X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=blobdiff_plain;f=doc%2Ftelemetrum.xsl;h=70a7869318be95bf1b6726f6cb6b9e4aea5471b9;hp=97d8fb23469518d8a09c40a84b34e15cece1fc69;hb=641e76c5d419dab057298541b3a7546877643198;hpb=53ca3f98aeb70cb780031fee788de950e4388cf6 diff --git a/doc/telemetrum.xsl b/doc/telemetrum.xsl index 97d8fb23..70a78693 100644 --- a/doc/telemetrum.xsl +++ b/doc/telemetrum.xsl @@ -37,44 +37,366 @@ Introduction and Overview - Placeholder. + Welcome to the Altus Metrum community! Our circuits and software reflect + our passion for both hobby rocketry and Free Software. We hope their + capabilities and performance will delight you in every way, but by + releasing all of our hardware and software designs under open licenses, + we also hope to empower you to take as active a role in our collective + future as you wish! + + + The focal point of our community is TeleMetrum, a dual deploy altimeter + with fully integrated GPS and radio telemetry as standard features, and + a "companion interface" that will support optional capabilities in the + future. + + + Complementing TeleMetrum is TeleDongle, a USB to RF interface for + communicating with TeleMetrum. Combined with your choice of antenna and + notebook computer, TeleDongle and our associated user interface software + form a complete ground station capable of logging and displaying in-flight + telemetry, aiding rocket recovery, then processing and archiving flight + data for analysis and review. Specifications - - Placeholder. - + + + + Recording altimeter for model rocketry. + + + + + Supports dual deployment (can fire 2 ejection charges). + + + + + 70cm ham-band transceiver for telemetry downlink. + + + + + Barometric pressure sensor good to 45k feet MSL. + + + + + 1-axis high-g accelerometer for motor characterization, capable of + +/- 50g using default part. + + + + + On-board, integrated GPS receiver with 5hz update rate capability. + + + + + On-board 1 megabyte non-volatile memory for flight data storage. + + + + + USB interface for battery charging, configuration, and data recovery. + + + + + Fully integrated support for LiPo rechargeable batteries. + + + + + Uses LiPo to fire e-matches, support for optional separate pyro + battery if needed. + + + + + 2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube. + + + Handling Precautions - Placeholder. + TeleMetrum is a sophisticated electronic device. When handled gently and + properly installed in an airframe, it will deliver extraordinary results. + However, like all electronic devices, there are some precautions you + must take. + + + The Lithium Polymer rechargeable batteries used with TeleMetrum have an + extraordinary power density. This is great because we can fly with + much less battery mass than if we used alkaline batteries or previous + generation rechargeable batteries... but if they are punctured + or their leads are allowed to short, they can and will release their + energy very rapidly! + Thus we recommend that you take some care when handling our batteries + and consider giving them some extra protection in your airframe. We + often wrap them in suitable scraps of closed-cell packing foam before + strapping them down, for example. + + + The TeleMetrum barometric sensor is sensitive to sunlight. In normal + mounting situations, it and all of the other surface mount components + are "down" towards whatever the underlying mounting surface is, so + this is not normally a problem. Please consider this, though, when + designing an installation, for example, in a 29mm airframe's see-through + plastic payload bay. + + + The TeleMetrum barometric sensor sampling port must be able to "breathe", + both by not being covered by foam or tape or other materials that might + directly block the hole on the top of the sensor, but also by having a + suitable static vent to outside air. + + + As with all other rocketry electronics, TeleMetrum must be protected + from exposure to corrosive motor exhaust and ejection charge gasses. Hardware Overview - Placeholder. + TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to + fit inside coupler for 29mm airframe 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 + 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 + bay for TeleMetrum should have at least 10 inches of interior length. - - - Operation - Placeholder. + A typical TeleMetrum installation using the on-board GPS antenna 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. - - - System Overview - Placeholder. + By default, we use the unregulated output of the LiPo battery directly + to fire ejection charges. This works marvelously with standard e-matches + from companies like [insert company and product names for e-matches we've + tried and like] and with Quest Q2G2 igniters. However, if you + want or need to use a separate pyro battery, you can do so by adding + a second 2mm connector to position B2 on the board and cutting the + thick pcb trace connecting the LiPo battery to the pyro circuit between + the two silk screen marks on the surface mount side of the board shown + here [insert photo] + + + We offer two choices of pyro and power switch connector, or you can + choose neither and solder wires directly to the board. All three choices + are reasonable depending on the constraints of your airframe. Our + favorite option when there is sufficient room above the board is to use + the Tyco pin header with polarization and locking. If you choose this + option, you crimp individual wires for the power switch and e-matches + into a mating connector, and installing and removing the TeleMetrum + board from an airframe is as easy as plugging or unplugging two + connectors. If the airframe will not support this much height or if + you want to be able to directly attach e-match leads to the board, we + offer a screw terminal block. This is very similar to what most other + altimeter vendors provide by default 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. Finally, you can forego both options and + solder wires directly to the board, which may be the best choice for + minimum diameter and/or minimum mass designs. - - - System Overview - Placeholder. + For most airframes, the integrated GPS antenna and wire UHF antenna are + a great combination. However, if you are installing in a carbon-fiber + electronics bay which is opaque to RF signals, you may need to use + off-board external antennas instead. In this case, you can order + TeleMetrum with an SMA connector for the UHF antenna connection, and + you can unplug the integrated GPS antenna and select an appropriate + off-board GPS antenna with cable terminating in a U.FL connector. + + Operation +
