Telemetrum and TeleDongle can be directly communicated 
      with using USB ports. The first thing you should try after getting 
      both units plugged into to your computer's usb port(s) is to run 
      'ao-list' from a terminal-window to see what port-device-name each 
      device has been assigned by the operating system. 
      You will need this information to access the devices via their 
      respective on-board firmware and data using other command line
      programs in the AltOS software suite.
    </para>
    <para>
      To access the device's firmware for configuration you need a terminal
      program such as you would use to talk to a modem.  The software 
      authors prefer using the program 'cu' which comes from the UUCP package
      on most Unix-like systems such as Linux.  An example command line for
      cu might be 'cu -l /dev/ttyACM0', substituting the correct number 
      indicated from running the
      ao-list program.  Another reasonable terminal program for Linux is
      'cutecom'.  The default 'escape' 
      character used by CU (i.e. the character you use to
      issue commands to cu itself instead of sending the command as input 
      to the connected device) is a '~'. You will need this for use in 
      only two different ways during normal operations. First is to exit 
      the program by sending a '~.' which is called a 'escape-disconnect' 
      and allows you to close-out from 'cu'. The
      second use will be outlined later.
    </para>
    <para>
      Both TeleMetrum and TeleDongle share the concept of a two level 
      command set in their firmware.  
      The first layer has several single letter commands. Once 
      you are using 'cu' (or 'cutecom') sending (typing) a '?' 
      returns a full list of these
      commands. The second level are configuration sub-commands accessed 
      using the 'c' command, for 
      instance typing 'c?' will give you this second level of commands 
      (all of which require the
      letter 'c' to access).  Please note that most configuration options
      are stored only in DataFlash memory, and only TeleMetrum has this
      memory to save the various values entered like the channel number 
      and your callsign when powered off.  TeleDongle requires that you
      set these each time you plug it in, which ao-view can help with.
    </para>
    <para>
      Try setting these config ('c' or second level menu) values.  A good
      place to start is by setting your call sign.  By default, the boards
      use 'N0CALL' which is cute, but not exactly legal!
      Spend a few minutes getting comfortable with the units, their 
      firmware, and 'cu' (or possibly 'cutecom').
      For instance, try to send 
      (type) a 'c r 2' and verify the channel change by sending a 'c s'. 
      Verify you can connect and disconnect from the units while in your
      terminal program by sending the escape-disconnect mentioned above.
    </para>
    <para>
      Note that the 'reboot' command, which is very useful on TeleMetrum, 
      will likely just cause problems with the dongle.  The *correct* way
      to reset the dongle is just to unplug and re-plug it.
    </para>
    <para>
      A fun thing to do at the launch site and something you can do while 
      learning how to use these units is to play with the rf-link access 
      of the TeleMetrum from the TeleDongle.  Be aware that you *must* create
      some physical separation between the devices, otherwise the link will 
      not function due to signal overload in the receivers in each device.
    </para>
    <para>
      Now might be a good time to take a break and read the rest of this
      manual, particularly about the two "modes" that the TeleMetrum 
      can be placed in and how the position of the TeleMetrum when booting 
      up will determine whether the unit is in "pad" or "idle" mode.
    </para>
    <para>
      You can access a TeleMetrum in idle mode from the Teledongle's USB 
      connection using the rf link
      by issuing a 'p' command to the TeleDongle. Practice connecting and
      disconnecting ('~~' while using 'cu') from the TeleMetrum.  If 
      you cannot escape out of the "p" command, (by using a '~~' when in 
      CU) then it is likely that your kernel has issues.  Try a newer version.
    </para>
    <para>
      Using this rf link allows you to configure the TeleMetrum, test 
      fire e-matches and igniters from the flight line, check pyro-match 
      continuity and so forth. You can leave the unit turned on while it 
      is in 'idle mode' and then place the
      rocket vertically on the launch pad, walk away and then issue a 
      reboot command.  The TeleMetrum will reboot and start sending data 
      having changed to the "pad" mode. If the TeleDongle is not receiving 
      this data, you can disconnect 'cu' from the Teledongle using the 
      procedures mentioned above and THEN connect to the TeleDongle from 
      inside 'ao-view'. If this doesn't work, disconnect from the
      TeleDongle, unplug it, and try again after plugging it back in.
    </para>
    <para>
      Eventually the GPS will find enough satellites, lock in on them, 
      and 'ao-view' will both auditorially announce and visually indicate 
      that GPS is ready.
      Now you can launch knowing that you have a good data path and 
      good satellite lock for flight data and recovery.  Remember 
      you MUST tell ao-view to connect to the TeleDongle explicitly in 
      order for ao-view to be able to receive data.
    </para>
    <para>
      Both RDF (radio direction finding) tones from the TeleMetrum and 
      GPS trekking data are available and together are very useful in 
      locating the rocket once it has landed. (The last good GPS data 
      received before touch-down will be on the data screen of 'ao-view'.)
    </para>
    <para>
      Once you have recovered the rocket you can download the eeprom 
      contents using either 'ao-dumplog' (or possibly 'ao-eeprom'), over
      either a USB cable or over the radio link using TeleDongle.
      And by following the man page for 'ao-postflight' you can create 
      various data output reports, graphs, and even kml data to see the 
      flight trajectory in google-earth. (Moving the viewing angle making 
      sure to connect the yellow lines while in google-earth is the proper
      technique.)
    </para>
    <para>
      As for ao-view.... some things are in the menu but don't do anything 
      very useful.  The developers have stopped working on ao-view to focus
      on a new, cross-platform ground station program.  So ao-view may or 
      may not be updated in the future.  Mostly you just use 
      the Log and Device menus.  It has a wonderful display of the incoming 
      flight data and I am sure you will enjoy what it has to say to you 
      once you enable the voice output!
    </para>
    <section>
      <title>FAQ</title>
      <para>
        The altimeter (TeleMetrum) seems to shut off when disconnected from the
        computer.  Make sure the battery is adequately charged.  Remember the
        unit will pull more power than the USB port can deliver before the 
        GPS enters "locked" mode.  The battery charges best when TeleMetrum
        is turned off.
