Kit" which has turned into the Getting Started chapter in this
book. 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!
+ this section is immensely gratifying and highly appreciated!
</para>
<para>
And thanks to Anthony (AJ) Towns for contributing the
future as you wish!
</para>
<para>
- The first device created for our community is TeleMetrum, a dual
+ The first device created for our community was 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>
The newest device is TeleMini, a dual deploy altimeter with
radio telemetry and radio direction finding. This device is only
- 13mm by 38mm (½ inch by 1½ inches) and can fit easily in an 18mm airframe.
+ 13mm by 38mm (½ inch by 1½ inches) and can fit easily in an 18mm air-frame.
</para>
<para>
Complementing TeleMetrum and TeleMini is TeleDongle, a USB to RF interface for
The TeleMetrum battery can be charged by plugging it into the
corresponding socket of the TeleMetrum and then using the USB A to
mini B
- cable to plug the Telemetrum into your computer's USB socket. The
+ cable to plug the TeleMetrum into your computer's USB socket. The
TeleMetrum circuitry will charge the battery whenever it is plugged
in, because the TeleMetrum's on-off switch does NOT control the
charging circuitry.
<para>
When the GPS chip is initially searching for
satellites, TeleMetrum will consume more current than it can pull
- from the usb port, so the battery must be attached in order to get
+ from the USB port, so the battery must be attached in order to get
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
</para>
<para>
The TeleMini battery can be charged by disconnecting it from the
- TeleMini board and plugging it into the battery charger board,
- and connecting that via a USB cable to a laptop or other USB
+ TeleMini board and plugging it into a standalone battery charger
+ board, and connecting that via a USB cable to a laptop or other USB
power source
</para>
<para>
RF interface. If you plug it in to your Mac or Linux computer it should
"just work", showing up as a serial port device. Windows systems need
driver information that is part of the AltOS download to know that the
- existing USB modem driver will work. If you are using Linux and are
- having problems, try moving to a fresher kernel (2.6.33 or newer), as
- the USB serial driver had ugly bugs in some earlier versions.
+ existing USB modem driver will work. We therefore recommend installing
+ our software before plugging in TeleDongle if you are using a Windows
+ computer. If you are using Linux and are having problems, try moving
+ to a fresher kernel (2.6.33 or newer), as the USB serial driver had
+ ugly bugs in some earlier versions.
</para>
<para>
Next you should obtain and install the AltOS utilities. These include
the AltosUI ground station program, current firmware images for
TeleMetrum, TeleMini and TeleDongle, and a number of standalone utilities that
are rarely needed. Pre-built binary packages are available for Debian
- Linux, Microsoft Windows, and recent MacOSX versions. Full sourcecode
+ Linux, Microsoft Windows, and recent MacOSX versions. Full source code
and build instructions for some other Linux variants are also available.
The latest version may always be downloaded from
<ulink url="http://altusmetrum.org/AltOS"/>.
<chapter>
<title>Handling Precautions</title>
<para>
- All Altus Metrum products are sophisticated electronic device. When handled gently and
- properly installed in an airframe, theywill deliver impressive results.
- However, like all electronic devices, there are some precautions you
- must take.
+ All Altus Metrum products are sophisticated electronic devices.
+ When handled gently and properly installed in an air-frame, they
+ will deliver impressive results. However, like all electronic
+ devices, there are some precautions you must take.
</para>
<para>
The Lithium Polymer rechargeable batteries have an
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
+ and consider giving them some extra protection in your air-frame. We
often wrap them in suitable scraps of closed-cell packing foam before
strapping them down, for example.
</para>
<para>
- The barometric sensor is sensitive to sunlight. In normal
- mounting situations, it and all of the other surface mount components
+ The barometric sensors used on both TeleMetrum and TeleMini are
+ sensitive to sunlight. In normal TeleMetrum 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 an airframe with a
- see-through plastic payload bay.
+ designing an installation, for example, in an air-frame with a
+ see-through plastic payload bay. It is particularly important to
+ consider this with TeleMini, both because the baro sensor is on the
+ "top" of the board, and because many model rockets with payload bays
+ use clear plastic for the payload bay! Replacing these with an opaque
+ cardboard tube, painting them, or wrapping them with a layer of masking
+ tape are all reasonable approaches to keep the sensor out of direct
+ sunlight.
</para>
<para>
- The barometric sensor sampling port must be able to
- "breathe",
+ The 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
+ directly block the hole on the top of the sensor, and also by having a
suitable static vent to outside air.
