Methods and systems to discriminate between PSK and FSK signals
First Claim
1. A method for discriminating between phase-shift-key (PSK) modulation and frequency-shift-key (FSK) modulation in a received signal stream, comprising:
- receiving an analog signal stream with receive path circuitry;
converting the analog signal stream to a digital signal stream;
analyzing bit frequency for a plurality of bit segments within the digital signal stream to determine for a each bit segment a frequency (fmax) at which a maximum signal energy occurs within the bit segment;
combining the maximum frequencies (fmax) to generate a bit frequency histogram for the bit frequency of the plurality of bit segments;
determining that the digital signal stream includes PSK modulated signals if a number of frequency spikes in the bit frequency histogram is one, that the digital signal stream includes FSK modulated signals if a number of frequency spikes in the bit frequency histogram is greater than one, and that a PSK/FSK determination cannot be made if a number of frequency spikes is not determinable; and
outputting PSK/FSK determination signals representing the results of the determining step.
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Abstract
Methods and systems are disclosed herein for discriminating phase-shift-key (PSK) modulated signals from frequency-shift-key (FSK) modulated signals in received signal streams. First, a bit frequency analysis is applied to a digital signal stream representing the received signal stream. The bit frequency analysis computes bit frequencies for bit segments within the digital signal stream. These bit frequencies are then summed in an array to form a bit frequency histogram. Second, a bit phase analysis is applied to the digital signal stream. The bit phase analysis computes bit phases for bit segments within the digital signal stream. These bit phases are then summed in an array to form a bit phase histogram. Spikes within the bit frequency and bit phase histograms can be used to determine whether the received signal stream includes FSK or PSK signals. An enhanced bit phase analysis can also used, if needed.
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Citations
20 Claims
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1. A method for discriminating between phase-shift-key (PSK) modulation and frequency-shift-key (FSK) modulation in a received signal stream, comprising:
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receiving an analog signal stream with receive path circuitry; converting the analog signal stream to a digital signal stream; analyzing bit frequency for a plurality of bit segments within the digital signal stream to determine for a each bit segment a frequency (fmax) at which a maximum signal energy occurs within the bit segment; combining the maximum frequencies (fmax) to generate a bit frequency histogram for the bit frequency of the plurality of bit segments; determining that the digital signal stream includes PSK modulated signals if a number of frequency spikes in the bit frequency histogram is one, that the digital signal stream includes FSK modulated signals if a number of frequency spikes in the bit frequency histogram is greater than one, and that a PSK/FSK determination cannot be made if a number of frequency spikes is not determinable; and outputting PSK/FSK determination signals representing the results of the determining step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A receiver system for discriminating between phase-shift-key (PSK) modulation and frequency-shift-key (FSK) modulation in a received signal stream, comprising:
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receive path circuitry configured to receive an analog signal stream and to output a digital signal stream; detection circuitry configured to analyze bit frequency for a plurality of bit segments within the digital signal stream to determine for a each bit segment a frequency (fmax) at which a maximum signal energy occurs within the bit segment and to combine the maximum frequencies (fmax) to generate a bit frequency histogram for the bit frequency of the plurality of bit segments; wherein the detection circuitry is further configured to determine that the digital signal stream includes PSK modulated signals if a number of frequency spikes in the bit frequency histogram is one, that the digital signal stream includes FSK modulated signals if a number of frequency spikes in the bit frequency histogram is greater than one, and that a PSK/FSK determination cannot be made if a number of frequency spikes is not determinable; and wherein the detection circuitry is further configured to output PSK/FSK determination signals representing the PSK/FSK determination. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification