Index by title

Ground Sphere Test Transmitter Block Diagram v0.1

The following block diagram describes the key components of the Ground Sphere Test Transmitter.

Ground Sphere Test Transmitter BOM v0.1

Test Transmitter BOM v0.1

Ground Sphere Test Transmitter - Initial Questions v0.1

Project Background Questions

BQ1. Why are we making this?

BA1. There are two reasons for building this test transmitter. First, it helps to have an initial "smoke test" for the Ground Sphere Ground Station. What this means is that when someone assembles a copy of the Ground Sphere hardware, they should be able to easily test it to make sure that nothing major is wrong. Second, there are very few other 915 MHz satellites in orbit that are useful for testing the Ground Sphere Ground Station at the time of this project's inception. Having a test apparatus like this allows us to simulate satellite reception through terrestrial tests and possibly even High Altitude Balloon launches.

BQ2. Who is this for?

BA2. The Ground Sphere Ground Station is for SkyCube backers, students, teachers, scouting troops, space enthusiasts, and anyone who wishes to directly participate in the SkyCube mission. Therefore, this test transmitter is intended for the same audience.

BQ3. How will this be used?

BA3. Ground Sphere Ground Station operators will use the test transmitter to:

BQ4. Who's going to build this?

BA4. The designs will be open so that anyone, without necessarily a technical education in amateur radio or satellite operations, would be able to build and operate a Ground Sphere Test Transmitter.

Technical Requirement Questions

TQ1a. What features does it need to have (now)?

TA1a. The test transmitter needs to:

TQ1b. What features does it need to have (later)?

TA1b. In the future, the project (or related projects) may need to:

TQ2. What are the legacy requirements?

TA2. To maintain compatibility with other projects, the system should:

Project Requirement Questions

PQ1. How many do we want to make?

PA1. As an open source hardware kit, the long term objective is to promote and sell as many ground station kits to as large of an audience (schools, scouting troops, makerspaces, space enthusiasts, etc) as possible. However, the narrow focus on supporting SkyCube operations with the Ground Sphere may limit the number of kits which will be sold for this specific ground station, especially since the SkyCube is going to be on orbit for a very limited period of time. The sales lifetime of this specific kit (and in turn the number of kits we will want to sell) will depend on how many other satellites there are to observe in the same frequency range as the SkyCube.

PQ2. What is the budget?

PA2. The materials cost should be kept under $75 to limit the retail cost of any kit versions.

PQ3. What is the timeline?

PA3. The timeline for this project is dictated by the SkyCube launch and deployment timeline. SkyCube is currently scheduled was launched in January 2014, with deployment from the ISS in Q1 or Q2 of 2014. Southern Stars has stated they would be comfortable with a February 2014 delivery date for the kits.

PQ4. What waste products will be produced by the manufacture and/or operation of this?


Ground Sphere Test Transmitter Operating Manual v0.1


The Bill of Materials outlines the components needed to build a functional unit. For lab testing purposes the TI Launchpad can be connected directly to a laptop and not powered by the battery.

User provided laptop, minimum system requirements

The Quick Start Guide for the Air Boosterpack outlines the instructions to connect a MSP430 based Launchpad evaluation unit and the boosterpack. These instructions will also help the user bring the unit up to a point where it is running the example software used for testing. Please note that the testing procedure in the guide requires two sets of launchpads and boosterpacks, but this procedure uses one set with a Ground Sphere Ground Station.

Power Level Setting

The quick start guide instructs the user to install the "Install ATC-Booster Stack Lite GUI". Once this is installed and the Launchpad/Boosterpack combo is plugged into a USB port, follow the steps below.

  1. Set the proper Logical Radio for your region (FCC for the United States).
  2. Choose a Configuration that matches your application. If in doubt, choose configuration 0.
  3. Set the channel to 915.05 MHz, 7 dBm Max since that is the frequency that Ground Sphere is designed for.
  4. Set the RF Power level. Your options for the 915 MHz channel will be -60 dBm to 7 dBm. You can set this to the desired level depending on the operational conditions you are simulating and testing Ground Sphere with.

