+ </p></div></div><div class="chapter" title="Chapter 8. Altimeter Installation Recommendations"><div class="titlepage"><div><div><h2 class="title"><a name="idp3340600"></a>Chapter 8. Altimeter Installation Recommendations</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#idp3522016">1. Mounting the Altimeter</a></span></dt><dt><span class="section"><a href="#idp2062944">2. Dealing with the Antenna</a></span></dt><dt><span class="section"><a href="#idp2075472">3. Preserving GPS Reception</a></span></dt><dt><span class="section"><a href="#idp1887864">4. Radio Frequency Interference</a></span></dt><dt><span class="section"><a href="#idp2902592">5. The Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp2991488">6. Ground Testing</a></span></dt></dl></div><p>
+ Building high-power rockets that fly safely is hard enough. Mix
+ in some sophisticated electronics and a bunch of radio energy
+ and oftentimes you find few perfect solutions. This chapter
+ contains some suggestions about how to install Altus Metrum
+ products into the rocket air-frame, including how to safely and
+ reliably mix a variety of electronics into the same air-frame.
+ </p><div class="section" title="1. Mounting the Altimeter"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp3522016"></a>1. Mounting the Altimeter</h2></div></div></div><p>
+ The first consideration is to ensure that the altimeter is
+ securely fastened to the air-frame. For TeleMetrum, we use
+ nylon standoffs and nylon screws; they're good to at least 50G
+ and cannot cause any electrical issues on the board. For
+ TeleMini, we usually cut small pieces of 1/16" balsa to fit
+ under the screw holes, and then take 2x56 nylon screws and
+ screw them through the TeleMini mounting holes, through the
+ balsa and into the underlying material.
+ </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
+ Make sure TeleMetrum is aligned precisely along the axis of
+ acceleration so that the accelerometer can accurately
+ capture data during the flight.
+ </li><li class="listitem">
+ Watch for any metal touching components on the
+ board. Shorting out connections on the bottom of the board
+ can cause the altimeter to fail during flight.
+ </li></ol></div></div><div class="section" title="2. Dealing with the Antenna"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2062944"></a>2. Dealing with the Antenna</h2></div></div></div><p>
+ The antenna supplied is just a piece of solid, insulated,
+ wire. If it gets damaged or broken, it can be easily
+ replaced. It should be kept straight and not cut; bending or
+ cutting it will change the resonant frequency and/or
+ impedance, making it a less efficient radiator and thus
+ reducing the range of the telemetry signal.
+ </p><p>
+ Keeping metal away from the antenna will provide better range
+ and a more even radiation pattern. In most rockets, it's not
+ entirely possible to isolate the antenna from metal
+ components; there are often bolts, all-thread and wires from other
+ electronics to contend with. Just be aware that the more stuff
+ like this around the antenna, the lower the range.
+ </p><p>
+ Make sure the antenna is not inside a tube made or covered
+ with conducting material. Carbon fiber is the most common
+ culprit here -- CF is a good conductor and will effectively
+ shield the antenna, dramatically reducing signal strength and
+ range. Metallic flake paint is another effective shielding
+ material which is to be avoided around any antennas.
+ </p><p>
+ If the ebay is large enough, it can be convenient to simply
+ mount the altimeter at one end and stretch the antenna out
+ inside. Taping the antenna to the sled can keep it straight
+ under acceleration. If there are metal rods, keep the
+ antenna as far away as possible.
+ </p><p>
+ For a shorter ebay, it's quite practical to have the antenna
+ run through a bulkhead and into an adjacent bay. Drill a small
+ hole in the bulkhead, pass the antenna wire through it and
+ then seal it up with glue or clay. We've also used acrylic
+ tubing to create a cavity for the antenna wire. This works a
+ bit better in that the antenna is known to stay straight and
+ not get folded by recovery components in the bay. Angle the
+ tubing towards the side wall of the rocket and it ends up
+ consuming very little space.
+ </p><p>
+ If you need to place the antenna at a distance from the
+ altimeter, you can replace the antenna with an edge-mounted
+ SMA connector, and then run 50Ω coax from the board to the
+ antenna. Building a remote antenna is beyond the scope of this
+ manual.
+ </p></div><div class="section" title="3. Preserving GPS Reception"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2075472"></a>3. Preserving GPS Reception</h2></div></div></div><p>
+ The GPS antenna and receiver in TeleMetrum are highly
+ sensitive and normally have no trouble tracking enough
+ satellites to provide accurate position information for
+ recovering the rocket. However, there are many ways to
+ attenuate the GPS signal.
+ </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
+ Conductive tubing or coatings. Carbon fiber and metal
+ tubing, or metallic paint will all dramatically attenuate the
+ GPS signal. We've never heard of anyone successfully
+ receiving GPS from inside these materials.
