Minimum Frequency Shift Keying Research Articles

GMSK Demodulation Combining 1D‐CNN and Bi‐LSTM Network Over Strong Solar Wind Turbulence Channel

AbstractTo solve the problem of bit error rate (BER) performance degradation over strong solar wind turbulence channel, this paper addresses to Gaussian minimum frequency shift keying (GMSK) demodulation using machine learning. First, by analyzing the scintillation characteristics of the telemetry signal caused by solar wind turbulence during the solar superior conjunction, the K distribution channel model is innovatively established over strong solar wind turbulence channel. Then, the approximate probability density function of the K distribution of the established channel is studied by using Laguerre orthogonal polynomial for convenience. Additionally, the BER performance of GMSK over strong solar wind turbulence channel is analyzed. Second, using a one‐dimensional convolutional neural network (1D‐CNN) and bidirectional long short‐term memory network (Bi‐LSTM), two demodulators for GMSK are proposed. By integrating the 1D‐CNN and LSTM to extract local features and process the dynamic information of GMSK signals, we propose a novel GMSK demodulator over strong solar wind turbulence channel with combining 1D‐CNN and Bi‐LSTM. The simulation results show that, even if the solar wind turbulence has serious effects on the signal at a low signal‐to‐noise ratio, the proposed combining neural network demodulation can obtain better BER performance than the classical Viterbi algorithm, demodulation using only a single 1D‐CNN or Bi‐LSTM. The proposed GMSK demodulator is more suitable for the deep space exploration of the solar system.

Performance Evaluation of a Tactical Data-Link System Based on MSK and 16QAM

Tactical data links are becoming more widely used in the military, as they can greatly improve the efficiency of various combat units. Such tactical data links must be able to transmit large volumes of data at high speed in complex communication environments while ensuring reliability. This paper studies the influence of 16-ary Quadrature Amplitude Modulation (16QAM) and Minimum Frequency-shift Keying(MSK) modulation on the transmission performance of data chain system. The simulation results show that 16QAM modulation can meet the requirements of tactical data link system for BER and data transmission rate, and the technical complexity is in the middle; the system BER of MSK modulation is lower, and a large number of data transmission can be realized at high speed. When the SNR reaches 50dB, the BER of MSK modulation can be reduced to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> order of magnitude, which is better than Quadrature Phase Shift Keying (QPSK) modulation, that is, the data chain system based on MSK modulation can meet the transmission requirements of data chain when the signal-to-noise ratio is large.

Algorithms for the Encoding and Reception of OFDM Signals Based on Manipulation with Minimum Frequency Shift

The developed algorithms for the encoding and reception of OFDM signals using minimum frequency shift keying (OFDM-MSK signals) are considered and investigated. OFDM-MSK signals have low out-of-band power compared to OFDM signals using phase shift keying. It is shown that the developed algorithms for the encoding and reception use a lattice structure of signals with a continuous phase with a minimum frequency shift in combination with a productive algorithm for fast spectral transformation in the Fourier basis.

Mathematical model сoherent demodulation of synchronous mutually nonorthogonal digital signals with minimum frequency-shift keying

Introduction. The synthesis mathematical model procedure of coherent demodulation of synchronous mutually nonorthogonal digital signals with minimum frequency-shift keying is the basic and purpose of this article. Synthesis method of mathematical model coherent demodulation of synchronous mutually nonorthogonal digital signals with minimum frequency-shift keying. Coherent demodulations of powerful signal interference with minimum frequency-shift keying and useful digital signal with minimum frequency-shift keying in a channel with additive white noise are showed. In absence of signal interference this procedure degenerates in classic coherent demodulation of digital signal with minimum frequency-shift keying. When the power of signal interference is much greater power of the useful digital signal with a minimum frequency-shift keying the interference protection receiving in the channel with additive white noise there is such when a signal interference missing. Conclusions. This mathematical model procedure can be used in modem compensators for realization of the repeated use of frequency resource and in development of perspective protection from signal interference of radio contact facilities.