Ground Sphere Test Transmitter Requirements v0.1

Technical Requirements

TR 1.1 Transmit radio signals on 915 MHz

The Ground Sphere Test Transmitter will transmit radio signals on 915 MHz

TR 1.2 Test Transmitter Mobility

Be mobile so that the terrestrial tests can be done by adding distance between the transmitter and Ground Sphere receiver

TR 1.3 Be easy to assemble from kit components

TR 1.4 Be easy to assemble from kit components

TR 1.4.1 Tools for assembly

The Ground Sphere Test Transmitter will only require simple tools (screw drivers, pliers, wrenches, etc) for assembly

TR 1.4.2 Time to assemble

The Ground Sphere Test Transmitter will take no longer than 60 minutes (threshold)/30 minutes (objective) to assemble by an average maker

TR 1.5 Have low shipping costs for the packaged kit

The Ground Sphere Test Transmitter kit will cost no more than $15 (threshold)/$7.50 (objective) to ship by ground across the USA.

TR 1.6 Operate using a modern Windows PC

TR 1.6.1 Software must run on Windows

The Ground Sphere Test Transmitter software must run on Windows 7 or Windows 8 (32bit or 64bit)

TR 1.6.2 Software must be easy to install

The Ground Sphere Test Transmitter software must ship in a Windows installer

TR 1.7 Hardware must connect to PC using standard port(s)

The Ground Sphere Test Transmitter radio must connect to the ground station computer through a commonly available port (for example: USB)

TR 1.8 Hardware must be robust

The Ground Sphere Test Transmitter hardware should minimize the opportunity for mechanical failures (from things such as broken connectors or a lack of strain relief)

Project Requirements

PR 1.1 Number to produce

The Ground Sphere Test Transmitter design must enable the production of at least 30 +/- 5 v1.0 kits by volunteers in one or more makerspaces

PR 2.1 Budget

PR 2.1.1 Unit cost

The materials cost must be under $75 per kit.

PR 2.1.2 Development cost

The project budget (covering three prototypes) must be no more than $200 (threshold)/$100 (objective)

PR 3.1 Timeline

Version 1.0 of the Ground Sphere Test Transmitter will be ready for kit production no later than Feb 14, 2014.


Ground Sphere Ground Station Test Transmitter

User Manuals

End user manuals, including how to assemble and operating instructions for performing tests with the Ground Sphere Ground Station.


Full OSHW project documentation - covers component acquisition and assembly, packaging of kits, and other project level documentation needed to replicate the Ground Sphere from source.

Systems Engineering Process

Full OSHW project design documentation - covers design from concept through final design.

  1. Initial Questions
  2. Requirements Document
  3. Block Diagram
  4. Budget
  5. Timeline
  6. Preliminary Design
  7. Detailed Design
  8. Design Review
  9. Procurement
  10. Manufacture
  11. Integration
  12. Testing
  13. Disposal
  14. Meeting Minutes/Notes
  15. Resources/Links


v0.1 Description Documentation

Ground Sphere Test Transmitter Wiki v0.1


Welcome to the Ground Sphere Test Transmitter wiki. This is a Mach 30 project designed to give an initial "smoke test" for Ground Sphere hardware before trying to receive Skycube transmissions from orbit.

Ground Sphere for Makers

Mach 30 believes that Makers and Makerspaces will be a large part of the new spacefaring workforce, partnering with us in our mission "[t]o hasten the advancement of humanity into a spacefaring civilization through sustainable leadership, open design practices, and a bias toward mature technology." If that sounds like something you want to be involved in, we encourage you to jump right in. If you want to start with our design rationale, take a look at the Systems Engineering Process section in the navigation bar at the right. If building, testing, and operating a ground station is more your speed, start with the Documentation section of the navigation bar. Always make sure to read any Safety Procedures first so that you can have the safest experience possible with Ground Sphere and this project. Also, don't forget to register for an Open Design Engine account so you can start posting to the forums.

Ground Sphere for Educators

We intend to have Ground Sphere kits available sometime in the first quarter of 2014. If you're interested in finding out more about Ground Sphere in education, please contact Mach 30 . If you're planning to build and operate a Ground Sphere ground station on your own, please start by reading the Safety Procedures.

Ground Sphere for Students

If you're a student who's ready to start working with Ground Sphere, be sure to start with the Safety Procedures. Once you're up to speed on those, you'll want to take a look at the Operating Manual to learn how to operate the ground station. Any other documentation that you may need should be in the navigation bar at the right under Documentation. Also, don't forget to register for an Open Design Engine account so you can start posting to the forums.