      </para>
      <para>
        It's impossible to stop the TeleDongle when it's in "p" mode, I have
        to unplug the USB cable?  Make sure you have tried to "escape out" of 
        this mode.  If this doesn't work the reboot procedure for the 
        TeleDongle *is* to simply unplug it. 'cu' however will retain it's 
        outgoing buffer IF your "escape out" ('~~') does not work. 
        At this point using either 'ao-view' (or possibly
        'cutemon') instead of 'cu' will 'clear' the issue and allow renewed
        communication.
      </para>
      <para>
        The amber LED (on the TeleMetrum/altimeter) lights up when both 
        battery and USB are connected. Does this mean it's charging? 
        Yes, the yellow LED indicates the charging at the 'regular' rate. 
        If the led is out but the unit is still plugged into a USB port, 
        then the battery is being charged at a 'trickle' rate.
      </para>
      <para>
        There are no "dit-dah-dah-dit" sound like the manual mentions?
        That's the "pad" mode.  Weak batteries might be the problem.
        It is also possible that the unit is horizontal and the output 
        is instead a "dit-dit" meaning 'idle'.
      </para>
      <para>
        It's unclear how to use 'ao-view' and other programs when 'cu' 
        is running. You cannot have more than one program connected to 
        the TeleDongle at one time without apparent data loss as the 
        incoming data will not make it to both programs intact. 
        Disconnect whatever programs aren't currently being used.
      </para>
      <para>
        How do I save flight data?   
        Live telemetry is written to file(s) whenever 'ao-view' is connected 
        to the TeleDongle.  The file area defaults to ~/altos
        but is easily changed using the menus in 'ao-view'. The files that 
        are written end in '.telem'. The after-flight
        data-dumped files will end in .eeprom and represent continuous data 
        unlike the rf-linked .telem files that are subject to the 
        turnarounds/data-packaging time slots in the half-duplex rf data path. 
        See the above instructions on what and how to save the eeprom stored 
        data after physically retrieving your TeleMetrum.  Make sure to save
        the on-board data after each flight, as the current firmware will
        over-write any previous flight data during a new flight.
      </para>
    </section>
  </chapter>
  <chapter>
    <title>Specifications</title>
    <itemizedlist>
      <listitem>
        <para>
          Recording altimeter for model rocketry.
        </para>
      </listitem>
      <listitem>
        <para>
          Supports dual deployment (can fire 2 ejection charges).
        </para>
      </listitem>
      <listitem>
        <para>
          70cm ham-band transceiver for telemetry downlink.
        </para>
      </listitem>
      <listitem>
        <para>
          Barometric pressure sensor good to 45k feet MSL.
        </para>
      </listitem>
      <listitem>
        <para>
          1-axis high-g accelerometer for motor characterization, capable of 
          +/- 50g using default part.
        </para>
      </listitem>
      <listitem>
        <para>
          On-board, integrated GPS receiver with 5hz update rate capability.
        </para>
      </listitem>
      <listitem>
        <para>
          On-board 1 megabyte non-volatile memory for flight data storage.
        </para>
      </listitem>
      <listitem>
        <para>
          USB interface for battery charging, configuration, and data recovery.
        </para>
      </listitem>
      <listitem>
        <para>
          Fully integrated support for LiPo rechargeable batteries.
        </para>
      </listitem>
      <listitem>
        <para>
          Uses LiPo to fire e-matches, support for optional separate pyro 
          battery if needed.
        </para>
      </listitem>
      <listitem>
        <para>
          2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube.
        </para>
      </listitem>
    </itemizedlist>
  </chapter>
  <chapter>
    <title>Handling Precautions</title>
    <para>
      TeleMetrum is a sophisticated electronic device.  When handled gently and
      properly installed in an airframe, it will deliver impressive results.
      However, like all electronic devices, there are some precautions you
      must take.
    </para>
    <para>
      The Lithium Polymer rechargeable batteries used with TeleMetrum have an 
      extraordinary power density.  This is great because we can fly with
      much less battery mass than if we used alkaline batteries or previous
      generation rechargeable batteries... but if they are punctured 
      or their leads are allowed to short, they can and will release their 
      energy very rapidly!
      Thus we recommend that you take some care when handling our batteries 
      and consider giving them some extra protection in your airframe.  We 
      often wrap them in suitable scraps of closed-cell packing foam before 
      strapping them down, for example.
    </para>
    <para>
      The TeleMetrum barometric sensor is sensitive to sunlight.  In normal 
      mounting situations, it and all of the other surface mount components 
      are "down" towards whatever the underlying mounting surface is, so
      this is not normally a problem.  Please consider this, though, when
      designing an installation, for example, in a 29mm airframe with a 
      see-through plastic payload bay.
    </para>
    <para>
      The TeleMetrum barometric sensor sampling port must be able to 
      "breathe",
      both by not being covered by foam or tape or other materials that might
      directly block the hole on the top of the sensor, but also by having a
      suitable static vent to outside air.  
    </para>
    <para>
      As with all other rocketry electronics, TeleMetrum must be protected 
      from exposure to corrosive motor exhaust and ejection charge gasses.
    </para>
  </chapter>
  <chapter>
    <title>Hardware Overview</title>
    <para>
      TeleMetrum is a 1 inch by 2.75 inch circuit board.  It was designed to
      fit inside coupler for 29mm airframe tubing, but using it in a tube that
      small in diameter may require some creativity in mounting and wiring 
      to succeed!  The default 1/4
      wave UHF wire antenna attached to the center of the nose-cone end of
      the board is about 7 inches long, and wiring for a power switch and
      the e-matches for apogee and main ejection charges depart from the 
      fin can end of the board.  Given all this, an ideal "simple" avionics 
      bay for TeleMetrum should have at least 10 inches of interior length.
    </para>
    <para>
      A typical TeleMetrum installation using the on-board GPS antenna and
      default wire UHF antenna involves attaching only a suitable
      Lithium Polymer battery, a single pole switch for power on/off, and 
      two pairs of wires connecting e-matches for the apogee and main ejection
      charges.  
