The TeleMetrum payload does much more than tell you where the rocket is (a GPS dog-tracker mounted in a rocket can do that...)

This is the first GPS payload designed specifically for rockets, and not created from off-the-shelf components that are simply spliced together. Because of this, it smaller, lighter, and has significantly more capability in controlling dual deployment of the rocket's chutes. And all the components are matched together perfectly so things just work without a lot of fuss or electrical interference between components.

Know Where Your Rocket Is At All Times During The Flight
...and how High it Went
...and If the Dual-Deployment Circuits are Working Correctly
...and...

Finally, one single small payload gives you all the advanced features you've desired in rocket electronics:

• GPS Tracking data so you know your rocket's position.
  
  
• Barometric recording altimeter. Barometric pressure sensor good to 45k feet MSL. Allows you to have perfect dual-deployment flights.

• 1-axis 70-g (+/-) accelerometer: Used to verify the speed of the rocket, should the vehicle exceed Mach 1. This simplifies setting up dual-deployment settings, because you don't have to worry about mach pressure effects fooling the baro sensor.
  
  The accelerometer also works for "motor characterization." This means you'll be able to verify after the launch that your rocket motor produced as much thrust as you expected. You'll be able to see the actual motor's thrust curve after each launch and compare it to the predicted thrust. This is great for people that make experimental rocket motors; you can fly the motors you make, instead of burning them all on a thrust stand just to get a thrust curve.
  
  In addition, because of the accelerometer, the payload also knows the rocket's orientation at power-up (nose up, or laying on its side). The TeleMetrum takes advantage of this to make arming of parachute ejection charges safer. With the TeleMetrum, you have the capability of remote arming of rocket on the launch pad (NO other payload can do this!). This means no more risking your neck climbing a wobbly step-ladder or a tall launch towers to turn on your vehicle's electronics just prior to launch. You can do it from the safety of your ground station. This greatly speeds up launch preparations out on the pad, which means your high-power friends will thank you for making the range run faster so they can fly their rockets too.
  
  
• Telemetry transmitter (70cm ham-band transceiver) allows all the flight data to be seen real-time during the mission. The telemetry system sends flight data 10 times per second during ascent, and once per second after apogee. It also transmits an audio tone once every five seconds that is used for tracking purposes on the ground with a directional rocket locator. The range is over 20 miles (Line-of-sight distance. Of course, this depends antenna you connect with the receiver).
  
  
• Dual deployment parachute control - fires two separate ejection charges. The first is fired at apogee. By default, TeleMetrum will fire the main deployment charge at an elevation of 250 meters (about 820 feet) above ground. There is an override command in the software to allow both the apogee and the main chutes to deploy at different altitudes. This "apogee delay" feature is to ensure multiple altimeters don't fire at the same time when you're flying redundant electronics, which is a requirement when flying a Level-3 high-power certification attempt.
  
  
• On-board non-volatile memory (2 MB) for flight data storage records data at 100 samples/second from the barometer and accelerometer, it also captures data at 3 samples/second for battery voltage, temperature and deployment charge continuity. GPS is recorded once per second. With 2MB of memory on-board, it can capture over 40 minutes of flight data. This allows you to download flight data after the mission is over, just in case your telemetry signal drops out. There's actually more data logged (particularly during the ascent phase) than is sent over the telemetry link, so you'll get a huge data cache after you get your rocket back. And you don't even have to remove the payload from the rocket or hook up any wires. After the rocket has landed and you have it sitting on your prep-table, you can simply command it to transmit all its stored flight data to your computer.
  
  
• Rechargeable Lithium Ion Polymer (LiPo) battery is included. It automatically gets recharged whenever the USB cord (included too) is connected to your computer.
  
  
• Use it as a rocket tracker too. You can use your radio direction finder to home in on the rocket should it land in rough scrub or a forested area.
  
  
• Open-source software allows you to expand the functionality of the product should you wish to add extra features.

Part 1

Part 2

Part 3

This java-based software connects you to the TeleMetrum during flight so you can see how many GPS satellites it is receiving data from as well as displaying the current and max values for key parameters during flight. It also logs all the telemetry data to disk for post-processing after the flight.

The software even includes voice synthesis during the flight so that your eyes can stay on the rocket while it speaks to you and tells how high and where downrange it is. Watching the rocket is a lot more fun than staring at a computer screen, wouldn't you agree?

The AltosUI software includes post flight analysis tools that makes it easy to extract usable things 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 (such as the ones show here to the left).

The program also export the flight data to a standard CSV (comma separated values) file format that can be read in to a spreadsheet program. This allows you to do additional analysis on your flight data.

