Front-end Saturation

Some RF interferences with a relatively high power level can saturate the front-end of a GNSS receiver. This saturation can cause issues in signal processing, and ultimately in the receiver's ability to provide a reliable PVT solution. 

Monitoring Saturation in Spectrum View

Several peaks may be seen in the spectrum view during saturation even if the interfering signal is a narrow-band pulse. Figure 1 shows an example of the spectrum view plot taken from a PolaRx5 near a DME beacon. Although the DME beacon only transmitted a narrow-band pulse centered at 1197MHz, several other peaks can be seen across the L5 band. The narrow and wide-band mitigation filters (AIM+) were disabled on this receiver when the capture was taken. These peaks are the result of non-linear operation in the receiver's front-end. 
 

Figure 1, Multiple Peaks Caused by Saturation
 

Saturation of the front-end can be confirmed using the raw samples tab of the spectrum analyzer view. During saturation the raw samples will hit the lower and upper limits of -128 and 127 respectively, as seen below in Figure 2.
 

  

Figure 2, Raw Samples During Saturation

摘錄自：

https://customersupport.septentrio.com/s/article/Front-end-Saturation-Caused-by-Interference