+ </li><li class="listitem">
+ Metal components near the GPS patch antenna. These will
+ de-tune the patch antenna, changing the resonant frequency
+ away from the L1 carrier and reduce the effectiveness of the
+ antenna. You can place as much stuff as you like beneath the
+ antenna as that's covered with a ground plane. But, keep
+ wires and metal out from above the patch antenna.
+ </li></ol></div><p>
+ </p></div><div class="section" title="4. Radio Frequency Interference"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1887864"></a>4. Radio Frequency Interference</h2></div></div></div><p>
+ Any altimeter will generate RFI; the digital circuits use
+ high-frequency clocks that spray radio interference across a
+ wide band. Altus Metrum altimeters generate intentional radio
+ signals as well, increasing the amount of RF energy around the board.
+ </p><p>
+ Rocketry altimeters also use precise sensors measuring air
+ pressure and acceleration. Tiny changes in voltage can cause
+ these sensor readings to vary by a huge amount. When the
+ sensors start mis-reporting data, the altimeter can either
+ fire the igniters at the wrong time, or not fire them at all.
+ </p><p>
+ Voltages are induced when radio frequency energy is
+ transmitted from one circuit to another. Here are things that
+ influence the induced voltage and current:
+ </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+ Keep wires from different circuits apart. Moving circuits
+ further apart will reduce RFI.
+ </li><li class="listitem">
+ Avoid parallel wires from different circuits. The longer two
+ wires run parallel to one another, the larger the amount of
+ transferred energy. Cross wires at right angles to reduce
+ RFI.
+ </li><li class="listitem">
+ Twist wires from the same circuits. Two wires the same
+ distance from the transmitter will get the same amount of
+ induced energy which will then cancel out. Any time you have
+ a wire pair running together, twist the pair together to
+ even out distances and reduce RFI. For altimeters, this
+ includes battery leads, switch hookups and igniter
+ circuits.
+ </li><li class="listitem">
+ Avoid resonant lengths. Know what frequencies are present
+ in the environment and avoid having wire lengths near a
+ natural resonant length. Altusmetrum products transmit on the
+ 70cm amateur band, so you should avoid lengths that are a
+ simple ratio of that length; essentially any multiple of 1/4
+ of the wavelength (17.5cm).
+ </li></ul></div></div><div class="section" title="5. The Barometric Sensor"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2902592"></a>5. The Barometric Sensor</h2></div></div></div><p>
+ Altusmetrum altimeters measure altitude with a barometric
+ sensor, essentially measuring the amount of air above the
+ rocket to figure out how high it is. A large number of
+ measurements are taken as the altimeter initializes itself to
+ figure out the pad altitude. Subsequent measurements are then
+ used to compute the height above the pad.
+ </p><p>
+ To accurately measure atmospheric pressure, the ebay
+ containing the altimeter must be vented outside the
+ air-frame. The vent must be placed in a region of linear
+ airflow, have smooth edges, and away from areas of increasing or
+ decreasing pressure.
+ </p><p>
+ The barometric sensor in the altimeter is quite sensitive to
+ chemical damage from the products of APCP or BP combustion, so
+ make sure the ebay is carefully sealed from any compartment
+ which contains ejection charges or motors.
+ </p></div><div class="section" title="6. Ground Testing"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2991488"></a>6. Ground Testing</h2></div></div></div><p>
+ The most important aspect of any installation is careful
+ ground testing. Bringing an air-frame up to the LCO table which
+ hasn't been ground tested can lead to delays or ejection
+ charges firing on the pad, or, even worse, a recovery system
+ failure.
+ </p><p>
+ Do a 'full systems' test that includes wiring up all igniters
+ without any BP and turning on all of the electronics in flight
+ mode. This will catch any mistakes in wiring and any residual
+ RFI issues that might accidentally fire igniters at the wrong
+ time. Let the air-frame sit for several minutes, checking for
+ adequate telemetry signal strength and GPS lock. If any igniters
+ fire unexpectedly, find and resolve the issue before loading any
+ BP charges!
+ </p><p>
+ Ground test the ejection charges. Prepare the rocket for
+ flight, loading ejection charges and igniters. Completely
+ assemble the air-frame and then use the 'Fire Igniters'
+ interface through a TeleDongle to command each charge to
+ fire. Make sure the charge is sufficient to robustly separate
+ the air-frame and deploy the recovery system.