</para>
<para>
- As with all other rocketry electronics, Altus Metrum altimeters must be protected
- from exposure to corrosive motor exhaust and ejection charge gasses.
+ As with all other rocketry electronics, Altus Metrum altimeters 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
+ fit inside coupler for 29mm air-frame 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
</para>
<para>
TeleMini is a 0.5 inch by 1.5 inch circuit board. It was designed to
- fit inside an 18mm airframe tube, but using it in a tube that
+ fit inside an 18mm air-frame tube, 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
charges.
</para>
<para>
- By default, we use the unregulated output of the LiPo battery directly
+ By default, we use the unregulated output of the Li-Po 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
directly to the board and can be connected directly to the switch.
</para>
<para>
- For most airframes, the integrated antennas are more than
+ For most air-frames, the integrated antennas are more than
adequate 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
<para>
The AltOS firmware build for the altimeters has two
fundamental modes, "idle" and "flight". Which of these modes
- the firmware operates in is determined at startup time. For
+ the firmware operates in is determined at start up time. For
TeleMetrum, the mode is controlled 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
</para>
<para>
At power on, you will hear three beeps or see three flashes
- ("S" in Morse code for startup) and then a pause while
+ ("S" in Morse code for start up) and then a pause while
the altimeter completes initialization and self tests, and decides which
mode to enter next.
</para>
</para>
<para>
One "neat trick" of particular value when the altimeter is used with very
- large airframes, is that you can power the board up while the rocket
+ large air-frames, 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
+ raise the air-frame to launch position, use a TeleDongle to open
a packet connection, and issue a 'reset' command which will cause
the altimeter to reboot and come up in
flight mode. This is much safer than standing on the top step of a
what time it is!
</para>
<para>
- TeleMetrum provides backup power to the GPS chip any time a LiPo
+ TeleMetrum provides backup power to the GPS chip any time a Li-Po
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
+ on the flight line in idle mode while performing final air-frame
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
</para>
<para>
Just prep the rocket for flight, then power up the altimeter
- in "idle" mode (placing airframe horizontal for TeleMetrum or
+ in "idle" mode (placing air-frame horizontal for TeleMetrum or
starting the RF packet connection for TeleMini). 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
it's in "idle mode", 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
+ crack open the air-frame. However, when the board is in "flight
mode", the altimeter 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
<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
+ base-band 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
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):
+ the standard calibration reference frequency, 'S', (normally 434.550MHz):
<programlisting>
R = F / S * C
</programlisting>
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
+ air-frames this way quite happily, including Keith's
successful L3 cert.
</para>
</section>
<para>
By default, the altimeter 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
+ is a good elevation for most air-frames, 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
<section>
<title>Radio Frequency</title>
<para>
- The radio frequency is synthesized from a clock based on the 48 Mhz
+ 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
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
+ 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'
<section>
<title>TeleMetrum Accelerometer</title>
<para>
- The TeleMerum accelerometer we use has its own 5 volt power supply and
+ 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 ratiometric to
+ sensor, the output of the acceleration sensor is not ratio-metric 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,
the TeleMetrum with new firmware, showing a progress bar.
</listitem>
<listitem>
- Confirm that the TeleMetrum board seems to have updated ok, which you
+ 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.
the TeleMini with new firmware, showing a progress bar.
</listitem>
<listitem>
- Confirm that the TeleMini board seems to have updated ok, which you
+ Confirm that the TeleMini board seems to have updated OK, which you
can do by configuring it over the RF link through the TeleDongle, or
letting it come up in "flight" mode and listening for telemetry.
</listitem>
the TeleDongle with new firmware, showing a progress bar.
</listitem>
<listitem>
- Confirm that the TeleDongle board seems to have updated ok, which you
+ 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
<para>
The radio frequency being monitored by the TeleDongle device is
displayed at the top of the window. You can configure the
- frequecy by clicking on the frequency box and selecting the desired
+ frequency by clicking on the frequency box and selecting the desired
frequency. AltosUI remembers the last frequency selected for each
TeleDongle and selects that automatically the next time you use
that device.
</para>
<itemizedlist>
<listitem>
- <para>The configured callsign</para>
+ <para>The configured call-sign</para>
</listitem>
<listitem>
<para>The device serial number</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
+ weaker signals may not be receivable. The packet link uses
error correction and detection techniques which prevent
incorrect data from being reported.
