Digital Fiber-Optic Transmission of the CSRH

This paper presents the basic scheme, configuration, principle, and advantages of the digital fiber-optic transmission in the Chinese Solar Radioheliograph (CSRH). For reducing costs an RF broadband solar signal in the CSRH high-frequency domain (2GHz-15GHz) is divided into different parts, each of which is converted to a narrow-band signal of a specific frequency. In total 32 bands of signals with a 5MHz bandwidth are chosen from an RF signal and are converted into the IF band for digital sampling. The solar signals are sent to 3km away from the central controlling house by a digital fiber-optic transmission system. In the transmission system, the solar signals are formatted to counter environmental interferences. Through the optical modulation, optical-fiber transmission, and demodulation, the signals are unformatted for the next-step process. In addition, this paper describes some important parameters in the digital fiber-optic transmission, such as the bit-error rate, jitter frequency/amplitude, and fiber-characteristic drift.