The AltosUI program even generates KML files for viewing flights in GoogleEarth (see image to the left)! The data is color-coded so you can see the boost phase, the coast phase, and the descent phase.

The coast phase is distinguished in two parts called "fast coast" and "slow-coast". During fast coast, the rocket's speed is higher than 200 m/s, which tells the TeleMetrum payload that the rocket is going way too fast for safe parachute deployment. It will inhibit the ejection charges during this phase because the rocket would probably shred the chutes if they deployed at this speed.

Launch Pad State

Descent State

Site map

Ascent State

Landed State

You can even program other Altus Metrum payloads by connecting them together with the programming cable. And guess what? The rechargeable Lithium Ion Polymer flight battery is included!

But wait, there's more! You also get a USB cable so you can charge the battery while it is on the ground, and it also allows your computer to download the flight data after the mission.

Plus, you get a cut vinyl decal for your rocket!

Compare our package price to other telemetry systems. You'll save HUNDREDS of dollars!

That little blue box included in your starter set is called the "TeleDongle" device. This is both a transmitter and receiver that allows your computer to issue commands remotely to the Altus Metrum payload (such as arm the igniters for launch), and to receive back telemetry data while the rocket is in the air. It connects to your computer using a standard USB connector. Software is available for Mac, Linux and Windows computers.

Note: An antenna needs to be connected to the TeleDongle, but is not included in this package. See Below.

An RF cable or adapter is required to connect the antenna to the TeleDongle.

The battery is recharged whenever you connect the USB cable from the Altus Metrum payload to your computer through the USB cable.

Note that the battery is wider than the TeleMetrum payload (just in case you're building minimum diameter rockets for 29mm motors).

You'll also receive a USB (A to mini-B) cable so you can connect your Altus Metrum payload to your computer. When connected, the battery is recharged, plus you can download the last flight data and program the TeleMetrum for it's next dual deployment flight.

Not Included: TeleDongle Antenna

For low altitude flights (less than 2,500 feet) and for ground-testing your telemetrum, this whip antenna (not included with the TeleMetrum) is perfect. It is a dual-band, flexible antenna that covers the amateur radio 2-meter and 70 cm bands (140 & 440MHz), including the frequencies used by all Altus Metrum products.

Overall length is approximately 7.5 inches, and the whip portion is roughly 1/8 inch in diameter. The whip is highly flexible, it can be bent into a circle and will spring back into position when released.

For high altitude flights, we recommend using a hand-held directional antenna connected to the TeleDongle to receive data back from the rocket. A good low-cost antenna can be purchased from Arrow Antennas (model number 440-5ii) at: www.arrowantennas.com/arrowii/440-5ii.html

The TeleMetrum payload works by sensing the altitude of the rocket. In simple terms, it is an altimeter. But this one is different, it has three sensors and a sophisticated brain and extra hook-ups to to send electricity to two different ejection charges.

As the rocket takes off, this electronic payload is calculating the altitude of the rocket. When it senses the peak altitude, called apogee, it sends electricity to one of the igniters. This igniter sets off a small charge of black powder. That pressurizes one section of the rocket and spits out the small parachute (called a drogue chute).

While the drogue chute brings down the rocket quickly, the payload is still sensing the altitude of the rocket. When it descends to a pre-programmed height (which you can control), it then triggers a second time. This time it ignites another black powder ejection charge which pushes out the main parachute. Since the rocket is now closer to the ground, the wind really doesn't have the time to push it downrange too far. So it lands slowly, but much closer to the launch pad. That means you don't have to walk very far to retrieve your rocket.

I built a big rocket based around the 5.5-inch diameter Blue-Tube airframe tube with a LOC 5.5" nose cone. Other features included a 38mm motor mount with a Cesaroni J285 reloadable rocket motor. I also choose a 52 inch diameter SkyAngle parachute to bring the rocket back down to the ground. To hold the motor in, I used the 38mm Aero Pack motor retainer. It was a stout rocket that I was sure would survive the flight.

But when we got the TeleMetrum payload in from the Altus Metrum company, I was so impressed that I decided to modify the rocket to use dual deployment. It was an easy modification, as all I had to do was cut the main tube in half and insert an Always Ready Rocketry 5.5" Electronics Bay and an extra length of 1500# Kevlar for the shock cord and an additional Heat Shield parachute protector.

The electronics bay was more than adequate to mount the TeleMetrum payload. In fact, even the 7-inch long antenna on the TeleMetrum fit on the plywood sled inside the electronics-bay.

