Data Transmission by Combined AM and PM

Abstract

This paper presents theoretical analysis and experimental verification of the performance of a digital data modem which uses combined amplitude and phase modulation (AM—PM). The theoretical model assumes operation over the bandlimited additive Gaussian channel. The receiver used in the experiment, and for which theoretical results are presented, uses an envelope detector in parallel with a phase detector to recover the data. The criteria of error rate and communication efficiency (measured in bits per cycle of bandwidth) as functions of average signal‐to‐noise ratio (S/N) are used to make comparisons with other modulation schemes. The theory predicts a performance from 1 to 4 dB poorer than what can be realized from single sideband (SSB) modulation. We present experimental results which indicate excellent agreement with the theory.

A Survey on Higher-Order QAM Constellations: Technical Challenges, Recent Advances, and Future Trends

“…al. of Bell Labs proposed some actual QAM constellations [25]. They used both the coherent and non-coherent demodulations and implemented circular constellations with the help of 2 and 4 amplitude positions along with 4 and 8 phase positions.…”

“…Salz et al of Bell Labs implemented circular QAM constellations with the help of 2 and 4 amplitude positions along with 4 and 8 phase positions for both the coherent and non-coherent demodulation [25].…”

“…Later in 1962, Campopiano and Glazer proposed properly organized square QAM constellation and denoted it as Type III constellation [24]. There were some initial works [18], [25]- [29], where various QAM constellations were proposed. Since then, such constellations have received tremendous attention for high data-rates in various fields of communication with different applications.…”

Data-Derived Symbol Synchronization of MASK and QASK Signals

“…It is interesting to note that in arriving at (16), the same result would be obtained if the feed-forward signal had been completely eliminated. The conclusion to be drawn from this is that, on the average, the loop S-curve is unaffected by the bias previously discussed.…”

“…By comparison, the literature is virtually devoid of information relating to the extraction of symbol sync from multilevel baseband data. With the recent interest [16]- [27] in multilevel amplitude-shift-keying (MASK) and quadrature' amplitude-shift-keying (QASK) as signaling techniques for multilevel digital communication systems, the problem of providing symbol synchronization in the receivers of such systems becomes paramount.…”