+ </p></div></div><div class="chapter" title="Chapter 9. Updating Device Firmware"><div class="titlepage"><div><div><h2 class="title"><a name="idp2336184"></a>Chapter 9. Updating Device Firmware</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#idp3061016">1. Updating TeleMetrum Firmware</a></span></dt><dt><span class="section"><a href="#idp1980776">2. Updating TeleMini Firmware</a></span></dt><dt><span class="section"><a href="#idp2731488">3. Updating TeleDongle Firmware</a></span></dt></dl></div><p>
+ The big concept to understand is that you have to use a
+ TeleDongle as a programmer to update a TeleMetrum or TeleMini,
+ and a TeleMetrum or other TeleDongle to program the TeleDongle
+ Due to limited memory resources in the cc1111, we don't support
+ programming directly over USB.
+ </p><p>
+ You may wish to begin by ensuring you have current firmware images.
+ These are distributed as part of the AltOS software bundle that
+ also includes the AltosUI ground station program. Newer ground
+ station versions typically work fine with older firmware versions,
+ so you don't need to update your devices just to try out new
+ software features. You can always download the most recent
+ version from <a class="ulink" href="http://www.altusmetrum.org/AltOS/" target="_top">http://www.altusmetrum.org/AltOS/</a>.
+ </p><p>
+ We recommend updating the altimeter first, before updating TeleDongle.
+ </p><div class="section" title="1. Updating TeleMetrum Firmware"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp3061016"></a>1. Updating TeleMetrum Firmware</h2></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
+ Find the 'programming cable' that you got as part of the starter
+ kit, that has a red 8-pin MicroMaTch connector on one end and a
+ red 4-pin MicroMaTch connector on the other end.
+ </li><li class="listitem">
+ Take the 2 screws out of the TeleDongle case to get access
+ to the circuit board.
+ </li><li class="listitem">
+ Plug the 8-pin end of the programming cable to the
+ matching connector on the TeleDongle, and the 4-pin end to the
+ matching connector on the TeleMetrum.
+ Note that each MicroMaTch connector has an alignment pin that
+ goes through a hole in the PC board when you have the cable
+ oriented correctly.
+ </li><li class="listitem">
+ Attach a battery to the TeleMetrum board.
+ </li><li class="listitem">
+ Plug the TeleDongle into your computer's USB port, and power
+ up the TeleMetrum.
+ </li><li class="listitem">
+ Run AltosUI, and select 'Flash Image' from the File menu.
+ </li><li class="listitem">
+ Pick the TeleDongle device from the list, identifying it as the
+ programming device.
+ </li><li class="listitem">
+ Select the image you want put on the TeleMetrum, which should have a
+ name in the form telemetrum-v1.1-1.0.0.ihx. It should be visible
+ in the default directory, if not you may have to poke around
+ your system to find it.
+ </li><li class="listitem">
+ Make sure the configuration parameters are reasonable
+ looking. If the serial number and/or RF configuration
+ values aren't right, you'll need to change them.
+ </li><li class="listitem">
+ Hit the 'OK' button and the software should proceed to flash
+ the TeleMetrum with new firmware, showing a progress bar.
+ </li><li class="listitem">
+ Confirm that the TeleMetrum board seems to have updated OK, which you
+ can do by plugging in to it over USB and using a terminal program
+ to connect to the board and issue the 'v' command to check
+ the version, etc.
+ </li><li class="listitem">
+ If something goes wrong, give it another try.
+ </li></ol></div></div><div class="section" title="2. Updating TeleMini Firmware"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1980776"></a>2. Updating TeleMini Firmware</h2></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
+ You'll need a special 'programming cable' to reprogram the
+ TeleMini. It's available on the Altus Metrum web store, or
+ you can make your own using an 8-pin MicroMaTch connector on
+ one end and a set of four pins on the other.
+ </li><li class="listitem">
+ Take the 2 screws out of the TeleDongle case to get access
+ to the circuit board.
+ </li><li class="listitem">
+ Plug the 8-pin end of the programming cable to the matching
+ connector on the TeleDongle, and the 4-pins into the holes
+ in the TeleMini circuit board. Note that the MicroMaTch
+ connector has an alignment pin that goes through a hole in
+ the PC board when you have the cable oriented correctly, and
+ that pin 1 on the TeleMini board is marked with a square pad
+ while the other pins have round pads.
+ </li><li class="listitem">
+ Attach a battery to the TeleMini board.
+ </li><li class="listitem">
+ Plug the TeleDongle into your computer's USB port, and power
+ up the TeleMini
+ </li><li class="listitem">
+ Run AltosUI, and select 'Flash Image' from the File menu.
+ </li><li class="listitem">
+ Pick the TeleDongle device from the list, identifying it as the
+ programming device.
+ </li><li class="listitem">
+ Select the image you want put on the TeleMini, which should have a
+ name in the form telemini-v1.0-1.0.0.ihx. It should be visible
+ in the default directory, if not you may have to poke around
+ your system to find it.
