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.

Selection of an optimal modulation scheme for digital communications over low voltage power lines

Abstract: There is an ever increasing demand for environmental management of buildings, office automation, security monitoring or remote control of customer appliances and remote meter reading. The AC low voltage power line would be an ideal communications medium for digital data. Several systems for power line communications (PLC) were presented. The reliability of PLC is strongly influenced by time-variant and frequency-selective attenuation and interference on the power line channel. Various experiments were made to evaluate different PLC systems and set up a channel model. This paper gives a short summary of typical transfer characteristics and interference to be observed at power line networks. It is shown that at transmission over a single phase of the power supply system the maximum phase jitter of the time-variant transfer function is in most cases below 90/spl deg/. In the second part important modulation schemes are evaluated for applicability to power line communications. This evaluation considers chirp modulation, direct sequencing phase shift keying modulation (PN/PSK) and hopping techniques with spectral redundancy given by carriers with M different frequencies. The selection of the optimal modulation technique considers the European standard EN 50065, which restricts both the frequency range and the maximum signal amplitude. This paper deals with modulation schemes, using M frequencies, namely classic frequency hopping modulation (MFH) and the multifrequency,phase modulation (MFH/PSK and MF/PSK). Significant advantages of M frequency phase modulation in comparison with classic frequency hopping are pointed out.

Coherent Demodulation of Continuous Phase Binary FSK Signals

Abstract: This paper gives achievable bounds for the probability of error of continuous phase binary FSK signals on the white gaussian noise channel. Phase continuity, like convolutional encoding, introduces a dependence between adjacent transmitted signals which can be used to advantage in the demodulation process. It is shown that continuous phase binary FSK can provide a given probability of error with 0.8 db less signal-to-noise ratio than antipodal PSK. The paper also shows how the ideas developed for decoding convolutional codes apply to the demodulation of continuous phase FSK with rational deviation ratio.

Spectrum, distance, and receiver complexity of encoded continuous phase modulation

Abstract: A comparison of different classes of encoded continuous phase modulation (CPM) schemes is presented. In terms of joint power-bandwidth performance, it is found that coded eight-level systems are better than coded four-level systems and that partial-response signalling is better than full-response signalling. In general, the price paid for better performance is increased receiver complexity. Heuristic design rules have been used to find good codes for CPM. In most cases the coding gains found are identical to published results that were generated by exhaustive search, indicating that the choice of design rules is quite appropriate. In the present study bandwidth efficiency is considered from both the 99% and 99.9% power-bandwidth points of view. It is found that partial-response signalling is even more jointly power and bandwidth efficient for the latter than for the former bandwidth criterion. >

Carrier recovery network for QPSK modems employing synchronized oscillators

Abstract: A carrier recovery network for QPSK modems employs a synchronous oscillator which may be used as a frequency multiplier, divider and tracking bandpass filter A preferred embodiment of the carrier recovery network includes a multiply-by-four circuit to remove QPSK data modulation, and a synchronous oscillator tuned to one-fourth the input frequency to thereby act as a frequency divider and tracking bandpass filter to provide a recovered carrier signal

Apparatus and method for carrier frequency offset and phase compensation in communication system

Abstract: The present invention provides apparatus and methods for carrier frequency offset and phase compensation, which can compensate the phase rotation of an OFDM symbol resulted from carrier frequency offset between the receiver and transmitter of an OFDM System. The apparatus and method for carrier frequency offset compensation generates an estimated carrier frequency offset according to a phase error between estimated frequency responses of two consecutive received OFDM symbols within the pilot subchannel, and calculates an accumulated phase rotation, according to the estimated carrier frequency offset, for compensating the received OFDM symbol. On the other hand, the apparatus and method for phase compensation generates an estimated residual phase error according to the pilot signal of a frequency offset-compensated OFDM symbol and the original pilot signal transmitted by the transmitter, and compensates the frequency offset-compensated OFDM symbol or a following one according to the estimated residual phase error.