## 4 Discussion
In terms of physical layer security, the FM-ACSK system demonstrates several traits that can be discussed, although proper assessment would require an additional study dedicated to this subject. While the system transmits digital information and employs a digital foundation, its modulation and transmission are analog, limiting the scope of potential attacks. For example, eavesdropping would require knowledge of the modulation scheme. Although FM demodulation is straightforward and can be performed, for example, using software-defined radio (SDR), decoding the ACSK signal would ideally require replicating the system's exact setup, including the precise configuration of the slave chaos generators. If channel noise is low, distinguishing between direct and inverted \"R_out\" signals might allow an attacker to decode the ACSK signal by observing its properties. However, this vulnerability can be mitigated by using a chaos generator with output signal properties that make such distinctions more difficult while maintaining reliable synchronization. Potential attack scenarios such as jamming and man-in-the-middle attacks are also considered. The FM-ACSK system benefits from spread-spectrum properties, which offer some level of resistance to interference. However, deliberate jamming is possible if the attacker exploits the FM receiver's capture effect [32] by transmitting a higher-power carrier signal on the same frequency. The exact power differential required for successful jamming varies by FM demodulator and should be studied further. Resistance to jamming also depends on the design of the communication system's radio components, which were outside the scope of the present prototype. For a man-in-the-middle attack, the attacker would first need to successfully eavesdrop the communication and then replicate the FM-ACSK modulation in real time while altering the transmitted data. Although SDR could replicate the FM-ACSK signal using pre-recorded segments, real-time replication is challenging due to the FPGA's higher processing speed compared to SDR. Furthermore, the use of transmission packets with code keys, which can be updated at will, complicates the attacker's task of replicating and modifying the FM-ACSK transmission. Overall, the security features of the FM-ACSK system prototype warrant further experimental analysis and comparative testing with other communication systems. The chaotic coherent detection scheme offers a significant advantage over more popular non-coherent chaotic systems, which are more susceptible to eavesdropping. Compared to non-chaotic communication systems, where modulation techniques are well-documented and pose minimal theoretical challenges to interception, the FM-ACSK system benefits from a more intricate design that enhances its security potential. Future research will focus on further evaluating the system's performance, including its resistance to multipath propagation. Over time, key performance bottlenecks will be identified and optimized to achieve greater noise immunity, higher data rates, and improved overall efficiency, enhancing the system's robustness and adaptability for practical secure communication applications.