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diff --git a/doc/telemetrum.xsl b/doc/telemetrum.xsl index 70a78693..793347f9 100644 --- a/doc/telemetrum.xsl +++ b/doc/telemetrum.xsl @@ -223,6 +223,97 @@ <chapter> <title>Operation</title> <section> + <title>Firmware Modes </title> +<para> + The AltOS firmware build for TeleMetrum has two fundamental modes, + "idle" and "flight". Which of these modes the firmware operates in + is determined by the orientation of the rocket (well, actually the + board, of course...) at the time power is switched on. If the rocket + is "nose up", then 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. +</para> +<para> + In flight mode, TeleMetrum turns on the GPS system, engages the flight + state machine, goes into transmit-only mode on the RF link sending + telemetry, and waits for launch to be detected. Flight mode is + indicated by an audible "di-dah-dah-dit" on the beeper, followed by + beeps indicating the state of the pyrotechnic igniter continuity. + One beep indicates [FIXME] apogee continuity, two beeps indicate + main continuity, three beeps indicate both apogee and main continuity, + and one longer "brap" sound indicates no continuity. For a dual + deploy flight, make sure you're getting three beeps before launching! + For apogee-only or motor eject flights, do what makes sense. +</para> +<para> + In idle mode, the normal flight state machine is disengaged, and thus + no ejection charges will fire. TeleMetrum also listens on the RF + link when in idle mode for packet mode requests sent from TeleDongle. + Commands can thus be issues to a TeleMetrum in idle mode over either + USB or the RF link equivalently. + Idle mode is useful for configuring TeleMetrum, 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 TeleMetrum is used with very + large airframes, 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 airframe to launch position, use a TeleDongle to open + a packet connection, and issue a 'reset' command which will cause + TeleMetrum to reboot, realize it's now nose-up, and thus choose + 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! +</para> +<para> + TeleMetrum provides backup power to the GPS chip any time a LiPo + 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 + on the flight line in idle mode while performing final airframe + preparation will be sufficient to allow the GPS receiver to cold + start and acquire lock. Then the board can be powered down during + RSO review and installation on a launch rod or rail. When the board + is turned back on, the GPS system should lock very quickly, typically + long before igniter installation and return to the flight line are + complete. +</para> + </section> + <section> + <title>Ground Testing </title> + <para> + 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-equipped rocket without as + much work as you may be accustomed to with other systems. It can + even be fun! + </para> + <para> + Just prep the rocket for flight, then power up TeleMetrum while the + airframe is horizontal. 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 TeleMetrum to + fire the apogee or main charges to complete your testing. + </para> + </section> + <section> <title>Radio Link </title> <para> The chip our boards are based on incorporates an RF transceiver, but @@ -397,6 +488,14 @@ </para> </section> </section> + <section> + <title> + How GPS Works + </title> + <para> + Placeholder. + </para> + </section> </chapter> </book> |