Performance evaluation of MSK and OFDM modulations for future GNSS signals

The objective of this work is to investigate the performances of orthogonal frequency division multiplexing (OFDM) and minimum frequency shift keying (MSK) modulations as potential future global navigation satellite systems (GNSS) signal modulation schemes. MSK is used in global system for mobile communications because of its spectral efficiency, while OFDM is used in WLAN and digital video broadcast-terrestrial because of its multipath mitigation capability. These advantages of MSK and OFDM modulations render them as promising modulation candidates for future GNSS signals to offer enhanced performances in challenging environments. Gabor bandwidth and multipath error envelopes of these two modulations were computed and compared with those of the current global positioning system (GPS), Galileo, and Beidou signal modulations. The results show that OFDM modulation demonstrated promises as a viable future GNSS modulation, especially for signals that require pre-filtering bandwidths larger than 2 MHz, while MSK modulation is more desirable for pre-filtering bandwidth below 2 MHz where it exhibits the largest Gabor bandwidth.

Noise immunity of a quasi-optimal correlation receiver of noiselike signals with minimum frequency-shift keying

A quasi-optimal algorithm for correlation processing of noiselike signals with minimum frequency-shift keying is proposed and its noise immunity is analyzed. It is shown that the immunity of the quasi-optimal receiver to a structural noise is the same as that of the optimal correlation receiver and, in the case of a fluctuation noise, the loss in the signal-to-noise ratio is ∼ 1 dB relative to the optimal algorithm.

The Implementation of MSK Based on DSP and Complex Bandpass Processing

A novel method of minimum frequency shift keying (MSK) which based on digital signal processing (DSP) and complex bandpass processing is proposed in the article. According to the bit value of the input data, the MSK complex bandpass signal is directly produced and then is complex bandpass filtered, the real part of the complex bandpass signal is fetched to achieve the MSK modulation. The receiving signal of MSK is sampled, and then complex bandpass filtered to attain the complex bandpass signal. The complex bandpass signal and conjugate signal of its delayed version and the phase shift factor are multiplied together. According to the imaginary part of the product, the original data is recovered. The design method of complex bandpass filter is introduced also.

10.1007/s11487-008-2014-2

An optimal algorithm for seeking a noiselike signal with the minimum frequency-shift keying is synthesized. The algorithm involves estimation of the signal delay time. The noise immunity of quasi-optimal algorithms is analyzed. The proposed algorithms are recommended for application in correlation receivers of noiselike signals with the minimum frequency-shift keying.

An optimal algorithm for searching a noiselike signal with the minimum frequency-shift keying

An optimal algorithm for seeking a noiselike signal with the minimum frequency-shift keying is synthesized. The algorithm involves estimation of the signal delay time. The noise immunity of quasi-optimal algorithms is analyzed. The proposed algorithms are recommended for application in correlation receivers of noiselike signals with the minimum frequency-shift keying.

Optimal phase discriminator of a spread-spectrum frequency-shift keyed signal

An optimal phase discrimination algorithm for phase tracking of a spread-spectrum signal with minimum frequency-shift keying is proposed. The noise immunity of the algorithm is analyzed.

Design of switched-capacitor FIR filters with application to a low-power MFSK receiver

Finite impulse response (FIR) switched-capacitor (SC) filters for minimum frequency-shift keying (MFSK) demodulation techniques have been developed and are discussed. The proposed filters comprise combinations of the following building blocks: sample-and-hold circuits, even-odd delay circuits, Gillingham delay circuits, recharge memory elements, Lee-Martin summer circuits, recharge summer circuits, and rotator switches. These are described in the paper. Furthermore, composite SC filter structures are derived using a morphological approach. The FIR SC filter structures are compared and evaluated with respect to the required chip area when implemented in 3 μm CMOS technology, and, by computer simulation, with regard to bit error probability when used in an MFSK receiver. It is shown that the receiver performance is independent of the FIR filter structure used. Furthermore, using the FIR filters, and for a given bit error probability, the required signal-to-noise ratio (SNR) is actually 3 dB lower than for a typical commercial MFSK receiver (e.g. an MB87002).

A Class of MSK Baseband Pulse Formats with Sharp Spectral Roll-Off

Minimum frequency-shift-keying (MSK) is a very attractive modulation technique because of its spectral properties and the constant envelope property of the signal, but out-of-band energy spillover must sometimes be minimized to control co-channel interference. This problem has recently received attention in published articles and, since the pulse shape is the main parameter, many different MSK pulse formats have been described. In this note, a general shaping function, which allows various asymptotic spectral fall-off characteristics, is presented; then DSFSK (Double Sine Frequency Shift Keying) is derived from it, and its spectrum is computed, analyzed and compared with Rabzel's results.