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How are the channel full scale voltages
determined?
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| Answer: The current release of the Sine control application has several methods to allow the user to establish the full scale input channel voltage range. In all cases, the user has the ability to select a given full scale (FS) range by entering that voltage value into the channel setup table dialog. Internal ranges are available from about 27 mvolts to 10 volts in 3 dB increments. The user input range is automatically scaled upwards to the next available setting should a non-exact value be entered. A special setting called "Auto" is also allowed to simplify the range selection. Control channels will have their FS value determined based on the maximum expected G level (including any positive abort tolerances). Auxiliary channels are generally set to 10 volts when using "Auto". The Auto setting should be the normal setting unless the user expects higher levels of distortion (or out of band energy) on the control channel. |
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What do the different status panel colors
indicate in Sine?
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| Answer: A simplified voltage "tracking" system is provided by observing the channel status view panel. The colors of the various channel values will change based on the current channel voltage level being processed. |
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| The following table allows the user to identify the channel voltage observed relative to the full scale (FS) channel range: |
| Color |
Meaning |
| Grey |
Channel is inactive or not available. |
| Yellow |
Channel voltage is less than or equal to 5% of the FS value. |
| Green |
Channel voltage is above 5% and less than or equal to 100% of the FS value. |
| Red |
Channel voltage is above 100% but less than 140% of the FS value. |
| White |
OVERLOAD (Channel voltage exceeds the "hard" overload limit (FS + 3 dB). |
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| Note that the input channel FS value allows for up to a 3 dB exceedance before a hardware overload indication is presented. This "extra" range is intended to allow for short duration transients to be properly digitized without an overload. A hard Overload on a control channel will cause a test abort. |
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• In the random vibration control application,
what is the "Prestored Drive" option and how is it used?
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| Answer: The random vibration control application utilizes dynamic measurements to constantly modify the spectral content of the shaker "drive" function. The time domain drive function is a constantly randomized time history which has the required spectral attributes to insure that the measured control points remain in spectral compliance. The generation of the spectral drive function begins with the low level equalization phase of the test and then continues until the end of the test. Due to the nature of the data acquisition process, the drive generation/modification process can take many (usually exponentially averaged) measurements to converge to a stable drive spectrum. The drive spectrum is constantly monitored and modified to ensure control compliance during the test. The intent of the "Prestored Drive" option is to start the test application with an already converged drive spectrum rather than forcing the control system to regenerate the spectrum. By starting with a prestored drive spectrum, the test can be allowed to start essentially at the transition to full level. This can significantly decrease the test startup times, especially for high resolution or low bandwidth test cases. Successful use of this feature generally is a function of the linearity of the shaker/amplifier system. The user has 2 options in determining and loading the source of the prestored drive spectrum. One simple method is to use the previous test's drive spectrum. This (first) option (PREV) assumes that the prior test was successful and that a drive spectrum is available. This spectrum option would not be available for the first test run. The drive spectrum is automatically stored/updated (locally) at the conclusion of each successfully completed test run. Should this option be selected, the first test run will execute without using the prestored drive feature. All SUBSEQUENT tests will invoke the prestored drive feature by utilizing the previous test's drive spectrum. The second option (YES/LOAD) is to select a drive spectrum from a previously stored test run's data file. This option allows an opportunity to have a drive spectrum loaded from a prior test run even if the current test is the first run. In either option case, the test specifications must be the same as the currently loaded run where the prestored drive is to be utilized. In other words, the number of lines, bandwidth and reference profile must be the same as that employed in the run from which the prestored drive spectrum was extracted. If the reference profile is modified, the system will reset any active prestored drive request to the PREV option. Finally, as a safety precaution, the user may elect to have the application request a verification at the start of any prestored drive enabled test run. This ensures that this option is not inadvertently left enabled when the user may have wanted to begin the test using the normal convergence process for drive spectrum generation. |
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