"/usr/share/xml/docbook/schema/dtd/4.5/docbookx.dtd">
<book>
<title>MicroPeak Owner's Manual</title>
- <subtitle>A peak-recording altimeter for hobby rocketry</subtitle>
+ <subtitle>A recording altimeter for hobby rocketry</subtitle>
<bookinfo>
<author>
<firstname>Keith</firstname>
Add comments about EEPROM storage format and programming jig.
</revremark>
</revision>
+ <revision>
+ <revnumber>1.2</revnumber>
+ <date>20 January 2013</date>
+ <revremark>
+ Add documentation for the MicroPeak USB adapter board. Note
+ the switch to a Kalman filter for peak altitude
+ determination.
+ </revremark>
+ </revision>
</revhistory>
</bookinfo>
- <acknowledgements>
+ <dedication>
+ <title>Acknowledgements</title>
<para>
Thanks to John Lyngdal for suggesting that we build something like this.
</para>
NAR #88757, TRA #12200
</literallayout>
</para>
- </acknowledgements>
+ </dedication>
<chapter>
<title>Quick Start Guide</title>
<para>
<para>
Finish preparing the rocket for flight. After the
previous flight data have been reported, MicroPeak waits for
- 30 seconds before starting to check for launch. This gives
+ one minute before starting to check for launch. This gives
you time to finish assembling the rocket. As those
activities might cause pressure changes inside the airframe,
MicroPeak might accidentally detect boost. If you need to do
- anything to the airframe after the 30 second window passes,
+ anything to the airframe after the one minute window passes,
make sure to be careful not to disturb the altimeter. The
- LED will remain dark during the 30 second delay, but after
+ LED will remain dark during the one minute delay, but after
that, it will start blinking once every 3 seconds.
</para>
</listitem>
<listitem>
<para>
- Fly the rocket. Once the rocket passes about 10m in height
- (32 feet), the micro-controller will record the ground
+ Fly the rocket. Once the rocket passes about 30m in height
+ (100 feet), the micro-controller will record the ground
pressure and track the pressure seen during the flight. In
this mode, the LED flickers rapidly. When the rocket lands,
and the pressure stabilizes, the micro-controller will record
charge gasses.
</para>
</chapter>
+ <chapter>
+ <title>The MicroPeak USB adapter</title>
+ <para>
+ MicroPeak stores barometric pressure information for the first
+ 48 seconds of the flight in on-board non-volatile memory. The
+ contents of this memory can be downloaded to a computer using
+ the MicroPeak USB adapter.
+ </para>
+ <section>
+ <title>Installing the MicroPeak software</title>
+ <para>
+ The MicroPeak application runs on Linux, Mac OS X and
+ Windows. You can download the latest version from
+ <ulink url="http://altusmetrum.org/AltOS"/>.
+ </para>
+ <para>
+ On Mac OS X and Windows, the FTDI USB device driver needs to
+ be installed. A compatible version of this driver is included
+ with the MicroPeak application, but you may want to download a
+ newer version from <ulink
+ url="http://www.ftdichip.com/FTDrivers.htm"/>.
+ </para>
+ </section>
+ <section>
+ <title>Downloading Micro Peak data</title>
+ <itemizedlist>
+ <listitem>
+ <para>
+ Connect the MicroPeak USB adapter to a USB cable and plug it
+ in to your computer.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Start the MicroPeak application, locate the File menu and
+ select the Download entry.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ The MicroPeak USB adapter has a small phototransistor on
+ the end of the board furthest from the USB
+ connector. Locate this and place the LED on the MicroPeak
+ directly in contact with it. The MicroPeak LED and the
+ MicroPeak USB adapter photo need to be touching—even a
+ millimeters of space between them will reduce the light
+ intensity from the LED enough that the phototransistor
+ will not sense it. Turn on the MicroPeak board and adjust
+ the position until the blue LED on the MicroPeak USB
+ adapter blinks in time with the orange LED on the
+ MicroPeak board.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ After the maximum flight height is reported, MicroPeak will
+ pause for a few seconds, blink the LED four times rapidly
+ and then send the data in one long blur on the LED. The
+ MicroPeak application should receive the data. When it does,
+ it will present the data in a graph and offer to save the
+ data to a file. If not, you can power cycle the MicroPeak
+ board and try again.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </section>
+ <section>
+ <title>Analyzing MicroPeak Data</title>
+ <para>
+ The MicroPeak application can present flight data in the form
+ of a graph, a collection of computed statistics or in tabular
+ form.
