Single and multiple sinewave modulation and demodulation techniques employing carrier-zero and carrier-peak data-word start and stop

Abstract

A method for detecting encoded digital data from a substantially sinusoidal waveform, the encoded digital data having one of a first value and a second value at selected phase angles θn comprises generating the waveform having an amplitude Y defined by a first function at phase angles lying outside of regions having a range Δθ beginning at each phase angle θn, said first function being Y=sin θ; generating the waveform having an amplitude Y defined by the first function at phase angles lying inside the regions having a range of Δθ beginning at each phase angle θn where data of the first value is to be encoded; and generating the waveform having an amplitude Y defined by a second function at phase angles lying inside the regions having a range of Δθ associated with each phase angle θn where data of the second value is to be encoded, the second function being different from Y=sin θ, the detection including deriving sync pulses from minima and maxima of the substantially sinusoidal waveform to frame data words.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to transmission of information through media such as wire, cable, and radio-frequency propagation, both terrestrial and satellite. More particularly, the present invention relates to a single and multiple sinewave modulation technique, apparatus for modulating and demodulating information according to the modulation technique, and communications systems employing the modulation technique. [0003] 2. The Prior Art [0004] Digital data is often transferred from point to point by exploiting one or more of the three characteristic properties of an AC signal: Amplitude, Frequency and Phase. [0005] Some of the modulation methods using the amplitude property are OOK (On-Off Keying) and common AM (amplitude modulation). In OOK a data bit is represented by the presence or absence of a carrier. In AM data bits are represented by a difference in the relative amplitude of the carrier or by using diff...

AI Technical Summary

Benefits of technology

[0012] According to one aspect of the present invention, carrier-peak and carrier-zero detection can be employed in place of data start and stop bits, thus reducing the overhead and increasing the real data rate. Either carrier wave peaks or carrier wave zero crossings can be detected and used to frame data words in place of data-word start and stop bits. Use of this technique eliminates the use of two non-data overhead bits per data word.

Problems solved by technology

Phase modulation is also a common modulation method also but when used alone is difficult to distinguish from FM.

A few undesirable characteristics common to all of these modulation methods is they all require several cycles to transmit one bit and in doing so generate significant sidebands.

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