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.

Frequency domain analysis of fiber bragg grating based phase modulation to intensity modulation conversion

Abstract: In this paper, optical phase modulation to intensity modulation by the use of a fiber Bragg grating (FBG) based frequency discriminator is proposed and experimentally demonstrated. In the proposed approach, the optical carrier frequency is placed at the quadrature point of the positive or negative slope of the reflection response of the FBG. The phase modulated light reflected from the two opposite slopes will have a π phase difference, which makes bipolar operation possible in an all-optical microwave signal processor or an optical code division multiple-access system. Both the frequency and phase responses of the FBG are taken into account to build a theoretical model in a frequency domain. Phase modulation to intensity modulation conversion based on a Gaussian apodized FBG is experimentally implemented. The results confirm the theoretical analysis.

Channel selecting apparatus for simultaneous use with both phase-continuous modulation signals and digital modulation signals

Abstract: A channel selecting apparatus simultaneously selects both the modulation signals, which are simultaneously received at different channels where modulation signals having a continuous phase and digital modulation signals having a discontinuous phase are located. As both the modulation signals are propagated on the same transmission path or approximately the same inclination of transmission path, modulation signals existing on different channel frequencies suffer approximately similar frequency shift from the transmission path before being inputted to the channel selecting apparatus. Therefore, the frequency of the digitally modulated IF signal can be controlled in accordance with the frequency shift information related to an IF signal having a continuous phase and the frequency of the digitally modulated IF signal may be focused into the comparatively narrow frequency range around the synchronous pull-in frequency of the digital demodulating circuit and the modulation signal having a continuous phase may be focused into the comparatively narrow frequency range around the optimum input frequency of the demodulation circuit.

On higher-order representations of Polyphase-Coded FM radar waveforms

Abstract: It has recently been shown that arbitrary polyphase codes can be implemented as FM waveforms through a radar-specific version of the Continuous Phase Modulation (CPM) framework. These waveforms, denoted as Polyphase-Coded FM (PCFM) can be viewed as a first-order hold representation of the phase function (where traditional codes represent a zero-order hold). Here we examine higher-order representations as a means to achieve further variety over the space of possible waveform functions one may optimize. Specifically, the relationships between the first, second, and third-order representations are considered, along with the optimization of the coding for each.

Integrated optical waveform modulation

Abstract: A method of modulating an optical carrier. A target carrier modulation is computed based on an input data signal. An effective length of an optical modulator is then controlled based on the target carrier modulation.

Differential detection via the Viterbi algorithm for offset modulation and MSK-type signals

Abstract: The differentially coherent reception of two families of constant-envelope signals, the linear offset quaternary phase shift keying and the binary partial response continuous phase modulation with index 0.5, is addressed. When the conventional (PSK-type) differentially coherent detector is used, a large performance degradation, compared with that of coherent receiver, is observed. The reason for this is the presence of an inherent intersymbol interference (ISI) in the signal and also noise enhancement and correlation introduced by the receiver filter. A differential detection strategy which compensates for ISI and avoids noise enhancement is presented. A phase estimate that takes into account the presence of the inherent ISI is derived. This phase estimate is then used in the decision metric of a coherent receiver. The resulting decision rule can be implemented using the Viterbi algorithm. Simple Viterbi receivers with good performance are obtained. Simulation results are given. >