+ <section>
+ <title>Configurable Parameters</title>
+ <para>
+ Configuring a TeleMetrum board for flight is very simple. Because we
+ have both acceleration and pressure sensors, there is no need to set
+ a "mach delay", for example. The few configurable parameters can all
+ be set using a simple terminal program over the USB port or RF link
+ via TeleDongle.
+ </para>
+ <section>
+ <title>Radio Channel</title>
+ <para>
+ Our firmware supports 10 channels. The default channel 0 corresponds
+ to a center frequency of 434.550 Mhz, and channels are spaced every
+ 100 khz. Thus, channel 1 is 434.650 Mhz, and channel 9 is 435.550 Mhz.
+ At any given launch, we highly recommend coordinating who will use
+ each channel and when to avoid interference. And of course, both
+ TeleMetrum and TeleDongle must be configured to the same channel to
+ successfully communicate with each other.
+ </para>
+ <para>
+ To set the radio channel, use the 'c r' command, like 'c r 3' to set
+ channel 3.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board DataFlash chip.
+ </para>
+ </section>
+ <section>
+ <title>Apogee Delay</title>
+ <para>
+ Apogee delay is the number of seconds after TeleMetrum detects flight
+ apogee that the drogue charge should be fired. In most cases, this
+ should be left at the default of 0. However, if you are flying
+ redundant electronics such as for an L3 certification, you may wish
+ to set one of your altimeters to a positive delay so that both
+ primary and backup pyrotechnic charges do not fire simultaneously.
+ </para>
+ <para>
+ To set the apogee delay, use the [FIXME] command.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board DataFlash chip.
+ </para>
+ </section>
+ <section>
+ <title>Main Deployment Altitude</title>
+ <para>
+ By default, TeleMetrum will fire the main deployment charge at an
+ elevation of 250 meters (about 820 feet) above ground. We think this
+ is a good elevation for most airframes, but feel free to change this
+ to suit. In particular, if you are flying two altimeters, you may
+ wish to set the
+ deployment elevation for the backup altimeter to be something lower
+ than the primary so that both pyrotechnic charges don't fire
+ simultaneously.
+ </para>
+ <para>
+ To set the main deployment altitude, use the [FIXME] command.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board DataFlash chip.
+ </para>
+ </section>
+ </section>
+ <section>
+ <title>Calibration</title>
+ <para>
+ There are only two calibrations required for a TeleMetrum board, and
+ only one for TeleDongle.
+ </para>
+ <section>
+ <title>Radio Frequency</title>
+ <para>
+ The radio frequency is synthesized from a clock based on the 48 Mhz
+ crystal on the board. The actual frequency of this oscillator must be
+ measured to generate a calibration constant. While our GFSK modulation
+ bandwidth is wide enough to allow boards to communicate even when
+ their oscillators are not on exactly the same frequency, performance
+ is best when they are closely matched.
+ Radio frequency calibration requires a calibrated frequency counter.
+ Fortunately, once set, the variation in frequency due to aging and
+ temperature changes is small enough that re-calibration by customers
+ should generally not be required.
+ </para>
+ <para>
+ To calibrate the radio frequency, connect the UHF antenna port to a
+ frequency counter, set the board to channel 0, and use the 'C'
+ command to generate a CW carrier. Wait for the transmitter temperature
+ to stabilize and the frequency to settle down.
+ Then, divide 434.550 Mhz by the
+ measured frequency and multiply by the current radio cal value show
+ in the 'c s' command. For an unprogrammed board, the default value
+ is 1186611. Take the resulting integer and program it using the 'c f'
+ command. Testing with the 'C' command again should show a carrier
+ within a few tens of Hertz of the intended frequency.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board DataFlash chip.
+ </para>
+ </section>
+ <section>
+ <title>Accelerometer</title>
+ <para>
+ The accelerometer we use has its own 5 volt power supply and
+ the output must be passed through a resistive voltage divider to match
+ the input of our 3.3 volt ADC. This means that unlike the barometric
+ sensor, the output of the acceleration sensor is not ratiometric to
+ the ADC converter, and calibration is required. We also support the
+ use of any of several accelerometers from a Freescale family that
+ includes at least +/- 40g, 50g, 100g, and 200g parts. Using gravity,
+ a simple 2-point calibration yields acceptable results capturing both
+ the different sensitivities and ranges of the different accelerometer
+ parts and any variation in power supply voltages or resistor values
+ in the divider network.
+ </para>
+ <para>
+ To calibrate the acceleration sensor, use the 'c a 0' command. You
+ will be prompted to orient the board vertically with the UHF antenna
+ up and press a key, then to orient the board vertically with the
+ UHF antenna down and press a key.
+ As with all 'c' sub-commands, follow this with a 'c w' to write the
+ change to the parameter block in the on-board DataFlash chip.
+ </para>
+ <para>
+ The +1g and -1g calibration points are included in each telemetry
+ frame and are part of the header extracted by ao-dumplog after flight.
+ Note that we always store and return raw ADC samples for each
+ sensor... nothing is permanently "lost" or "damaged" if the
+ calibration is poor.
+ </para>
+ </section>
+ </section>
+ </chapter>
+ <chapter>
+ <title>Using Altus Metrum Products</title>
+ <section>
+ <title>Being Legal</title>
+ <para>
+ First off, in the US, you need an [amateur radio license](../Radio) or
+ other authorization to legally operate the radio transmitters that are part
+ of our products.