+ </li><li class="listitem">
+ Make sure the configuration parameters are reasonable
+ looking. If the serial number and/or RF configuration
+ values aren't right, you'll need to change them.
+ </li><li class="listitem">
+ Hit the 'OK' button and the software should proceed to flash
+ the TeleMini with new firmware, showing a progress bar.
+ </li><li class="listitem">
+ Confirm that the TeleMini board seems to have updated OK, which you
+ can do by configuring it over the radio link through the TeleDongle, or
+ letting it come up in "flight" mode and listening for telemetry.
+ </li><li class="listitem">
+ If something goes wrong, give it another try.
+ </li></ol></div></div><div class="section" title="3. Updating TeleDongle Firmware"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2731488"></a>3. Updating TeleDongle Firmware</h2></div></div></div><p>
+ Updating TeleDongle's firmware is just like updating TeleMetrum or TeleMini
+ firmware, but you use either a TeleMetrum or another TeleDongle as the programmer.
+ </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
+ Find the 'programming cable' that you got as part of the starter
+ kit, that has a red 8-pin MicroMaTch connector on one end and a
+ red 4-pin MicroMaTch connector on the other end.
+ </li><li class="listitem">
+ Find the USB cable that you got as part of the starter kit, and
+ plug the "mini" end in to the mating connector on TeleMetrum or TeleDongle.
+ </li><li class="listitem">
+ Take the 2 screws out of the TeleDongle case to get access
+ to the circuit board.
+ </li><li class="listitem">
+ Plug the 8-pin end of the programming cable to the
+ matching connector on the programmer, and the 4-pin end to the
+ matching connector on the TeleDongle.
+ Note that each MicroMaTch connector has an alignment pin that
+ goes through a hole in the PC board when you have the cable
+ oriented correctly.
+ </li><li class="listitem">
+ Attach a battery to the TeleMetrum board if you're using one.
+ </li><li class="listitem">
+ Plug both the programmer and the TeleDongle into your computer's USB
+ ports, and power up the programmer.
+ </li><li class="listitem">
+ Run AltosUI, and select 'Flash Image' from the File menu.
+ </li><li class="listitem">
+ Pick the programmer device from the list, identifying it as the
+ programming device.
+ </li><li class="listitem">
+ Select the image you want put on the TeleDongle, which should have a
+ name in the form teledongle-v0.2-1.0.0.ihx. It should be visible
+ in the default directory, if not you may have to poke around
+ your system to find it.
+ </li><li class="listitem">
+ Make sure the configuration parameters are reasonable
+ looking. If the serial number and/or RF configuration
+ values aren't right, you'll need to change them. The TeleDongle
+ serial number is on the "bottom" of the circuit board, and can
+ usually be read through the translucent blue plastic case without
+ needing to remove the board from the case.
+ </li><li class="listitem">
+ Hit the 'OK' button and the software should proceed to flash
+ the TeleDongle with new firmware, showing a progress bar.
+ </li><li class="listitem">
+ Confirm that the TeleDongle board seems to have updated OK, which you
+ can do by plugging in to it over USB and using a terminal program
+ to connect to the board and issue the 'v' command to check
+ the version, etc. Once you're happy, remove the programming cable
+ and put the cover back on the TeleDongle.
+ </li><li class="listitem">
+ If something goes wrong, give it another try.
+ </li></ol></div><p>
+ Be careful removing the programming cable from the locking 8-pin
+ connector on TeleMetrum. You'll need a fingernail or perhaps a thin
+ screwdriver or knife blade to gently pry the locking ears out
+ slightly to extract the connector. We used a locking connector on
+ TeleMetrum to help ensure that the cabling to companion boards
+ used in a rocket don't ever come loose accidentally in flight.
+ </p></div></div><div class="chapter" title="Chapter 10. Hardware Specifications"><div class="titlepage"><div><div><h2 class="title"><a name="idp2742616"></a>Chapter 10. Hardware Specifications</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#idp3450088">1. TeleMetrum Specifications</a></span></dt><dt><span class="section"><a href="#idp2397848">2. TeleMini Specifications</a></span></dt></dl></div><div class="section" title="1. TeleMetrum Specifications"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp3450088"></a>1. TeleMetrum Specifications</h2></div></div></div><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
+ Recording altimeter for model rocketry.
+ </p></li><li class="listitem"><p>
+ Supports dual deployment (can fire 2 ejection charges).
+ </p></li><li class="listitem"><p>
+ 70cm ham-band transceiver for telemetry down-link.
+ </p></li><li class="listitem"><p>
+ Barometric pressure sensor good to 45k feet MSL.
+ </p></li><li class="listitem"><p>
+ 1-axis high-g accelerometer for motor characterization, capable of
+ +/- 50g using default part.
