Bandwidth (signal processing)

About: Bandwidth (signal processing) is a research topic. Over the lifetime, 48550 publications have been published within this topic receiving 600741 citations. The topic is also known as: Bandwidth (signal processing) & bandwidth.

An analog integrated polyphase filter for a high performance low-IF receiver

Abstract: An analog integrated asymmetric polyphase filter is a key building block for the development of a high performance fully integrated low-IF receiver. The asymmetric polyphase filter makes it possible to suppress the mirror signal not at HF, but after quadrature demodulation at a low IF. The most important parameters for the polyphase filter are a high dynamic range and a good mirror signal suppression. This paper reports on the realisation in a 1.2 /spl mu/m CMOS process of a 5th order Butterworth polyphase filter with a bandwidth of 220 kHz centered around 250 kHz. Its measured mirror signal suppression is 64 dB. The active-RC implementation renders a 94.2 dB dynamic range at the input.

Simplified high frequency tuner and tuning method

Abstract: A disclosed method tunes a signal from a channelized spectrum having a predetermined channel spacing. A signal of interest having a predetermined maximum bandwidth is mixed with a local oscillator signal, which has a frequency that is an integer multiple of the channel spacing or one-half of a channel spacing displaced from an integer multiple of the channel spacing. The local oscillator signal is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest. Problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished. Other methods and systems are also disclosed.

Extended Active Interference Cancellation for Sidelobe Suppression in Cognitive Radio OFDM Systems With Cyclic Prefix

Abstract: The sidelobe of noncontiguous orthogonal frequency-division multiplexing (OFDM) signals is required to be deeply suppressed in the licensed user's band in cognitive radio (CR) systems. To this end, we propose a novel method of adding extended active interference cancellation (EAIC) signals to suppress sidelobes and to shape the spectrum of the CR-OFDM signal with a cyclic prefix (CP). For simplicity, we called the proposed scheme EAIC-CP. The key idea of the proposed EAIC-CP is to employ some cancellation signals consisting of tones spaced closer than the interval of OFDM subcarriers to cancel the sidelobes of OFDM signals. Moreover, we derive the optimal cancellation signals to minimize the total sidelobe power subject to a self-interference constraint. Numerical results show that, when the guard bandwidth is equal to one OFDM subcarrier interval, the EAIC-CP scheme offers more than a 45.0-dB sidelobe suppression with unnoticeable signal-to-noise ratio (SNR) loss at a symbol error rate (SER) from 10-2 to 10-3 for 64 quadratic-amplitude modulation (64QAM). Moreover, the EAIC-CP scheme can achieve high spectrum efficiency with low implementation complexity.

On the performance of multichannel digital backpropagation in high-capacity long-haul optical transmission.

Abstract: The performance of digital backpropagation (DBP) equalization when applied over multiple channels to compensate for the nonlinear impairments in optical fiber transmission systems is investigated. The impact of a suboptimal multichannel DBP operation is evaluated, where implementation complexity is reduced by varying parameters such as the number of nonlinear steps per span and sampling rate. Results have been obtained for a reference system consisting of a 5×32 Gbaud PDM-16QAM superchannel with 33 GHz subchannel spacing and Nyquist pulse shaping under long-haul transmission. The reduction in the effectiveness of the algorithm is evaluated and compared with the ideal gain expected from the cancellation of the nonlinear signal distortion. The detrimental effects of polarization mode dispersion (PMD) with varying DBP bandwidth are also studied. Key parameters which ensure the effectiveness of multichannel DBP are identified.