Ground Sphere Requirements v0.2

Technical Requirements

TR 1.1 Enable users to receive "space tweets"

TR 1.1.1 Predict SkyCube flyover opportunities

The Ground Sphere will include software which predicts when the SkyCube satellite will flyover the ground station and be within signal reception range

TR 1.1.2 Receive radio signals on 915 MHz

The Ground Sphere will receive radio signals on 915 MHz with sufficient gain to enable decoder software to decode the "space tweet" text message

TR 1.1.3 Decode "space tweet" message from SkyCube

Decode BPSK-modulated, unencrypted AX.25 data packets sent at 9600 baud

TR 1.1.4 Account for Doppler shift

The Ground Sphere needs to account for Doppler shift during satellite flyovers

TR 1.2 Be easy to assemble from kit components

TR 1.2.1 Time to assemble

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

TR 1.2.2 Tools for assembly

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

TR 1.3 Have low shipping costs for the packaged kit

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

TR 1.4 Operate using a modern Windows PC

TR 1.4.1 Software must run on Windows

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

TR 1.4.2 Software must be easy to install

The Ground Sphere software must ship in a Windows installer

TR 1.4.3 Hardware must connect to PC using standard port(s)

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

TR 1.5 Hardware must be robust

The Ground Sphere 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 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 $100 per kit.

PR 2.1.2 Development cost

The project budget (covering three prototypes) must be no more than $500 (threshold)/$400 (objective)

PR 3.1 Timeline

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

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