+ </p></li><li class="listitem"><p>
+ On-board, integrated GPS receiver with 5Hz update rate capability.
+ </p></li><li class="listitem"><p>
+ On-board 1 megabyte non-volatile memory for flight data storage.
+ </p></li><li class="listitem"><p>
+ USB interface for battery charging, configuration, and data recovery.
+ </p></li><li class="listitem"><p>
+ Fully integrated support for Li-Po rechargeable batteries.
+ </p></li><li class="listitem"><p>
+ Uses Li-Po to fire e-matches, can be modified to support
+ optional separate pyro battery if needed.
+ </p></li><li class="listitem"><p>
+ 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
+ </p></li></ul></div></div><div class="section" title="2. TeleMini Specifications"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2397848"></a>2. TeleMini Specifications</h2></div></div></div><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
+ Recording altimeter for model rocketry.
+ </p></li><li class="listitem"><p>
+ Supports dual deployment (can fire 2 ejection charges).
+ </p></li><li class="listitem"><p>
+ 70cm ham-band transceiver for telemetry down-link.
+ </p></li><li class="listitem"><p>
+ Barometric pressure sensor good to 45k feet MSL.
+ </p></li><li class="listitem"><p>
+ On-board 5 kilobyte non-volatile memory for flight data storage.
+ </p></li><li class="listitem"><p>
+ RF interface for battery charging, configuration, and data recovery.
+ </p></li><li class="listitem"><p>
+ Support for Li-Po rechargeable batteries, using an external charger.
+ </p></li><li class="listitem"><p>
+ Uses Li-Po to fire e-matches, can be modified to support
+ optional separate pyro battery if needed.
+ </p></li><li class="listitem"><p>
+ 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
+ </p></li></ul></div></div></div><div class="chapter" title="Chapter 11. FAQ"><div class="titlepage"><div><div><h2 class="title"><a name="idp3517088"></a>Chapter 11. FAQ</h2></div></div></div><p>
+ 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.
+ </p><p>
+ 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.
+ </p><p>
+ The amber LED (on the TeleMetrum) 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.
+ </p><p>
+ There are no "dit-dah-dah-dit" sound or lights like the manual mentions?
+ That's the "pad" mode. Weak batteries might be the problem.
+ It is also possible that the TeleMetrum is horizontal and the output
+ is instead a "dit-dit" meaning 'idle'. For TeleMini, it's possible that
+ it received a command packet which would have left it in "pad" mode.
+ </p><p>
+ How do I save flight data?
+ Live telemetry is written to file(s) whenever AltosUI is connected
+ to the TeleDongle. The file area defaults to ~/TeleMetrum
+ but is easily changed using the menus in AltosUI. The files that
+ are written end in '.telem'. The after-flight
+ data-dumped files will end in .eeprom and represent continuous data
+ unlike the .telem files that are subject to losses
+ along the RF data path.
+ See the above instructions on what and how to save the eeprom stored
+ data after physically retrieving your altimeter. Make sure to save
+ the on-board data after each flight; while the TeleMetrum can store
+ multiple flights, you never know when you'll lose the altimeter...
+ </p></div><div class="appendix" title="Appendix A. Notes for Older Software"><div class="titlepage"><div><div><h2 class="title"><a name="idp2358816"></a>Appendix A. Notes for Older Software</h2></div></div></div><p>
+ <span class="emphasis"><em>
+ Before AltosUI was written, using Altus Metrum devices required
+ some finesse with the Linux command line. There was a limited
+ GUI tool, ao-view, which provided functionality similar to the
+ Monitor Flight window in AltosUI, but everything else was a
+ fairly 80's experience. This appendix includes documentation for
+ using that software.
+ </em></span>
+ </p><p>
+ 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.
+ </p><p>
+ TeleMini can be communicated with through a TeleDongle device
+ over the radio link. When first booted, TeleMini listens for a
+ TeleDongle device and if it receives a packet, it goes into
+ 'idle' mode. Otherwise, it goes into 'pad' mode and waits to be
+ launched. The easiest way to get it talking is to start the
+ communication link on the TeleDongle and the power up the
+ TeleMini board.
+ </p><p>
+ 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.
+ </p><p>
+ All of the Altus Metrum devices 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 Flash memory; TeleDongle doesn't provide any storage
+ for these options and so they'll all be lost when you unplug it.
+ </p><p>
+ Try setting these configuration ('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.
+ </p><p>
+ To set the radio frequency, use the 'c R' command to specify the
+ radio transceiver configuration parameter. This parameter is computed
+ using the desired frequency, 'F', the radio calibration parameter, 'C' (showed by the 'c s' command) and
+ the standard calibration reference frequency, 'S', (normally 434.550MHz):
+ </p><pre class="programlisting">
+ R = F / S * C
+ </pre><p>
+ Round the result to the nearest integer value.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board flash on
+ your altimeter board if you want the change to stay in place across reboots.