    </para>
    <para>
      By default, we use the unregulated output of the LiPo battery directly
      to fire ejection charges.  This works marvelously with standard 
      low-current e-matches like the J-Tek from MJG Technologies, and with 
      Quest Q2G2 igniters.  However, if you
      want or need to use a separate pyro battery, you can do so by adding
      a second 2mm connector to position B2 on the board and cutting the
      thick pcb trace connecting the LiPo battery to the pyro circuit between
      the two silk screen marks on the surface mount side of the board shown
      here [insert photo]
    </para>
    <para>
      We offer two choices of pyro and power switch connector, or you can 
      choose neither and solder wires directly to the board.  All three choices
      are reasonable depending on the constraints of your airframe.  Our
      favorite option when there is sufficient room above the board is to use
      the Tyco pin header with polarization and locking.  If you choose this
      option, you crimp individual wires for the power switch and e-matches
      into a mating connector, and installing and removing the TeleMetrum
      board from an airframe is as easy as plugging or unplugging two 
      connectors.  If the airframe will not support this much height or if
      you want to be able to directly attach e-match leads to the board, we
      offer a screw terminal block.  This is very similar to what most other
      altimeter vendors provide and so may be the most familiar option.  
      You'll need a very small straight blade screwdriver to connect
      and disconnect the board in this case, such as you might find in a
      jeweler's screwdriver set.  Finally, you can forego both options and
      solder wires directly to the board, which may be the best choice for
      minimum diameter and/or minimum mass designs. 
    </para>
    <para>
      For most airframes, the integrated GPS antenna and wire UHF antenna are
      a great combination.  However, if you are installing in a carbon-fiber
      electronics bay which is opaque to RF signals, you may need to use 
      off-board external antennas instead.  In this case, you can order
      TeleMetrum with an SMA connector for the UHF antenna connection, and
      you can unplug the integrated GPS antenna and select an appropriate 
      off-board GPS antenna with cable terminating in a U.FL connector.
    </para>
  </chapter>
  <chapter>
    <title>System Operation</title>
    <section>
      <title>Firmware Modes </title>
      <para>
        The AltOS firmware build for TeleMetrum has two fundamental modes,
        "idle" and "flight".  Which of these modes the firmware operates in
        is determined by the orientation of the rocket (well, actually the
        board, of course...) at the time power is switched on.  If the rocket
        is "nose up", then TeleMetrum assumes it's on a rail or rod being
        prepared for launch, so the firmware chooses flight mode.  However,
        if the rocket is more or less horizontal, the firmware instead enters
        idle mode.
      </para>
      <para>
        At power on, you will hear three beeps 
        ("S" in Morse code for startup) and then a pause while 
        TeleMetrum completes initialization and self tests, and decides which
        mode to enter next.
      </para>
      <para>
        In flight or "pad" mode, TeleMetrum turns on the GPS system, 
        engages the flight
        state machine, goes into transmit-only mode on the RF link sending 
        telemetry, and waits for launch to be detected.  Flight mode is
        indicated by an audible "di-dah-dah-dit" ("P" for pad) on the 
        beeper, followed by
        beeps indicating the state of the pyrotechnic igniter continuity.
        One beep indicates apogee continuity, two beeps indicate
        main continuity, three beeps indicate both apogee and main continuity,
        and one longer "brap" sound indicates no continuity.  For a dual
        deploy flight, make sure you're getting three beeps before launching!
        For apogee-only or motor eject flights, do what makes sense.
      </para>
      <para>
        In idle mode, you will hear an audible "di-dit" ("I" for idle), and
        the normal flight state machine is disengaged, thus
        no ejection charges will fire.  TeleMetrum also listens on the RF
        link when in idle mode for packet mode requests sent from TeleDongle.
        Commands can be issued to a TeleMetrum in idle mode over either
        USB or the RF link equivalently.
        Idle mode is useful for configuring TeleMetrum, for extracting data 
        from the on-board storage chip after flight, and for ground testing
        pyro charges.
      </para>
      <para>
        One "neat trick" of particular value when TeleMetrum is used with very
        large airframes, is that you can power the board up while the rocket
        is horizontal, such that it comes up in idle mode.  Then you can 
        raise the airframe to launch position, use a TeleDongle to open
        a packet connection, and issue a 'reset' command which will cause
        TeleMetrum to reboot, realize it's now nose-up, and thus choose
        flight mode.  This is much safer than standing on the top step of a
        rickety step-ladder or hanging off the side of a launch tower with
        a screw-driver trying to turn on your avionics before installing
        igniters!
      </para>
    </section>
    <section>
      <title>GPS </title>
      <para>
        TeleMetrum includes a complete GPS receiver.  See a later section for
        a brief explanation of how GPS works that will help you understand
        the information in the telemetry stream.  The bottom line is that
        the TeleMetrum GPS receiver needs to lock onto at least four 
        satellites to obtain a solid 3 dimensional position fix and know 
        what time it is!
      </para>
      <para>
        TeleMetrum provides backup power to the GPS chip any time a LiPo
        battery is connected.  This allows the receiver to "warm start" on
        the launch rail much faster than if every power-on were a "cold start"
        for the GPS receiver.  In typical operations, powering up TeleMetrum
        on the flight line in idle mode while performing final airframe
        preparation will be sufficient to allow the GPS receiver to cold
        start and acquire lock.  Then the board can be powered down during
        RSO review and installation on a launch rod or rail.  When the board
        is turned back on, the GPS system should lock very quickly, typically
        long before igniter installation and return to the flight line are
        complete.
      </para>
    </section>
    <section>
      <title>Ground Testing </title>
      <para>
        An important aspect of preparing a rocket using electronic deployment
        for flight is ground testing the recovery system.  Thanks
        to the bi-directional RF link central to the Altus Metrum system, 
        this can be accomplished in a TeleMetrum-equipped rocket without as
        much work as you may be accustomed to with other systems.  It can
        even be fun!
      </para>
      <para>
        Just prep the rocket for flight, then power up TeleMetrum while the
        airframe is horizontal.  This will cause the firmware to go into 
        "idle" mode, in which the normal flight state machine is disabled and
        charges will not fire without manual command.  Then, establish an
        RF packet connection from a TeleDongle-equipped computer using the 
        P command from a safe distance.  You can now command TeleMetrum to
        fire the apogee or main charges to complete your testing.
