diff options
| -rw-r--r-- | doc/micropeak.xsl | 183 |
1 files changed, 181 insertions, 2 deletions
diff --git a/doc/micropeak.xsl b/doc/micropeak.xsl index aa1adaef..6c7bc289 100644 --- a/doc/micropeak.xsl +++ b/doc/micropeak.xsl @@ -44,6 +44,15 @@ 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> @@ -176,6 +185,176 @@ NAR #88757, TRA #12200 </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 right over + 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> <title>Barometric Sensor</title> @@ -193,8 +372,8 @@ NAR #88757, TRA #12200 <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> |