The BER performance of a BPSK system with sounder in the fast Rayleigh fading and cochannel interference environment is analyzed by means of the characteristic function of the decision statistic and calculating the residue, and compared with that of a DPSK system. The results show that the BPSK system with sounder can remove random FM effectively from the received fast fading signal even in the presence of cochannel interference. In addition, the optimum power distribution between the BPSK signal and sounder which minimizes the BER and the effect of a post-detection diversity are theoretically clarified.

In multi-carrier satellite communication systems, many modulated carriers have to be co-amplified through a TWTA (Traveling Wave Tube Amplifier). In such a case, the intermodulation due to the TWTA nonlinearities i.e., AM/AM and AM/PM conversions degrades that system performance. This paper analyzes the combined effects of the AM/AM and AM/PM conversions on the output properties of the TWTA using a quadrature nonlinear model. A general formula of the output autocorrelation function is derived as a function of the input autocorrelation function with an arbitrary input power spectrum. Based on this formula, the effects of the TWTA nonlinearities (both AM/AM and AM/PM conversions) on the output characteristics such as the output signal and intermodulation power, the intermodulation power spectral distribution, and the output signal-to-intermodulation ratio (SIMR) are theoretically evaluated.

Some practically optimal conditions for coexistence of analog and digital systems in an intersystem interference environment may be found in a compromise between both systems. To find them, as a first step we have investigated and discussed the effects of multiple wideband FM systems upon an M-ary coherent PSK system under the assumption that both systems are sharing the same radio frequency bands. For that, in this paper we propose an analysis method which is directly applicable to the wideband FM interferers. The symbol error performance of MCPSK system in the presence of Gaussian noise and cochannel or adjacent channel interference from wideband FM systems is evaluated and given in graphes as functions of CNR, CIR and normalized carrier separation. From the results obtained here, one can expect some optimal or suitable operating conditions (frequency allocation, bandwidth and power) for a PSK channel in the intersystem interference from analog FM channels.

We derived the optimum receiver structure for an M-ary PSK signal in the presence of Gaussian noise and a single sinusoidal (CW) interfere. And by computer simulation we confirmed that the derived optimum receiver performs better than the standard receiver (which is optimum only to Gaussian noise) in the interference environment.

In this paper, an unified analysis presented for evaluating the statistical properties of a general class of the quadratic detectors. The probability density function (pdf) for the output of the quadratic detectors is derived by the characteristic function method which requires the contour integration in a complex plane for the Laplace inversion operation, without enforcing to solve directly the eigenvalues of the integral equation as used by Kac, which is only possible for a special case of Gaussian input. We treat a general situation in which the tow inputs to the detector are narrowband signal-plus-interference-plus-noise. A general and closed-form expression of the output pdf of the quadratic detector is derived. We show that the unified analysis results can be applied not only to stationary Gaussian noise channels but also to Rayleigh fading channels, and that the results previously derived can easily be obtained using our unified results.