-<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>AltOS Telemetry</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="article"><div class="titlepage"><div><div><h2 class="title"><a name="idm
6236032"></a>AltOS Telemetry</h2></div><div><h3 class="subtitle"><i>Packet Definitions</i></h3></div><div><div class="author"><h3 class="author"><span class="firstname">Keith</span> <span class="surname">Packard</span></h3></div></div><div><p class="copyright">Copyright © 2011 Keith Packard</p></div><div><div class="legalnotice"><a name="idp47813152"></a><p>
+<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>AltOS Telemetry</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="article"><div class="titlepage"><div><div><h2 class="title"><a name="idm
4108400"></a>AltOS Telemetry</h2></div><div><h3 class="subtitle"><i>Packet Definitions</i></h3></div><div><div class="author"><h3 class="author"><span class="firstname">Keith</span> <span class="surname">Packard</span></h3></div></div><div><p class="copyright">Copyright © 2011 Keith Packard</p></div><div><div class="legalnotice"><a name="idp48154352"></a><p>
This document is released under the terms of the
<a class="ulink" href="http://creativecommons.org/licenses/by-sa/3.0/" target="_top">
Creative Commons ShareAlike 3.0
</a>
license.
- </p></div></div><div><div class="revhistory"><table style="border-style:solid; width:100%;" summary="Revision History"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr><tr><td align="left">Revision 0.1</td><td align="left">01 July 2011</td></tr><tr><td align="left" colspan="2">Initial content</td></tr></table></div></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp4
8622704">1. Packet Format Design</a></span></dt><dt><span class="section"><a href="#idp48625696">2. Packet Formats</a></span></dt><dd><dl><dt><span class="section"><a href="#idp48626896">2.1. Packet Header</a></span></dt><dt><span class="section"><a href="#idp47916992">2.2. Sensor Data</a></span></dt><dt><span class="section"><a href="#idp54290816">2.3. Configuration Data</a></span></dt><dt><span class="section"><a href="#idp54326544">2.4. GPS Location</a></span></dt><dt><span class="section"><a href="#idp54412352">2.5. GPS Satellite Data</a></span></dt></dl></dd><dt><span class="section"><a href="#idp54453072">3. Data Transmission</a></span></dt><dd><dl><dt><span class="section"><a href="#idp54454480">3.1. Modulation Scheme</a></span></dt><dt><span class="section"><a href="#idp54471888">3.2. Error Correction</a></span></dt></dl></dd><dt><span class="section"><a href="#idp54486096">4. TeleDongle packet format</a></span></dt><dt><span class="section"><a href="#idp54508656">5. History and Motivation</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp48622704"></a>1. Packet Format Design</h2></div></div></div><p>
+ </p></div></div><div><div class="revhistory"><table style="border-style:solid; width:100%;" summary="Revision History"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr><tr><td align="left">Revision 0.1</td><td align="left">01 July 2011</td></tr><tr><td align="left" colspan="2">Initial content</td></tr></table></div></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp4
7962800">1. Packet Format Design</a></span></dt><dt><span class="section"><a href="#idp47965792">2. Packet Formats</a></span></dt><dd><dl><dt><span class="section"><a href="#idp47966992">2.1. Packet Header</a></span></dt><dt><span class="section"><a href="#idp48032752">2.2. Sensor Data</a></span></dt><dt><span class="section"><a href="#idp53932256">2.3. Configuration Data</a></span></dt><dt><span class="section"><a href="#idp53967840">2.4. GPS Location</a></span></dt><dt><span class="section"><a href="#idp54053552">2.5. GPS Satellite Data</a></span></dt></dl></dd><dt><span class="section"><a href="#idp54094272">3. Data Transmission</a></span></dt><dd><dl><dt><span class="section"><a href="#idp54095680">3.1. Modulation Scheme</a></span></dt><dt><span class="section"><a href="#idp54113088">3.2. Error Correction</a></span></dt></dl></dd><dt><span class="section"><a href="#idp54127296">4. TeleDongle packet format</a></span></dt><dt><span class="section"><a href="#idp54150000">5. History and Motivation</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp47962800"></a>1. Packet Format Design</h2></div></div></div><p>
AltOS telemetry data is split into multiple different packets,
all the same size, but each includs an identifier so that the
ground station can distinguish among different types. A single
All packet types start with a five byte header which encodes the
device serial number, device clock value and the packet
type. The remaining 27 bytes encode type-specific data.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp4
8625696"></a>2. Packet Formats</h2></div></div></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp4
7965792"></a>2. Packet Formats</h2></div></div></div><p>
This section first defines the packet header common to all packets
and then the per-packet data layout.
- </p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp4
8626896"></a>2.1. Packet Header</h3></div></div></div><div class="table"><a name="idp48627568"></a><p class="title"><b>Table 1. Telemetry Packet Header</b></p><div class="table-contents"><table summary="Telemetry Packet Header" border="1"><colgroup><col align="center" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">0</td><td align="center">uint16_t</td><td align="left">serial</td><td align="left">Device serial Number</td></tr><tr><td align="center">2</td><td align="center">uint16_t</td><td align="left">tick</td><td align="left">Device time in 100ths of a second</td></tr><tr><td align="center">4</td><td align="center">uint8_t</td><td align="left">type</td><td align="left">Packet type</td></tr><tr><td align="center">5</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"><p>
+ </p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp4
7966992"></a>2.1. Packet Header</h3></div></div></div><div class="table"><a name="idp47967664"></a><p class="title"><b>Table 1. Telemetry Packet Header</b></p><div class="table-contents"><table summary="Telemetry Packet Header" border="1"><colgroup><col align="center" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">0</td><td align="center">uint16_t</td><td align="left">serial</td><td align="left">Device serial Number</td></tr><tr><td align="center">2</td><td align="center">uint16_t</td><td align="left">tick</td><td align="left">Device time in 100ths of a second</td></tr><tr><td align="center">4</td><td align="center">uint8_t</td><td align="left">type</td><td align="left">Packet type</td></tr><tr><td align="center">5</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"><p>
Each packet starts with these five bytes which serve to identify
which device has transmitted the packet, when it was transmitted
and what the rest of the packet contains.
- </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp4
7916992"></a>2.2. Sensor Data</h3></div></div></div><div class="informaltable"><table border="0"><colgroup><col align="center" class="Offset"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Type</th><th align="left">Description</th></tr></thead><tbody><tr><td align="center">0x01</td><td align="left">TeleMetrum Sensor Data</td></tr><tr><td align="center">0x02</td><td align="left">TeleMini Sensor Data</td></tr><tr><td align="center">0x03</td><td align="left">TeleNano Sensor Data</td></tr></tbody></table></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp4
8032752"></a>2.2. Sensor Data</h3></div></div></div><div class="informaltable"><table border="0"><colgroup><col align="center" class="Offset"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Type</th><th align="left">Description</th></tr></thead><tbody><tr><td align="center">0x01</td><td align="left">TeleMetrum Sensor Data</td></tr><tr><td align="center">0x02</td><td align="left">TeleMini Sensor Data</td></tr><tr><td align="center">0x03</td><td align="left">TeleNano Sensor Data</td></tr></tbody></table></div><p>
TeleMetrum, TeleMini and TeleNano share this same packet
format for sensor data. Each uses a distinct packet type so
that the receiver knows which data values are valid and which
Sensor Data packets are transmitted once per second on the
ground, 10 times per second during ascent and once per second
during descent and landing
- </p><div class="table"><a name="idp4
7739440"></a><p class="title"><b>Table 2. Sensor Packet Contents</b></p><div class="table-contents"><table summary="Sensor Packet Contents" border="1"><colgroup><col align="center" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">5</td><td align="center">uint8_t</td><td align="left">state</td><td align="left">Flight state</td></tr><tr><td align="center">6</td><td align="center">int16_t</td><td align="left">accel</td><td align="left">accelerometer (TM only)</td></tr><tr><td align="center">8</td><td align="center">int16_t</td><td align="left">pres</td><td align="left">pressure sensor</td></tr><tr><td align="center">10</td><td align="center">int16_t</td><td align="left">temp</td><td align="left">temperature sensor</td></tr><tr><td align="center">12</td><td align="center">int16_t</td><td align="left">v_batt</td><td align="left">battery voltage</td></tr><tr><td align="center">14</td><td align="center">int16_t</td><td align="left">sense_d</td><td align="left">drogue continuity sense (TM/Tm)</td></tr><tr><td align="center">16</td><td align="center">int16_t</td><td align="left">sense_m</td><td align="left">main continuity sense (TM/Tm)</td></tr><tr><td align="center">18</td><td align="center">int16_t</td><td align="left">acceleration</td><td align="left">m/s² * 16</td></tr><tr><td align="center">20</td><td align="center">int16_t</td><td align="left">speed</td><td align="left">m/s * 16</td></tr><tr><td align="center">22</td><td align="center">int16_t</td><td align="left">height</td><td align="left">m</td></tr><tr><td align="center">24</td><td align="center">int16_t</td><td align="left">ground_pres</td><td align="left">Average barometer reading on ground</td></tr><tr><td align="center">26</td><td align="center">int16_t</td><td align="left">ground_accel</td><td align="left">TM</td></tr><tr><td align="center">28</td><td align="center">int16_t</td><td align="left">accel_plus_g</td><td align="left">TM</td></tr><tr><td align="center">30</td><td align="center">int16_t</td><td align="left">accel_minus_g</td><td align="left">TM</td></tr><tr><td align="center">32</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp54290816"></a>2.3. Configuration Data</h3></div></div></div><div class="informaltable"><table border="0"><colgroup><col align="center" class="Offset"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Type</th><th align="left">Description</th></tr></thead><tbody><tr><td align="center">0x04</td><td align="left">Configuration Data</td></tr></tbody></table></div><p>
