The X-band Instantaneous Frequency Measurement Meter

IFM(Instantaneous Frequency Measurement) technology plays a great part in the modern EW(Electronic War) through its fast development for several decades. In the modern complex electromagnetic environment, it's one of the most important factors to grasp the inside track in the EW by intercepting and capturing the radar parameters transmitted by enemy, such as amplitude, pulse width, arriving time, carrier wave frequency, the characteristic of phase modulation, etc. With the development of the technology of radar, the airspace-alert radar and the fire-control radar, etc, have adopted the technology of frequency agility, so an IFM meter is used for tracking the carrier wave frequency of radar transmitter.The most common method to realize IFM is called interferometer phase-comparison, namely delay-line phase detection which is the theory foundation to realize the analog scheme of the project. Since the wide-band phase detector usually has poor precision, if we want to obtain high precision of frequency measurement, the delay line may be too long to realize. With the development of software radio-technology, very high-speed ADC, DSP and FPGA come forth continuously. By making use of digital frequency measurement arithmetic, we can get excellent precision of frequency measurement easily. This is one of the most important ways to realize IFM by using digital frequency measurement arithmetic in the future.At the beginning of the thesis, the main methods and related theory about the IFM and some digital frequency measurement arithmetic are introduced. The methods of multi-channel IFM and interferometer phase-comparison IFM and the phase-accumulation arithmetic adopted to realize IFM are discussed in detail. The simulation of phase-accumulation arithmetic is discussed. And then both digital and analog schemes are demonstrated. The precision and time of frequency measurement are analyzed detailedly and the analog scheme is adopted in the subject. Lastly, the IFM meter's hardware circuit design, software design and the system measurement result are presented.