</para>
</section>
<section>
- <title>Sensor Data</title>
+ <title>TeleMetrum v1.x, TeleMini and TeleNano Sensor Data</title>
<informaltable frame='none' label='' tocentry='0'>
<tgroup cols='2' align='center' colsep='1' rowsep='1'>
<colspec align='center' colwidth='*' colname='Offset'/>
<tbody>
<row>
<entry>0x01</entry>
- <entry>TeleMetrum Sensor Data</entry>
+ <entry>TeleMetrum v1.x Sensor Data</entry>
</row>
<row>
<entry>0x02</entry>
</tgroup>
</informaltable>
<para>
- TeleMetrum, TeleMini and TeleNano share this same packet
+ TeleMetrum v1.x, 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
are undefined.
</tgroup>
</table>
</section>
+ <section>
+ <title>TeleMega Sensor Data</title>
+ <informaltable frame='none' label='' tocentry='0'>
+ <tgroup cols='2' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='left' colwidth='3*' colname='Description'/>
+ <thead>
+ <row>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0x08</entry>
+ <entry>TeleMega IMU Sensor Data</entry>
+ </row>
+ <row>
+ <entry>0x09</entry>
+ <entry>TeleMega Kalman and Voltage Data</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <para>
+ TeleMega has a lot of sensors, and so it splits the sensor
+ data into two packets. The raw IMU data are sent more often;
+ the voltage values don't change very fast, and the Kalman
+ values can be reconstructed from the IMU data.
+ </para>
+ <para>
+ IMU 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
+ </para>
+ <para>
+ Kalman and Voltage Data packets are transmitted once per second on the
+ ground, 5 times per second during ascent and once per second
+ during descent and landing
+ </para>
+ <para>
+ The high-g accelerometer is reported separately from the data
+ for the 9-axis IMU (accel/gyro/mag). The 9-axis IMU is mounted
+ so that the X axis is "across" the board (along the short
+ axis0, the Y axis is "along" the board (along the long axis,
+ with the high-g accelerometer) and the Z axis is "through" the
+ board (perpendicular to the board). Rotation measurements are
+ around the respective axis, so Y rotation measures the spin
+ rate of the rocket while X and Z rotation measure the tilt
+ rate.
+ </para>
+ <para>
+ The overall tilt angle of the rocket is computed by first
+ measuring the orientation of the rocket on the pad using the 3
+ axis accelerometer, and then integrating the overall tilt rate
+ from the 3 axis gyroscope to compute the total orientation
+ change of the airframe since liftoff.
+ </para>
+ <table frame='all'>
+ <title>TeleMega IMU Sensor Packet Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>uint8_t</entry><entry>orient</entry><entry>Angle from vertical in degrees</entry>
+ </row>
+ <row>
+ <entry>6</entry><entry>int16_t</entry><entry>accel</entry><entry>High G accelerometer</entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>int32_t</entry><entry>pres</entry><entry>pressure (Pa * 10)</entry>
+ </row>
+ <row>
+ <entry>12</entry><entry>int16_t</entry><entry>temp</entry><entry>temperature (°C * 100)</entry>
+ </row>
+ <row>
+ <entry>14</entry><entry>int16_t</entry><entry>accel_x</entry><entry>X axis acceleration (across)</entry>
+ </row>
+ <row>