As you can see in the photo to the right, the layout is rather clean and straight forward. The red and black wires run to a push-switch to turn the unit on and off, and the green wires run to the forward ejection charge igniter. The battery is smaller than the TeleMetrum and was mounted on the back-side of the plywood sled. The only thing not shown in the photo is the third set of wires that go to the rear ejection charge igniter.

On launch day, I got telemetry help from Bob Finch, who was the first customer to purchase the TeleMetrum from Altus Metrum. Bob knows much more about the computer aspects of the TeleMetrum than I do, and he is also a licensed Ham radio operator. Really, all I had to do was turn on the TeleMetrum when the rocket was brought out to the pad. Bob then checked the radio link from his computer to my TeleMetrum and we were ready for launch.

The TeleMetrum is already pre-set for dual deployment capability, so our radio connection was only to download the flight data.

I had some butterflies in my stomach, like all fliers get when they go through a certification attempt. I tried to video-tape the launch, but my hands were so shaky that I couldn't keep the camera focused on the flight. So all I got were these great flight photos taken by other onlookers to the launch.

The TeleMetrum didn't care. It sensed apogee and kicked out the small drogue parachute right at the top. Less than 30 seconds later, as the rocket was descending, the TeleMetrum fired off the igniter for the ejection charge that popped out the 52" diameter SkyAngle parachute. When it blossomed open, I could hear an eruption of applause from the crowd of spectators. They all love to see a great dual-deployment flight, as the extra suspense of waiting for the 2nd chute always grabs their attention. But with the TeleMetrum payload, it was almost a forgone conclusion.

And while the flight wasn't all that high, we got reams of flight data back via telemetry. Cool!

In the video shown below, you'll see a quick-and-dirty ejection charge test on a high power rocket.

The main reason is to make sure you have enough black-powder in the ejection charge to separate the rocket and kick out the parachute. A lot of high power rockets use shear pins to hold the rocket together to prevent pre-mature separation while the rocket is still ascending. The ejection charge must be strong enough to break those pins when it is time for the parachute to pop out.

Performing this test also verifies that your electronics is configured properly.

Q. Where do I get a HAM radio "Technician Class License" so I can use this product?

A. It is not hard. If non-rocketry people can get licensed, so can you. You're a rocket scientist, right? Start here: http://www.arrl.org/getting-your-technician-license

Q. Why is a HAM radio license required?

A. While some competing products claim they do not require a license, they do not have the features of the TeleMetrum. These other GPS transmitters are made from off-the-shelf components, and all they do is tell you the position of the rocket based on GPS satellites. That is all they are licensed for by the Federal Communications Commission (FCC). Once you start transmitting more data, like the TeleMetrum does, the FCC requires {Part 15 of the FCC regulations} that the entire device (the complete radio system and the antenna) needs to be re-certified to make sure they are not radiating too much power and leaking out of their assigned frequency. Or... you need to have a HAM license to use them.

To be honest, the guys at Altus Metrum wish they could get it certified to use without a HAM license. It probably could pass easily. But the certification fee is over $20,000. When you're talking that amount of money, it is hard to justify that amount of investment in a small hobby like rocketry.

The other products simply do not have the same data transmitting capability as the TeleMetrum. And if they claim they do, it might be a good idea to check to see if their products have actually been tested and certified by the FCC.

Q. What changed in the lasted release of the Telemetrum (v0.9)?

A. Please see the manufacturer's website for information.

Q. What is the range of the TeleMetrum system?

A. There are 4 variables that determine the maximum range of the telemetry system. Those are the transmit power output, the transmit antenna gain, the receive antenna gain, and the receiver sensitivity. Improving any one of the four will give greater range. The easiest one to make better is the receive antenna gain.

The theoretical maximum range for the system with a 3-element yagi antenna on the ground is about 50km (or 30 miles). However, there are a number of sources of loss that are hard to model that conspire to make the *actual* range something less than the theoretical range. Tests performed at Altus Metrum have shown that a 3-element yagi antenna yields good telemetry from rockets to 20 Km (65,600 feet) altitude, and that a 11-element yagi antenna can receive telemetry from the TeleMetrum to around 100 Km (62 miles). Finally, the software reports the signal strength, so it's pretty easy for someone to "ground test" the range of the system in a given airframe before they fly it.

Q. Can you tune the operating frequency of the TeleMetrum?

A. As of software version 1.0.2 there's a very convenient user interface for managing custom frequency choices withinthe range of the hardware.

