Jun 12, 2009
The original communications system received power and audio feeds through hard-wired point-to-point connections inside the instrument manifold. Field service and preventative maintenance (PM) was a constant and costly challenge. In-flight failure rates were disturbingly high.
Engineers at Orchid began with an evaluation of the original system. They discussed the requirement that the new unit fit within the physical envelope of the old, and that power and signaling maintain compatibility with the existing installation procedures.
The original unit was merely an intercom, but the new device had to fulfill the functions of intercom and sophisticated data logger/emergency recovery system. The design tasks included circuit board area studies with mechanical drawings of how the new circuitry fit within the old envelope. For the front panel, the team settled on IIC-based control systems from NXP. These drove multiple multi-color high-intensity LED indicators. Now, all operator indicator lights' brightness and color could be digitally controlled. The audio system redesign followed a similar digital architecture using codec devices from Texas Instruments. The codecs were connected in a channelized, synchronous serial manner. The codecs provide audio filtering, some simple processing and the ability to time slot multiplex many separate audio channels onto a single digital stream.
The Marvell PXA270 processor was selected as the main processing element. IIC bus-mapped front panel indicators and controls make for a flexible user interface design. Rounding out the design were multiplexed audio codecs from Texas Instruments, USB Bus expanders from OKI, and video decoding solutions from NXP to complete the design. CCIR-565 decoded video was supplied to the Freescale I.MX27 system processor. Data storage was accomplished using a ruggeddized USB memory stick connector to the I.MX27 processor's USB 2.0 ports.
Completing the new communication subassembly design were power supply devices from Linear Technologies and transient suppressors from On Semiconductor. Panasonic gold-capacitors served as the system's energy store for catastrophic power loss. Electrical and mechanical engineering worked closely together to define the circuit board layout, interconnection system, keep out areas and mechanical restrictions.
Read more about the cockpit audio/video system at http://www.cotsjournalonline.com.
Orchid develops custom electronic products for OEM's. Orchid has successfully completed hundreds of electronic product designs. Visit Orchid Technologies at http://www.orchid-tech.com or call Paul Nickelsberg, President and CTO of Orchid Technologies at 978-461-2000 X111.