+ <entry>16</entry><entry>int16_t</entry><entry>accel_y</entry><entry>Y axis acceleration (along)</entry>
+ </row>
+ <row>
+ <entry>18</entry><entry>int16_t</entry><entry>accel_z</entry><entry>Z axis acceleration (through)</entry>
+ </row>
+ <row>
+ <entry>20</entry><entry>int16_t</entry><entry>gyro_x</entry><entry>X axis rotation (across)</entry>
+ </row>
+ <row>
+ <entry>22</entry><entry>int16_t</entry><entry>gyro_y</entry><entry>Y axis rotation (along)</entry>
+ </row>
+ <row>
+ <entry>24</entry><entry>int16_t</entry><entry>gyro_z</entry><entry>Z axis rotation (through)</entry>
+ </row>
+ <row>
+ <entry>26</entry><entry>int16_t</entry><entry>mag_x</entry><entry>X field strength (across)</entry>
+ </row>
+ <row>
+ <entry>28</entry><entry>int16_t</entry><entry>mag_y</entry><entry>Y field strength (along)</entry>
+ </row>
+ <row>
+ <entry>30</entry><entry>int16_t</entry><entry>mag_z</entry><entry>Z field strength (through)</entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ <table frame='all'>
+ <title>TeleMega Kalman and Voltage Data Packet Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>uint8_t</entry><entry>state</entry><entry>Flight state</entry>
+ </row>
+ <row>
+ <entry>6</entry><entry>int16_t</entry><entry>v_batt</entry><entry>battery voltage</entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>int16_t</entry><entry>v_pyro</entry><entry>pyro battery voltage</entry>
+ </row>
+ <row>
+ <entry>10</entry><entry>int8_t[6]</entry><entry>sense</entry><entry>pyro continuity sense</entry>
+ </row>
+ <row>
+ <entry>16</entry><entry>int32_t</entry><entry>ground_pres</entry><entry>Average barometer reading on ground</entry>
+ </row>
+ <row>
+ <entry>20</entry><entry>int16_t</entry><entry>ground_accel</entry><entry>Average accelerometer reading on ground</entry>
+ </row>
+ <row>
+ <entry>22</entry><entry>int16_t</entry><entry>accel_plus_g</entry><entry>Accel calibration at +1g</entry>
+ </row>
+ <row>
+ <entry>24</entry><entry>int16_t</entry><entry>accel_minus_g</entry><entry>Accel calibration at -1g</entry>
+ </row>
+ <row>
+ <entry>26</entry><entry>int16_t</entry><entry>acceleration</entry><entry>m/s² * 16</entry>
+ </row>
+ <row>
+ <entry>28</entry><entry>int16_t</entry><entry>speed</entry><entry>m/s * 16</entry>
+ </row>
+ <row>
+ <entry>30</entry><entry>int16_t</entry><entry>height</entry><entry>m</entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </section>
+ <section>
+ <title>TeleMetrum v2 Sensor Data</title>
+ <informaltable frame='none' label='' tocentry='0'>
+ <tgroup cols='2' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='left' colwidth='3*' colname='Description'/>
+ <thead>
+ <row>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0x0A</entry>
+ <entry>TeleMetrum v2 Sensor Data</entry>
+ </row>
+ <row>
+ <entry>0x0B</entry>
+ <entry>TeleMetrum v2 Calibration Data</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <para>
+ TeleMetrum v2 has higher resolution barometric data than
+ TeleMetrum v1, and so the constant calibration data is
+ split out into a separate packet.
+ </para>
+ <para>
+ TeleMetrum v2 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
+ </para>
+ <para>
+ TeleMetrum v2 Calibration Data packets are always transmitted once per second.
