## 4 Validation Through Sea Trials
### Processing and Analysis of the Third Group of Sea Trial Data  
Through the analysis of the aforementioned sea trial data, it can be concluded that CCF-MSS outperforms other reception methods under conditions of high speed and high acceleration. Next, we analyzed the noise resistance performance of CCF-MSS based on the third group of data. Figure 15 illustrates the speed and channel impulse response during the third group of sea trials. It is evident that significant noise interference occurred during the third group of sea trials. Figure 9e,f displays the frame accuracy for decoding using different methods. It can be observed that during periods of strong noise interference, the performance of WDE-MSS and CDE-MSS significantly deteriorates, whereas CCF-MSS maintains a high accuracy rate, indicating that the use of the CCF-MSS reception  
Figure 14: (**a**,**c**) is despreading correlation peaks of symbols 3 and 4 by CCF-MSS, (**b**,**d**) is despreading correlation peaks of symbols 3 and 4 by FDE-MSS (third frame of second group).  
Figure 13: (**a**) is the CFO compensation estimated by CCF-MSS, (**b**) is the CFO compensation estimated by BDS output speed, (**c**) is the CFO compensation estimated by FDE-MSS (second group).  
method can still achieve high spreading gain under high-speed conditions, demonstrating a stronger noise resilience capability.  
In the processing of the third group of data, the BER for FDE-MSS and CDE-MSS is relatively high at frame 13, which corresponds to the position of the white box in Figure 15, indicating that there is significant noise interference at this time. Figure 16 presents the CFO compensation results for frame 13. It can be observed that the CFO compensation results of CCF-MSS are largely consistent with the speed compensation results output by the BDS, while significant discrepancies are noted for FDE-MSS at symbols 20 and 31. We analyze that this is due to the high noise levels at that time, where the decline in spreading gain caused by frequency offset cannot overcome the prevailing noise environment. The following section will illustrate the despreading correlation peaks for symbols 21 and 31 in frame 13 as examples. Symbol 21 is correctly decoded using the CCF-MSS reception method, and while it is incorrectly decoded by the FDE-MSS reception method, Symbol 31 is incorrectly decoded by both methods. Figure 17 illustrates the despreading correlation peaks for symbols 21 and 31 in frame 13. It can be observed that the range of CFO compensations for symbol 21 differs significantly between the two reception methods. This also indicates that even under high noise conditions, the accuracy of Doppler estimation using correlation cost factors remains high. During the CFO compensation process for symbol 31, although the CFO compensation results from both methods are quite similar to the output results of the BDS, neither method is able to achieve correct decoding. We attribute this decoding failure to the high instantaneous noise levels.  
Figure 15: (**a**) is the speed of the third group processes recorded by BDS, (**b**) is the third group processes channel impulse response.