+ </p><div class="table"><a name="idp4
8044816"></a><p class="title"><b>Table 2. Sensor Packet Contents</b></p><div class="table-contents"><table summary="Sensor Packet Contents" border="1"><colgroup><col align="center" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">5</td><td align="center">uint8_t</td><td align="left">state</td><td align="left">Flight state</td></tr><tr><td align="center">6</td><td align="center">int16_t</td><td align="left">accel</td><td align="left">accelerometer (TM only)</td></tr><tr><td align="center">8</td><td align="center">int16_t</td><td align="left">pres</td><td align="left">pressure sensor</td></tr><tr><td align="center">10</td><td align="center">int16_t</td><td align="left">temp</td><td align="left">temperature sensor</td></tr><tr><td align="center">12</td><td align="center">int16_t</td><td align="left">v_batt</td><td align="left">battery voltage</td></tr><tr><td align="center">14</td><td align="center">int16_t</td><td align="left">sense_d</td><td align="left">drogue continuity sense (TM/Tm)</td></tr><tr><td align="center">16</td><td align="center">int16_t</td><td align="left">sense_m</td><td align="left">main continuity sense (TM/Tm)</td></tr><tr><td align="center">18</td><td align="center">int16_t</td><td align="left">acceleration</td><td align="left">m/s² * 16</td></tr><tr><td align="center">20</td><td align="center">int16_t</td><td align="left">speed</td><td align="left">m/s * 16</td></tr><tr><td align="center">22</td><td align="center">int16_t</td><td align="left">height</td><td align="left">m</td></tr><tr><td align="center">24</td><td align="center">int16_t</td><td align="left">ground_pres</td><td align="left">Average barometer reading on ground</td></tr><tr><td align="center">26</td><td align="center">int16_t</td><td align="left">ground_accel</td><td align="left">TM</td></tr><tr><td align="center">28</td><td align="center">int16_t</td><td align="left">accel_plus_g</td><td align="left">TM</td></tr><tr><td align="center">30</td><td align="center">int16_t</td><td align="left">accel_minus_g</td><td align="left">TM</td></tr><tr><td align="center">32</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp53932256"></a>2.3. Configuration Data</h3></div></div></div><div class="informaltable"><table border="0"><colgroup><col align="center" class="Offset"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Type</th><th align="left">Description</th></tr></thead><tbody><tr><td align="center">0x04</td><td align="left">Configuration Data</td></tr></tbody></table></div><p>
This provides a description of the software installed on the
flight computer as well as any user-specified configuration data.
</p><p>
Configuration data packets are transmitted once per second
during all phases of the flight
- </p><div class="table"><a name="idp5
4300096"></a><p class="title"><b>Table 3. Sensor Packet Contents</b></p><div class="table-contents"><table summary="Sensor Packet Contents" border="1"><colgroup><col align="center" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">5</td><td align="center">uint8_t</td><td align="left">type</td><td align="left">Device type</td></tr><tr><td align="center">6</td><td align="center">uint16_t</td><td align="left">flight</td><td align="left">Flight number</td></tr><tr><td align="center">8</td><td align="center">uint8_t</td><td align="left">config_major</td><td align="left">Config major version</td></tr><tr><td align="center">9</td><td align="center">uint8_t</td><td align="left">config_minor</td><td align="left">Config minor version</td></tr><tr><td align="center">10</td><td align="center">uint16_t</td><td align="left">apogee_delay</td><td align="left">Apogee deploy delay in seconds</td></tr><tr><td align="center">12</td><td align="center">uint16_t</td><td align="left">main_deploy</td><td align="left">Main deploy alt in meters</td></tr><tr><td align="center">14</td><td align="center">uint16_t</td><td align="left">flight_log_max</td><td align="left">Maximum flight log size (kB)</td></tr><tr><td align="center">16</td><td align="center">char</td><td align="left">callsign[8]</td><td align="left">Radio operator identifier</td></tr><tr><td align="center">24</td><td align="center">char</td><td align="left">version[8]</td><td align="left">Software version identifier</td></tr><tr><td align="center">32</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp54326544"></a>2.4. GPS Location</h3></div></div></div><div class="informaltable"><table border="0"><colgroup><col align="center" class="Offset"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Type</th><th align="left">Description</th></tr></thead><tbody><tr><td align="center">0x05</td><td align="left">GPS Location</td></tr></tbody></table></div><p>
