Signal Transmission Integrity in Software-Defined RF Transceivers

This paper presents a detailed evaluation of software-defined RF transceivers, focusing on signal transmission performance across a range of Universal Software Radio Peripherals (USRPs) with different architectures, as well as Vector Signal Transceivers (VSTs). Three key experiments were conducted: first, power variations were observed during Frequency Modulated Continuous Wave (FMCW) signal transmission across different USRP models, revealing significant differences in signal retention. Second, we evaluated 4QAM, 16QAM, and 256QAM modulation schemes, focusing on power efficiency and signal integrity. QAM was chosen due to its balanced use of amplitude and phase, making it ideal for high-bandwidth applications and providing valuable insights into how transceivers handle complex signal demands. The observed phase and frequency offsets revealed device-specific characteristics in signal retention and stability, important for transceiver performance evaluation under various conditions. Additionally, tone modulation experiments examined backscattered and undirected signal behavior, demonstrating how internal distortions, combined with multi-path reflections, can degrade performance, particularly in scenarios with multiple surface reflections before the signal reaches the receiver. A dual-spectrum analysis approach was employed to capture these effects. The performance variations among the evaluated USRP models can be linked to architectural differences, such as Field-Programmable Gate Arrays (FPGA) configurations, ADC/DAC precision, and clock stability. Our findings offer valuable insights for optimizing Software-Defined Radio (SDR) platforms in wireless communication and sensing systems, with practical implications for advanced applications such as Integrated Sensing and Communication (ISAC) in 6G and future wireless networks.