+ Radio Link + + The chip our boards are based on incorporates an RF transceiver, but + it's not a full duplex system... each end can only be transmitting or + receiving at any given moment. So we have to decide how to manage the + link... + + + By design, TeleMetrum firmware listens for an RF connection when + it's in "idle mode" (turned on while the rocket is horizontal), which + allows us to use the RF link to configure the rocket, do things like + ejection tests, and extract data after a flight without having to + crack open the airframe. However, when the board is in "flight + mode" (turned on when the rocket is vertical) the TeleMetrum only + transmits and doesn't listen at all. That's because we want to put + ultimate priority on event detection and getting telemetry out of + the rocket and out over + the RF link in case the rocket crashes and we aren't able to extract + data later... + + + We don't use a 'normal packet radio' mode because they're just too + inefficient. GFSK is just FSK with the baseband pulses passed through a + Gaussian filter before they go into the modulator to limit the + transmitted bandwidth. When combined with the hardware forward error + correction support in the cc1111 chip, this allows us to have a very + robust 38.4 kilobit data link with only 10 milliwatts of transmit power, + a whip antenna in the rocket, and a hand-held Yagi on the ground. We've + had a test flight above 12k AGL with good reception, and my calculations + say we should be good to 40k AGL or more with just a 5-element yagi on + the ground. I expect to push 30k with a 54mm minimum airframe I'm + working on now, so we'll hopefully have further practical confirmation + of our link margin in a few months. + + + Placeholder. + +
+ + + Using Altus Metrum Products +
+ Being Legal + + First off, in the US, you need an [amateur radio license](../Radio) or + other authorization to legally operate the radio transmitters that are part + of our products. + +
+ In the Rocket + + In the rocket itself, you just need a [TeleMetrum](../TeleMetrum) board and + a LiPo rechargeable battery. An 860mAh battery weighs less than a 9V + alkaline battery, and will run a [TeleMetrum](../TeleMetrum) for hours. + + + By default, we ship TeleMetrum with a simple wire antenna. If your + electronics bay or the airframe it resides within is made of carbon fiber, + which is opaque to RF signals, you may choose to have an SMA connector + installed so that you can run a coaxial cable to an antenna mounted + elsewhere in the rocket. + +
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+ On the Ground + + To receive the data stream from the rocket, you need an antenna and short + feedline connected to one of our [TeleDongle](../TeleDongle) units. The + TeleDongle in turn plugs directly into the USB port on a notebook + computer. Because TeleDongle looks like a simple serial port, your computer + does not require special device drivers... just plug it in. + + + Right now, all of our application software is written for Linux. However, + because we understand that many people run Windows or MacOS, we are working + on a new ground station program written in Java that should work on all + operating systems. + + + After the flight, you can use the RF link to extract the more detailed data + logged in the rocket, or you can use a mini USB cable to plug into the + TeleMetrum board directly. Pulling out the data without having to open up + the rocket is pretty cool! A USB cable is also how you charge the LiPo + battery, so you'll want one of those anyway... the same cable used by lots + of digital cameras and other modern electronic stuff will work fine. + + + If your rocket lands out of sight, you may enjoy having a hand-held GPS + receiver, so that you can put in a waypoint for the last reported rocket + position before touch-down. This makes looking for your rocket a lot like + Geo-Cacheing... just go to the waypoint and look around starting from there. + + + You may also enjoy having a ham radio "HT" that covers the 70cm band... you + can use that with your antenna to direction-find the rocket on the ground + the same way you can use a Walston or Beeline tracker. This can be handy + if the rocket is hiding in sage brush or a tree, or if the last GPS position + doesn't get you close enough because the rocket dropped into a canyon, or + the wind is blowing it across a dry lake bed, or something like that... Keith + and Bdale both currently own and use the Yaesu VX-7R at launches. + + + So, to recap, on the ground the hardware you'll need includes: + + + an antenna and feedline + + + a TeleDongle + + + a notebook computer + + + optionally, a handheld GPS receiver + + + optionally, an HT or receiver covering 435 Mhz + + + + + The best hand-held commercial directional antennas we've found for radio + direction finding rockets are from + + Arrow Antennas. + + The 440-3 and 440-5 are both good choices for finding a + TeleMetrum-equipped rocket when used with a suitable 70cm HT. + +
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+ Data Analysis + + Our software makes it easy to log the data from each flight, both the + telemetry received over the RF link during the flight itself, and the more + complete data log recorded in the DataFlash memory on the TeleMetrum + board. Once this data is on your computer, our postflight tools make it + easy to quickly get to the numbers everyone wants, like apogee altitude, + max acceleration, and max velocity. You can also generate and view a + standard set of plots showing the altitude, acceleration, and + velocity of the rocket during flight. And you can even export a data file + useable with Google Maps and Google Earth for visualizing the flight path + in two or three dimensions! + + + Our ultimate goal is to emit a set of files for each flight that can be + published as a web page per flight, or just viewed on your local disk with + a web browser. + +
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+ Future Plans + + In the future, we intend to offer "companion boards" for the rocket that will + plug in to TeleMetrum to collect additional data, provide more pyro channels, + and so forth. A reference design for a companion board will be documented + soon, and will be compatible with open source Arduino programming tools. + + + We are also working on the design of a hand-held ground terminal that will + allow monitoring the rocket's status, collecting data during flight, and + logging data after flight without the need for a notebook computer on the + flight line. Particularly since it is so difficult to read most notebook + screens in direct sunlight, we think this will be a great thing to have. + + + Because all of our work is open, both the hardware designs and the software, + if you have some great idea for an addition to the current Altus Metrum family, + feel free to dive in and help! Or let us know what you'd like to see that + we aren't already working on, and maybe we'll get excited about it too... + +
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