Hi - 零跨度中使用的频谱分析仪本质上是一个频率选择示波器，其带宽由分辨率带宽（RBW）设置决定。
仅观察到在中心频率的RBW / 2内的频率。
例如，如果您的中心频率为1 GHz且RBW为3 MHz，则分析仪将响应998.5 MHz至1001.5 MHz的信号，并具有合理的幅度精度。
当施加信号的频率移动到该范围之外时，由于RBW滤波器的形状，显示的幅度将下降。
如果将函数发生器的信号直接应用到分析仪输入时，中心频率设置为0 Hz，您将观察到频谱分析仪的LO馈通（扫描调谐频谱分析仪的0 Hz“信号”）
）。
由于LO馈通基本上是CW信号，因此它在零跨度中显示为平直线。
在这种情况下，即使中心频率不是精确的0 Hz，如果RBW足够宽以包括LO馈通，并且LO馈通幅度明显高于所施加的脉冲信号，您仍然会看到平坦线。
当施加的信号幅度达到LO馈通的幅度电平时，您将看到LO馈通和施加的信号相互干扰。
您的观察结果是我们不将频谱分析仪作为示波器推广的关键原因。
问候 -
以上来自于谷歌翻译
以下为原文
Hi -
A spectrum analyzer used in zero span is essentially a frequency-selective oscilloscope, with the bandwidth determined by the Resolution Bandwidth (RBW) setting. Only frequencies well within RBW/2 of the center frequency will be observed. For example, if your center frequency is 1 GHz and your RBW is 3 MHz, the analyzer will respond to signals from 998.5 MHz to 1001.5 MHz with reasonable amplitude accuracy. As the frequency of the applied signal moves outside of this range, the displayed amplitude will drop due to the shape of the RBW filter.
If the center frequency was set to 0 Hz when you applied the signal from the function generator directly into the analyzer input, you would be observing the LO feedthrough of the spectrum analyzer (the “signal” at 0 Hz of a swept-tuned spectrum analyzer). Since the LO feedthrough is essentially a CW signal, it appears as a flat line in zero span.
Even if the center frequency were not exactly 0 Hz in this case, if the RBW was wide enough to include the LO feedthrough, and the LO feedthrough amplitude is significantly higher than the pulse signal applied, you would still see a flat line. As the applied signal’s amplitude reaches the amplitude level of the LO feedthrough, you will see the LO feedthrough and the applied signal interfering with each other.
Your observations are a key reason we do not market spectrum analyzers as oscilloscopes.
Regards -
Hi - 零跨度中使用的频谱分析仪本质上是一个频率选择示波器，其带宽由分辨率带宽（RBW）设置决定。
仅观察到在中心频率的RBW / 2内的频率。
例如，如果您的中心频率为1 GHz且RBW为3 MHz，则分析仪将响应998.5 MHz至1001.5 MHz的信号，并具有合理的幅度精度。
当施加信号的频率移动到该范围之外时，由于RBW滤波器的形状，显示的幅度将下降。
如果将函数发生器的信号直接应用到分析仪输入时，中心频率设置为0 Hz，您将观察到频谱分析仪的LO馈通（扫描调谐频谱分析仪的0 Hz“信号”）
）。
由于LO馈通基本上是CW信号，因此它在零跨度中显示为平直线。
在这种情况下，即使中心频率不是精确的0 Hz，如果RBW足够宽以包括LO馈通，并且LO馈通幅度明显高于所施加的脉冲信号，您仍然会看到平坦线。
当施加的信号幅度达到LO馈通的幅度电平时，您将看到LO馈通和施加的信号相互干扰。
您的观察结果是我们不将频谱分析仪作为示波器推广的关键原因。
问候 -
以上来自于谷歌翻译
以下为原文
Hi -
A spectrum analyzer used in zero span is essentially a frequency-selective oscilloscope, with the bandwidth determined by the Resolution Bandwidth (RBW) setting. Only frequencies well within RBW/2 of the center frequency will be observed. For example, if your center frequency is 1 GHz and your RBW is 3 MHz, the analyzer will respond to signals from 998.5 MHz to 1001.5 MHz with reasonable amplitude accuracy. As the frequency of the applied signal moves outside of this range, the displayed amplitude will drop due to the shape of the RBW filter.
If the center frequency was set to 0 Hz when you applied the signal from the function generator directly into the analyzer input, you would be observing the LO feedthrough of the spectrum analyzer (the “signal” at 0 Hz of a swept-tuned spectrum analyzer). Since the LO feedthrough is essentially a CW signal, it appears as a flat line in zero span.
Even if the center frequency were not exactly 0 Hz in this case, if the RBW was wide enough to include the LO feedthrough, and the LO feedthrough amplitude is significantly higher than the pulse signal applied, you would still see a flat line. As the applied signal’s amplitude reaches the amplitude level of the LO feedthrough, you will see the LO feedthrough and the applied signal interfering with each other.
Your observations are a key reason we do not market spectrum analyzers as oscilloscopes.
Regards -
举报