+ </p><p>
+ To set the apogee delay, use the 'c d' 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.
+ </p><p>
+ To set the main deployment altitude, use the 'c m' 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.
+ </p><p>
+ To calibrate the radio frequency, connect the UHF antenna port to a
+ frequency counter, set the board to 434.550MHz, 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.
+ </p><p>
+ Note that the 'reboot' command, which is very useful on the altimeters,
+ will likely just cause problems with the dongle. The *correct* way
+ to reset the dongle is just to unplug and re-plug it.
+ </p><p>
+ 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 radio link access
+ between an altimeter and 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.
+ </p><p>
+ Now might be a good time to take a break and read the rest of this
+ manual, particularly about the two "modes" that the altimeters
+ can be placed in. TeleMetrum uses the position of the device when booting
+ up will determine whether the unit is in "pad" or "idle" mode. TeleMini
+ enters "idle" mode when it receives a command packet within the first 5 seconds
+ of being powered up, otherwise it enters "pad" mode.
+ </p><p>
+ You can access an altimeter in idle mode from the TeleDongle's USB
+ connection using the radio link
+ by issuing a 'p' command to the TeleDongle. Practice connecting and
+ disconnecting ('~~' while using 'cu') from the altimeter. 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.
+ </p><p>
+ Using this radio link allows you to configure the altimeter, 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 altimeter 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.
+ </p><p>
+ 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'.
+ </p><p>
+ On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
+ and 'ao-view' will both auditorily 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.
+ </p><p>
+ The altimeters provide RDF (radio direction finding) tones on
+ the pad, during descent and after landing. These can be used to
+ locate the rocket using a directional antenna; the signal
+ strength providing an indication of the direction from receiver to rocket.
+ </p><p>
+ TeleMetrum also provides GPS tracking data, which can further simplify
+ 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'.)
+ </p><p>
+ 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.)
+ </p><p>
+ 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!
+ </p></div><div class="appendix" title="Appendix B. Calibration"><div class="titlepage"><div><div><h2 class="title"><a name="idp2555760"></a>Appendix B. Calibration</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#idp1119368">1. Radio Frequency</a></span></dt><dt><span class="section"><a href="#idp3257080">2. TeleMetrum Accelerometer</a></span></dt></dl></div><p>
+ There are only two calibrations required for a TeleMetrum board, and
+ only one for TeleDongle and TeleMini. All boards are shipped from
+ the factory pre-calibrated, but the procedures are documented here
+ in case they are ever needed. Re-calibration is not supported by
+ AltosUI, you must connect to the board with a serial terminal program
+ and interact directly with the on-board command interpreter to effect
+ calibration.
+ </p><div class="section" title="1. Radio Frequency"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1119368"></a>1. Radio Frequency</h2></div></div></div><p>
+ 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.
+ </p><p>
+ To calibrate the radio frequency, connect the UHF antenna port to a
+ frequency counter, set the board to 434.550MHz, and use the 'C'
+ command in the on-board command interpreter to generate a CW
+ carrier. For TeleMetrum, this is best done over USB. For TeleMini,
+ note that the only way to escape the 'C' command is via power cycle
+ since the board will no longer be listening for commands once it
+ starts generating a CW carrier.
+ </p><p>
+ 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.
+ </p><p>
+ Note that any time you re-do the radio frequency calibration, the
+ radio frequency is reset to the default 434.550 Mhz. If you want
+ to use another frequency, you will have to set that again after
+ calibration is completed.
+ </p></div><div class="section" title="2. TeleMetrum Accelerometer"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp3257080"></a>2. TeleMetrum Accelerometer</h2></div></div></div><p>
+ The TeleMetrum 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 ratio-metric to
+ the ADC converter, and calibration is required. Explicitly
+ calibrating the accelerometers also allows us to load any device
+ 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.
+ </p><p>
+ 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. Note that the accuracy of this
+ calibration depends primarily on how perfectly vertical and still
+ the board is held during the cal process. 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.
+ </p><p>
+ The +1g and -1g calibration points are included in each telemetry
+ frame and are part of the header stored in onboard flash to be
+ downloaded after flight. We always store and return raw ADC
+ samples for each sensor... so nothing is permanently "lost" or
+ "damaged" if the calibration is poor.
