An instantaneous frequency measurement scheme based on carrier phase-shifted double sideband modulation

A scheme for instantaneous frequency measurement (IFM) based on carrier phase-shifted double sideband (CPS-DSB) modulation is proposed. In the proposed scheme, two CPS-DSB modulations with different phase shifts are utilized, in conjunction with a dispersion device, an amplitude comparison function (ACF) is constructed by mapping the relation between the output power ratio of two photodetectors and the unknown frequency, therefore, the frequency measurement is achieved. Simulation results indicate that a frequency measurement range of 0.1–15.7 GHz with an error of less than 80 MHz is achieved, and the larger the slope, the smaller the measured error. In addition, by adjusting two phase shifts, a two-step frequency measurement is adopted by coordinated operation of a large range rough measurement and a small range precise measurement, the measured error of the unknown frequency can be improved significantly.