A broadband, high-dynamic-range, and high-fidelity distributed data acquisition instrument

To address the need for distributed acquisition and high-quality reconstruction of broadband transient radar signals at multiple measurement points, a broadband, high-dynamic-range, and high-fidelity distributed data acquisition instrument is designed and implemented. The instrument comprises front-end acquisition boxes, receiving boxes, an Ethernet switch, and host-computer software. Each acquisition box integrates signal-conditioning circuits, a time-interleaved analog-to-digital converter, a low-jitter clock network, a field-programmable gate array (FPGA), local buffering, and an optical-fiber interface to perform high-quality acquisition, digitization, and transmission of broadband signals. A joint amplitude-phase compensation filtering algorithm is implemented in the FPGA to compensate for amplitude and phase distortions and improve the amplitude-frequency response and transient waveform fidelity of the acquisition channel. Experiments demonstrate a maximum sampling rate of 10.4 GSPS, a 1 GHz operating bandwidth, an effective number of bits of at least 8.2 bits, and a dynamic range of at least 57 dB over all ranges. Within the target bandwidth, the passband flatness is within ±0.5 dB, the fast-edge rise time is below 350 ps, and the minimum measured synchronization time differences within one acquisition box and between different acquisition boxes are both less than one sampling period.