      </para>
      <para>
        In order to reduce the chance of accidental firing of pyrotechnic
        charges, the command to fire a charge is intentionally somewhat
        difficult to type, and the built-in help is slightly cryptic to 
        prevent accidental echoing of characters from the help text back at
        the board from firing a charge.  The command to fire the apogee
        drogue charge is 'i DoIt drogue' and the command to fire the main
        charge is 'i DoIt main'.
      </para>
    </section>
    <section>
      <title>Radio Link </title>
      <para>
        The chip our boards are based on incorporates an RF transceiver, but
        it's not a full duplex system... each end can only be transmitting or
        receiving at any given moment.  So we had to decide how to manage the
        link.
      </para>
      <para>
        By design, TeleMetrum firmware listens for an RF connection when
        it's in "idle mode" (turned on while the rocket is horizontal), which
        allows us to use the RF link to configure the rocket, do things like
        ejection tests, and extract data after a flight without having to 
        crack open the airframe.  However, when the board is in "flight 
        mode" (turned on when the rocket is vertical) the TeleMetrum only 
        transmits and doesn't listen at all.  That's because we want to put 
        ultimate priority on event detection and getting telemetry out of 
        the rocket and out over
        the RF link in case the rocket crashes and we aren't able to extract
        data later... 
      </para>
      <para>
        We don't use a 'normal packet radio' mode because they're just too
        inefficient.  The GFSK modulation we use is just FSK with the 
        baseband pulses passed through a
        Gaussian filter before they go into the modulator to limit the
        transmitted bandwidth.  When combined with the hardware forward error
        correction support in the cc1111 chip, this allows us to have a very
        robust 38.4 kilobit data link with only 10 milliwatts of transmit power,
        a whip antenna in the rocket, and a hand-held Yagi on the ground.  We've
        had flights to above 21k feet AGL with good reception, and calculations
        suggest we should be good to well over 40k feet AGL with a 5-element yagi on
        the ground.  We hope to fly boards to higher altitudes soon, and would
        of course appreciate customer feedback on performance in higher
        altitude flights!
      </para>
    </section>
    <section>
      <title>Configurable Parameters</title>
      <para>
        Configuring a TeleMetrum board for flight is very simple.  Because we
        have both acceleration and pressure sensors, there is no need to set
        a "mach delay", for example.  The few configurable parameters can all
        be set using a simple terminal program over the USB port or RF link
        via TeleDongle.
      </para>
      <section>
        <title>Radio Channel</title>
        <para>
          Our firmware supports 10 channels.  The default channel 0 corresponds
          to a center frequency of 434.550 Mhz, and channels are spaced every 
          100 khz.  Thus, channel 1 is 434.650 Mhz, and channel 9 is 435.550 Mhz.
          At any given launch, we highly recommend coordinating who will use
          each channel and when to avoid interference.  And of course, both 
          TeleMetrum and TeleDongle must be configured to the same channel to
          successfully communicate with each other.
        </para>
        <para>
          To set the radio channel, use the 'c r' command, like 'c r 3' to set
          channel 3.  
          As with all 'c' sub-commands, follow this with a 'c w' to write the 
          change to the parameter block in the on-board DataFlash chip on
          your TeleMetrum board if you want the change to stay in place across reboots.
        </para>
      </section>
      <section>
        <title>Apogee Delay</title>
        <para>
          Apogee delay is the number of seconds after TeleMetrum detects flight
          apogee that the drogue charge should be fired.  In most cases, this
          should be left at the default of 0.  However, if you are flying
          redundant electronics such as for an L3 certification, you may wish 
          to set one of your altimeters to a positive delay so that both 
          primary and backup pyrotechnic charges do not fire simultaneously.
        </para>
        <para>
          To set the apogee delay, use the [FIXME] command.
          As with all 'c' sub-commands, follow this with a 'c w' to write the 
          change to the parameter block in the on-board DataFlash chip.
        </para>
        <para>
          Please note that the TeleMetrum apogee detection algorithm always
          fires a fraction of a second *after* apogee.  If you are also flying
          an altimeter like the PerfectFlite MAWD, which only supports selecting
          0 or 1 seconds of apogee delay, you may wish to set the MAWD to 0
          seconds delay and set the TeleMetrum to fire your backup 2 or 3
          seconds later to avoid any chance of both charges firing 
          simultaneously.  We've flown several airframes this way quite happily,
          including Keith's successful L3 cert.
        </para>
      </section>
      <section>
        <title>Main Deployment Altitude</title>
        <para>
          By default, TeleMetrum will fire the main deployment charge at an
          elevation of 250 meters (about 820 feet) above ground.  We think this
          is a good elevation for most airframes, but feel free to change this 
          to suit.  In particular, if you are flying two altimeters, you may
          wish to set the
          deployment elevation for the backup altimeter to be something lower
          than the primary so that both pyrotechnic charges don't fire
          simultaneously.
        </para>
        <para>
          To set the main deployment altitude, use the [FIXME] command.
          As with all 'c' sub-commands, follow this with a 'c w' to write the 
          change to the parameter block in the on-board DataFlash chip.
        </para>
      </section>
    </section>
    <section>
      <title>Calibration</title>
      <para>
        There are only two calibrations required for a TeleMetrum board, and
        only one for TeleDongle.
      </para>
      <section>
        <title>Radio Frequency</title>
        <para>
          The radio frequency is synthesized from a clock based on the 48 Mhz
          crystal on the board.  The actual frequency of this oscillator must be
          measured to generate a calibration constant.  While our GFSK modulation
          bandwidth is wide enough to allow boards to communicate even when 
          their oscillators are not on exactly the same frequency, performance
          is best when they are closely matched.
          Radio frequency calibration requires a calibrated frequency counter.
          Fortunately, once set, the variation in frequency due to aging and
          temperature changes is small enough that re-calibration by customers
          should generally not be required.
        </para>
        <para>
          To calibrate the radio frequency, connect the UHF antenna port to a
          frequency counter, set the board to channel 0, and use the 'C' 
          command to generate a CW carrier.  Wait for the transmitter temperature
          to stabilize and the frequency to settle down.  
          Then, divide 434.550 Mhz by the 
          measured frequency and multiply by the current radio cal value show
          in the 'c s' command.  For an unprogrammed board, the default value
          is 1186611.  Take the resulting integer and program it using the 'c f'
          command.  Testing with the 'C' command again should show a carrier
          within a few tens of Hertz of the intended frequency.
