TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
fit inside coupler for 29mm air-frame tubing, but using it in a tube that
small in diameter may require some creativity in mounting and wiring
- to succeed! The default 1/4
- wave UHF wire antenna attached to the center of the nose-cone end of
- the board is about 7 inches long, and wiring for a power switch and
+ to succeed! The presence of an accelerometer means TeleMetrum should
+ be aligned along the flight axis of the airframe, and by default the 1/4
+ wave UHF wire antenna should be on the nose-cone end of the board. The
+ antenna wire is about 7 inches long, and wiring for a power switch and
the e-matches for apogee and main ejection charges depart from the
- fin can end of the board. Given all this, an ideal "simple" avionics
+ fin can end of the board, meaning an ideal "simple" avionics
bay for TeleMetrum should have at least 10 inches of interior length.
</para>
<para>
TeleMini is a 0.5 inch by 1.5 inch circuit board. It was designed to
fit inside an 18mm air-frame tube, but using it in a tube that
small in diameter may require some creativity in mounting and wiring
- to succeed! The default 1/4
- wave UHF wire antenna attached to the center of the nose-cone end of
+ to succeed! Since there is no accelerometer, TeleMini can be mounted
+ in any convenient orientation. The default 1/4
+ wave UHF wire antenna attached to the center of one end of
the board is about 7 inches long, and wiring for a power switch and
the e-matches for apogee and main ejection charges depart from the
- fin can end of the board. Given all this, an ideal "simple" avionics
+ other end of the board, meaning an ideal "simple" avionics
bay for TeleMini should have at least 9 inches of interior length.
</para>
<para>
- A typical TeleMetrum or TeleMini installation using the on-board devices and
- default wire UHF antenna involves attaching only a suitable
- Lithium Polymer battery, a single pole switch for power on/off, and
- two pairs of wires connecting e-matches for the apogee and main ejection
- charges.
+ A typical TeleMetrum or TeleMini installation involves attaching
+ only a suitable Lithium Polymer battery, a single pole switch for
+ power on/off, and two pairs of wires connecting e-matches for the
+ apogee and main ejection charges.
</para>
<para>
By default, we use the unregulated output of the Li-Po battery directly
to fire ejection charges. This works marvelously with standard
low-current e-matches like the J-Tek from MJG Technologies, and with
- Quest Q2G2 igniters. However, if you
- want or need to use a separate pyro battery, check out the "External Pyro Battery"
- section in this manual for instructions on how to wire that up. The
- altimeters are designed to work with an external pyro battery of up to 15V.
+ Quest Q2G2 igniters. However, if you want or need to use a separate
+ pyro battery, check out the "External Pyro Battery" section in this
+ manual for instructions on how to wire that up. The altimeters are
+ designed to work with an external pyro battery of no more than 15 volts.
</para>
<para>
Ejection charges are wired directly to the screw terminal block
- at the aft end of the altimeter. This is very similar to what
- most other altimeter vendors provide and so may be the most
- familiar option. You'll need a very small straight blade
- screwdriver to connect and disconnect the board in this case,
- such as you might find in a jeweler's screwdriver set.
+ at the aft end of the altimeter. You'll need a very small straight
+ blade screwdriver for these screws, such as you might find in a
+ jeweler's screwdriver set.
</para>
<para>
TeleMetrum also uses the screw terminal block for the power
switch leads. On TeleMini, the power switch leads are soldered
- directly to the board and can be connected directly to the switch.
+ directly to the board and can be connected directly to a switch.
</para>
<para>
For most air-frames, the integrated antennas are more than
- adequate However, if you are installing in a carbon-fiber
- electronics bay which is opaque to RF signals, you may need to
+ adequate. However, if you are installing in a carbon-fiber or
+ metal electronics bay which is opaque to RF signals, you may need to
use off-board external antennas instead. In this case, you can
order an altimeter with an SMA connector for the UHF antenna
connection, and, on TeleMetrum, you can unplug the integrated GPS
TeleMetrum assumes it's on a rail or rod being prepared for
launch, so the firmware chooses flight mode. However, if the
rocket is more or less horizontal, the firmware instead enters
- idle mode. For TeleMini, "idle" mode is selected when the
+ idle mode. Since TeleMini doesn't have an accelerometer we can
+ use to determine orientation, "idle" mode is selected when the
board receives a command packet within the first five seconds
of operation; if no packet is received, the board enters
"flight" mode.
<para>
At power on, you will hear three beeps or see three flashes
("S" in Morse code for start up) and then a pause while
- the altimeter completes initialization and self tests, and decides which
- mode to enter next.
+ the altimeter completes initialization and self test, and decides
+ which mode to enter next.
</para>
<para>
In flight or "pad" mode, the altimeter engages the flight
flights, do what makes sense.
</para>
<para>
- In idle mode, you will hear an audible "di-dit" or see two short flashes ("I" for idle), and
- the normal flight state machine is disengaged, thus
- no ejection charges will fire. The altimeters also listen on the RF
- link when in idle mode for packet mode requests sent from TeleDongle.
- Commands can be issued to a TeleMetrum in idle mode over either
- USB or the RF link equivalently. TeleMini uses only the RF link.
