DSOX3024 FFT奇怪的行为

这与ASV无关，但这是我在摆弄通道阻抗时发现的。
当我第一次打开示波器时，之前配置的FFT会自动启动。
当我将通道阻抗从50欧姆更改为1兆欧姆时，最大测量值从dbm变为dbv。
当我将阻抗切换回50欧姆时，它保持这种状态。
当我使用FFT /更多FFT /垂直单位时，默认值为分贝。
当我将菜单切换到V RMS并返回Decibles时，Max测量值将锁定到dbm。
在再次使用FFT /更多FFT /垂直单位后，它处于一种模式，当我选择V RMS时，FFT消失，最大测量显示0dbm。
当我启动FFT /更多自动设置时，测量值回到0dbm但是当我选择V RMS时，测量值为223mv，本底噪声和电平下降。
回到Decibles并且测量是正确的。
事情并不一致，看起来测量结果都不合时宜。
没有明确的方法来纠正问题，通过更改其他设置，FFT可以关闭。编辑：Willco788于2012年6月9日上午6:25 fft_problems.bmp1.2 MBscope_4.bmp1.2 MB



     以下为原文

  This has nothing to do with the ASV but it's something I discovered while fiddling with channel impedance.   When I first turn-on the scope, the FFT that was configured previously, launches automatically.  When I change the channel impedance from 50 ohm to 1 MegOhm, the Max measurement changes from dbm to dbv.  It stays that way when I toggle the impedance back to 50 Ohms.  When I go the the FFT/More FFT/Vertical Units, the default is Decibels.   When I toggle the menu to V RMS and back to Decibles, then Max measurements is locked to dbm.   

After fiddling with  FFT/More FFT/Vertical Units again, It's in a mode where when I select V RMS, the FFT dissapears and the Max Measurement shows 0dbm.  When I launch  FFT/More Auto Setup, the measurement is back to 0dbm but when I select V RMS the the measurement is 223mv, the noise floor and the level drops. Back to Decibles and the measurement is correct.

Things aren't consistant and it appears the the measurements are all out of wack.  There's no clear way to correct the problem and by changing other settings, the FFT can shut down.

Edited by: Willco788 on Jun 9, 2012 6:25 AM   
附件

• fft_problems1.bmp1.2 MB
• fft_problems.bmp1.2 MB
• scope_4.bmp1.2 MB