+ </p><div class="table"><a name="idp5
3941440"></a><p class="title"><b>Table 3. Sensor Packet Contents</b></p><div class="table-contents"><table summary="Sensor Packet Contents" border="1"><colgroup><col align="center" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">5</td><td align="center">uint8_t</td><td align="left">type</td><td align="left">Device type</td></tr><tr><td align="center">6</td><td align="center">uint16_t</td><td align="left">flight</td><td align="left">Flight number</td></tr><tr><td align="center">8</td><td align="center">uint8_t</td><td align="left">config_major</td><td align="left">Config major version</td></tr><tr><td align="center">9</td><td align="center">uint8_t</td><td align="left">config_minor</td><td align="left">Config minor version</td></tr><tr><td align="center">10</td><td align="center">uint16_t</td><td align="left">apogee_delay</td><td align="left">Apogee deploy delay in seconds</td></tr><tr><td align="center">12</td><td align="center">uint16_t</td><td align="left">main_deploy</td><td align="left">Main deploy alt in meters</td></tr><tr><td align="center">14</td><td align="center">uint16_t</td><td align="left">flight_log_max</td><td align="left">Maximum flight log size (kB)</td></tr><tr><td align="center">16</td><td align="center">char</td><td align="left">callsign[8]</td><td align="left">Radio operator identifier</td></tr><tr><td align="center">24</td><td align="center">char</td><td align="left">version[8]</td><td align="left">Software version identifier</td></tr><tr><td align="center">32</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp53967840"></a>2.4. GPS Location</h3></div></div></div><div class="informaltable"><table border="0"><colgroup><col align="center" class="Offset"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Type</th><th align="left">Description</th></tr></thead><tbody><tr><td align="center">0x05</td><td align="left">GPS Location</td></tr></tbody></table></div><p>
This packet provides all of the information available from the
Venus SkyTraq GPS receiver—position, time, speed and precision
estimates.
</p><p>
GPS Location packets are transmitted once per second during
all phases of the flight
- </p><div class="table"><a name="idp5
4336208"></a><p class="title"><b>Table 4. GPS Location Packet Contents</b></p><div class="table-contents"><table summary="GPS Location Packet Contents" border="1"><colgroup><col align="center" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">5</td><td align="center">uint8_t</td><td align="left">flags</td><td align="left">See GPS Flags table below</td></tr><tr><td align="center">6</td><td align="center">int16_t</td><td align="left">altitude</td><td align="left">m</td></tr><tr><td align="center">8</td><td align="center">int32_t</td><td align="left">latitude</td><td align="left">degrees * 10<sup>7</sup></td></tr><tr><td align="center">12</td><td align="center">int32_t</td><td align="left">longitude</td><td align="left">degrees * 10<sup>7</sup></td></tr><tr><td align="center">16</td><td align="center">uint8_t</td><td align="left">year</td><td class="auto-generated"> </td></tr><tr><td align="center">17</td><td align="center">uint8_t</td><td align="left">month</td><td class="auto-generated"> </td></tr><tr><td align="center">18</td><td align="center">uint8_t</td><td align="left">day</td><td class="auto-generated"> </td></tr><tr><td align="center">19</td><td align="center">uint8_t</td><td align="left">hour</td><td class="auto-generated"> </td></tr><tr><td align="center">20</td><td align="center">uint8_t</td><td align="left">minute</td><td class="auto-generated"> </td></tr><tr><td align="center">21</td><td align="center">uint8_t</td><td align="left">second</td><td class="auto-generated"> </td></tr><tr><td align="center">22</td><td align="center">uint8_t</td><td align="left">pdop</td><td align="left">* 5</td></tr><tr><td align="center">23</td><td align="center">uint8_t</td><td align="left">hdop</td><td align="left">* 5</td></tr><tr><td align="center">24</td><td align="center">uint8_t</td><td align="left">vdop</td><td align="left">* 5</td></tr><tr><td align="center">25</td><td align="center">uint8_t</td><td align="left">mode</td><td align="left">See GPS Mode table below</td></tr><tr><td align="center">26</td><td align="center">uint16_t</td><td align="left">ground_speed</td><td align="left">cm/s</td></tr><tr><td align="center">28</td><td align="center">int16_t</td><td align="left">climb_rate</td><td align="left">cm/s</td></tr><tr><td align="center">30</td><td align="center">uint8_t</td><td align="left">course</td><td align="left">/ 2</td></tr><tr><td align="center">31</td><td align="center">uint8_t</td><td align="left">unused[1]</td><td class="auto-generated"> </td></tr><tr><td align="center">32</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"><p>
+ </p><div class="table"><a name="idp5
3977504"></a><p class="title"><b>Table 4. GPS Location Packet Contents</b></p><div class="table-contents"><table summary="GPS Location Packet Contents" border="1"><colgroup><col align="center" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">5</td><td align="center">uint8_t</td><td align="left">flags</td><td align="left">See GPS Flags table below</td></tr><tr><td align="center">6</td><td align="center">int16_t</td><td align="left">altitude</td><td align="left">m</td></tr><tr><td align="center">8</td><td align="center">int32_t</td><td align="left">latitude</td><td align="left">degrees * 10<sup>7</sup></td></tr><tr><td align="center">12</td><td align="center">int32_t</td><td align="left">longitude</td><td align="left">degrees * 10<sup>7</sup></td></tr><tr><td align="center">16</td><td align="center">uint8_t</td><td align="left">year</td><td class="auto-generated"> </td></tr><tr><td align="center">17</td><td align="center">uint8_t</td><td align="left">month</td><td class="auto-generated"> </td></tr><tr><td align="center">18</td><td align="center">uint8_t</td><td align="left">day</td><td class="auto-generated"> </td></tr><tr><td align="center">19</td><td align="center">uint8_t</td><td align="left">hour</td><td class="auto-generated"> </td></tr><tr><td align="center">20</td><td align="center">uint8_t</td><td align="left">minute</td><td class="auto-generated"> </td></tr><tr><td align="center">21</td><td align="center">uint8_t</td><td align="left">second</td><td class="auto-generated"> </td></tr><tr><td align="center">22</td><td align="center">uint8_t</td><td align="left">pdop</td><td align="left">* 5</td></tr><tr><td align="center">23</td><td align="center">uint8_t</td><td align="left">hdop</td><td align="left">* 5</td></tr><tr><td align="center">24</td><td align="center">uint8_t</td><td align="left">vdop</td><td align="left">* 5</td></tr><tr><td align="center">25</td><td align="center">uint8_t</td><td align="left">mode</td><td align="left">See GPS Mode table below</td></tr><tr><td align="center">26</td><td align="center">uint16_t</td><td align="left">ground_speed</td><td align="left">cm/s</td></tr><tr><td align="center">28</td><td align="center">int16_t</td><td align="left">climb_rate</td><td align="left">cm/s</td></tr><tr><td align="center">30</td><td align="center">uint8_t</td><td align="left">course</td><td align="left">/ 2</td></tr><tr><td align="center">31</td><td align="center">uint8_t</td><td align="left">unused[1]</td><td class="auto-generated"> </td></tr><tr><td align="center">32</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"><p>
Packed into a one byte field are status flags and the count of
satellites used to compute the position fix. Note that this
number may be lower than the number of satellites being
tracked; the receiver will not use information from satellites
with weak signals or which are close enough to the horizon to
have significantly degraded position accuracy.
- </p><div class="table"><a name="idp54
376496"></a><p class="title"><b>Table 5. GPS Flags</b></p><div class="table-contents"><table summary="GPS Flags" border="1"><colgroup><col align="center" class="bits"><col align="left" class="name"><col align="left" class="description"></colgroup><thead><tr><th align="center">Bits</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">0-3</td><td align="left">nsats</td><td align="left">Number of satellites in solution</td></tr><tr><td align="center">4</td><td align="left">valid</td><td align="left">GPS solution is valid</td></tr><tr><td align="center">5</td><td align="left">running</td><td align="left">GPS receiver is operational</td></tr><tr><td align="center">6</td><td align="left">date_valid</td><td align="left">Reported date is valid</td></tr><tr><td align="center">7</td><td align="left">course_valid</td><td align="left">ground speed, course and climb rates are valid</td></tr></tbody></table></div></div><br class="table-break"><p>
+ </p><div class="table"><a name="idp54
017792"></a><p class="title"><b>Table 5. GPS Flags</b></p><div class="table-contents"><table summary="GPS Flags" border="1"><colgroup><col align="center" class="bits"><col align="left" class="name"><col align="left" class="description"></colgroup><thead><tr><th align="center">Bits</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">0-3</td><td align="left">nsats</td><td align="left">Number of satellites in solution</td></tr><tr><td align="center">4</td><td align="left">valid</td><td align="left">GPS solution is valid</td></tr><tr><td align="center">5</td><td align="left">running</td><td align="left">GPS receiver is operational</td></tr><tr><td align="center">6</td><td align="left">date_valid</td><td align="left">Reported date is valid</td></tr><tr><td align="center">7</td><td align="left">course_valid</td><td align="left">ground speed, course and climb rates are valid</td></tr></tbody></table></div></div><br class="table-break"><p>
Here are all of the valid GPS operational modes. Altus Metrum
products will only ever report 'N' (not valid), 'A'
(Autonomous) modes or 'E' (Estimated). The remaining modes
are either testing modes or require additional data.
