Continuous phase modulation

About: Continuous phase modulation is a research topic. Over the lifetime, 3199 publications have been published within this topic receiving 37245 citations. The topic is also known as: CPM.

Feedforward carrier frequency estimation with MSK-type signals

Abstract: We propose a non-data-aided technique for the estimation of the carrier frequency offset in minimum-shift keying (MSK)-type modulations. The proposed algorithm has a feedforward structure and is suited for burst-mode transmissions. Computer simulations are used to assess its performance and make comparisons with other existing methods in terms of estimation accuracy and minimum operating signal-to-noise ratio (threshold). Numerical results are provided for modulation schemes of practical interest such as MSK and Gaussian MSK.

Serially concatenated systems : an iterative coding approach with application to continuous phase modulation

Abstract: Iterative methods for concatenated coding and modulation in digital communication systems are considered. It is assumed that the code and modulation can be described by finite-state machines (FSM). An iterative decoder for such a system typically consists of a posteriori probability (APP) algorithms for the constituent FSMs. Starting with a detailed examination of these algorithms, it is found that their initialization values can be formally justified. Then, possible iterative methods such as fix-point iteration, Jacobi over-relaxation, damped substitution, and Newton’s method are presented and evaluated. The result is that fix-point iteration seems to be the best choice in most situations. As an application of iterative decoding in serially concatenated systems, coded and interleaved continuous phase modulation (CPM) is investigated. An APP algorithm (or maximum APP (MAP) detector) for CPM is derived, based on the classic APP algorithm for channel codes. It is then shown that a good suboptimal algorithm can be obtained using only a small set of receiver filters, which are optimal with respect to the size of the set. The resulting system is analyzed with the aim to determine the main parameters affecting performance. The weight spectrum for coded and interleaved minimum shift keying (MSK) is computed, resulting in a transfer function bound. This is cumbersome for a general CPM system; instead only the most significant error events contributing to the weight spectrum are identified, resulting in a new performance measure. Extensive computer simulations show good coherence with theory, and also remarkably good performance for some simple systems. Finally, the power spectral density and bandwidth are computed, allowing for a bandwidth/performance comparison of different combinations.

A Hybrid ICA-SVM Approach to Continuous Phase Modulation Recognition

Abstract: Automatic modulation recognition is a topic of interest in many fields including signal surveillance, multi-user detection and radio frequency spectrum monitoring. In this paper, we present an algorithm for recognition of different types of continuous phase modulation signals that uses a combination of features extracted through cyclic spectral analysis and an ICA-SVM hybrid recognition system. Simulation results demonstrate the ability of the algorithm to correctly identify modulation types over a wide range of SNR scenarios. The effects of pulse shaping and partial response waveforms are also investigated.

Near Optimal Common Detection Techniques for Shaped Offset QPSK and Feher's QPSK

Abstract: A detector architecture capable of detecting both shaped offset quadrature phase shift keying (SOQPSK-TG) and Feher's quadrature phase shift keying (FQPSK-JR) is developed and analyzed. Both modulations are embodied as fully interoperable modulations in the Interrange Instrumentation Group (IRIG) standard IRIG-106. It is shown that the common detector achieves near optimal bit error rate performance without knowledge of which modulation is used by the transmitter. The detection techniques are based on a common trellis-coded modulation representation and a common continuous phase modulation (CPM) representation for these two modulations. In addition the common pulse amplitude modulation (PAM) decomposition of the common CPM representation is developed. The common PAM-based detector offers the best performance- complexity trade-off among the detectors considered.

An automatic modulation recognition algorithm for spectrum monitoring applications

Abstract: An algorithm based on a decision-tree approach for the automatic modulation recognition of communications signals is presented. This algorithm can discriminate between continuous wave (CW), amplitude modulation (AM), double sideband suppressed carrier (DSB-SC), frequency modulation (FM), frequency shift keying (FSK), binary phase shift keying (BPSK) and quaternary phase shift keying (QPSK) modulations. Requirements for a priori knowledge of the signals are minimized by the inclusion of an efficient carrier frequency estimator and low sensitivity to variations in the sampling epochs. Computer simulations indicate good performance on an AWGN channel, even at signal-to-noise ratios as low as 5 dB. This compares favorably with the performance obtained with most algorithms based on pattern recognition techniques.