## 5 Experiment and Analysis  
To test the applicability and performance of the novel structure, we build an experiment with hardware implementation on real chains shown in Figure 10. Limited by the processing difficulty and high-cost manufacturing of the SAW filter, an S2P file is instead used to produce the SAW filter. As shown in Figure 10, an arbitrary waveform generator (AWG7082C) is used for the generation of the chirp signal \(f_{chirp}\left(t\right)\) and the input measured signal \(f\left(t\right)\). Frequency of the chirp signal starts from 2.5 GHz to 3.7 GHz, the time duration is 20 us, and the chirp rate is 60 MHz/us. The measured signal with four frequencies of 1.8 GHz, 1.9 GHz, 2.0 GHz, and 2.1 GHz is generated by the AWG. The measured signal is first mixed with the chirp signal though the mixer 1 to get the modulated signal \(f_{mix}\left(t\right)\). The modulated signal is then divided into two channels shown in Figure 10. Signals of channel 2 are mixed with a fixed frequency signal (600 MHz) generated by an analog signal generator and then combine with channel 1. Signals from the combiner are then filtered by the bandpass filter with band-pass width ranging from 700 MHz to 1.3 GHz. Then, a digital phosphor oscilloscope (DPO) with 2-GHz bandwidth is used to sample and store the output signals for the final pulse compression. At last, the sampled signals from DPO are sent to the ADS for pulse compression. Figure 11 shows the final compression results. The pulses appearing at m1, m2, m3, and m4 result from the pulse compression of channel 1. It can be seen that there are some differences in the amplitudes of these pulses. This is mainly caused by two aspects. One is the different convention loss for different input RF signals of mixer 1. Another is that the insertion loss of the power splitter and combiner changes slightly over the input frequency range. The pulses appearing at m5, m6, m7, and m8 result from the pulse compression of channel 2. The amplitudes of these pulses are much lower than that of pulses resulting from channel 1, and the difference ranges from roughly 10 dB to 12 dB. Not only are they influenced by mixer 1, power splitter, and combiner, but the amplitude differences between these pluses are also affected by the difference convention loss for different input RF signals as well as the difference convention loss between up-conversion and down-conversion of mixer 2. The up-conversion loss and down-conversion loss are shown in Figures 12 and 13, respectively. The horizontal axes of Figures 12 and 13 show the sweep range of RF input signal when the LO input signal is fixed to 600 MHz. It can be seen that the conversion loss of mixer 2 is approximately equal to the amplitude differences between pulses at m1, m2, m3, m4, and pulses at m5, m6, m7, and m8. The influence on amplitudes due to the mixers, power splitter, and combiner can be compensated in the later digital signal processing. Figure 9: Output pulses of the single-channel system with four input frequencies of the model with nonideal devices. Figure 11: Output pulses from experiment results of the novel single-channel CTS structure. Figure 12: Up-conversion loss of mixer 2. Figure 10: Hardware testing for the novel single-channel CTS structure. Usually, there are two ways to retrieve the instrument's spectral resolution. One is to obtain the time difference between the maximum value and the first zero-crossing point from the amplitude envelope of the output pulses, and the spectral resolution is approximately equal to the product of the time difference and the chirp rate. Another is to derive the full-width half-maximum (FWHM) to obtain the average FWHM [15]. Here, we use the FWHM method to retrieve the spectral resolution. Firstly, the response of the novel single-channel CTS system to a sinusoidal input is measured at different input frequencies. Then, the relative half-width half-maximum (HWHM) to the right and left could be obtained from the measurements and thus, the full-width half-maximum (FWHM) is derived.