- </p><div class="table"><a name="idp54
393760"></a><p class="title"><b>Table 6. GPS Mode</b></p><div class="table-contents"><table summary="GPS Mode" border="1"><colgroup><col align="center" class="value"><col align="center" class="name"><col align="left" class="description"></colgroup><thead><tr><th align="center">Mode</th><th align="center">Name</th><th align="center">Decsription</th></tr></thead><tbody><tr><td align="center">N</td><td align="center">Not Valid</td><td align="left">All data are invalid</td></tr><tr><td align="center">A</td><td align="center">Autonomous mode</td><td align="left">Data are derived from satellite data</td></tr><tr><td align="center">D</td><td align="center">Differential Mode</td><td align="left">
+ </p><div class="table"><a name="idp54
035008"></a><p class="title"><b>Table 6. GPS Mode</b></p><div class="table-contents"><table summary="GPS Mode" border="1"><colgroup><col align="center" class="value"><col align="center" class="name"><col align="left" class="description"></colgroup><thead><tr><th align="center">Mode</th><th align="center">Name</th><th align="center">Decsription</th></tr></thead><tbody><tr><td align="center">N</td><td align="center">Not Valid</td><td align="left">All data are invalid</td></tr><tr><td align="center">A</td><td align="center">Autonomous mode</td><td align="left">Data are derived from satellite data</td></tr><tr><td align="center">D</td><td align="center">Differential Mode</td><td align="left">
Data are augmented with differential data from a
known ground station. The SkyTraq unit in TeleMetrum
does not support this mode
</td></tr><tr><td align="center">E</td><td align="center">Estimated</td><td align="left">
Data are estimated using dead reckoning from the
last known data
- </td></tr><tr><td align="center">M</td><td align="center">Manual</td><td align="left">Data were entered manually</td></tr><tr><td align="center">S</td><td align="center">Simulated</td><td align="left">GPS receiver testing mode</td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp54
412352"></a>2.5. GPS Satellite Data</h3></div></div></div><div class="informaltable"><table border="0"><colgroup><col align="center" class="Offset"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Type</th><th align="left">Description</th></tr></thead><tbody><tr><td align="center">0x06</td><td align="left">GPS Satellite Data</td></tr></tbody></table></div><p>
+ </td></tr><tr><td align="center">M</td><td align="center">Manual</td><td align="left">Data were entered manually</td></tr><tr><td align="center">S</td><td align="center">Simulated</td><td align="left">GPS receiver testing mode</td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp54
053552"></a>2.5. GPS Satellite Data</h3></div></div></div><div class="informaltable"><table border="0"><colgroup><col align="center" class="Offset"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Type</th><th align="left">Description</th></tr></thead><tbody><tr><td align="center">0x06</td><td align="left">GPS Satellite Data</td></tr></tbody></table></div><p>
This packet provides space vehicle identifiers and signal
quality information in the form of a C/N1 number for up to 12
satellites. The order of the svids is not specified.
</p><p>
GPS Satellite data are transmitted once per second during all
phases of the flight.
