| 摘要 |
<p>Systems and methods for testing a signal generated by a Direct Digital Synthesizer (DDS) 100 in a radar altimeter 20. In an embodiment of the method, a voltage signal derived by comparing a fixed reference frequency to a ramped frequency signal generated by the DDS based on a clock-based reference signal is generated. The generated voltage signal is integrated over a predefined range of clock signals. The integration is sampled at a previously defined clock tick. The sample is compared to a desired value and an indication that the radar altimeter is malfunctioning is provided if the comparison exceeds a predefined threshold value. The radar altimeter system is deactivate if an indication that the radar altimeter is malfunctioning has been provided.</p> |
