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This paper describes a method to increase the sensitivity of a digital radio receiver based on the time synchronous averaging (TSA). The data to be send are grouped into a block and the block is retransmitted multiple times. Received blocks are synchronously averaged thus increasing the signal-to-noise ratio. The TSA can be performed on the analog signal at the demodulator output (soft TSA) or on...
A low power Software-Defined radio receiver operating between 400 MHz and 1.5 GHz is presented in this paper. The receiver is based on differential switched 4-path passive mixer architecture. The sampling frequency fixes the carrier frequency of the received signal and a simple RC time constant determines the receiver bandwidth. The mixer structure permits to implement flexible high-Q band-pass filters...
A low-power sampling receiver dedicated to Industrial, Scientific and Medical (ISM) frequency bands applications is described in this paper. The receiver is based on a 4 path passive mixer. The mixer sampling rate fixes the carrier frequency of the received signal. A simple RC low-pass filter at the mixer's output determines the receiver bandwidth. The structure used allows implementing flexible high-Q...
Vertical-Cavity Surface-Emitting Lasers (VCSELs) represent many advantages for high data rate and low cost communication systems. However, they have a nonlinear transfer function, which could drastically affect the multicarrier modulations performances. The static characteristic is usually used to estimate the VCSEL nonlinearity impact on the Discrete MultiTone (DMT) modulation performances. In this...
This paper describes a low complexity, medium data rate, short-range, ultra-wideband (UWB) communication system suitable for low-cost and low-power personal area wireless network (PAN) applications. The system combines pulsed and orthogonal frequency communication techniques. The data bits to be transmitted are encoded with antipodal base-band signals generated using a set of orthogonal sinusoidal...
Optical forms of orthogonal frequency division multiplexing (OFDM) are widely used in intensity modulated direct detection (IM/DD) systems. These forms use the Hermitian symmetry of the frequency symbols to generate real OFDM signals compatible with the optical transmitters characteristics. Thus, to modulate and demodulate N frequency symbols, 2N-point inverse fast Fourier transform (IFFT) and fast...
A low power Software-Defined radio receiver operating between 400MHz and 1.5GHz is presented, with the property to be robust to out-of-band blockers, thanks to the 4-path passive mixer architecture which acts as a high-Q bandpass filter for RF signals. The filter formed by the mixer at baseband fixes the receiver bandwidth at 10MHz. A common-gate cross-coupled LNA realizes a wideband input matching...
An ultra-wideband (UWB) short range communication system is investigated in this paper. The system is based on an on-off-keying (OOK) modulation where the transmitted data pulse is obtained by using a set of orthogonal frequency (OF) signals. This optimizes the transmitted signal power and maximizes the equivalent signal-to-noise ratio (SNR) at the receiver. The receiver uses a non-coherent energy...
The present paper describes an Ultra-Wideband (UWB) communication system based on the Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme. The system uses a small number of sub-carrier frequencies which allow the straightforward implementation of the OFDM modulator and demodulator without the use of Discrete Fourier Transform (DFT). An experimental RF transceiver based upon the proposed...
The estimation and detection of surface EMG signals provides us with more detailed information on the functional state of a muscle, when measurement applied with smaller pickup areas. In fact the signal to noise ratio (SNR) of the observed EMG activity is proportional to the area of the pickup electrodes, and depends on the type of the muscle. The activity of small muscles is more difficult to sensed...
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