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In target searching stage of radar seeker in modern encounter, the transmitted signal is required to have characteristics of high resolution, low probability of intercept and high Doppler tolerance. In order to overcome the disadvantage of OFDM signal's low Doppler tolerance, a new type of multicarrier signal with nonuniform frequency density is proposed, whose subcarriers and amplitude weighting...
To realize high-speed big data transmission, we combine the advantages of Nyquist Super-channel and Software Defined Optical Networks (SDON), thus establishing the SDNyquist platform that dynamically manages the whole optical network. This platform has the features of flexible resource allocation, high spectrum efficiency and global network optimization with the help of Routing, Modulation Level and...
Optimized FDM subcarriers modulation and allocation are demonstrated to overcome VCSEL-based system bandwidth limitations and to match the not-uniform frequency response due to direct modulation/detection, achieving at least 25-Gb/s capacity also over 20-km SSMF reach.
A 10–20 Gb/s clock and data recovery (CDR) circuit with frequency tracking is presented. Two digital phase interpolators (PIs) are used to track the frequency of input data. The loop bandwidth of the CDR circuit is adaptively adjusted. A mixed-mode PI is used to generate the recovered clock. This CDR circuit is fabricated in a 40nm CMOS process and its area is 0.33×1.0 mm2. Its power consumption is...
With advances of CMOS technologies, the high-speed characteristic of transistors gives additional design margin for millimeter-wave (mm-Wave) PAs. The design of prior-art mm-Wave PAs is now focusing on the optimizations of back-off efficiency while maintaining linearity. This facilitates the transmission of broadband high-order digital modulated signals with decent system efficiency. This paper reviews...
In this paper, a bang-bang phase detector (BBPD) and delay-line frequency discriminator (FD) based phase noise filter (PNF) is presented. With a large gain, BBPD based PNF enhances PNF sensitivity by suppressing charge pump noise. Moreover, the proposed BBPD based PNF features wide noise suppression bandwidth and wide input frequency range. At 1 MHz offset, the PNF demonstrates 12.6 dB phase noise...
Underwater acoustic communications based on Orthogonal Frequency Division Multiplexing (OFDM) are realized usually in high frequency for high communication rate, and the channel and hardware conditions make our communication band is limited. Conventional modulation of these OFDM scenarios are FFT, it will face the problem of oversize FFT number and large computation complexity in the conditions of...
The design of the communication system follows the Nyquist intersymbol interference (ISI) criterion, which explains the design principle of the transmitting and receiving filters to mitigate the effects of ISI. In this work, we study how to utilize the ISI to benefit a communication system. We propose a novel modulation framework, which transmits the constellation symbols much faster than the Nyquist...
The existing study and application of Prolate Spheroidal Wave Function (PSWF) primarily around the characteristics of PSWF in a single energy domain, the characteristics of PSWF in two-dimensional time-frequency energy domain have not been mining and using, from the perspective of signal time-frequency distribution, Wigner-Ville Distribution with higher time-frequency resolution was introduced to...
Detection of underwater buried objects requires low-frequency wave as the detecting source and high-resolution imaging. Taken these into account, this paper proposes a method to process the linear frequency modulated signal (LFM) based on parametric array theory. The distortion of the LFM demodulated by the parametric array and corresponding matched filter are studied by numerical method. The numerical...
Because the ability of handling multiple signals at the same arriving time and has a high intercept probability, wideband Channelized receiver has become a hot research topic in domestic and foreign. Channelized receiver based on polyphase filtering has less computational and more channels. In this paper, a new efficient structure model based on real signal non-maximally decimated channelization is...
This paper investigates the capability of a miniaturized radar sensor developed for Micro Aerial Vehicles (MAVs) to cope with complex mission scenarios that involve integrating and satisfying either Synthetic Aperture Radar (SAR) or Interferometric SAR and navigation and Sense-and-Avoid (SAA) requirements. A radar sensor based on Frequency Modulated Continuous Wave (FMCW) technology developed by IMST...
State of the art UAV technology shows its advantage in both civil and military applications, and it is required to meet the needs for payloads special designed for UAVs. However, electric powered multi-rotor UAV provides limited power and more sensitive to the payloads mass. Linear frequency modulated quasi continuous wave SAR leads to small and efficiency radar system which meets multi-rotor UAV's...
We experimentally demonstrated a 2×2 multiple-input multiple-output (MIMO) visible light communication (VLC) system using commercial phosphorescent white light emitting diodes (LEDs) and low-cost PIN photodiodes (PDs). Additionally, a pre-equalizer was used to extend the available modulation bandwidth up to 100 MHz. Using spectral-efficient orthogonal frequency division multiplexing (OFDM) modulation...
We report on recent progress in the field of visible light communications including direct modulation of blue laser devices at data rates beyond 10 Gbit/s, and the transmission of 2.5 Gbit/s OOK data through water. We also discuss the advantages of operating with single mode laser devices and matched filtering at the receiver in the context of applications with significant solar background. The system...
This paper presents a low cost and efficient method to compensate the phase and magnitude errors of transmitting ultra-wideband (UWB) linear frequency modulation (LFM) waveform with complex pre-distortion correction coefficients. In this method, a high linearity LFM waveform is generated by a direct digital synthesis (DDS) module. The phase and magnitude errors of the output LFM signal are sampled...
In this paper, we investigate the feasibility of substantial bandwidth enhancement of a low-frequency miniaturized antenna on a robotic flyer through magnetic coupling with similar elements in a tight flight formation. The dimensions of a single radiating element are confined to within λ/10 × λ/10 × λ/10 for operation at around 300 MHz. Variations of end-loaded meandered line dipoles are studied and...
This paper presents a dual-mode delta-sigma modulator. The modulator can be configured for two structures, 3rd-order 4-bit in low-frequency high-resolution applications, and 2nd-order 4-bit in high-frequency low-resolution applications. Most of the circuit parts including the capacitors and switches are shared in both modes. An efficient OTA and comparators with Input Offset Calibration technique...
We propose a hybrid modulation scheme which has a wider 3-dB bandwidth and higher dispersion tolerance compared with a direct current modulation (DM) scheme. Frequency responses and eye diagrams are calculated by using rate equations. The calculated frequency response shows that the hybrid modulation scheme improves modulation sensitivity degradation at a high-frequency region and enhances 3-dB bandwidth...
This paper introduces a new way to increase the transmission rate of data in Orthogonal-Frequency-Division-Multiplexing (OFDM) system. The data rate is doubled by doubling the number of the subcarriers in the OFDM signal. The bandwidth of the OFDM signal and the OFDM-symbol rate are not changed. Complex Exponential Subcarriers (CESs) are used instead of Real Sinusoidal Subcarriers (RSSs). Two different...
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