</para>
<itemizedlist>
<listitem>
<para>
- Battery Voltage. This indicates whether the LiPo battery
+ Battery Voltage. This indicates whether the Li-Po 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.
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
+ to the Li-Po battery voltage. A value greater than 3.2V is
required for a 'GO' status.
</para>
</listitem>
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
+ to the Li-Po battery voltage. A value greater than 3.2V is
required for a 'GO' status.
</para>
</listitem>
</listitem>
</itemizedlist>
<para>
- The LaunchPad tab also shows the computed launch pad position
+ 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>
<para>
The height, speed and acceleration are shown along with the
- maxium values for each of them. This allows you to quickly
+ maximum values for each of them. This allows you to quickly
answer the most commonly asked questions you'll hear during
flight.
</para>
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
+ latitude and longitude and enter them into your hand-held GPS
unit and have that compute a track to the landing location.
</para>
<para>
When the TeleMetrum gets a GPS fix, the Site Map tab will map
the rocket's position to make it easier for you to locate the
rocket, both while it is in the air, and when it has landed. The
- rocket's state is indicated by colour: white for pad, red for
+ rocket's state is indicated by color: white for pad, red for
boost, pink for fast, yellow for coast, light blue for drogue,
dark blue for main, and black for landed.
</para>
<para>
The map's scale is approximately 3m (10ft) per pixel. The map
can be dragged using the left mouse button. The map will attempt
- to keep the rocket roughly centred while data is being received.
+ to keep the rocket roughly centered while data is being received.
</para>
<para>
Images are fetched automatically via the Google Maps Static API,
and are cached for reuse. If map images cannot be downloaded,
- the rocket's path will be traced on a dark grey background
+ the rocket's path will be traced on a dark gray background
instead.
</para>
<para>
to respond to changing launch conditions. You can also
'reboot' the altimeter. Use this to remotely enable the
flight computer by turning TeleMetrum on in "idle" mode,
- then once the airframe is oriented for launch, you can
+ then once the air-frame is oriented for launch, you can
reboot the altimeter and have it restart in pad mode
without having to climb the scary ladder.
</para>
<listitem>
<para>
Fire Igniters—Test your deployment charges without snaking
- wires out through holes in the airframe. Simply assembly the
+ wires out through holes in the air-frame. Simply assembly the
rocket as if for flight with the apogee and main charges
loaded, then remotely command the altimeter to fire the
igniters.
data will be recorded for a flight.
</para>
<para>
- The filename for each flight log is computed automatically
+ The file name for each flight log is computed automatically
from the recorded flight date, altimeter serial number and
flight number information.
</para>
dragging down and to the right. Once zoomed, the graph can be
reset by clicking and dragging up and to the left. Holding down
control and clicking and dragging allows the graph to be panned.
- The right mouse button causes a popup menu to be displayed, giving
+ The right mouse button causes a pop-up menu to be displayed, giving
you the option save or print the plot.
</para>
<para>
<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 a remote
+ device will use Packet Command Mode to configure a remote
altimeter. Learn how to use this in the Packet Command
Mode chapter.
</para>
<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
+ the same time as that can over pressurize the apogee deployment
+ bay and cause a structural failure of the air-frame. The Apogee
Delay parameter tells the flight computer to fire the apogee
charge a certain number of seconds after apogee has been
detected.
<section>
<title>Callsign</title>
<para>
- This sets the callsign included in each telemetry packet. Set this
+ This sets the call sign included in each telemetry packet. Set this
as needed to conform to your local radio regulations.
</para>
</section>
<section>
<title>Voice Settings</title>
<para>
- AltosUI provides voice annoucements during flight so that you
+ AltosUI provides voice announcements 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.
<listitem>
<para>
Test Voice—Plays a short message allowing you to verify
- that the audio systme is working and the volume settings
+ that the audio system is working and the volume settings
are reasonable
</para>
</listitem>
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
+ with the AltosUI operators call sign as needed to comply with
your local radio regulations.
</para>
</section>
+ <section>
+ <title>Font Size</title>
+ <para>
+ Selects the set of fonts used in the flight monitor
+ window. Choose between the small, medium and large sets.
+ </para>
+ </section>
<section>
<title>Serial Debug</title>
<para>
recovery systems deployment. Because this command can operate
over the Packet Command Link, you can prepare the rocket as
for flight and then test the recovery system without needing
- to snake wires inside the airframe.
+ to snake wires inside the air-frame.
</para>
<para>
Selecting the 'Fire Igniter' button brings up the usual device
selection dialog. Pick the desired TeleDongle or TeleMetrum
device. This brings up another window which shows the current
- continutity test status for both apogee and main charges.
+ continuity test status for both apogee and main charges.
</para>
<para>
Next, select the desired igniter to fire. This will enable the
<para>
In the rocket itself, you just need a <ulink url="http://www.altusmetrum.org/TeleMetrum/">TeleMetrum</ulink> or
<ulink url="http://www.altusmetrum.org/TeleMini/">TeleMini</ulink> board and
- a LiPo rechargeable battery. An 860mAh battery weighs less than a 9V
+ a Li-Po rechargeable battery. An 860mAh battery weighs less than a 9V
alkaline battery, and will run a TeleMetrum for hours.
A 110mAh battery weighs less than a triple A battery and will run a TeleMetrum for
a few hours, or a TeleMini for much (much) longer.
</para>
<para>
By default, we ship the altimeters with a simple wire antenna. If your
- electronics bay or the airframe it resides within is made of carbon fiber,
+ electronics bay or the air-frame 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.
<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 <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> units. The
+ feed
-line connected to one of our <ulink url="http://www.altusmetrum.org/TeleDongle/">TeleDongle</ulink> 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.
After the flight, you can use the RF link to extract the more detailed data
logged in either TeleMetrum or TeleMini devices, 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
+ the rocket is pretty cool! A USB cable is also how you charge the Li-Po
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 TeleMetrum-equiped 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
+ If your TeleMetrum-equipped rocket lands out of sight, you may enjoy having a hand-held GPS
+ receiver, so that you can put in a way-point 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.
+ Geo-Caching... just go to the way-point and look around starting from there.
</para>
<para>
You may also enjoy having a ham radio "HT" that covers the 70cm band... you
So, to recap, on the ground the hardware you'll need includes:
<orderedlist inheritnum='inherit' numeration='arabic'>
<listitem>
- an antenna and feedline
+ an antenna and feed-line
</listitem>
<listitem>
a TeleDongle
a notebook computer
</listitem>
<listitem>
- optionally, a handheld GPS receiver
+ optionally, a hand-held GPS receiver
</listitem>
<listitem>
- optionally, an HT or receiver covering 435 Mhz
+ optionally, an HT or receiver covering 435 MHz
</listitem>
</orderedlist>
</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 flash memory on the altimeter
- board. Once this data is on your computer, our postflight tools make it
+ board. Once this data is on your computer, our post-flight 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 TeleMetrum data file
- useable with Google Maps and Google Earth for visualizing the flight path
+ usable with Google Maps and Google Earth for visualizing the flight path
in two or three dimensions!
</para>
<para>
</para>
</section>
</chapter>
+ <chapter>
+ <title>Altimeter Installation Recommendations</title>
+ <para>
+ 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.
+ </para>
+ <section>
+ <title>Mounting the Altimeter</title>
+ <para>
+ 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.
+ </para>
+ <orderedlist inheritnum='inherit' numeration='arabic'>
+ <listitem>
+ Make sure TeleMetrum is aligned precisely along the axis of
+ acceleration so that the accelerometer can accurately
+ capture data during the flight.
+ </listitem>
+ <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.
+ </listitem>
+ </orderedlist>
+ </section>
+ <section>
+ <title>Dealing with the Antenna</title>
+ <para>
+ 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.
+ </para>
+ <para>
+ 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.
+ </para>
+ <para>
+ 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.
+ </para>
+ <para>
+ 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.
+ </para>
+ <para>
+ 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.
+ </para>
+ <para>
+ 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.
+ </para>
+ </section>
+ <section>
+ <title>Preserving GPS Reception</title>
+ <para>
+ 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.
+ <orderedlist inheritnum='inherit' numeration='arabic'>
+ <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.
+ </listitem>
+ <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.
+ </listitem>
+ </orderedlist>
+ </para>
+ </section>
+ <section>
+ <title>Radio Frequency Interference</title>
+ <para>
+ Any altimeter will generate RFI; the digital circuits use
+ high-frequency clocks that spray radio interference across a
+ wide band. Altusmetrum altimeters generate intentional radio
+ signals as well, increasing the amount of RF energy around the board.
+ </para>
+ <para>
+ 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.