+ If idle mode is entered, you will hear an audible "di-dit" or see
+ two short flashes ("I" for idle), and the flight state machine is
+ disengaged, thus no ejection charges will fire. The altimeters also
+ listen on the RF link when in idle mode for requests sent via
+ TeleDongle. Commands can be issued to a TeleMetrum in idle mode
+ over either
+ USB or the RF link equivalently. TeleMini only has the RF link.
Idle mode is useful for configuring the altimeter, for extracting data
from the on-board storage chip after flight, and for ground testing
pyro charges.
</para>
<para>
- One "neat trick" of particular value when the altimeter is used with very
- large air-frames, is that you can power the board up while the rocket
- is horizontal, such that it comes up in idle mode. Then you can
- raise the air-frame to launch position, use a TeleDongle to open
- a packet connection, and issue a 'reset' command which will cause
- the altimeter to reboot and come up in
- flight mode. This is much safer than standing on the top step of a
- rickety step-ladder or hanging off the side of a launch tower with
- a screw-driver trying to turn on your avionics before installing
- igniters!
+ One "neat trick" of particular value when TeleMetrum is used with
+ very large air-frames, is that you can power the board up while the
+ rocket is horizontal, such that it comes up in idle mode. Then you can
+ raise the air-frame to launch position, and issue a 'reset' command
+ via TeleDongle over the RF link to cause the altimeter to reboot and
+ come up in flight mode. This is much safer than standing on the top
+ step of a rickety step-ladder or hanging off the side of a launch
+ tower with a screw-driver trying to turn on your avionics before
+ installing igniters!
</para>
</section>
<section>
<title>GPS </title>
<para>
- TeleMetrum includes a complete GPS receiver. See a later section for
- a brief explanation of how GPS works that will help you understand
- the information in the telemetry stream. The bottom line is that
- the TeleMetrum GPS receiver needs to lock onto at least four
- satellites to obtain a solid 3 dimensional position fix and know
- what time it is!
+ TeleMetrum includes a complete GPS receiver. A complete explanation
+ of how GPS works is beyond the scope of this manual, but the bottom
+ line is that the TeleMetrum GPS receiver needs to lock onto at least
+ four satellites to obtain a solid 3 dimensional position fix and know
+ what time it is.
</para>
<para>
- TeleMetrum provides backup power to the GPS chip any time a Li-Po
+ TeleMetrum provides backup power to the GPS chip any time a
battery is connected. This allows the receiver to "warm start" on
- the launch rail much faster than if every power-on were a "cold start"
- for the GPS receiver. In typical operations, powering up TeleMetrum
+ the launch rail much faster than if every power-on were a GPS
+ "cold start". In typical operations, powering up TeleMetrum
on the flight line in idle mode while performing final air-frame
preparation will be sufficient to allow the GPS receiver to cold
start and acquire lock. Then the board can be powered down during
An important aspect of preparing a rocket using electronic deployment
for flight is ground testing the recovery system. Thanks
to the bi-directional RF link central to the Altus Metrum system,
- this can be accomplished in a TeleMetrum- or TeleMini- equipped rocket without as
- much work as you may be accustomed to with other systems. It can
- even be fun!
+ this can be accomplished in a TeleMetrum or TeleMini equipped rocket
+ with less work than you may be accustomed to with other systems. It
+ can even be fun!
</para>
<para>
Just prep the rocket for flight, then power up the altimeter
in "idle" mode (placing air-frame horizontal for TeleMetrum or
- starting the RF packet connection for TeleMini). This will cause the
- firmware to go into "idle" mode, in which the normal flight
+ selected the Configure Altimeter tab for TeleMini). This will cause
+ the firmware to go into "idle" mode, in which the normal flight
state machine is disabled and charges will not fire without
- manual command. Then, establish an RF packet connection from
- a TeleDongle-equipped computer using the P command from a safe
- distance. You can now command the altimeter to fire the apogee
- or main charges to complete your testing.
- </para>
- <para>
- In order to reduce the chance of accidental firing of pyrotechnic
- charges, the command to fire a charge is intentionally somewhat
- difficult to type, and the built-in help is slightly cryptic to
- prevent accidental echoing of characters from the help text back at
- the board from firing a charge. The command to fire the apogee
- drogue charge is 'i DoIt drogue' and the command to fire the main
- charge is 'i DoIt main'.
+ manual command. You can now command the altimeter to fire the apogee
+ or main charges from a safe distance using your computer and
+ TeleDongle and the Fire Igniter tab to complete ejection testing.
</para>
</section>
<section>
inside 'ao-view'. If this doesn't work, disconnect from the
TeleDongle, unplug it, and try again after plugging it back in.
</para>
+ <para>
+ In order to reduce the chance of accidental firing of pyrotechnic
+ charges, the command to fire a charge is intentionally somewhat
+ difficult to type, and the built-in help is slightly cryptic to
+ prevent accidental echoing of characters from the help text back at
+ the board from firing a charge. The command to fire the apogee
+ drogue charge is 'i DoIt drogue' and the command to fire the main
+ charge is 'i DoIt main'.
+ </para>
<para>
On TeleMetrum, the GPS will eventually find enough satellites, lock in on them,
and 'ao-view' will both auditorily announce and visually indicate
projects / fw / altos / commitdiff