In this paper, we pursue the study of the radar ambiguity problem started in [Ja, GJP]. More precisely, for a given function u we ask for all functions v (called ambiguity partners) such that the ambiguity functions of u and v have same modulus. In some cases, v may be given by some elementary transformation of u and is then called a trivial partner of u otherwise we call it a strange partner. ...

Establishing measures for local stationarity is an open problem in the field of time-frequency analysis. One promising theoretical measure, known as the spread, provides a means for quantizing potential correlation between signal elements. In this paper we undertake the issue of generalizing techniques developed by the Authors to better estimate the spread of a signal. Existing techniques estim...

Properties of chirped-train waveforms such as their multi-band power spectra and the resulting point spread and ambiguity functions are described. Possible advantages in the utilization of chirped trains in “multi-spectral” imaging (i.e., imaging based on frequency sub-bands of the chirped train signal) allowing extraction of frequency dependent information with improved signal-to-noise ratio a...

A crucial assumption in the optimal auction literature is that each bidder’s valuation is known to be drawn from a unique distribution. In this paper, we study the optimal auction problem allowing for ambiguity about the distribution of valuations. Agents may be ambiguity averse (modeled using the maxmin expected utility model of Gilboa and Schmeidler 1989). When the bidders face more ambiguity...

In the paper we address the problem of constructing frequency hop codes for use in multiuser communication systems such as multiple-access spread-spectrum communications and multiuser radar and sonar systems. Previous frequency hopping techniques are reviewed. The construction of a new family of frequency hop codes called hyperbolic frequency hop codes is given. Exactly p-1 codes of length p-1 ...

We present a survey on the current status of the constructions of polyphase sequences with low correlation, discrete Fourier transform (DFT), and ambiguity in both time and phase domain, including some new insights and results. Firstly, we systematically introduce the concepts of phase-shift operators and ambiguity functions of sequences, and give a new construction of polyphase sequences from ...

In this paper the application of chaotic signals in continuous wave (CW) ranging systems is addressed. Diierent chaos generators that can be applied in this application are presented and analysed with respect to their signal properties. In the case of a CW ranging system the important requirement is an unambigu-ous range estimation. If classical correlation processing is applied in the CW rangi...

Integer ambiguity resolution is critical for achieving positions of high precision and for shortening the convergence time of precise point positioning (PPP). However, GLONASS adopts the signal processing technology of frequency division multiple access and results in inter-frequency code biases (IFCBs), which are currently difficult to correct. This bias makes the methods proposed for GPS ambi...

Viewing intrusion detection as a problem of plan recognition presents unique problems. Real world security domains are highly ambiguous and this creates significant problems for plan recognition. This paper distinguishes three sources of ambiguity: action ambiguity, syntactic ambiguity and attachment ambiguity. Previous work in plan recognition has often conflated these different sources of amb...