This dissertation makes a study of frequency discriminators and their role in instantaneous frequency measuring (IFM) signal acquisition receivers. Frequency discriminators are the major building blocks of IFM. They are required to measure frequency accurately over very broad bandwidths and to have near unity probabilities of pulse intercept. The major difficulties of the most commonly reported version are identified as a lack of component symmetry and a need to cross over two transmission lines while maintaining isolation. The accuracy due to lack of symmetry shows up analytically. effect on TOUCHSTONE, a micro-computer analysis package, is demonstrated as an excellent analysis tool while alternatives are also suggested. Variations of the standard discriminator are discussed. These are intended to improve performance due to lack of symmetry. None completely solve the cross over problem. A new type of discriminator requiring fewer components is introduced. It requires no cross over and exhibits greater symmetry. Analysis indicates that it performs better than the standard version. Two prototypes show the methods to be reliable and confirm the promise of the new version.