Open Source Flight Intrument Documentation [index]
The following requirements apply to all variants of the OSFI instruments.
The instrument shall provide a serial data interface to a GPS device. Through this interface, ground position, ground speed, direction, and time of day will be read from the GPS. The interface shall allow data to be received in NMEA format. An objective is to also allow data to be received using the Garmin protocol.
The instrument shall provide a serial data interface to a personal computer. Through this interface the instrument shall be capable of accepting user settings, as well as sending flight statistics and logged data to the PC. This interface may be the same physical port as the GPS port or it may be a physically seperate port.
The following measurements shall be taken at least once per second.
| Measurement | Min | Max | Accuracy |
| Altitude | 0 | 6000m | 20m? |
| Rate of Climb | -10m/s | +10m/s | 0.2m/s? |
| Air Speed | 0 | 300km/h | 3km/h? |
For each flight that the instrument is involved in, the following statistics shall be recorded in non-volatile memory.
For a flight in which a GPS was connected, the following statistics shall also be recorded.
The following data shall be logged at regular intervals during a flight.
The following items shall be configurable by the user and shall be stored in non-volatile memory.
The instrument shall be capable of transmitting audio signal to represent one of the measured quantities. One of these quantities shall be the the rate of climb. The tone and beat of the signal shall be dependant upon the value of the measured quantity so that with experience the pilot may intuitively recognise the approximate value without any visual reference.
The instrument shall be capable of running for at least 20hrs from one 9V alkaline battery.
The instrument shall be capable of operating in the temperature range of -20..60degC.