In this paper, a multiple-access spread-spectrum communication system using binary frequency shift keying (BFSK) or M -ary frequency shift keying (MFSK), and noncoherent demodulation is considered. In contrast to previous work typically assuming that the FSK tones are non-overlapping after direct-sequence (DS) spreading, here we consider a spread spectrum multiple access (SSMA) system under the...

This paper describes the implementation of a scanning signal detector and automatic modulation classification system. The classification technique is a completely blind method, with no prior knowledge of the signal’s center frequency, bandwidth, or symbol rate. An energy detector forms the initial approximations of the signal parameters. The energy detector used in the wideband sweep is reused ...

We propose a novel binary polarization shift keying modulation scheme for line-of-sight environment by exploiting the control ability of reconfigurable intelligent surface (RIS). The RIS encodes information data in terms states either reflected wave from or composite wireless channel between an RF source and receiver. In first case, mismatch correction becomes essential at second pre-codes to c...

Low power consumption and high data rate are the most important requirements for the communication system. Especially, very low power consumption modulation method is required for the short range communication systems such as the medical implantable communication devices or capsule endoscope, and so on. For the higher data rate, we like to combine the OFDM system into the QAPM since the OFDM sy...

We present a new digital modulation technique that introduces covertness in digital communications in a simple fashion. The basic principle is to transmit realizations of a stochastic process in such a manner that the transmitted waveform appears noiselike. The transmitted waveform is expressed in a subspace formalism, allowing for an elegant geometrical interpretation of the waveform, and a si...

<span lang="EN-US">A 27-MHz wireless system with binary frequency shift keying (BFSK) modulation at 400-kHz is reported. The receiver has been designed to handle in-band interference corrupting the BFSK signal use of complex filters and amplitude comparison method. carried out a voltage-controlled oscillator before up-converting local oscillator. bipolar junction transistors (BJT-based) p...

This paper presents application of the low Duty Cycle Ratio (DCR) modulations: isochronous Digital Pulse Position Modulation (DPPM) and anisochronous Digital Pulse Interval Modulation (DPIM) in backscatter based passive RFID communication system. The proposed modulations are compared to commonly used Amplitude Shift Keying (ASK) modulation. Low DCR modulations are customized for data transmissi...

-The paper is focus on the performance of fast frequency hopped spread spectrum by using M-ary frequency shift keying (MFSK) modulations. In fast FH systems, the frequency-hop rate Rh is some multiple of the symbol rate. Basically, each (M-ary) symbol interval is subdivided into N subintervals, which are called chips and one of M frequencies is transmitted in each subinterval. The probability o...

Multiuser underwater acoustic communication is one of the enabling technologies for the autonomous ocean-sampling network (AOSN). Multiuser communication allows vehicles, moorings, and bottom instruments to interact without human intervention to perform adaptive sampling tasks. In addition, multiuser communication may be used to send data from many autonomous users to one buoy with RF communica...