+ </para>
+ <section>
+ <title>In the Rocket</title>
+ <para>
+ In the rocket itself, you just need a [TeleMetrum](../TeleMetrum) board and
+ a LiPo rechargeable battery. An 860mAh battery weighs less than a 9V
+ alkaline battery, and will run a [TeleMetrum](../TeleMetrum) for hours.
+ </para>
+ <para>
+ By default, we ship TeleMetrum with a simple wire antenna. If your
+ electronics bay or the airframe it resides within is made of carbon fiber,
+ which is opaque to RF signals, you may choose to have an SMA connector
+ installed so that you can run a coaxial cable to an antenna mounted
+ elsewhere in the rocket.
+ </para>
+ </section>
+ <section>
+ <title>On the Ground</title>
+ <para>
+ To receive the data stream from the rocket, you need an antenna and short
+ feedline connected to one of our [TeleDongle](../TeleDongle) units. The
+ TeleDongle in turn plugs directly into the USB port on a notebook
+ computer. Because TeleDongle looks like a simple serial port, your computer
+ does not require special device drivers... just plug it in.
+ </para>
+ <para>
+ Right now, all of our application software is written for Linux. However,
+ because we understand that many people run Windows or MacOS, we are working
+ on a new ground station program written in Java that should work on all
+ operating systems.
+ </para>
+ <para>
+ After the flight, you can use the RF link to extract the more detailed data
+ logged in the rocket, or you can use a mini USB cable to plug into the
+ TeleMetrum board directly. Pulling out the data without having to open up
+ the rocket is pretty cool! A USB cable is also how you charge the LiPo
+ battery, so you'll want one of those anyway... the same cable used by lots
+ of digital cameras and other modern electronic stuff will work fine.
+ </para>
+ <para>
+ If your rocket lands out of sight, you may enjoy having a hand-held GPS
+ receiver, so that you can put in a waypoint for the last reported rocket
+ position before touch-down. This makes looking for your rocket a lot like
+ Geo-Cacheing... just go to the waypoint and look around starting from there.
+ </para>
+ <para>
+ You may also enjoy having a ham radio "HT" that covers the 70cm band... you
+ can use that with your antenna to direction-find the rocket on the ground
+ the same way you can use a Walston or Beeline tracker. This can be handy
+ if the rocket is hiding in sage brush or a tree, or if the last GPS position
+ doesn't get you close enough because the rocket dropped into a canyon, or
+ the wind is blowing it across a dry lake bed, or something like that... Keith
+ and Bdale both currently own and use the Yaesu VX-7R at launches.
+ </para>
+ <para>
+ So, to recap, on the ground the hardware you'll need includes:
+ <orderedlist inheritnum='inherit' numeration='arabic'>
+ <listitem>
+ an antenna and feedline
+ </listitem>
+ <listitem>
+ a TeleDongle
+ </listitem>
+ <listitem>
+ a notebook computer
+ </listitem>
+ <listitem>
+ optionally, a handheld GPS receiver
+ </listitem>
+ <listitem>
+ optionally, an HT or receiver covering 435 Mhz
+ </listitem>
+ </orderedlist>
+ </para>
+ <para>
+ The best hand-held commercial directional antennas we've found for radio
+ direction finding rockets are from
+ <ulink url="http://www.arrowantennas.com/" >
+ Arrow Antennas.
+ </ulink>
+ The 440-3 and 440-5 are both good choices for finding a
+ TeleMetrum-equipped rocket when used with a suitable 70cm HT.
+ </para>
+ </section>
+ <section>
+ <title>Data Analysis</title>
+ <para>
+ Our software makes it easy to log the data from each flight, both the
+ telemetry received over the RF link during the flight itself, and the more
+ complete data log recorded in the DataFlash memory on the TeleMetrum
+ board. Once this data is on your computer, our postflight tools make it
+ easy to quickly get to the numbers everyone wants, like apogee altitude,
+ max acceleration, and max velocity. You can also generate and view a
+ standard set of plots showing the altitude, acceleration, and
+ velocity of the rocket during flight. And you can even export a data file
+ useable with Google Maps and Google Earth for visualizing the flight path
+ in two or three dimensions!
+ </para>
+ <para>
+ Our ultimate goal is to emit a set of files for each flight that can be
+ published as a web page per flight, or just viewed on your local disk with
+ a web browser.
+ </para>
+ </section>
+ <section>
+ <title>Future Plans</title>
+ <para>
+ In the future, we intend to offer "companion boards" for the rocket that will
+ plug in to TeleMetrum to collect additional data, provide more pyro channels,
+ and so forth. A reference design for a companion board will be documented
+ soon, and will be compatible with open source Arduino programming tools.
+ </para>
+ <para>
+ We are also working on the design of a hand-held ground terminal that will
+ allow monitoring the rocket's status, collecting data during flight, and
+ logging data after flight without the need for a notebook computer on the
+ flight line. Particularly since it is so difficult to read most notebook
+ screens in direct sunlight, we think this will be a great thing to have.
+ </para>
+ <para>
+ Because all of our work is open, both the hardware designs and the software,
+ if you have some great idea for an addition to the current Altus Metrum family,
+ feel free to dive in and help! Or let us know what you'd like to see that
+ we aren't already working on, and maybe we'll get excited about it too...
+ </para>
+ </section>
+ </section>
+ <section>
+ <title>
+ How GPS Works
+ </title>
+ <para>
+ Placeholder.
+ </para>
+ </section>
+ </chapter>
+ </book>
+