          As with all 'c' sub-commands, follow this with a 'c w' to write the 
          change to the parameter block in the on-board DataFlash chip.
        </para>
      </section>
      <section>
        <title>Accelerometer</title>
        <para>
          The accelerometer we use has its own 5 volt power supply and
          the output must be passed through a resistive voltage divider to match
          the input of our 3.3 volt ADC.  This means that unlike the barometric
          sensor, the output of the acceleration sensor is not ratiometric to 
          the ADC converter, and calibration is required.  We also support the 
          use of any of several accelerometers from a Freescale family that 
          includes at least +/- 40g, 50g, 100g, and 200g parts.  Using gravity,
          a simple 2-point calibration yields acceptable results capturing both
          the different sensitivities and ranges of the different accelerometer
          parts and any variation in power supply voltages or resistor values
          in the divider network.
        </para>
        <para>
          To calibrate the acceleration sensor, use the 'c a 0' command.  You
          will be prompted to orient the board vertically with the UHF antenna
          up and press a key, then to orient the board vertically with the 
          UHF antenna down and press a key.
          As with all 'c' sub-commands, follow this with a 'c w' to write the 
          change to the parameter block in the on-board DataFlash chip.
        </para>
        <para>
          The +1g and -1g calibration points are included in each telemetry
          frame and are part of the header extracted by ao-dumplog after flight.
          Note that we always store and return raw ADC samples for each
          sensor... nothing is permanently "lost" or "damaged" if the 
          calibration is poor.
        </para>
      </section>
    </section>
  </chapter>
  <chapter>
    
    <title>AltosUI</title>
    <para>
      The AltosUI program provides a graphical user interface for
      interacting with the Altus Metrum product family, including
      TeleMetrum and TeleDongle. AltosUI can monitor telemetry data,
      configure TeleMetrum and TeleDongle devices and many other
      tasks. The primary interface window provides a selection of
      buttons, one for each major activity in the system.  This manual
      is split into chapters, each of which documents one of the tasks
      provided from the top-level toolbar.
    </para>
    <section>
      <title>Packet Command Mode</title>
      <subtitle>Controlling TeleMetrum Over The Radio Link</subtitle>
      <para>
        One of the unique features of the Altos Metrum environment is
        the ability to create a two way command link between TeleDongle
        and TeleMetrum using the digital radio transceivers built into
        each device. This allows you to interact with TeleMetrum from
        afar, as if it were directly connected to the computer.
      </para>
      <para>
        Any operation which can be performed with TeleMetrum
        can either be done with TeleMetrum directly connected to
        the computer via the USB cable, or through the packet
        link. Simply select the appropriate TeleDongle device when
        the list of devices is presented and AltosUI will use packet
        command mode.
      </para>
      <itemizedlist>
        <listitem>
          <para>
            Save Flight Data—Recover flight data from the rocket without
            opening it up.
          </para>
        </listitem>
        <listitem>
          <para>
            Configure TeleMetrum—Reset apogee delays or main deploy
            heights to respond to changing launch conditions. You can
            also 'reboot' the TeleMetrum device. Use this to remotely
            enable the flight computer by turning TeleMetrum on while
            horizontal, then once the airframe is oriented for launch,
            you can reboot TeleMetrum and have it restart in pad mode
            without having to climb the scary ladder.
          </para>
        </listitem>
        <listitem>
          <para>
            Fire Igniters—Test your deployment charges without snaking
            wires out through holes in the airframe. Simply assembly the
            rocket as if for flight with the apogee and main charges
            loaded, then remotely command TeleMetrum to fire the
            igniters.
          </para>
        </listitem>
      </itemizedlist>
      <para>
        Packet command mode uses the same RF channels as telemetry
        mode. Configure the desired TeleDongle channel using the
        flight monitor window channel selector and then close that
        window before performing the desired operation.
      </para>
      <para>
        TeleMetrum only enables packet command mode in 'idle' mode, so
        make sure you have TeleMetrum lying horizontally when you turn
        it on. Otherwise, TeleMetrum will start in 'pad' mode ready for
        flight and will not be listening for command packets from TeleDongle.
      </para>
      <para>
        When packet command mode is enabled, you can monitor the link
        by watching the lights on the TeleDongle and TeleMetrum
        devices. The red LED will flash each time TeleDongle or
        TeleMetrum transmit a packet while the green LED will light up
        on TeleDongle while it is waiting to receive a packet from
        TeleMetrum.
      </para>
    </section>
    <section>
      <title>Monitor Flight</title>
      <subtitle>Receive, Record and Display Telemetry Data</subtitle>
      <para>
        Selecting this item brings up a dialog box listing all of the
        connected TeleDongle devices. When you choose one of these,
        AltosUI will create a window to display telemetry data as
        received by the selected TeleDongle device.
      </para>
      <para>
        All telemetry data received are automatically recorded in
        suitable log files. The name of the files includes the current
        date and rocket serial and flight numbers.
      </para>
      <para>
        The radio channel being monitored by the TeleDongle device is
        displayed at the top of the window. You can configure the
        channel by clicking on the channel box and selecting the desired
        channel. AltosUI remembers the last channel selected for each
        TeleDongle and selects that automatically the next time you use
        that device.
      </para>
      <para>
        Below the TeleDongle channel selector, the window contains a few
        significant pieces of information about the TeleMetrum providing
        the telemetry data stream:
      </para>
      <itemizedlist>
        <listitem>
          <para>The TeleMetrum callsign</para>
        </listitem>
        <listitem>
          <para>The TeleMetrum serial number</para>
        </listitem>
        <listitem>
          <para>The flight number. Each TeleMetrum remembers how many
            times it has flown.
          </para>
        </listitem>
        <listitem>
          <para>
            The rocket flight state. Each flight passes through several
            states including Pad, Boost, Fast, Coast, Drogue, Main and
            Landed.
          </para>
        </listitem>
        <listitem>
          <para>
            The Received Signal Strength Indicator value. This lets
            you know how strong a signal TeleDongle is receiving. The
            radio inside TeleDongle operates down to about -99dBm;
            weaker signals may not be receiveable. The packet link uses
            error correction and detection techniques which prevent
            incorrect data from being reported.