TeleMetrum is shipped intended for use around 435 Mhz, but the filter bandwidth should cover most / all of the amateur 70cm band. If you choose to operate far from 435 Mhz, I suggest careful ground testing to ensure you're not in a funny place in the filter skirts or something...

The original TeleMetrum firmware offered 10 channels on 100kHz spacing starting at 434.550 and going through 435.450

New firmware, starting with version 1.0.1, allows you to specify any frequency that the radio supports, with the caveat that the impedance matching circuit is tuned for 435MHz, so moving far from that may reduce your radio performance.

Q. How long can the TeleMetrum sit in idle mode prior to launch with the supplied battery?

A. The TeleMetrum turns down the radio so that it's only transmitting once per second on the pad prior to detecting launch. During this time, it draws something like 60-80mAh of power. With the 900mAh battery, that's somewhere more than 10 hours of run time.

Of course, the TeleMetrum is also transmitting the battery voltage too. So you'll be confident that everything will work before the motor ignites, because you'll be able to check on the status of your battery while you're waiting on the other flyers to get their butts in gear so you can launch your rocket.

Q. How long will the supplied battery last before dead? I'm planning on using it in a High Altitude Balloon project I'm running.

A. The maximum power consumed by the electronics is less than 150mAh, and the supplied battery is rated for 900mAh, so even using as much power as possible, the battery should last for 6 hours. The system doesn't use maximum power all of the time though, telemetry packets take about 50ms each, and once the GPS chip is locked, it uses less than half its maximum power.

The capacity of the battery will be affected by temperature, so at altitude you might see significantly lower battery capacity. A bit of testing in a local freezer might demonstrate the effective working capacity of the battery under worst-cast conditions.

In regards to memory for data storage, please remember that the regular TeleMetrum firmware is designed for rocket flights. It reports ascent telemetry data at 10Hz, records ascent readings to flash at 100Hz. These are both possibly faster than you'd like and will use up more of the memory. At 100Hz, even at the largest possible flight storage, you'll consume the flash storage in about 40 minutes.

If you know someone with experience in microcontrollers, you might consider changing the firmware to be more 'balloon friendly', recording and reporting data at a lower rate through the whole flight. All of the source code for the firmware is available on the altusmetrum.org web site, and the sdcc compiler is available from sdcc.sourceforge.net

Q. Do you sell any type of ejection charges that could be used with the device on this page?

A. No. The ejection charge is always made from loose black powder. Because black powder is regulated by the government, you have to purchase it from a gun store (one that specializes in muzzle-loading supplies). You also need to be at least 18 years old to use loose black powder in this manner.

Q. Does it matter what elevation the launch field is?

A. The altimeter samples the air on the ground, so it knows the altitude of the ground level. So when you set it to deploy the main chute at 500 feet, it will know that is above ground level. It doesn't matter where you start.

Q. Can the Telemetrum work in high-altitude balloons?

A. Yes. The GPS system will work in balloons to altitudes greater than what a typical balloon can reach (this is significantly higher the barometric sensor, which tops out at 13Km). However, because the flights in balloons are longer duration, it requires a firmware software upload from the manufacturer to conserve battery power.

Q. What if I want to use a Pyro battery in addition? Where do I connect it?

A. It will work with separate pyro batteries less than 15 volts, see the manual for details on how to connect it.

Q. Does the TeleMetrum work with Hybrid-Propellant rocket engines which vibrate the rocket at high frequencies?

A. It should work just fine. The TeleMetrum use the accelerometer to detect high speed flight, but not for apogee detection. The unit integrates the accelerometer output to find velocity; when that value is >200m/s, it ignores any barometric readings that might indicate apogee.  Apogee-detection is done purely with the barometric sensor which does not suffer from systematic errors due to vibration. The TeleMetrum has been tested in a shake-table mounted inside a vacuum chamber to characterize the amount of noise that introduces so that it could correctly compensate for for hybrid propellant motors.

Q. Does the TeleMetrum work in Hybrid Rockets?

A. Here is a link to a video of Hybrid rocket that used the Telemetrum.  The page is in Italian, please click here for a Google Translation into English. 

Q. How easy is it to set up dual-deployment?

A. To be honest, it is not a beginner-level operation. For starters, you have to design your rocket with two separate parachute compartments. This is detailed extensively in the book Modern High Power Rocketry 2. We highly recommend this book if you are new to large rocket or dual deployment techniques.

Q. How does this electronic gizmo compare to other dual-deployment devices?

A. This device uses a barometric sensor, and accelerometer, and GPS receiver to determine how high the rocket is. If you don't need the GPS receiver, then the G-Wiz Flight Computer may be sufficient for your complex project.