High sensitivity detection techniques are required for indoor navigation using Global Navigation Satellite System (GNSS) receivers, and typically, a combination of coherent and non- coherent integration is used as the test statistic for detection. The coherent integration exploits the deterministic part of the signal and is limited due to the residual frequency error, navigation data bits and user dynamics, which are not known apriori. So, non- coherent integration, which involves squaring of the coherent integration output, is used to improve the detection sensitivity. Due to this squaring, it is robust against the artifacts introduced due to data bits and/or frequency error. However, it is susceptible to uncertainty in the noise variance, and this can lead to fundamental sensitivity limits in detecting weak signals. In this work, the performance of the conventional non-coherent integration-based GNSS signal detection is studied in the presence of noise uncertainty. It is shown that the performance of the current state of the art GNSS receivers is close to the theoretical SNR limit for reliable detection at moderate levels of noise uncertainty. Alternate robust post-coherent detectors are also analyzed, and are shown to alleviate the noise uncertainty problem. Monte-Carlo simulations are used to confirm the theoretical predictions.

J.-Y. Girard's (1992) new translation from classical to constructive logic is explained. A compatible continuation-passing-style (CPS) translation is given and converted to a C-rewriting machine evaluator for control-operator programs and a set of reduction/computation rules sufficient to represent the evaluator. It is found necessary to add one reduction rule to M. Felleisen's (Ph.D. thesis, Indiana Univ., 1987) calculus (evaluation under lambda -abstraction). This reduction rule arises from a modified call-by-name CPS-translation. Turning to Girard's new classical logic LC, an intuitionistic term-extraction procedure is provided for it, producing CPS functional programs. Using the syntactic properties of this language, it is possible to give simple proofs for the evidence properties of LC. This work sheds light on the design space of CPS-translations and extends the relation between control-operator languages and classical logic.>

It is shown how to interpret classical proofs as programs in a way that agrees with the well-known treatment of constructive proofs as programs and moreover extends it to give a computational meaning to proofs claiming the existence of a value satisfying a recursive predicate. The method turns out to be equivalent to H. Friedman's (Lecture Notes in Mathematics, vol.699, p.21-28, 1978) proof by A-transition of the conservative extension of classical cover constructive arithmetic for II/sub 2//sup 0/ sentences. It is shown that Friedman's result is a proof-theoretic version of a semantics-preserving CPS-translation from a nonfunctional programming language back to a functional programming language. A sound evaluation semantics for proofs in classical number theory (PA) of such sentences is presented as a modification of the standard semantics for proofs in constructive number theory (HA). The results soundly extend the proofs-as-programs paradigm to classical logics and to programs with the control operator, C.>

G. Higman's lemma (1952) is a special case of the more general Kruskal's tree embedding theorem and the graph minor theorem. A direct constructive proof of the lemma with manifest computational content is presented. This is done by reducing the problem to a construction of certain sets of sequential regular expressions. A well-founded order on such sets is exhibited, and the lemma then follows by induction.>