The technique of interpolated arrays is applied to ESPRIT-type direction-finding methods. The resulting method uses sensor arrays with arbitrary configuration, thus eliminating the basic restrictive requirement of ESPRIT for two (or more) identical arrays. The approach allows for resolving D narrowband signals if the number of sensors is at least D+1, while the original ESPRIT method requires at least 2D sensors. Moreover, it is shown that while ESPRIT performs poorly for signals propagating in parallel (or close to parallel) with the array-displacement vector, this technique does not exhibit such weakness. While using two subarrays ESPRIT cannot resolve azimuth and elevation, even when the sensors are not collinear. The interpolated ESPRIT procedure resolves azimuth and elevation using only a single array. These advantages are obtained with a reasonable increase in computation load, thus preserving the basic and most outstanding advantage of ESPRIT.>

Bit synchronization algorithms based on signal zero-crossing analysis are investigated. Their performance is compared to conventional maximum-likelihood-type techniques for symbol timing recovery. The zero-crossing bit synchronizers are shown to be superior for bandlimited pulses such as raised cosine and double-jump frequency rolloff, except for very low signal-to-noise ratios.>

Measurements of a process described by t(i)=k/sub i/T+ tau + eta (i), (i=1, 2, . . .), where k/sub i/ are unknown integers and ( eta (i)) is a white noise, are considered. The estimation of the 'period' T and 'phase' tau of such processes is often required in communications and radar. Popular linear regression techniques for this estimation problem are shown to fail and new algorithms are derived. Statistical properties of the estimators are presented, under reasonable assumptions. The suggested procedure is illustrated in the digital communications symbol timing recovery from eye-diagram zero crossings. The new bit synchronizer obtained is shown to be superior in many practical situations to known maximum-likelihood-type algorithms.>

An analytical expression for evaluating the mean-square crosstalk between adjacent channels in coherent tamed frequency modulation (TFM) systems is presented. Numerical results are obtained and compared to previous crosstalk results for minimum shift keying (MSK); the substantial superiority of TFM is confirmed. An equivalent white Gaussian noise model for crosstalk is included and used to estimate performance degradation as a function of frequency separation between channels. The crosstalk results are also used to show that TFM is about 0.9 dB more sensitive to tone jamming than MSK.