- </p><div class="table"><a name="idp54
421888"></a><p class="title"><b>Table 7. GPS Satellite Data Contents</b></p><div class="table-contents"><table summary="GPS Satellite Data Contents" border="1"><colgroup><col align="right" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="right">5</td><td align="center">uint8_t</td><td align="left">channels</td><td align="left">Number of reported satellite information</td></tr><tr><td align="right">6</td><td align="center">sat_info_t</td><td align="left">sats[12]</td><td align="left">See Per-Satellite data table below</td></tr><tr><td align="right">30</td><td align="center">uint8_t</td><td align="left">unused[2]</td><td class="auto-generated"> </td></tr><tr><td align="right">32</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"><div class="table"><a name="idp54438000"></a><p class="title"><b>Table 8. GPS Per-Satellite data (sat_info_t)</b></p><div class="table-contents"><table summary="GPS Per-Satellite data (sat_info_t)" border="1"><colgroup><col align="right" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="right">0</td><td align="center">uint8_t</td><td align="left">svid</td><td align="left">Space Vehicle Identifier</td></tr><tr><td align="right">1</td><td align="center">uint8_t</td><td align="left">c_n_1</td><td align="left">C/N1 signal quality indicator</td></tr><tr><td align="right">2</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp54453072"></a>3. Data Transmission</h2></div></div></div><p>
+ </p><div class="table"><a name="idp54
063088"></a><p class="title"><b>Table 7. GPS Satellite Data Contents</b></p><div class="table-contents"><table summary="GPS Satellite Data Contents" border="1"><colgroup><col align="right" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="right">5</td><td align="center">uint8_t</td><td align="left">channels</td><td align="left">Number of reported satellite information</td></tr><tr><td align="right">6</td><td align="center">sat_info_t</td><td align="left">sats[12]</td><td align="left">See Per-Satellite data table below</td></tr><tr><td align="right">30</td><td align="center">uint8_t</td><td align="left">unused[2]</td><td class="auto-generated"> </td></tr><tr><td align="right">32</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"><div class="table"><a name="idp54079200"></a><p class="title"><b>Table 8. GPS Per-Satellite data (sat_info_t)</b></p><div class="table-contents"><table summary="GPS Per-Satellite data (sat_info_t)" border="1"><colgroup><col align="right" class="Offset"><col align="center" class="Data Type"><col align="left" class="Name"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Data Type</th><th align="center">Name</th><th align="center">Description</th></tr></thead><tbody><tr><td align="right">0</td><td align="center">uint8_t</td><td align="left">svid</td><td align="left">Space Vehicle Identifier</td></tr><tr><td align="right">1</td><td align="center">uint8_t</td><td align="left">c_n_1</td><td align="left">C/N1 signal quality indicator</td></tr><tr><td align="right">2</td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break"></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp54094272"></a>3. Data Transmission</h2></div></div></div><p>
Altus Metrum devices use the Texas Instruments CC1111
microcontroller which includes an integrated sub-GHz digital
transceiver. This transceiver is used to both transmit and
receive the telemetry packets. This section discusses what
modulation scheme is used and how this device is configured.
- </p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp54
454480"></a>3.1. Modulation Scheme</h3></div></div></div><p>
+ </p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp54
095680"></a>3.1. Modulation Scheme</h3></div></div></div><p>
Texas Instruments provides a tool for computing modulation
parameters given a desired modulation format and basic bit
rate. For AltOS, the basic bit rate was specified as 38 kBaud,
resulting in the following signal parmeters:
- </p><div class="table"><a name="idp54
455792"></a><p class="title"><b>Table 9. Modulation Scheme</b></p><div class="table-contents"><table summary="Modulation Scheme" border="1"><colgroup><col align="center" class="parameter"><col align="center" class="value"><col align="center" class="description"></colgroup><thead><tr><th align="center">Parameter</th><th align="center">Value</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">Modulation</td><td align="center">GFSK</td><td align="center">Gaussian Frequency Shift Keying</td></tr><tr><td align="center">Deviation</td><td align="center">20.507812 kHz</td><td align="center">Frequency modulation</td></tr><tr><td align="center">Data rate</td><td align="center">38.360596 kBaud</td><td align="center">Raw bit rate</td></tr><tr><td align="center">RX Filter Bandwidth</td><td align="center">93.75 kHz</td><td align="center">Receiver Band pass filter bandwidth</td></tr><tr><td align="center">IF Frequency</td><td align="center">140.62 kHz</td><td align="center">Receiver intermediate frequency</td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp54471888"></a>3.2. Error Correction</h3></div></div></div><p>
+ </p><div class="table"><a name="idp54
096992"></a><p class="title"><b>Table 9. Modulation Scheme</b></p><div class="table-contents"><table summary="Modulation Scheme" border="1"><colgroup><col align="center" class="parameter"><col align="center" class="value"><col align="center" class="description"></colgroup><thead><tr><th align="center">Parameter</th><th align="center">Value</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">Modulation</td><td align="center">GFSK</td><td align="center">Gaussian Frequency Shift Keying</td></tr><tr><td align="center">Deviation</td><td align="center">20.507812 kHz</td><td align="center">Frequency modulation</td></tr><tr><td align="center">Data rate</td><td align="center">38.360596 kBaud</td><td align="center">Raw bit rate</td></tr><tr><td align="center">RX Filter Bandwidth</td><td align="center">93.75 kHz</td><td align="center">Receiver Band pass filter bandwidth</td></tr><tr><td align="center">IF Frequency</td><td align="center">140.62 kHz</td><td align="center">Receiver intermediate frequency</td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp54113088"></a>3.2. Error Correction</h3></div></div></div><p>
The cc1111 provides forward error correction in hardware,
which AltOS uses to improve reception of weak signals. The
overall effect of this is to halve the available bandwidth for
data from 38 kBaud to 19 kBaud.