+ </para>
+ <table frame='all'>
+ <title>TeleMetrum v2 Sensor Packet Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>uint8_t</entry><entry>state</entry><entry>Flight state</entry>
+ </row>
+ <row>
+ <entry>6</entry><entry>int16_t</entry><entry>accel</entry><entry>accelerometer</entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>int32_t</entry><entry>pres</entry><entry>pressure sensor (Pa * 10)</entry>
+ </row>
+ <row>
+ <entry>12</entry><entry>int16_t</entry><entry>temp</entry><entry>temperature sensor (°C * 100)</entry>
+ </row>
+
+ <row>
+ <entry>14</entry><entry>int16_t</entry><entry>acceleration</entry><entry>m/s² * 16</entry>
+ </row>
+ <row>
+ <entry>16</entry><entry>int16_t</entry><entry>speed</entry><entry>m/s * 16</entry>
+ </row>
+ <row>
+ <entry>18</entry><entry>int16_t</entry><entry>height</entry><entry>m</entry>
+ </row>
+
+ <row>
+ <entry>20</entry><entry>int16_t</entry><entry>v_batt</entry><entry>battery voltage</entry>
+ </row>
+ <row>
+ <entry>22</entry><entry>int16_t</entry><entry>sense_d</entry><entry>drogue continuity sense</entry>
+ </row>
+ <row>
+ <entry>24</entry><entry>int16_t</entry><entry>sense_m</entry><entry>main continuity sense</entry>
+ </row>
+ <row>
+ <entry>26</entry><entry>pad[6]</entry><entry>pad bytes</entry><entry></entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ <table frame='all'>
+ <title>TeleMetrum v2 Calibration Data Packet Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>pad[3]</entry><entry>pad bytes</entry><entry></entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>int32_t</entry><entry>ground_pres</entry><entry>Average barometer reading on ground</entry>
+ </row>
+ <row>
+ <entry>12</entry><entry>int16_t</entry><entry>ground_accel</entry><entry>Average accelerometer reading on ground</entry>
+ </row>
+ <row>
+ <entry>14</entry><entry>int16_t</entry><entry>accel_plus_g</entry><entry>Accel calibration at +1g</entry>
+ </row>
+ <row>
+ <entry>16</entry><entry>int16_t</entry><entry>accel_minus_g</entry><entry>Accel calibration at -1g</entry>
+ </row>
+ <row>
+ <entry>18</entry><entry>pad[14]</entry><entry>pad bytes</entry><entry></entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </section>
<section>
<title>Configuration Data</title>
<informaltable frame='none' label='' tocentry='0'>
</informaltable>
<para>
This packet provides all of the information available from the
- Venus SkyTraq GPS receiver—position, time, speed and precision
+ GPS receiver—position, time, speed and precision
estimates.
</para>
<para>
</tgroup>
</table>
</section>
+ <section>
+ <title>Companion Data Data</title>
+ <informaltable frame='none' label='' tocentry='0'>
+ <tgroup cols='2' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='left' colwidth='3*' colname='Description'/>
+ <thead>
+ <row>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0x07</entry>
+ <entry>Companion Data Data</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <para>
+ When a companion board is attached to TeleMega or TeleMetrum,
+ it can provide telemetry data to be included in the
+ downlink. The companion board can provide up to 12 16-bit data
+ values.
+ </para>
+ <para>
+ The companion board itself specifies the transmission rate. On
+ the ground and during descent, that rate is limited to one
+ packet per second. During ascent, that rate is limited to 10
+ packets per second.
+ </para>
+ <table frame='all'>
+ <title>Companion Data Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='right' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>uint8_t</entry><entry>board_id</entry>
+ <entry>Type of companion board attached</entry>
+ </row>
+ <row>
+ <entry>6</entry><entry>uint8_t</entry><entry>update_period</entry>
+ <entry>How often telemetry is sent, in 1/100ths of a second</entry>
+ </row>
+ <row>
+ <entry>7</entry><entry>uint8_t</entry><entry>channels</entry>
+ <entry>Number of data channels supplied</entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>uint16_t[12]</entry><entry>companion_data</entry>
+ <entry>Up to 12 channels of 16-bit companion data</entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </section>
</section>
<section>
<title>Data Transmission</title>
<para>
- 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.
+ Altus Metrum devices use Texas Instruments sub-GHz digital radio
+ products. Ground stations use parts with HW FEC while some
+ flight computers perform FEC in software. TeleGPS is
+ transmit-only.
