In this paper, we address the challenge of detecting bottom cracks in railway tracks by proposing a signal enhancement technique designed to boost the signal-to-noise ratio of guided wave signals, thereby optimizing sensor performance. Utilizing Barker codes and binary phase shift keying technology, we modulated the original excitation signal to achieve spread spectrum processing and the subsequent despreading of received signals. This approach aims to overcome hardware and sensor limitations, enhancing the operational efficiency of the sensors used in ultrasonic guided wave detection systems. An experimental platform was established to test this technique on railway tracks with artificial bottom cracks of varying sizes. The results showed that the enhanced signals can travel further and detect cracks with a higher sensitivity than the original signals. This not only validates the effectiveness of our method in improving sensor capabilities but also supports the application of ultrasonic guided wave detection for bottom cracks in railway tracks.