ETTC'2003 - SEE

segments can include time marks, an IRIG time stamp and grid information that
provide the host with expanded control over the chart.
One of the most recent advances in the networking aspect of the telemetry
recording workstation is peer-to-peer networking. Utilizing the latest peer-to-peer
technologies, flight test recorders can now be linked to provide instantaneous
communication between systems. This fully distributed, network-based
architecture can be used for command and control of multiple recorders, as well
as message passing between them. A centralized server is no longer required,
resulting in considerable logistical and cost savings. For the flight test engineer,
an important application is marking points of interest during real-time and having
those areas identified and synchronized on other systems. Another application is
having any one of several engineers be able to change the display or chart
speed resolution of all connected systems based on a real-time event.
Airborne Flight Test Considerations
Regarding airborne Flight Test considerations, three mean factors are focused
upon: environmental conditions, appropriate user interface and monitoring.
Environmental Conditions
Telemetry recorder for airborne applications takes into account the compliance
with environmental conditions. Airborne recorder design will pay attention to
several factors: temperature, altitude and pressure, humidity, vibrations, emission
of radio frequency and electrostatic discharge.
3 specific factors are discussed in this paper: temperature, vibrations and
emission RF.
The use of COTS (Commercial Off-the-Shelf) components is the main problem
with temperature device. The typical range for onboard airborne equipment is –
15°C / +55°C and the typical range for COTS components is generally 0°C /
50°C. To deal with this difference, recorder design has to ease thermal
dissipation. Air inlets and warming system can also be considered as optional
devices.
For vibrations factor, the sensitive vertical axis (Z axis) should have an influence
in the inner disposition of discrete elements. Attention will also be paid with the
choice of connectors. Hardened lockable solution is a basic requirement for
connectors. The design of all moving part will be properly studied. Introduction of
ruggedized discrete elements can also allow complying with vibrations
requirements.
The RF emission of the recorder has to comply with airborne general
requirement. The equipment must be submitted to category M test “Maximum
Level of Radiated RF interference” described in DO160 document.