Inband noise cancelling in FM systems: the white noise case (original) (raw)

Modulation discrimination interference for narrow-band noise modulators

Journal of The Acoustical Society of America, 1995

The discrimination of the depth of amplitude modulation of a sJignal carrier frequency can be disrupted by the presence of other modulated carriers (maskers), an effect called modulation discrimination interference (MDI). This paper examines whether MDI is influenced by the similarity in the envelope pattern of the signal and masker. A narrow-band noise (centered at 10 Hz) was used as the signal modulator. The first experiment used masker modulators that were narrow-band noises identical in spectral characteristics to the signal modulator. The [nasker modulators were either identical to the signal modulator, negatively correlated with it, or uncorrelated with it. The amount of MDI was similar for all three cases. In experiment 2, the masker was sinusoidally modulated at rates varying from 2 to 64 Hz. The results showed a broad tuning for modulation rate, comparable to that found for sinusoidal modulation of the signal. The maximum amount of MDI produced by the sinusoidally modulated masker was similar to that produced big the noise-modulated maskers when modulation depths were expressed as their root-mean-square values. It is concluded that similarity of the moment-by-moment envelope pattern of the signal and masker modulators plays only a minor role in MDI, although similarity in modulation rate has some influence. PACS numbers: 43.66.Mk, 43.66.Dc [HSC]

Noise-from a receiver perspective

Proceedings of the 34th Annual Convention and …, 2005

His research and thesis was on the analysis and design of H-field antennas for low-frequency applications. Mr. Pelgrum started his PhD at Delft University of Technology in 2002. His PhD study, partly financed by The Gauss Research Foundation, involves studying the theoretical and practical performance and design of low-frequency radio navigation systems in various environments. Wouter Pelgrum works part-time for Reelektronika B.V. since 2001 on low frequency antennas as also on the development and implementation of algorithms for Reelektronika's integrated GPS-Loran-C 'LORADD' receiver. During the second half of 2005, Mr. Pelgrum works at the Avionics Engineering Department of Ohio University on ASF measurements and analysis and on the collection and processing of LF-noise data.

Unique Measurement and Modeling of Total Phase Noise in RF Receiver

RF (radio frequency) receivers are common in many modern communications and radar systems, and they suffer from many performance degradation factors due to hardware limitations. Among all performance degradation contributors, phase noise and time jitter are especially troublesome since they cause random errors which are difficult to compensate. The local oscillator (LO) in the receiver frontend is a major contributor of phase noise, while the analog to digital converter (ADC) introduces time jitter. It is desired to know the accumulated effect of individual phase noise sources and time jitter. The total effect of all phase noise and jitter can be represented by an accumulated phase noise term at the ADC's output, called total phase noise (TPN) in this paper. The focus of this work is on measuring and modeling TPN in RF receiver by applying optimization techniques. In contrast to traditional phase noise measurement that typically requires a high-quality tunable downconverter, a digital approach using the data captured directly by the RF receiver is proposed. In addition, iterative optimization-based TPN spectral model fitting and statistic modeling are introduced. The model is examined using the measured TPN. It is confirmed that the RF receiver TPN can be viewed as a wide sense stationary (WSS) zero-mean Gaussian process with certain spectral profile.

Analysis of the effects of phase noise in filtered multitone (FMT) modulated systems

IEEE Global Telecommunications Conference, 2004. GLOBECOM '04., 2004

In this paper, we study the effects of phase noise in a multicarrier system. We show that the phase noise introduces interference components, and we evaluate their second order statistics. The analysis is then applied to two particular multicarrier architectures: discrete multitone (DMT) modulation, and filtered multitone (FMT) modulation. For the DMT case our results are in agreement with other related work that considers DMT only. For FMT modulation we demonstrate that the phase noise power spectral density as well as the frequency response of the prototype filters play a key role on the resulting interference power value. Finally, we show that the analytical performance results are close to the simulation results.

Noise figure vs. PM noise measurements: a study at microwave frequencies

2003

This paper addresses two issues: (i) it compares the usefulness of phase-modulation (PM) noise measurements vs. noise figure (NF) measurements in characterizing the merit of an amplifier, and (ii) it reconciles a general misunderstanding in using -174 dBc/Hz (relative to carrier input power of 0 dBm) as thermal noise level. The residual broadband (white PM) noise is used as the basis for estimating the noise figure (NF) of an amplifier.

IF estimation of FM signals in multiplicative noise

Most IF estimation techniques, such as those presented in the previous articles of this chapter, assume that the signal of interest has a constant amplitude. While this is a valid assumption in a wide range of scenarios, there are several important applications in which this assumption does not hold. Indeed, in many situations the signal may be subjected to a random amplitude modulation which behaves as multiplicative noise. Examples include fading in wireless communications [1], fluctuating targets in radar [2], and structural vibration of a spacecraft during launch and atmospheric turbulence . In this article, we focus on non-parametric methods. In particular, we show that the Wigner-Ville distribution (defined in Section 2.1.4) is able to display the IF of a signal affected by multiplicative noise, and that this representation is optimal in the sense of maximum energy concentration for a linear FM signal. For higher-order polynomial FM signals, the use of the polynomial Wigner-Ville distribution (PWVD), presented in Article 5.4, is shown to give optimal representations. Statistical performance of each case will be presented here.

Analysis of FM Demodulator Output Noise with Applications to the Space Lift Range System

2006 IEEE Aerospace Conference

We present an analysis for evaluating the probability density function (pdf) of the noise at the output of the frequency demodulator. It is shown that the noise is non-Gaussian and that for low to medium signal-to-noise power ratios, its pdf differs very significantly from the Gaussian pdf commonly assumed in simplified analysis. These results are very important for analyzing the performance of the PCM/FM type of modulation schemes used in telemetry systems as illustrated in the paper.

Analysis of frequency modulated signals in multiplicative noise

Proceedings of the Sixth International Symposium on Signal Processing and its Applications (Cat.No.01EX467), 2001

In this paper, we address the problem of analysing nonlinear frequency modulated (FM) signals in the presence of complex circular Gaussian multiplicative and additive noise processes. In particular, we consider the estimation of the instantaneous frequency of these signals using the peak of the polynomial Wigner-Ville distribution. We derive the bias and the variance of this estimator. We show that for the case of polynomial FM signals, the present results reduce to those obtained in [l] where-a different method was used in the derivations. 0-7803-6703-0/01/$ IO. 00 a 0 0 I IEEE