Microwave Frequency Measurement System Using Fixed Low Frequency Detection Based on Photonic Assisted Brillouin Technique

Microwave frequency measurement system is the chief component of the receiver, which is of indispensable significance in electronic warfare and modern radar. In this work, a simple and novel frequency measurement system that detects at fixed low-frequency point is established, which is implemented by introducing a frequency down-conversion, in conjunction with Brillouin Technique. A swept frequency signal is applied for the purpose of carrying the sideband of unknown signal. The frequency-shifted carrier is realized through the all-optical Brillouin frequency shifting process, which is used to downconvert unknown signals. Eventually, the unknown signal can be obtained by recording the frequency of the sweep signal when the beat signal occurs at a preset fixed frequency of 828 MHz. The proposed approach does not require broadband electronic monitoring equipment, which reduces the pressure of subsequent processing and acquisition. An experiment has been performed to vindicate the feasibility of the measurement system, which shows that a measurement ranges from 1 to 9.5 GHz. Meanwhile, the savitzky-golay algorithm is utilized to improve the frequency resolution to 15 MHz. Furthermore, a large bandwidth measurement range and the expanded uncertainty (95.45% coverage) of 3.604 MHz in the system are also discussed and verified.