- </p><div class="table"><a name="idp54
473184"></a><p class="title"><b>Table 10. Error Correction</b></p><div class="table-contents"><table summary="Error Correction" border="1"><colgroup><col align="center" class="parameter"><col align="center" class="value"><col align="center" class="description"></colgroup><thead><tr><th align="center">Parameter</th><th align="center">Value</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">Error Correction</td><td align="center">Convolutional coding</td><td align="center">1/2 rate, constraint length m=4</td></tr><tr><td align="center">Interleaving</td><td align="center">4 x 4</td><td align="center">Reduce effect of noise burst</td></tr><tr><td align="center">Data Whitening</td><td align="center">XOR with 9-bit PNR</td><td align="center">Rotate right with bit 8 = bit 0 xor bit 5, initial
- value 111111111</td></tr></tbody></table></div></div><br class="table-break"></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp54
486096"></a>4. TeleDongle packet format</h2></div></div></div><p>
+ </p><div class="table"><a name="idp54
114384"></a><p class="title"><b>Table 10. Error Correction</b></p><div class="table-contents"><table summary="Error Correction" border="1"><colgroup><col align="center" class="parameter"><col align="center" class="value"><col align="center" class="description"></colgroup><thead><tr><th align="center">Parameter</th><th align="center">Value</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">Error Correction</td><td align="center">Convolutional coding</td><td align="center">1/2 rate, constraint length m=4</td></tr><tr><td align="center">Interleaving</td><td align="center">4 x 4</td><td align="center">Reduce effect of noise burst</td></tr><tr><td align="center">Data Whitening</td><td align="center">XOR with 9-bit PNR</td><td align="center">Rotate right with bit 8 = bit 0 xor bit 5, initial
+ value 111111111</td></tr></tbody></table></div></div><br class="table-break"></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp54
127296"></a>4. TeleDongle packet format</h2></div></div></div><p>
TeleDongle does not do any interpretation of the packet data,
instead it is configured to receive packets of a specified
length (32 bytes in this case). For each received packet,
the packet data, two bytes added by the cc1111 radio receiver
hardware and finally a checksum so that the host software can
validate that the line was transmitted without any errors.
- </p><div class="table"><a name="idp54
488880"></a><p class="title"><b>Table 11. Packet Format</b></p><div class="table-contents"><table summary="Packet Format" border="1"><colgroup><col align="center" class="offset"><col align="center" class="name"><col align="center" class="value"><col align="center" class="description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Name</th><th align="center">Example</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">0</td><td align="center">length</td><td align="center">22</td><td align="center">Total length of data bytes in the line. Note that
+ </p><div class="table"><a name="idp54
130080"></a><p class="title"><b>Table 11. Packet Format</b></p><div class="table-contents"><table summary="Packet Format" border="1"><colgroup><col align="center" class="offset"><col align="center" class="name"><col align="center" class="value"><col align="center" class="description"></colgroup><thead><tr><th align="center">Offset</th><th align="center">Name</th><th align="center">Example</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">0</td><td align="center">length</td><td align="center">22</td><td align="center">Total length of data bytes in the line. Note that
this includes the added RSSI and status bytes</td></tr><tr><td align="center">1 ·· length-3</td><td align="center">packet</td><td align="center">4f ·· 00</td><td align="center">Bytes of actual packet data</td></tr><tr><td align="center">length-2</td><td align="center">rssi</td><td align="center">3f</td><td align="center">Received signal strength. dBm = rssi / 2 - 74</td></tr><tr><td align="center">length-1</td><td align="center">lqi</td><td align="center">a9</td><td align="center">Link Quality Indicator and CRC status. Bit 7
- is set when the CRC is correct</td></tr><tr><td align="center">length</td><td align="center">checksum</td><td align="center">88</td><td align="center">(0x5a + sum(bytes 1 ·· length-1)) % 256</td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp54
508656"></a>5. History and Motivation</h2></div></div></div><p>
+ is set when the CRC is correct</td></tr><tr><td align="center">length</td><td align="center">checksum</td><td align="center">88</td><td align="center">(0x5a + sum(bytes 1 ·· length-1)) % 256</td></tr></tbody></table></div></div><br class="table-break"></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp54
150000"></a>5. History and Motivation</h2></div></div></div><p>
The original AltoOS telemetry mechanism encoded everything
available piece of information on the TeleMetrum hardware into a
single unified packet. Initially, the packets contained very
projects / web / altusmetrum / blobdiff