+ </p><p>
+ In the unlikely event an accel cal goes badly, it is possible
+ that TeleMetrum may always come up in 'pad mode' and as such not be
+ listening to either the USB or radio link. If that happens,
+ there is a special hook in the firmware to force the board back
+ in to 'idle mode' so you can re-do the cal. To use this hook, you
+ just need to ground the SPI clock pin at power-on. This pin is
+ available as pin 2 on the 8-pin companion connector, and pin 1 is
+ ground. So either carefully install a fine-gauge wire jumper
+ between the two pins closest to the index hole end of the 8-pin
+ connector, or plug in the programming cable to the 8-pin connector
+ and use a small screwdriver or similar to short the two pins closest
+ to the index post on the 4-pin end of the programming cable, and
+ power up the board. It should come up in 'idle mode' (two beeps),
+ allowing a re-cal.
+ </p></div></div><div class="appendix" title="Appendix C. Release Notes"><div class="titlepage"><div><div><h2 class="title"><a name="idp2653672"></a>Appendix C. Release Notes</h2></div></div></div><p>
+ Version 1.0 is a major release, adding support for the TeleMini
+ device and lots of new AltosUI features
+ </p><p>
+ AltOS Firmware Changes
+ </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+ Add TeleMini v1.0 support. Firmware images for TeleMini are
+ included in AltOS releases.
+ </li><li class="listitem">
+ Change telemetry to be encoded in multiple 32-byte packets. This
+ enables support for TeleMini and other devices without requiring
+ further updates to the TeleDongle firmware.
+ </li><li class="listitem">
+ Support operation of TeleMetrum with the antenna pointing
+ aft. Previous firmware versions required the antenna to be
+ pointing upwards, now there is a configuration option allowing
+ the antenna to point aft, to aid installation in some airframes.
+ </li><li class="listitem">
+ Ability to disable telemetry. For airframes where an antenna
+ just isn't possible, or where radio transmissions might cause
+ trouble with other electronics, there's a configuration option
+ to disable all telemetry. Note that the board will still
+ enable the radio link in idle mode.
+ </li><li class="listitem">
+ Arbitrary frequency selection. The radios in Altus Metrum
+ devices can be programmed to a wide range of frequencies, so
+ instead of limiting devices to 10 pre-selected 'channels', the
+ new firmware allows the user to choose any frequency in the
+ 70cm band. Note that the RF matching circuit on the boards is
+ tuned for around 435MHz, so frequencies far from that may
+ reduce the available range.
+ </li><li class="listitem">
+ Kalman-filter based flight-tracking. The model based sensor
+ fusion approach of a Kalman filter means that AltOS now
+ computes apogee much more accurately than before, generally
+ within a fraction of a second. In addition, this approach
+ allows the baro-only TeleMini device to correctly identify
+ Mach transitions, avoiding the error-prone selection of a Mach
+ delay.
+ </li></ul></div><p>
+ </p><p>
+ AltosUI Changes
+ </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+ Wait for altimeter when using packet mode. Instead of quicly
+ timing out when trying to initialize a packet mode
+ configuration connection, AltosUI now waits indefinitely for
+ the remote device to appear, providing a cancel button should
+ the user get bored. This is necessary as the TeleMini can only
+ be placed in "Idle" mode if AltosUI is polling it.
+ </li><li class="listitem">
+ Add main/apogee voltage graphs to the data plot. This provides
+ a visual indication if the igniters fail before being fired.
+ </li><li class="listitem">
+ Scan for altimeter devices by watching the defined telemetry
+ frequencies. This avoids the problem of remembering what
+ frequency a device was configured to use, which is especially
+ important with TeleMini which does not include a USB connection.
+ </li><li class="listitem">
+ Monitor altimeter state in "Idle" mode. This provides much of
+ the information presented in the "Pad" dialog from the Monitor
+ Flight command, monitoring the igniters, battery and GPS
+ status withing requiring the flight computer to be armed and
+ ready for flight.
+ </li><li class="listitem">
+ Pre-load map images from home. For those launch sites which
+ don't provide free Wi-Fi, this allows you to download the
+ necessary satellite images given the location of the launch
+ site. A list of known launch sites is maintained at
+ altusmetrum.org which AltosUI downloads to populate a menu; if
+ you've got a launch site not on that list, please send the
+ name of it, latitude and longitude along with a link to the
+ web site of the controlling club to the altusmetrum mailing list.
+ </li><li class="listitem">
+ Flight statistics are now displayed in the Graph data
+ window. These include max height/speed/accel, average descent
+ rates and a few other bits of information. The Graph Data
+ window can now be reached from the 'Landed' tab in the Monitor
+ Flight window so you can immediately see the results of a
+ flight.
+ </li></ul></div><p>
+ </p><p>
+ Version 0.9.2 is an AltosUI bug-fix release, with no firmware changes.
+ </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+ Fix plotting problems due to missing file in the Mac OS install image.
+ </li><li class="listitem">
+ Always read whole eeprom blocks, mark empty records invalid, display parsing errors to user.