+ </para>
+ <para>
+ MicroPeak collects raw barometric pressure data which is
+ then used to compute the remaining data. Altitude is computed
+ through a standard atmospheric model. Absolute error in this
+ data will be affected by local atmospheric
+ conditions. Fortunately, these errors tend to mostly cancel
+ out, so the error in the height computation is much smaller
+ than the error in altitude would be.
+ </para>
+ <para>
+ Speed and acceleration are computed by first smoothing the
+ height data with a Gaussian window averaging filter. For speed
+ data, this average uses seven samples. For acceleration data,
+ eleven samples are used. These were chosen to provide
+ reasonably smooth speed and acceleration data, which would
+ otherwise be swamped with noise.
+ </para>
+ <para>
+ Under the Graph tab, the height, speed and acceleration values
+ are displayed together. You can zoom in on the graph by
+ clicking and dragging to sweep out an area of
+ interest. Right-click on the plot to bring up a menu that will
+ let you save, copy or print the graph.
+ </para>
+ <para>
+ The Statistics tab presents overall data from the flight. Note
+ that the Maximum height value is taken from the minumum
+ pressure captured in flight, and may be different from the
+ apparant apogee value as the on-board data are sampled twice
+ as fast as the recorded values, or because the true apogee
+ occurred after the on-board memory was full. Each value is
+ presented in several units as appropriate.
+ </para>
+ <para>
+ A table consisting of the both the raw barometric pressure
+ data and values computed from that for each recorded time.
+ </para>
+ <para>
+ The File menu has operations to open existing flight logs,
+ Download new data from MicroPeak, Save a copy of the flight
+ log to a new file, Export the tabular data (as seen in the Raw
+ Data tab) to a file, change the application Preferences, Close
+ the current window or close all windows and Exit the
+ application.
+ </para>
+ </section>
+ <section>
+ <title>Configuring the MicroPeak application</title>
+ <para>
+ The MicroPeak application has a few user settings which are
+ configured through the Preferences dialog, which can be
+ accessed from the File menu.
+ <itemizedlist>
+ <listitem>
+ <para>
+ The Log Directory is where flight data will be saved to
+ and loaded from by default. Of course, you can always
+ navigate to other directories in the file chooser windows,
+ this setting is just the starting point.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ If you prefer to see your graph data in feet and
+ miles per hour instead of meters and meters per second,
+ you can select Imperial Units.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ To see what data is actually arriving over the serial
+ port, start the MicroPeak application from a command
+ prompt and select the Serial Debug option. This can be
+ useful in debugging serial communication problems, but
+ most people need never choose this.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ You can adjust the size of the text in the Statistics tab
+ by changing the Font size preference. There are three
+ settings, with luck one will both fit on your screen and
+ provide readable values.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ The Look & feel menu shows a list of available
+ application appearance choices. By default, the MicroPeak
+ application tries to blend in with other applications, but
+ you may choose some other appearance if you like.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+ <para>
+ Note that MicroPeak shares a subset of the AltosUI
+ preferences, so if you use both of these applications, change
+ in one application will affect the other.
+ </para>
+ </section>
+ </chapter>
<chapter>
<title>Technical Information</title>
<section>
<para>
Ground pressure is computed from an average of 16 samples,
taken while the altimeter is at rest. Flight pressure is
- computed from an exponential IIR filter designed to smooth out
- transients caused by mechanical stress on the barometer.
+ computed from a Kalman filter designed to smooth out any minor
+ noise in the sensor values.
</para>
</section>
<section>
<section>
<title>Lithium Battery</title>
<para>
- The CR1025 battery used by MicroPeak holes 30mAh of power,
+ The CR1025 battery used by MicroPeak holds 30mAh of power,
which is sufficient to run for over 40 hours. Because
MicroPeak powers down on landing, run time includes only time
sitting on the launch pad or during flight.
with the negative battery terminal.
</para>
<para>
- Shipping restrictions prevent us from including a CR1025
- battery with MicroPeak. Many stores carry CR1025 batteries as
- they are commonly used in small electronic devices such as
- flash lights.
+ Shipping restrictions may prevent us from including a CR1025
+ battery with MicroPeak. If so, many stores carry CR1025
+ batteries as they are commonly used in small electronic
+ devices such as flash lights.
</para>
</section>
<section>
projects / fw / altos / blobdiff