A new low cost method for implementing an Instantaneous Frequency Measurement (IFM) system is presented in this paper. The proposed method is based on dividing the incoming RF signal into four signals and filtering each one by an appropriate band-pass filter. The frequency is then estimated from the power level of the filtered signals. A closed form for the Standard Deviation (STD) and the bias of the frequency estimator is derived. A design example for an IFM system with a working frequency band of 2 to 4 GHz is presented with simulated and measured results. The design is implemented on a commercial FR-4(DE104) substrate using printed circuit board technology. Experiments in a laboratory show a maximum error of about 15 MHz in estimating the frequency value.
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