Apparatus and method for transmitting information with a subminimally modulated transmission signal
First Claim
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1. Communication system apparatus capable of transmitting information via a frequency modulated signal over a transmission media with bandwidth ≧
- fdev +2 * fd at transmission rates not achievable using conventional demodulators comprising;
subminimal modulation means capable of generating a phase continuous carrier signal with a modulation index less than 0.5 and wherein the timing of said means is independent of zero crossings or other DC levels of said modulated signal and wherein said means processes data at a constant rate independent of the data content;
FM signal processing and transmission means connected to said modulation means, wherein the carrier signal is transmitted over a transmission media;
FM signal receiving and processing means, configured to receive the carrier wave;
nonlinear signal processing means, connected to said signal receiving and processing means, wherein the modulation index of the carrier signal is increased;
a linear frequency demodulator serially connected to the output of said nonlinear signal processing means;
an analog to digital converter serially connected to the output of said linear frequency demodulator; and
a symbol decoder serially connected to the output lines of said analog to digital converter.
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Abstract
Applicant'"'"'s invention includes an apparatus and associated method for transmitting information at a high rate using an undermodulated frequency shift keyed signal. The transmission rate is independent of the data content and the system requires no zero crossing detectors. The demodulator combines non-linear processing circuitry with a conventional demodulator.
13 Citations
40 Claims
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1. Communication system apparatus capable of transmitting information via a frequency modulated signal over a transmission media with bandwidth ≧
- fdev +2 * fd at transmission rates not achievable using conventional demodulators comprising;
subminimal modulation means capable of generating a phase continuous carrier signal with a modulation index less than 0.5 and wherein the timing of said means is independent of zero crossings or other DC levels of said modulated signal and wherein said means processes data at a constant rate independent of the data content; FM signal processing and transmission means connected to said modulation means, wherein the carrier signal is transmitted over a transmission media; FM signal receiving and processing means, configured to receive the carrier wave; nonlinear signal processing means, connected to said signal receiving and processing means, wherein the modulation index of the carrier signal is increased; a linear frequency demodulator serially connected to the output of said nonlinear signal processing means; an analog to digital converter serially connected to the output of said linear frequency demodulator; and a symbol decoder serially connected to the output lines of said analog to digital converter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- fdev +2 * fd at transmission rates not achievable using conventional demodulators comprising;
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21. A method of transmitting information over a media with bandwidth limited to fdev +2 * fd via a frequency modulated signal at a higher rate than is achievable using a linear demodulator comprising the steps of:
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selecting a communication system comprising; subminimal modulation means capable of generating a phase continuous carrier signal with a modulation index less than 0.5 and wherein the timing of said means is independent of zero crossings or other DC levels of said modulated signal and wherein said means processes data at a constant rate independent of the data content; FM signal processing and transmission means connected to said modulation means, wherein the carrier signal is transmitted over a transmission media; FM signal receiving and processing means, configured to receive the carrier wave; nonlinear signal processing means, connected to said signal receiving and processing means, wherein the modulation index of the carrier signal is increased; a frequency demodulator serially connected to the output of said nonlinear signal processing means; an analog to digital converter serially connected to the output of said linear frequency demodulator; and a symbol decoder serially connected to the output lines of said analog to digital converter; generating a phase continuous carrier signal with a with a modulation index less than 0.5 and wherein the timing of said modulation means is independent of zero crossings or other DC levels of said modulated signal and wherein said means processes data at a constant rate independent of the data content; processing and transmitting said carrier signal over a transmission media with said processing and transmitting means; receiving and processing said transmitted signal over a transmission media; increasing the modulation index of said received signal with said nonlinear signal processing means; demodulating said the output signal of said nonlinear processing means with said frequency demodulator; converting the analog output of said frequency demodulator to a digital symbol with said analog to digital converter; and recovering the original data from said digital word with said symbol decoder. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification