Frequestly Asked Questions

What is EyasSAT?

EyasSAT is the name of a working satellite model for classroom use.

It was originally developed for use in the Astronautics Department at the U.S. Air Force Academy.

The mascot of the USAFA is the falcon and satellites built at the USAFA are called Falconsats.

An "eyas" is a baby falcon.

Are discounts available?

EyasSAT LLC would be glad to discuss volume discounts for orders of more than 10 EyasSATs.

Since we primarily sell to educational institutions, our pricing is already the educational pricing.

EyasSAT, LLC builds to order only and runs two or three production cycles each year. Please see the home page for the datas of the current production cycle. We accept POs via FAX. Please contact us to order your EyasSATs.

What does an EyasSAT system cost?

The EyasSAT complete core system is priced at $7,995.

This includes a User's Manual that contains a complete set of lab exercises and Owner's Manual with hardware details and lab setup information.

We are pleased to also be able to include a CD containing all the curriculum material from the AFA Astro 331 course including lectures and instructor information (exams and some copyrighted material is deleted).

All you need to get started using the EysSat in your learning environment is a bench with a couple of power supplies and a PC or laptop.

You can also download our complete pricelist.

What computers or microprocessors are used in the EyasSAT?

The C&DH board uses an Atmel MEGA128. In Rev A EyasSAT the other modules used the Atmel AT90S8535 (or Mega8535).

The current model (Rev C) uses ATMega128s throughout.

Using these is one way the power consumption has been kept low enough to run on batteries for an hour or so in the lab. These processors are very well supported by CodeVision.

What language is EyasSAT programmed in?

All code/firmware for EyasSAT was done in C using the excellent CodeVision C development environment for the Atmel AVR RISC microcontrollers. See http://www.hpinfotech.ro .

My EyasSAT telemetry is displaying all "8"s (or all of some other character/garbage). Help!

Chances are, your batteries are depleted. Pull the power enable plug. or flip the "off" switch, then put your stack on the charger. Things should be back to normal in no time.

Can the modules operate without the IHU?

Yes. The EyasSAT uses a distributed processing design. The EPS and ADCS modules include processors and a direct serial interface that may be connected directly to a PC. Those boards may be operated stand-alone or in the stack.

How do the EyasSAT modules communicate?

The primary means of communications between the microprocessor in the C&DH modules and the other modules is an SPI bus.

The C&DH acts as the bus master, the modules are slaves. Chip select lines are assigned to each module.

Chip select lines are also reserved for up to three experiment boards that may be designed/built/used by owners and added to the EyasSAT stack.

Which are the "core" modules and what are "experiments"?

The core modules are those that are present in every satellite.

In EyasSAT these are the battery, power, IHU (includes the thermal sub-system), ADACS including two torque rods, and communications boards, the case, two light sensors, two solar panels, a pair of thermal differential plates, yaw sensors.

"Experiment" is the term we loosely apply to any other board or module.

The following add-on board and experiments have been built and attached by customers:

A cold gas thruster to spin the EyasSAT about the Z axis
A micro pulse plasma thruster
A camera and laser pointer

Other add-ons are under development or in the design stages including:

Fold out solar panels
Solar panels with more power output
A motion detection camera
An IR or sonic range sensor
A deployable articulated arm for mounting sensors
A pop up sensor head

Is the source code used in the processors available?

Not at this time. Thousands of hours of design and development have gone into making the EyasSAT a reality.

EyasSAT, LLC is interested in recovering that investment as well as continuing to improve the products. Releasing the source could undermine that objective.

As noted elsewhere EyasSAT, LLC is quite interested in receiving ideas and suggestions for other modules that could be added to EyasSAT and will endeavor to add interesting and useful experiment modules as time allows.

Are the technical details of each EyasSAT board available?

The functionality and operation of each board is available in the documentation section of this web site. It can be accessed by registered owners of the EyasSAT Classroom Satellite. Some hardware detail is proprietary and is not available.

Source code is also proprietary. However owners will find all the information they need to successfully use the EyeasSat in the classroom in our documentation.

Additionally the document "How to design an experiment" provides the detail needed to build an experiment board and plug it into the EyasSAT stack. It includes information on the EyaBus command and telemetry protocol and how the DH module interacts with experiment boards. Help making an experiment board work is always available from EyasSAT, LLC.

Why didn't you use existing PC-104 boards?

Several reasons:

While there a many types of boards available in the PC-104 format, none directly emulate the subsystems in a satellite.
EyasSAT must run for a reasonable period of time from batteries. Most commercial PC-104 boards require considerable current and are therefore not suitable
Most PC-104 boards are overkill for what is needed in EyasSAT. For example analog to digital conversion boards usually have a dozen or more channels when only 8 or so are needed for the thermal system in EyasSAT.
Adding custom boards would require each to have the hardware needed to interface to the PCI bus used between PC-104 boards. That's hardware not otherwise needed. Additionally, the firmware in each custom board would have to implement the PCI bus.

Can I use other PC-104 boards with the EyasSAT stack?

No. While we adopted the PC-104 size and connector arrangement, the signals on the EyaBus are not the same as the PC-104 standard. Stacking a PC-104 board on the EyasSAT stack may damage both boards.

What is the nature of the user interface via the Comm system?

All downlink data is in ASCII characters, plain text. This includes diagnostic and telemetry data. Uplink commands are from one to a few characters. A dumb terminal program (like Hyperterm) may be used on the PC. A GUI program to control the EyasSAT is also provided. Students may experience the raw telemetry and command flow using the text interface and/or the high level graphical interface.

How does the communications system work?

The COM system consists of a pair of 900 MHz or 2.4 Ghz ISM band digital spread spectrum radios, one on the EyasSAT Comm module and one on the bench acting as the "ground" end of the link. The one on the bench is connected via a serial or USB port to a PC. Two way communications is at 9k6 bps. The range, using the supplied rubber whip antennas, is about 200 yards across open ground. The units are channelized so several may be in use simultaneously in a classroom. No license is necessary.

Our newest (Rev C) units also include a high-speed Zigbee downlink.

What modules are included?

At present the following modules make up an EyasSAT stack:

Power (EPS), includes the battery
Computing and Data Handling (CH)
Attitude Control and Determination (ADCS), includes the reaction wheel
Structure with solar panels and sensors
Communications (COM)

These optional modules are available:

GPS, contains a functioning GPS
EyaFlex, contains a number of Analog and Digital inputs and outputs that can be hooked to other equipment.

Ideas for other modules and experiments are welcome! Please Contact Us to suggest module ideas.

How do I get support for my EyasSAT?

The best way to get support is to Contact Us.
Don't forget to check the Manuals.

Frequently Asked Questions