Index by title

Initial Questions

The discussion that led to this set of initial questions can be found here

Q1. Why are we making this?

Tracking, communication, and command & control of spacecraft are essential capabilities for a spacefaring civilization. Ground stations are the principle links between the spacecraft and Earth used to facilitate these capabilities. The series of ground station related projects will develop the necessary open source hardware to perform these functions. Version 1.0 was a good (good enough) proof of concept, but identified several weaknesses in the basic design which, while it was functional, it became clear that two versions were required: one low cost and simple to build for those just curious, and one powerful enough for limited professional use and extensible by changing modular components. The latter design is the 2.0 design of the ground station. It should be noted that this version will coexist with the 1.1 version, not supplant it.

Q2. Who is this for?

Mach 30 volunteers, Makerspaces and their members, Amateur (Ham) radio operators, CubeSat designers and operators (including universities). With some minor modifications, most of them software, radio astronomers could be added to the list of users as well.

Q3. How will this be used?

Early ground stations will be used to facilitate voice communications with orbiting satellites (including the ISS, HAM satellites, and CubeSats). Note, not all satellites will support voice communications, in which case the early ground stations will simply provide a means of listening to the satellites' other radio signals. Data capabilities can be added easily to the system, either by demodulating the audio stream (as in a computer modem), or by using an Software Defined Receiver (SDR) such as the AMSAT Funcube Dongle or USRP and running the demodulation through a software module (GNU radio) using a PC or Laptop.

Q4. What features does it need to have (now)?

Ability to predict opportunities for contact, aim an antenna array, and send and receive voice traffic.

Q5. What features does it need to have (later)?

a. In the future, our ground stations should be able to support sending and receiving command and control data from orbiting spacecraft.
b. Lock to precision timebase such as GPS or other external source.
c. Multiple ground stations should be able to be linked together to provide larger, contiguous coverage area.
d. A central server architecture would allow access to the global network from multiple clients (commercialization opportunity?).
d. Tracking of signals of unknown origin (subject to ITAR XIIa, XIII, and MTCR 121.16 item 12d2 and 12d3 restrictions).

Q6. What are the legacy requirements?

Transmitting will require HAM radio licenses (technician level or greater) in the US. Other countries may have other requirements.

Q7. Who's going to build this?

Since the current 2013 Mach 30 Annual Plan does not yet have hardware expenses budgeted for this project, but it will be part of an academic endeavor of a Mach 30 volunteer, the volunteer will construct this project with privately acquired funding.

Q8. How many do we want to make?

One for the academic credit, but some effort will be made to enable kits to be built from the mechanical and electronic modules. This kitification represents another commercial opportunity to purchase in bulk and ship complete kits for modest markup and postage to individuals, makerspaces, universities, etc.

Q9. What is the budget?

The build budget for the PC controlled Azimuth - Elevation mount and the antenna is $500.00. A dual band (VHF/UHF) ham radio transceiver and computer are all that are required to complete the ground station and should be acquired by the user.

Q10. What is the timeline?

To meet the academic credit requirements, this project must be complete by August 25th, 8 weeks after the start of the independent study class on July the 1st.

Q11. What waste products will be produced by the manufacture and/or operation of this?

It is likely that the first ground station will be used until a larger one is built, where the original will be kept as a backup. Any components that wear out, fail, or are damaged must be disposed of according to all federal, state and local guidelines in the US, or as regulations require in other parts of the world. Once no longer needed, the original ground station will be archived. It is also possible the university may wish to have the original for their display and/or use. Kits and copies will be made out of parts which allow the reuse of the materials for other projects, keeping them from being improperly disposed of.

Requirements Document for Ground Station v2.0

Introduction

The requirements list matches up to the Initial Questions in step one of the Systems Engineering process as shown below. Each requirement is labeled with GS2R (Ground Station 2.0 Requirement), followed by the number of the initial question that the requirement corresponds to, followed by a dot and then the ID number of the requirement.

Technical Requirements

Technical requirements are those requirements which include measurable performance values. Each technical requirement should be verified through testing to ensure the design meets the requirement.

Project Requirements

Project requirements are the remaining requirements which are not tied to specific performance values.

Future Requirements

These are for reference only so that future features can be accommodated in the current design where practical.

