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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
missile terminal guidance seeker minimum variance unbiased estimator an es^ timator of a parameter is said to have minimum variance and to be unbiased if ^ E = and ~ ^ E( - )2 E( - )2 , ~ where is any other estimator of . minimum-shift keying (MSK) a variant of FSK in which the separation between transmitted frequencies is 1/(2T ), where T is the symbol duration. In addition, the initial phase associated with each bit is adjusted so that phase transitions between successive bits are continuous. minimum-shift keying Gaussian (GMSK) a variant of MSK in which the transmitted frequency makes smooth transitions between the frequencies associated with the input bits. A GMSK signal can be generated when the input to the voltagecontrolled oscillator (VCO) is a PAM signal with a Gaussian baseband pulse shape. minisub station. in European usage, a miniature subMIPS millions of instructions per second, a measure of the speed of a computer. mirror optical element that reflects and may also transmit incident light rays and beams; used to provide feedback in laser oscillators. mirroring fault tolerance architecture for managing two or more hard disks as a unique disk by replicating the same data on all the disks in the mirroring system. The system also includes mechanism for verifying that all disks contain the same information. MISD See multiple instruction single data architecture. MISO See multi-input-single-output system. minterm a Boolean product term in which each variable is represented in either true or complement form. For example, u · v · w · z is a minterm for a four-variable function.
Frequency Discrimination Reception for Optical Minimum Shift Keying
Published in Le Nguyen Binh, Advanced Digital, 2017
The migration of externally modulated MSK format into optics has recently been reported in Refs. [1–6], and is also discussed in Chapters 9 and 10. If a multilevel scheme can be incorporated into the MSK format, the symbol rate would be reduced, which is of particular interest in optically amplified long-haul communications systems. This is the principal feature of the dual-level MSK modulation scheme, whose generation and detection configurations are proposed for the first time, to the best of the author’s knowledge. Dual-level MSK can be seen as a superposition of two optical MSK signals of different amplitudes [7]. This modulation scheme enables the transmission bandwidth efficiency due to the utilization of two bits per modulated symbol, at the same time exploiting the advantage of narrow spectral characteristics of the MSK format. The constellation of the dual-level MSK-modulated signals is shown in Figure 9.21.
Baseband Signalling and Pulse Shaping
Published in Jerry D. Gibson, The Communications Handbook, 2018
Michael L. Honig, Melbourne Barton
The European GSM standard for digital mobile cellular communications operates in the 900-MHz frequency band and is based on time-division multiple access (TDMA) [9]. The U.S. version operates at 1900 MHz, and is called PCS-1900. A special variant of binary FSK is used called Gaussian minimum-shift keying (GMSK). The GMSK modulator is illustrated in Fig. 24.13. The input to the modulator is a binary PAM signal s(t), given by Eq. (24.3), where the pulse p(t) is a Gaussian function and |s(t)| < 1. This waveform frequency modulates the carrier fc, so that the (passband) transmitted signal is
Modulation signal identification and classification based on the OA algorithm model
Published in International Journal of Electronics, 2023
Shaofei Wang, Zuliang Wang, Ting Zhang
In the field of modulators, a Gaussian minimum shift keying using in-phase and quadrature phase elements (IQ-GMSK) is a special form of continuous-phase frequency-shift keying (CPFSK) modulators (Linz & Hendrickson, 1996). With the advancements in modulation technologies, GMSK demodulators have been used in satellite communications (Govindaiah, 2012). Two categories of auto-modulation recognition algorithms have emerged in the literature, depending on the likelihood function and the feature of the received signal (Dobre et al., 2007). Wong and Asoke (2008) reported on maximum likelihood classifiers for phase amplitude modulation in coherent environments. An improved QPSK signal modulation and demodulation algorithm has been proposed by Zhou et al. (2014), who used numerical simulations to analyse the feasibility of the algorithm. Chen et al. (2016) presented a new multi-carrier joint detection algorithm exhibiting good demodulation performance for time hopping m-ary phase position shift keying (TH-MPPSK) signals. Daimei and Mathews (2016, 2017) proposed a likelihood-based Phase Shift Keying and Quadrature Amplitude Modulation signal identification algorithm in additive white Gaussian Noise channel. They showed that the modulated signal type can be accurately identified without assuming any prior knowledge of the signal or channel, especially for high-order Quadrature Amplitude Modulation. Based on the research on DBSCAN and OPTICS, a simple Automatic Modulation Classification method was proposed by Jacques et al. (2020), which is then performed in an additive white Gaussian noise channel with M-QAM and M-PSK Evaluate.
Mitigation of DME interference in LDACS1-based future air-to-ground (A/G) communications
Published in Cogent Engineering, 2018
The future communications study (FCS) (Future Communications Study Operational Concepts and Requirements Team, 2007) has preselected two technology decisions for the LDACS, specifically LDACS type 1 (LDACS1) and LDACS type 2 (LDACS2), as the most promising candidates for future aeronautical communications. LDACS1 is a broadband candidate technology using orthogonal frequency-division multiplexing (OFDM) for the future A/G and air-to-air (A/A) mode communication system (Sajatovic et al., 2009). Due to the limited amount of available spectrum in L-band, the transmission bandwidth for LDACS1 is limited to the 500 kHz spectral gap between the two adjacent distance measuring equipment (DME) channels of bandwidth 1 MHz, for each forward and reverse link (FL/RL). The frequency-division duplex (FDD) is applied to split up this limited bandwidth between FL and RL. The second choice, named LDACS2 (Fistas & Phillips, 2007), is a narrowband single-carrier technology with 200 kHz transmission bandwidth. It uses a Gaussian minimum shift keying modulation (GMSK). For duplexing, time-division duplex (TDD) is chosen. One of these two candidates (LDCAS1 or LDACS2) will be selected for deployment in aeronautical communications.