+ </para>
+ <para>
+ Voltages are induced when radio frequency energy is
+ transmitted from one circuit to another. Here are things that
+ increase the induced voltage and current:
+ </para>
+ <itemizedlist>
+ <listitem>
+ Keep wires from different circuits apart. Moving circuits
+ further apart will reduce RFI.
+ </listitem>
+ <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.
+ </listitem>
+ <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.
+ </listitem>
+ <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).
+ </listitem>
+ </itemizedlist>
+ </section>
+ <section>
+ <title>The Barometric Sensor</title>
+ <para>
+ 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.
+ </para>
+ <para>
+ 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, smooth and not in an area of increasing or decreasing
+ pressure.
+ </para>
+ <para>
+ 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.
+ </para>
+ </section>
+ <section>
+ <title>Ground Testing</title>
+ <para>
+ 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.
+ </para>
+ <para>
+ 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.
+ </para>
+ <para>
+ 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.
+ </para>
+ </section>
+ </chapter>
<chapter>
<title>Hardware Specifications</title>
<section>
</listitem>
<listitem>
<para>
- 70cm ham-band transceiver for telemetry downlink.
+ 70cm ham-band transceiver for telemetry down-link.
</para>
</listitem>
<listitem>
</listitem>
<listitem>
<para>
- On-board, integrated GPS receiver with 5hz update rate capability.
+ On-board, integrated GPS receiver with 5Hz update rate capability.
</para>
</listitem>
<listitem>
</listitem>
<listitem>
<para>
- Fully integrated support for LiPo rechargeable batteries.
+ Fully integrated support for Li-Po rechargeable batteries.
</para>
</listitem>
<listitem>
<para>
- Uses LiPo to fire e-matches, can be modiied to support
+ Uses Li-Po to fire e-matches, can be modified to support
optional separate pyro battery if needed.
</para>
</listitem>
<listitem>
<para>
- 2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube.
+ 2.75 x 1 inch board designed to fit inside 29mm air-frame coupler tube.
</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>
- 70cm ham-band transceiver for telemetry downlink.
+ 70cm ham-band transceiver for telemetry down-link.
</para>
</listitem>
<listitem>
</listitem>
<listitem>
<para>
- Support for LiPo rechargeable batteries, using an external charger.
+ Support for Li-Po rechargeable batteries, using an external charger.
</para>
</listitem>
<listitem>
<para>
- Uses LiPo to fire e-matches, can be modiied to support
+ Uses Li-Po to fire e-matches, can be modified to support
optional separate pyro battery if needed.
</para>
</listitem>
<listitem>
<para>
- 1.5 x .5 inch board designed to fit inside 18mm airframe coupler tube.
+ 1.5 x .5 inch board designed to fit inside 18mm air-frame coupler tube.
</para>
</listitem>
</itemizedlist>
<para>
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
+ 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.
</para>
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 rf-linked .telem files that are subject to losses
- along the rf data path.
+ unlike the RF-linked .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
</emphasis>
</para>
<para>
- Both Telemetrum and TeleDongle can be directly communicated
+ 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
+ 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
for these options and so they'll all be lost when you unplug it.
</para>
<para>
- Try setting these config ('c' or second level menu) values. A good
+ 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
</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
+ learning how to use these units is to play with the RF-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.
of being powered up, otherwise it enters "pad" mode.
</para>
<para>
- You can access an altimeter in idle mode from the Teledongle's USB
- connection using the rf link
+ You can access an altimeter 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 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.
</para>
<para>
- Using this rf link allows you to configure the altimeter, test
+ Using this RF 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
+ 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>
On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
- and 'ao-view' will both auditorially announce and visually indicate
+ 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
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
+ 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>
<appendix
xmlns:xi="http://www.w3.org/2001/XInclude">
<title>Release Notes</title>
+ <xi:include href="release-notes-1.0.xsl" xpointer="xpointer(/article/*)"/>
<xi:include href="release-notes-0.9.2.xsl" xpointer="xpointer(/article/*)"/>
<xi:include href="release-notes-0.9.xsl" xpointer="xpointer(/article/*)"/>
<xi:include href="release-notes-0.8.xsl" xpointer="xpointer(/article/*)"/>
<xi:include href="release-notes-0.7.1.xsl" xpointer="xpointer(/article/*)"/>
</appendix>
</book>
+
+<!-- LocalWords: Altusmetrum
+-->
projects / fw / altos / blobdiff