+ </li><li class="listitem">
+ Add software version to Configure AltosUI dialog
+ </li></ul></div><p>
+ Version 0.9 adds a few new firmware features and accompanying
+ AltosUI changes, along with new hardware support.
+ </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+ Support for TeleMetrum v1.1 hardware. Sources for the flash
+ memory part used in v1.0 dried up, so v1.1 uses a different part
+ which required a new driver and support for explicit flight log
+ erasing.
+ </li><li class="listitem">
+ Multiple flight log support. This stores more than one flight
+ log in the on-board flash memory. It also requires the user to
+ explicitly erase flights so that you won't lose flight logs just
+ because you fly the same board twice in one day.
+ </li><li class="listitem">
+ Telemetry support for devices with serial number >=
+ 256. Previous versions used a telemetry packet format that
+ provided only 8 bits for the device serial number. This change
+ requires that both ends of the telemetry link be running the 0.9
+ firmware or they will not communicate.
+ </li></ul></div><p>
+ Version 0.8 offers a major upgrade in the AltosUI
+ interface. Significant new features include:
+ </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+ Post-flight graphing tool. This lets you explore the behaviour
+ of your rocket after flight with a scroll-able and zoom-able
+ chart showing the altitude, speed and acceleration of the
+ airframe along with events recorded by the flight computer. You
+ can export graphs to PNG files, or print them directly.
+ </li><li class="listitem">
+ Real-time moving map which overlays the in-progress flight on
+ satellite imagery fetched from Google Maps. This lets you see in
+ pictures where your rocket has landed, allowing you to plan
+ recovery activities more accurately.
+ </li><li class="listitem">
+ Wireless recovery system testing. Prep your rocket for flight
+ and test fire the deployment charges to make sure things work as
+ expected. All without threading wires through holes in your
+ airframe.
+ </li><li class="listitem">
+ Optimized flight status displays. Each flight state now has it's
+ own custom 'tab' in the flight monitoring window so you can
+ focus on the most important details. Pre-flight, the system
+ shows a set of red/green status indicators for battery voltage,
+ apogee/main igniter continutity and GPS reception. Wait until
+ they're all green and your rocket is ready for flight. There are
+ also tabs for ascent, descent and landing along with the
+ original tabular view of the data.
+ </li><li class="listitem">
+ Monitor multiple flights simultaneously. If you have more than
+ one TeleDongle, you can monitor a flight with each one on the
+ same computer.
+ </li><li class="listitem">
+ Automatic flight monitoring at startup. Plug TeleDongle into the
+ machine before starting AltosUI and it will automatically
+ connect to it and prepare to monitor a flight.
+ </li><li class="listitem">
+ Exports Google Earth flight tracks. Using the Keyhole Markup
+ Language (.kml) file format, this provides a 3D view of your
+ rocket flight through the Google Earth program.
+ </li></ul></div><p>
+Version 0.7.1 is the first release containing our new cross-platform Java-based user interface. AltosUI can:
+ </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+ Receive and log telemetry from a connected TeleDongle
+ device. All data received is saved to log files named with the
+ current date and the connected rocket serial and flight
+ numbers. There is no mode in which telemetry data will not be
+ saved.
+ </li><li class="listitem">
+ Download logged data from TeleMetrum devices, either through a
+ direct USB connection or over the air through a TeleDongle
+ device.
+ </li><li class="listitem">
+ Configure a TeleMetrum device, setting the radio channel,
+ callsign, apogee delay and main deploy height. This can be done
+ through either a USB connection or over a radio link via a
+ TeleDongle device.
+ </li><li class="listitem">
+ Replay a flight in real-time. This takes a saved telemetry log
+ or eeprom download and replays it through the user interface so
+ you can relive your favorite rocket flights.
+ </li><li class="listitem">
+ Reprogram Altus Metrum devices. Using an Altus Metrum device
+ connected via USB, another Altus Metrum device can be
+ reprogrammed using the supplied programming cable between the
+ two devices.
+ </li><li class="listitem">
+ Export Flight data to a comma-separated-values file. This takes
+ either telemetry or on-board flight data and generates data
+ suitable for use in external applications. All data is exported
+ using standard units so that no device-specific knowledge is
+ needed to handle the data.
+ </li><li class="listitem">
+ Speak to you during the flight. Instead of spending the flight
+ hunched over your laptop looking at the screen, enjoy the view
+ while the computer tells you what’s going on up there. During
+ ascent, you hear the current flight state and altitude
+ information. During descent, you get azimuth, elevation and
+ range information to try and help you find your rocket in the
+ air. Once on the ground, the direction and distance are
+ reported.
+ </li></ul></div></div></div></body></html>