          </para>
        </listitem>
      </itemizedlist>
      <para>
        Finally, the largest portion of the window contains a set of
        tabs, each of which contain some information about the rocket.
        They're arranged in 'flight order' so that as the flight
        progresses, the selected tab automatically switches to display
        data relevant to the current state of the flight. You can select
        other tabs at any time. The final 'table' tab contains all of
        the telemetry data in one place.
      </para>
      <section>
        <title>Launch Pad</title>
        <para>
          The 'Launch Pad' tab shows information used to decide when the
          rocket is ready for flight. The first elements include red/green
          indicators, if any of these is red, you'll want to evaluate
          whether the rocket is ready to launch:
          <itemizedlist>
            <listitem>
              <para>
                Battery Voltage. This indicates whether the LiPo battery
                powering the TeleMetrum has sufficient charge to last for
                the duration of the flight. A value of more than
                3.7V is required for a 'GO' status.
              </para>
            </listitem>
            <listitem>
              <para>
                Apogee Igniter Voltage. This indicates whether the apogee
                igniter has continuity. If the igniter has a low
                resistance, then the voltage measured here will be close
                to the LiPo battery voltage. A value greater than 3.2V is
                required for a 'GO' status.
              </para>
            </listitem>
            <listitem>
              <para>
                Main Igniter Voltage. This indicates whether the main
                igniter has continuity. If the igniter has a low
                resistance, then the voltage measured here will be close
                to the LiPo battery voltage. A value greater than 3.2V is
                required for a 'GO' status.
              </para>
            </listitem>
            <listitem>
              <para>
                GPS Locked. This indicates whether the GPS receiver is
                currently able to compute position information. GPS requires
                at least 4 satellites to compute an accurate position.
              </para>
            </listitem>
            <listitem>
              <para>
                GPS Ready. This indicates whether GPS has reported at least
                10 consecutive positions without losing lock. This ensures
                that the GPS receiver has reliable reception from the
                satellites.
              </para>
            </listitem>
          </itemizedlist>
          <para>
            The LaunchPad tab also shows the computed launch pad position
            and altitude, averaging many reported positions to improve the
            accuracy of the fix.
          </para>
        </para>
      </section>
      <section>
        <title>Ascent</title>
        <para>
          This tab is shown during Boost, Fast and Coast
          phases. The information displayed here helps monitor the
          rocket as it heads towards apogee.
        </para>
        <para>
          The height, speed and acceleration are shown along with the
          maxium values for each of them. This allows you to quickly
          answer the most commonly asked questions you'll hear during
          flight.
        </para>
        <para>
          The current latitude and longitude reported by the GPS are
          also shown. Note that under high acceleration, these values
          may not get updated as the GPS receiver loses position
          fix. Once the rocket starts coasting, the receiver should
          start reporting position again.
        </para>
        <para>
          Finally, the current igniter voltages are reported as in the
          Launch Pad tab. This can help diagnose deployment failures
          caused by wiring which comes loose under high acceleration.
        </para>
      </section>
      <section>
        <title>Descent</title>
        <para>
          Once the rocket has reached apogee and (we hope) activated the
          apogee charge, attention switches to tracking the rocket on
          the way back to the ground, and for dual-deploy flights,
          waiting for the main charge to fire.
        </para>
        <para>
          To monitor whether the apogee charge operated correctly, the
          current descent rate is reported along with the current
          height. Good descent rates generally range from 15-30m/s.
        </para>
        <para>
          To help locate the rocket in the sky, use the elevation and
          bearing information to figure out where to look. Elevation is
          in degrees above the horizon. Bearing is reported in degrees
          relative to true north. Range can help figure out how big the
          rocket will appear. Note that all of these values are relative
          to the pad location. If the elevation is near 90°, the rocket
          is over the pad, not over you.
        </para>
        <para>
          Finally, the igniter voltages are reported in this tab as
          well, both to monitor the main charge as well as to see what
          the status of the apogee charge is.
        </para>
      </section>
      <section>
        <title>Landed</title>
        <para>
          Once the rocket is on the ground, attention switches to
          recovery. While the radio signal is generally lost once the
          rocket is on the ground, the last reported GPS position is
          generally within a short distance of the actual landing location.
        </para>
        <para>
          The last reported GPS position is reported both by
          latitude and longitude as well as a bearing and distance from
          the launch pad. The distance should give you a good idea of
          whether you'll want to walk or hitch a ride. Take the reported
          latitude and longitude and enter them into your handheld GPS
          unit and have that compute a track to the landing location.
        </para>
        <para>
          Finally, the maximum height, speed and acceleration reported
          during the flight are displayed for your admiring observers.
        </para>
      </section>
    </section>
    <section>
      <title>Save Flight Data</title>
      <para>
        TeleMetrum records flight data to its internal flash memory.
        This data is recorded at a much higher rate than the telemetry
        system can handle, and is not subject to radio drop-outs. As
        such, it provides a more complete and precise record of the
        flight. The 'Save Flight Data' button allows you to read the
        flash memory and write it to disk.
      </para>
      <para>
        Clicking on the 'Save Flight Data' button brings up a list of
        connected TeleMetrum and TeleDongle devices. If you select a
        TeleMetrum device, the flight data will be downloaded from that
        device directly. If you select a TeleDongle device, flight data
        will be downloaded from a TeleMetrum device connected via the
        packet command link to the specified TeleDongle. See the chapter
        on Packet Command Mode for more information about this.
      </para>
      <para>
        The filename for the data is computed automatically from the recorded
        flight date, TeleMetrum serial number and flight number
        information.
      </para>
    </section>
    <section>
      <title>Replay Flight</title>
      <para>
        Select this button and you are prompted to select a flight
        record file, either a .telem file recording telemetry data or a
        .eeprom file containing flight data saved from the TeleMetrum
        flash memory.
      </para>
      <para>
        Once a flight record is selected, the flight monitor interface
        is displayed and the flight is re-enacted in real time. Check
        the Monitor Flight chapter above to learn how this window operates.
      </para>
    </section>
    <section>
      <title>Graph Data</title>
      <para>
        This section should be written by AJ.
