: The paper addresses the issue of the send-on-delta data collecting strategy to capture information from the environment. Send-on-delta concept is the signal-dependent temporal sampling scheme, where the sampling is triggered if the signal deviates by delta defined as the significant change of its value. It is an attractive scheme for wireless sensor networking due to effective energy consumption. The quantitative evaluations of send-on-delta scheme for a general type continuous-time bandlimited signal are presented in the paper. The bounds on the mean traffic of reports for a given signal, and assumed sampling resolution, are evaluated. Furthermore, the send-on-delta effectiveness, defined as the reduction of the mean rate of reports in comparison to the periodic sampling for a given resolution, is derived. It is shown that the lower bound of the send-on-delta effectiveness (i.e. the guaranteed reduction) is independent of the sampling resolution, and constitutes the built-in feature of the input signal. The calculation of the effectiveness for standard signals, that model the state evolution of dynamic environment in time, is exemplified. Finally, the example of send-on-delta programming is shown.

/pdf/send-on-delta-concept-an-event-based-data-reporting-strategy-fnsgdkl8fy.pdf

Send-On-Delta Concept: An Event-Based Data Reporting Strategy

A sampling scheme that is based on multiple level-crossings is presented. This scheme generates samples of the input signal that are nonuniformly spaced in time by recording the time instants at which the signal crosses any of the fixed quantization levels. The nonuniform sample sequence is transformed to uniform samples by polynomial interpolation. The resolution is further increased by employing decimation. Various trade-offs involved in terms of speed, resolution and hardware complexity are discussed.

A level-crossing sampling scheme for A/D conversion

This paper introduces a filterbank interpretation of various sampling strategies, which leads to efficient interpolation and reconstruction methods An identity, which is referred to as the interpolation identity, is developed and is used to obtain particularly efficient discrete-time systems for interpolation of generalized samples as well as a class of nonuniform samples, to uniform Nyquist samples, either for further processing in that form or for conversion to continuous time The interpolation identity also leads to new sampling strategies including an extension of Papoulis' (1977) generalized sampling expansion

/pdf/filterbank-reconstruction-of-bandlimited-signals-from-46ygr8t34n.pdf

Filterbank reconstruction of bandlimited signals from nonuniform and generalized samples

This work is a contribution to a drastic change in standard signal processing chains. The main objective is to reduce the power consumption by one or two orders of magnitude. Integrated Smart Devices and Communicating Objects are application domains targeted by this work. In this context, we present a new class of Analog-to-Digital Converters (ADCs), based on an irregular sampling of the analog signal, and an asynchronous design. Because they are not conventional, a complete design methodology is presented. It determines their characteristics given the required effective number of bits and the analog signal properties. it is shown that our approach leads to a significant reduction in terms of hardware complexity and power consumption. A prototype has been designed for speech applications, using the STMicroelectronics 0.18-/spl mu/m CMOS technology. Electrical simulations prove that the factor of merit is increased by more than one order of magnitude compared to synchronous Nyquist ADCs.

A new class of asynchronous A/D converters based on time quantization

This paper presents the design and implementation of an analog signal processor (ASP) ASIC for portable ECG monitoring systems The ASP ASIC performs four major functionalities: 1) ECG signal extraction with high resolution, 2) ECG signal feature extraction, 3) adaptive sampling ADC for the compression of ECG signals, 4) continuous-time electrode-tissue impedance monitoring for signal integrity monitoring These functionalities enable the development of wireless ECG monitoring systems that have significantly lower power consumption yet that are more capable than their predecessors The ASP has been implemented in 05 μm CMOS process and consumes 30 μW from a 2 V supply The noise density of the ECG readout channel is 85 nV/√Hz and the CMRR is better that 105 dB The adaptive sampling ADC is capable of compressing the ECG data by a factor of 7 and the heterodyne chopper readout extracts the features of the ECG signals Combination of these two features leads to a factor 4 reduction in the power consumption of a wireless ECG monitoring system Furthermore, the proposed continuous-time impedance monitoring circuit enables the monitoring of the signal integrity

A 30 $\mu$ W Analog Signal Processor ASIC for Portable Biopotential Signal Monitoring

A signal acquisition technique that will provide a favorable tradeoff between speed and resolution is described. This technique is based on recording the time instants at which the input signal crosses any of the fixed quantization levels and extracting additional information from the nonuniform sample sequence by means of digital signal processing methods. The proposed concepts are verified using both software simulation and board level hardware implementation. The proposed scheme offers significant benefits in the VLSI implementation, mainly in terms of reduced power consumption and smaller chip area. >

A non-uniform sampling technique for A/D conversion

A signal acquisition technique that will result in a high-resolution high-speed analog-to-digital converter architecture is described. The basic idea is to have a simple analog circuit to acquire information about the input signal at high speed and a more complex digital signal processing block to generate a high-resolution digital output. This technique is based on recording the time instants at which the input signal crosses any of a fixed set of quantization levels and extracting additional information from the nonuniform sample sequence using interpolation methods. A board-level design was implemented to verify these principles for real input signals. >

N. Sayiner

Papers

A level-crossing sampling scheme for A/D conversion

A non-uniform sampling technique for A/D conversion

A new signal acquisition technique