63,111 research outputs found
Estimation of the modulation index of cpm signals using hos
Three simple methods are proposed for the estimation of the modulation index of continuous phase modulated signals in noise. These methods employ the estimated autocorrelation and fourth-order cumulant sequences of the received signal after sampling at the symbol rate. Analytic expressions are derived for the asymptotic mean and variance of the estimated parameters which are corroborated by means of Monte Carlo simulations. The performance of the methods is illustrated graphically and numerically. It is concluded that, under significant noise degradation, only the scheme based on the fourth-order cumulant sequence can be used to estimate consistently the modulation index h in the range 0(h(1.Peer ReviewedPostprint (published version
A 64-channel inductively-powered neural recording sensor array
This paper reports a 64-channel inductively powered neural recording sensor array. Neural signals are acquired, filtered, digitized and compressed in the channels. Additionally, each channel implements a local auto-calibration mechanism which configures the transfer characteristics of the recording site. The system has two operation modes; in one case the information captured by the channels is sent as uncompressed raw data; in the other, feature vectors extracted from the detected neural spikes are transmitted. Data streams coming from the channels are serialized by an embedded digital processor and transferred to the outside by means of the same inductive link used for powering the system. Simulation results show that the power consumption of the complete system is 377μW.Ministerio de Ciencia e Innovación TEC2009-0844
Blind multiuser deconvolution in fading and dispersive channels
An adaptive near-far resistant technique for the blind joint multiuser identification and detection in asynchronous CDMA systems is analyzed in fading and dispersive GSM channels.Peer ReviewedPostprint (published version
A relationship between the ideals of and the Fibonacci numbers
Let be the number of ideals of codimension of
, where is the
finite field with elements. Kassel and Reutenauer [KasselReutenauer2015A]
proved that is a polynomial in for any fixed value of .
For , this combinatorial interpretation of
is lost. Nevertheless, an unexpected connexion with Fibonacci numbers appears.
Let be the -th Fibonacci number (following the convention ,
). Define the series
We will prove that for each ,
where the integers are given by the following generating function
\prod_{m \geq 1} \left(1+F\left( t^m\right)\right) = 1 + \sum_{n \geq 1}
\lambda_n\,t^n. $
Middle divisors and -palindromic Dyck words
Given a real number , we say that is a -middle
divisor of if We
will prove that there are integers having an arbitrarily large number of
-middle divisors. Consider the word given by where is the set of
divisors of , and are the elements of the symmetric difference written in increasing order. We will prove that the language contains Dyck words having an
arbitrarily large number of centered tunnels. We will show a connection between
both results
A power efficient neural spike recording channel with data bandwidth reduction
This paper presents a mixed-signal neural spike recording channel which features, as an added value, a simple and low-power data compression mechanism. The channel uses a band-limited differential low noise amplifier and a binary search data converter, together with other digital and analog blocks for control, programming and spike characterization. The channel offers a self-calibration operation mode and it can be configured both for signal tracking (to raw digitize the acquired neural waveform) and feature extraction (to build a first-order PWL approximation of the spikes). The prototype has been fabricated in a standard CMOS 0.13μm and occupies 400μm×400μm. The overall power consumption of the channel during signal tracking is 2.8μW and increases to 3.0μW average when the feature extraction operation mode is programmed.Ministerio de Ciencia e Innovación TEC2009-08447Junta de Andalucía TIC-0281
On prime numbers of the form
Consider the set of integers for which there are infinitely
many primes such that is a power of . The aim of this paper is to
show a relationship between and the limits points of some set
rational numbers related to a sequence of polynomials introduced by
Kassel and Reutenauer [KasselReutenauer]
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