      </para>
    </section>
    <section>
      <title>Export Data</title>
      <para>
        This tool takes the raw data files and makes them available for
        external analysis. When you select this button, you are prompted to select a flight
        data file (either .eeprom or .telem will do, remember that
        .eeprom files contain higher resolution and more continuous
        data). Next, a second dialog appears which is used to select
        where to write the resulting file. It has a selector to choose
        between CSV and KML file formats.
      </para>
      <section>
        <title>Comma Separated Value Format</title>
        <para>
          This is a text file containing the data in a form suitable for
          import into a spreadsheet or other external data analysis
          tool. The first few lines of the file contain the version and
          configuration information from the TeleMetrum device, then
          there is a single header line which labels all of the
          fields. All of these lines start with a '#' character which
          most tools can be configured to skip over.
        </para>
        <para>
          The remaining lines of the file contain the data, with each
          field separated by a comma and at least one space. All of
          the sensor values are converted to standard units, with the
          barometric data reported in both pressure, altitude and
          height above pad units.
        </para>
      </section>
      <section>
        <title>Keyhole Markup Language (for Google Earth)</title>
        <para>
          This is the format used by
          Googleearth to provide an overlay within that
          application. With this, you can use Googleearth to see the
          whole flight path in 3D.
        </para>
      </section>
    </section>
    <section>
      <title>Configure TeleMetrum</title>
      <para>
        Select this button and then select either a TeleMetrum or
        TeleDongle Device from the list provided. Selecting a TeleDongle
        device will use Packet Comamnd Mode to configure remote
        TeleMetrum device. Learn how to use this in the Packet Command
        Mode chapter.
      </para>
      <para>
        The first few lines of the dialog provide information about the
        connected TeleMetrum device, including the product name,
        software version and hardware serial number. Below that are the
        individual configuration entries.
      </para>
      <para>
        At the bottom of the dialog, there are four buttons:
      </para>
      <itemizedlist>
        <listitem>
          <para>
            Save. This writes any changes to the TeleMetrum
            configuration parameter block in flash memory. If you don't
            press this button, any changes you make will be lost.
          </para>
        </listitem>
        <listitem>
          <para>
            Reset. This resets the dialog to the most recently saved values,
            erasing any changes you have made.
          </para>
        </listitem>
        <listitem>
          <para>
            Reboot. This reboots the TeleMetrum device. Use this to
            switch from idle to pad mode by rebooting once the rocket is
            oriented for flight.
          </para>
        </listitem>
        <listitem>
          <para>
            Close. This closes the dialog. Any unsaved changes will be
            lost.
          </para>
        </listitem>
      </itemizedlist>
      <para>
        The rest of the dialog contains the parameters to be configured.
      </para>
      <section>
        <title>Main Deploy Altitude</title>
        <para>
          This sets the altitude (above the recorded pad altitude) at
          which the 'main' igniter will fire. The drop-down menu shows
          some common values, but you can edit the text directly and
          choose whatever you like. If the apogee charge fires below
          this altitude, then the main charge will fire two seconds
          after the apogee charge fires.
        </para>
      </section>
      <section>
        <title>Apogee Delay</title>
        <para>
          When flying redundant electronics, it's often important to
          ensure that multiple apogee charges don't fire at precisely
          the same time as that can overpressurize the apogee deployment
          bay and cause a structural failure of the airframe. The Apogee
          Delay parameter tells the flight computer to fire the apogee
          charge a certain number of seconds after apogee has been
          detected.
        </para>
      </section>
      <section>
        <title>Radio Channel</title>
        <para>
          This configures which of the 10 radio channels to use for both
          telemetry and packet command mode. Note that if you set this
          value via packet command mode, you will have to reconfigure
          the TeleDongle channel before you will be able to use packet
          command mode again.
        </para>
      </section>
      <section>
        <title>Radio Calibration</title>
        <para>
          The radios in every Altus Metrum device are calibrated at the
          factory to ensure that they transmit and receive on the
          specified frequency for each channel. You can adjust that
          calibration by changing this value. To change the TeleDongle's
          calibration, you must reprogram the unit completely.
        </para>
      </section>
      <section>
        <title>Callsign</title>
        <para>
          This sets the callsign included in each telemetry packet. Set this
          as needed to conform to your local radio regulations.
        </para>
      </section>
    </section>
    <section>
      <title>Configure AltosUI</title>
      <para>
        This button presents a dialog so that you can configure the AltosUI global settings.
      </para>
      <section>
        <title>Voice Settings</title>
        <para>
          AltosUI provides voice annoucements during flight so that you
          can keep your eyes on the sky and still get information about
          the current flight status. However, sometimes you don't want
          to hear them.
        </para>
        <itemizedlist>
          <listitem>
            <para>Enable—turns all voice announcements on and off</para>
          </listitem>
          <listitem>
            <para>
              Test Voice—Plays a short message allowing you to verify
              that the audio systme is working and the volume settings
              are reasonable
            </para>
          </listitem>
        </itemizedlist>
      </section>
      <section>
        <title>Log Directory</title>
        <para>
          AltosUI logs all telemetry data and saves all TeleMetrum flash
          data to this directory. This directory is also used as the
          staring point when selecting data files for display or export.
        </para>
        <para>
          Click on the directory name to bring up a directory choosing
          dialog, select a new directory and click 'Select Directory' to
          change where AltosUI reads and writes data files.
        </para>
      </section>
      <section>
        <title>Callsign</title>
        <para>
          This value is used in command packet mode and is transmitted
          in each packet sent from TeleDongle and received from
          TeleMetrum. It is not used in telemetry mode as that transmits
          packets only from TeleMetrum to TeleDongle. Configure this
          with the AltosUI operators callsign as needed to comply with
          your local radio regulations.
        </para>
      </section>
    </section>
    <section>
      <title>Flash Image</title>
      <para>
        This reprograms any Altus Metrum device by using a TeleMetrum or
        TeleDongle as a programming dongle. Please read the directions
        for connecting the programming cable in the main TeleMetrum
        manual before reading these instructions.
      </para>
      <para>
        Once you have the programmer and target devices connected,
        push the 'Flash Image' button. That will present a dialog box
        listing all of the connected devices. Carefully select the
        programmer device, not the device to be programmed.
      </para>
      <para>
        Next, select the image to flash to the device. These are named
        with the product name and firmware version. The file selector
        will start in the directory containing the firmware included
        with the AltosUI package. Navigate to the directory containing
        the desired firmware if it isn't there.
