Generalized chirp modulation technique

Abstract

Chirp modulation is one of the proposed digital phase modulation schemes where positive and negative data are represented, respectively, by increasing and decreasing of the instantaneous frequency. Chirp modulation is resistive to Doppler effect while its error performance, due to the phase characteristics, is quite poor. The paper deals with a generalization of the Chirp technique leading to new classes of signal formats for digital communications with improved spectral efficiency and good error performance. To achieve this task, the second time derivative of an information carrying phase component of a modulated signal is set to be proportional to an information carrying data signal. Further, for a generation of specific signal formats, the alternate mark inversion encoding of data to be transmitted is applied.

Chirp Modulation

“…This can be done either by the use of balanced modu-A method for overcoming the weaknesses of the pure CM in lating pulses-that is, pulses fulfilling the condition narrowband systems and preserving some of its advantages (e.g., immunity to Doppler shift) was proposed by Wysocki (8). The method referred to as generalized chirp modulation ∞ −∞ q a (τ ) dτ = 0 ( 13) (GCM) is based on setting a relationship between a modulating signal m(t) and an instantaneous value (t) of the inforor by ensuring that a running digital sum, (N), of modulatmation-carrying phase component by means of the different ing data equation…”

“…A complete analysis of GCM signals AMI-GCM is presented in Ref. (8) for the case of rectangular pulses q a (t) and for both FRS and partial response signaling (PRS) scenarios. Further information on this topic, including analysis of AMI-GCM signals with nonlinear pulses q a (t), is available in Ref.…”

“…(8) and (9) in the time domain as a function of both time and data. Therefore, to find its PSD, we need to make an assumption about the statistics of modulating data.…”