| In nature, human activities cannot do without visual information. Visual systemis composed of people’s eyes receptors to receive the light signal from the certainfeatures of the outside world. Through the analysis of brain people get the lightinformation of outside things. Especially in aerospace flight, the pilots because of thetransfer of information between the driving position and driving environmentalrestrictions only observe instruments on the aircraft to learn the aircraft state. Airbornedisplay system is a pilot to get the aircraft state information,such as flyingaltitude,magneticmeteorological conditions, etc. Airborne electronic display systemsare essentially on-board sensors and electronic devices generated analog signal.Through the optical character image display format pilot give information to the pilotof a human-computer interaction interface. It converts the argument to visualinformation for pilot was able to read the information. Especially in emergency flights,the pilot must obtain in a very short time the aircraft status information to keep safeand timely operation. Which HDD(Head Down Display) airborne electronicequipment as an important part.The above illustrates the HDD is importance of airborne equipment. The need fora ground signal source can simulate a variety of real signal to maintenance HDD. Thetest in the presence of high cost, high risk, difficult, and the test task on an airborneequipment is needed many instruments. In order to overcome the above shortcomings,this design adopts the method based on CPCI bus test equipment. It is a newtechnology with the development of computer technology in the industrial fieldgenerated by the test equipment which can be made smart and integrated. CPCI bussystem has PCI bus performance characteristics. Data transmission up to132MB/s in32bit or to264MB/s in64bit and also support the system voltage of3.3V. PCIbridge to PCI/Local extension and plug and play Hot Swap capability, withspecialized system reference clock, star trigger.The test system controller design is based on CPCI bus specification.Architecture of the system use standard CPCI bus standard case. It based on CPCI busprovides information exchange environment. A general computer as the systemcontrol center with high performance ETX (Embedded Technology eXtended)embedded computer as the controller. ETX core board using ETX-AT-N270of ADlink,it with ETX load board builds up the slot0controller. When designing ETX carrier board using PCI2050as the PCI-PCI bridge allows the controller to control functionson the bus. Through the connector on ETX board the ETX can communicate with theCPCI backplane to control expansion card. The ETX board provides various computerperipheral interface and facilitate the development and operation.For this task, need to design the card waveform generator based on CPCI bus.Through the PC test software to generate specific test waveforms. WaveformGenerator boards using DDS(Direct Digital Synthesizer) technology to generatewaveforms. This article describes the DDS technology. FPGA is designed toimplement the core structure of DDS circuit. It though a signal conditioning outputsthe test waveform. It supports Microsoft development patterns or NI MeasurementStudio and Windows OS.This test system through on-site online debugging meets the technical indicators.It improves the testing environment. It greatly increases the functionality andreliability of the system as VI(virtual instrument).Maximize existing resources,rational use of existing technology. It flexible analog signal waveform and accuratelyreflect the equipment under test conditions. It meets the needs of test HDD. To buildthe aircraft repair line provides a reliable test scheme.Finally, This design is a universal test device to meet universities and factories.The test system can have commonality. It can complete the HDD test tasks. Expandand update the equipment can test other airborne instruments. It can solve thecomplex in the test,low test efficiency and poor scalability. |
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