      </para>
      <para>
        Next, a small dialog containing the device serial number and
        RF calibration values should appear. If these values are
        incorrect (possibly due to a corrupted image in the device),
        enter the correct values here.
      </para>
      <para>
        Finally, a dialog containing a progress bar will follow the
        programming process.
      </para>
      <para>
        When programming is complete, the target device will
        reboot. Note that if the target device is connected via USB, you
        will have to unplug it and then plug it back in for the USB
        connection to reset so that you can communicate with the device
        again.
      </para>
    </section>
    <section>
      <title>Fire Igniter</title>
      <para>
      </para>
    </section>
  </chapter>
  <chapter>
    <title>Using Altus Metrum Products</title>
    <section>
      <title>Being Legal</title>
      <para>
        First off, in the US, you need an [amateur radio license](../Radio) or 
        other authorization to legally operate the radio transmitters that are part
        of our products.
      </para>
      <section>
        <title>In the Rocket</title>
        <para>
          In the rocket itself, you just need a [TeleMetrum](../TeleMetrum) board and 
          a LiPo rechargeable battery.  An 860mAh battery weighs less than a 9V 
          alkaline battery, and will run a [TeleMetrum](../TeleMetrum) for hours.
        </para>
        <para>
          By default, we ship TeleMetrum with a simple wire antenna.  If your 
          electronics bay or the airframe it resides within is made of carbon fiber, 
          which is opaque to RF signals, you may choose to have an SMA connector 
          installed so that you can run a coaxial cable to an antenna mounted 
          elsewhere in the rocket.
        </para>
      </section>
      <section>
        <title>On the Ground</title>
        <para>
          To receive the data stream from the rocket, you need an antenna and short 
          feedline connected to one of our [TeleDongle](../TeleDongle) units.  The
          TeleDongle in turn plugs directly into the USB port on a notebook 
          computer.  Because TeleDongle looks like a simple serial port, your computer
          does not require special device drivers... just plug it in.
        </para>
        <para>
          Right now, all of our application software is written for Linux.  However, 
          because we understand that many people run Windows or MacOS, we are working 
          on a new ground station program written in Java that should work on all
          operating systems.
        </para>
        <para>
          After the flight, you can use the RF link to extract the more detailed data 
          logged in the rocket, or you can use a mini USB cable to plug into the 
          TeleMetrum board directly.  Pulling out the data without having to open up
          the rocket is pretty cool!  A USB cable is also how you charge the LiPo 
          battery, so you'll want one of those anyway... the same cable used by lots 
          of digital cameras and other modern electronic stuff will work fine.
        </para>
        <para>
          If your rocket lands out of sight, you may enjoy having a hand-held GPS 
          receiver, so that you can put in a waypoint for the last reported rocket 
          position before touch-down.  This makes looking for your rocket a lot like 
          Geo-Cacheing... just go to the waypoint and look around starting from there.
        </para>
        <para>
          You may also enjoy having a ham radio "HT" that covers the 70cm band... you 
          can use that with your antenna to direction-find the rocket on the ground 
          the same way you can use a Walston or Beeline tracker.  This can be handy 
          if the rocket is hiding in sage brush or a tree, or if the last GPS position 
          doesn't get you close enough because the rocket dropped into a canyon, or 
          the wind is blowing it across a dry lake bed, or something like that...  Keith
          and Bdale both currently own and use the Yaesu VX-7R at launches.
        </para>
        <para>
          So, to recap, on the ground the hardware you'll need includes:
          <orderedlist inheritnum='inherit' numeration='arabic'>
            <listitem> 
              an antenna and feedline
            </listitem>
            <listitem> 
              a TeleDongle
            </listitem>
            <listitem> 
              a notebook computer
            </listitem>
            <listitem> 
              optionally, a handheld GPS receiver
            </listitem>
            <listitem> 
              optionally, an HT or receiver covering 435 Mhz
            </listitem>
          </orderedlist>
        </para>
        <para>
          The best hand-held commercial directional antennas we've found for radio 
          direction finding rockets are from 
          <ulink url="http://www.arrowantennas.com/" >
            Arrow Antennas.
          </ulink>
          The 440-3 and 440-5 are both good choices for finding a 
          TeleMetrum-equipped rocket when used with a suitable 70cm HT.  
        </para>
      </section>
      <section>
        <title>Data Analysis</title>
        <para>
          Our software makes it easy to log the data from each flight, both the 
          telemetry received over the RF link during the flight itself, and the more
          complete data log recorded in the DataFlash memory on the TeleMetrum 
          board.  Once this data is on your computer, our postflight tools make it
          easy to quickly get to the numbers everyone wants, like apogee altitude, 
          max acceleration, and max velocity.  You can also generate and view a 
          standard set of plots showing the altitude, acceleration, and
          velocity of the rocket during flight.  And you can even export a data file 
          useable with Google Maps and Google Earth for visualizing the flight path 
          in two or three dimensions!
        </para>
        <para>
          Our ultimate goal is to emit a set of files for each flight that can be
          published as a web page per flight, or just viewed on your local disk with 
          a web browser.
        </para>
      </section>
      <section>
        <title>Future Plans</title>
        <para>
          In the future, we intend to offer "companion boards" for the rocket that will
          plug in to TeleMetrum to collect additional data, provide more pyro channels,
          and so forth.  A reference design for a companion board will be documented
          soon, and will be compatible with open source Arduino programming tools.
        </para>
        <para>
          We are also working on the design of a hand-held ground terminal that will
          allow monitoring the rocket's status, collecting data during flight, and
          logging data after flight without the need for a notebook computer on the
          flight line.  Particularly since it is so difficult to read most notebook
          screens in direct sunlight, we think this will be a great thing to have.
        </para>
        <para>
          Because all of our work is open, both the hardware designs and the software,
          if you have some great idea for an addition to the current Altus Metrum family,
          feel free to dive in and help!  Or let us know what you'd like to see that 
          we aren't already working on, and maybe we'll get excited about it too... 
        </para>
      </section>
    </section>
    <section>
      <title>
        How GPS Works
      </title>
      <para>
        Placeholder.
      </para>
    </section>
  </chapter>
</book>