Version 2.1: Beyond Version 2.1:

Glossary

Azimuth - A coordinate system of relative direction based upon polar direction in degrees parallel to the ground where 0 is true north, 90 is due east, etc.
BNC - A type of quick disconnect radio frequency connector which needs no tools to connect or disconnect from the jack.
Consumables - Items that are used and then discarded such as nylon zip ties or cleaning wipes.
Demodulation - The conversion of an analog signal to audio or digital information.
Directional - In this context, antennas which function best in one direction.
Dish - Parabolic dish (short form). In this context, a highly directional antenna system characterized by a parabolic reflector dish and a feed horn in the focal point.
Doppler shift - Frequency shift caused by relative motion between the sender and receiver.
Downlink - The signal from a spacecraft to the ground station(s).
Duplex - In this context, the capability to send and receive at the same time.
Elevation - A coordinate system of relative direction ranging from 0 degrees, parallel to the ground, to 90 degrees, straight up or zenith.
Feed Horn - A radio antenna and in some cases preamplifier (LNA) fixed to the vocal point of a parabolic dish.
Full Duplex - See Duplex.
GPS - Global Positioning System. While primarily used for navigation, the signal contains a precision time base.
GS - Ground Station (short form).
Half Duplex - The ability to transmit or receive, but not at the same time.
Ham - Amateur radio operator.
HT - Handheld Transceiver
IAW - In Accordance With (short form).
ISS - The International Space Station
Kitified - Designed to be made into a kit.
L-band - In this context, the Amateur radio frequency range from 1,240 to 1,300 MHz. Amateur satellite up-links are in the frequency range from 1,260 to 1,270 MHz
LNA - Low Noise Amplifier. A high performance antenna and preamplifier combined in a single assembly mounted to the focal point of a parabolic dish.
Modulation - Embedding an analog or digital information on an analog signal.
Omni - See Omnidirectional
Omnidirectional - In this context, antennas capable of functioning in any direction
OH - Open Hardware
OS - Operating System, also Open Source
Preamp - See Preamplifier
Preamplifier - An amplifier designed to be mounted between an antenna and radio receiver.
Repeater - A transciever set up to rebroadcast a signal on a different frequency for extended coverage.
RF - Radio Frequency
Rotator - A device to point a dish or directional antenna at the signal source, in this context a satellite.
SDR - Software Defined Radio. A radio system where its capabilities and tuning are defined in software.
Sensitivity - The ability of a radio receiver to pick up a faint signal. Measured in -dB where a higher negative number is more sensitive on a logarithmic scale.
SWR - Standing Wave Ratio. A factor of antenna system efficiency based upon matching components. Measured in a ratio with no units.
Timebase - In this context, a time measurement system which may be synchronized with others using a central source.
Transceiver - A transmitter and receiver combined in one physical unit.
UHF - Ultra High Frequency. In this context, the amateur radio UHF band from 430 to 440 MHZ.
Uplink - The signal from the ground station to the satellite.
USB - Universal Serial Bus. A physical data transfer standard for computer equipment.
VHF - Very High Frequency. In this context, the amateur radio VHF band from 144 to 148 MHz.
VPN - Virtual Private Network. A private and secure method of transferring data on the public Internet.
VSWR - See SWR.
Yagi - A type of directional antenna characterized by multiple straight elements mounted in parallel on a common backbone.

Navigation

Ground Station v.2.0

Systems Engineering Process

  1. Initial Questions
  2. Requirements Document
  3. Block Diagram
  4. Architecture Study
  5. Preliminary Design
  6. Detailed Design
  7. Design Review
  8. Procurement/Manufacture
  9. Assembly
  10. Integration
  11. Testing

Documentation

  1. Budget
  2. Timeline
  3. BOM
  4. Plans
  5. Source Code
  6. Assembly Instructions
  7. Operating Manual
  8. Safety
  9. Licensing and Attribution
  10. Errata

Wiki

Welcome to the Ground Station v.2.0 project Wiki. This wiki contains documentation covering the design, development, fabrication, and use of the ground station. Much of the information here started life over in the forums, where we hold discussions and work to achieve a consensus on all items within the time permitted. Due to this, the forums would be a good place to start if you have questions about the thought process behind an item. In most cases, links to the appropriate forum discussions will be included in the wiki pages.

The idea behind the Ground Station v.2.0 project is to start small and simple, and then build on what is learned when moving to larger and more complex devices later on. This is very much in keeping with Mach 30's philosophy of starting (literally) from the ground up to build the infrastructure required to facilitate safe, routine, reliable, and sustained access to space.

If you're interested in getting involved a good place to start would be the Initial Questions page. There you will find the foundational questions that will guide the rest of the Ground Station v.2.0 design process. There is also the navigation bar at the right to help you find a specific section of the documentation quickly.