NIST is currently investigating the design of a second-generation cesium-fountain primary frequency standard. The design goals of this standard include an ultimate frequency inaccuracy of δf/f < 10 and achievable stability better than σy(τ) < 10/τ. This standard is expected to eventually replace NIST-F1, the current U.S. primary frequency standard [1]. In the context of reaching frequency uncer...

In OFDM-based space division multiple access (SDMA) systems, multiple users are served by a multiantenna base station simultaneously on the same frequency resources. In the uplink, each user’s signal may be distorted by an independent carrier frequency offset (CFO), which impairs the orthogonality of the subcarrier signals and, if not properly compensated, results in performance degradations. W...

Measurement of the spatial frequency response (SFR) of digital still cameras by slanted-edge analysis has been established for several years. The method, described in standard ISO 12233, has also been applied to other image acquisition subsystems such as document and print scanners. With the frequent application of the method and use of supporting software, questions often arise about the form ...

The IEEE 802.11g physical layer is based on coded orthogonal frequency division multiplexing (COFDM) using the industry standard [133 171] binary convolutional code. In the presence of Bluetooth interference this code struggles to provide good packet error rate (PER) performance. In this paper Turbo coding is considered as an alternative to convolutional coding. The results show that Turbo codi...

This article introduces the design principle and implementation method of the automatic judgment software of terminal in sports competition. Image recognition technology makes the competition management level achieve equality, justice, precision and high efficiency, This actualizing automatic judgment by means of recognition model for sports imaging, which is based on the principle of radio fre...

a r t i c l e i n f o a b s t r a c t Keywords: Time–frequency analysis Windowed Fourier transform Wavelet transform Synchrosqueezing Time–frequency representations (TFRs) of signals, such as the windowed Fourier transform (WFT), wavelet transform (WT) and their synchrosqueezed versions (SWFT, SWT), provide powerful analysis tools. Here we present a thorough review of these TFRs, summarizing al...

Some listeners are insensitive to the direction of pure-tone frequency changes when the standard frequency is roved widely over trials, but less so when the standard frequency is fixed and trial-by-trial feedback is provided. The present experiment tested the hypothesis that fixing the standard frequency and providing feedback is advantageous for direction-impaired listeners because under these...