Altus Metrum/ Uses

Using Altus Metrum Products

Where to Buy

All Altus Metrum products are available from the Garbee and Garbee web store. TeleMetrum starter kits are also available from Apogee Components and Australian Rocketry.

Being Legal

In the US, you need an amateur radio license or other authorization to legally operate the radio transmitters that are part of our products. Rules vary in other countries.

In the Rocket

In the rocket itself, you just need a TeleMetrum board and a LiPo rechargeable battery. An 900mAh battery weighs less than a 9V alkaline battery, and will run a TeleMetrum for hours.

This document contains notes about how to install a flight computer such as TeleMetrum in a rocket.

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 nearly 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.

On the Ground

To receive the data stream from the rocket, you need an antenna and short feedline connected to one of our 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.

All of our application software is written in Java, and supports Linux, Windows, and MacOS systems equivalently. See our AltOS page for more details and to download a copy.

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-6R 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.

Find more information about antennas, HTs, and getting a ham radio license on our Radio page.

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, you can replay the flight in real time, get plots and summary information from your data, export a CSV file for further manipulation in your favorite spreadsheet, or export a KML file so that you can visualize the flight path in three dimensions with Google Earth!

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.

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. We've built and flown some prototypes including TeleScience, but no companion board designs have made it to production yet.

We intended to publish a reference design for a companion board, but one of our customers beat us to it! You can find his work on how to use an Arduino as a companion board on GitHub.

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...