</para>
+ <table>
+ <title>Altus Metrum Radio Parts</title>
+ <tgroup cols='3'>
+ <colspec align="center" colwidth="*" colname="Part Number"/>
+ <colspec align="center" colwidth="*" colname="Description"/>
+ <colspec align="left" colwidth="*" colname="Used in"/>
+ <thead>
+ <row>
+ <entry align="center">Part Number</entry>
+ <entry align="center">Description</entry>
+ <entry align="center">Used in</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>CC1111</entry><entry>10mW transceiver with integrated SoC</entry>
+ <entry>TeleDongle v0.2, TeleBT v1.0, TeleMetrum v1.x, TeleMini</entry>
+ </row>
+ <row>
+ <entry>CC1120</entry><entry>35mW transceiver with SW FEC</entry>
+ <entry>TeleMetrum v2, TeleMega</entry>
+ </row>
+ <row>
+ <entry>CC1200</entry><entry>35mW transceiver with HW FEC</entry>
+ <entry>TeleDongle v3.0, TeleBT v3.0</entry>
+ </row>
+ <row>
+ <entry>CC115L</entry><entry>14mW transmitter with SW FEC</entry>
+ <entry>TeleGPS</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
<section>
<title>Modulation Scheme</title>
<para>
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:
+ rate.
+
+ While we might like to use something with better low-signal
+ performance like BPSK, the radios we use don't support that,
+ but do support Gaussian frequency shift keying (GFSK). Regular
+ frequency shift keying (FSK) encodes the signal by switching
+ the carrier between two frequencies. The Gaussian version is
+ essentially the same, but the shift between frequencies gently
+ follows a gaussian curve, rather than switching
+ immediately. This tames the bandwidth of the signal without
+ affecting the ability to transmit data.
+
+ For AltOS, there are three available bit rates, 38.4kBaud,
+ 9.6kBaud and 2.4kBaud resulting in the following signal
+ parmeters:
+
</para>
<table>
<title>Modulation Scheme</title>
<tgroup cols='3'>
- <colspec align="center" colwidth="*" colname="parameter"/>
- <colspec align="center" colwidth="*" colname="value"/>
- <colspec align="center" colwidth="*" colname="description"/>
+ <colspec align="center" colwidth="*" colname="rate"/>
+ <colspec align="center" colwidth="*" colname="deviation"/>
+ <colspec align="center" colwidth="*" colname="bandwidth"/>
<thead>
<row>
- <entry align='center'>Parameter</entry>
- <entry align='center'>Value</entry>
- <entry align='center'>Description</entry>
+ <entry align='center'>Rate</entry>
+ <entry align='center'>Deviation</entry>
+ <entry align='center'>Receiver Bandwidth</entry>
</row>
</thead>
<tbody>
<row>
- <entry>Modulation</entry>
- <entry>GFSK</entry>
- <entry>Gaussian Frequency Shift Keying</entry>
- </row>
- <row>
- <entry>Deviation</entry>
- <entry>20.507812 kHz</entry>
- <entry>Frequency modulation</entry>
- </row>
- <row>
- <entry>Data rate</entry>
- <entry>38.360596 kBaud</entry>
- <entry>Raw bit rate</entry>
+ <entry>38.4kBaud</entry>
+ <entry>20.5kHz</entry>
+ <entry>100kHz</entry>
</row>
<row>
- <entry>RX Filter Bandwidth</entry>
- <entry>93.75 kHz</entry>
- <entry>Receiver Band pass filter bandwidth</entry>
+ <entry>9.6kBaud</entry>
+ <entry>5.125kHz</entry>
+ <entry>25kHz</entry>
</row>
<row>
- <entry>IF Frequency</entry>
- <entry>140.62 kHz</entry>
- <entry>Receiver intermediate frequency</entry>
+ <entry>2.4kBaud</entry>
+ <entry>1.5kHz</entry>
+ <entry>5kHz</entry>
</row>
</tbody>
</tgroup>
<section>
<title>Error Correction</title>
<para>
- 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.
+ The cc1111 and cc1200 provide forward error correction in
+ hardware; on the cc1120 and cc115l that's done in
+ software. AltOS uses this to improve reception of weak
+ signals. As it's a rate 1/2 encoding, each bit of data takes
+ two bits when transmitted, so the effective data rate is half
+ of the raw transmitted bit rate.
</para>
<table>
<title>Error Correction</title>
projects / fw / altos / blobdiff