Detection of time-frequency codes using a spectrogram
First Claim
1. An oscilloscope adapted for detecting a frequency hopping pattern of a frequency hopping signal, comprising:
- an input for receiving a signal under test;
an acquisition unit for sampling said signal under test, producing digital signal samples, and storing said digital signal samples in an acquisition memory;
waveform processing circuitry for processing said digital signal samples;
a waveform memory for storing said processed digital signal samples;
a display device for displaying a representation of said processed digital signal samples; and
a controller for controlling said acquisition unit, said waveform processing unit, and said display device;
wherein said controller controls calculation of a spectrogram from said digital signal samples, estimation of a TFC for said signal under test, determination of whether said estimated TFC matches a known TFC, and display of said TFC on said display screen.
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Abstract
A frequency hopping pattern of a frequency hopping signal is detected by use of spectrogram-generating software in a digital storage oscilloscope. By using a spectrogram, a hopping pattern can be determined without having to demodulate the signal, recover the phase or frequency of the carrier, determine optimal sample timing, or determine system timing. A block of data that contains at least one repetition of the hopping pattern in analyzed with respect to known hopping patterns as well as with respect to the duration in time of the relevant symbols of that data.
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Citations
25 Claims
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1. An oscilloscope adapted for detecting a frequency hopping pattern of a frequency hopping signal, comprising:
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an input for receiving a signal under test;
an acquisition unit for sampling said signal under test, producing digital signal samples, and storing said digital signal samples in an acquisition memory;
waveform processing circuitry for processing said digital signal samples;
a waveform memory for storing said processed digital signal samples;
a display device for displaying a representation of said processed digital signal samples; and
a controller for controlling said acquisition unit, said waveform processing unit, and said display device;
whereinsaid controller controls calculation of a spectrogram from said digital signal samples, estimation of a TFC for said signal under test, determination of whether said estimated TFC matches a known TFC, and display of said TFC on said display screen. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for use in a digital storage oscilloscope for detecting a frequency hopping pattern of a frequency hopping signal, comprising the steps of:
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a. acquiring samples of said signal;
b. calculating a spectrogram from said signal samples;
c. calculating a symbol length for a symbol of said signal;
d. mapping absolute frequency bands to discrete frequencies;
e. calculating power in each frequency band for each frequency slice;
f. calculating the power in said symbol g. repeating steps c through f for each active symbol;
h. determining if an entire Time-Frequency Code (TFC) is active and if so, estimating the current TFC;
i. comparing said estimated TFC to stored data representative of all possible TFC'"'"'s;
j. displaying a matching TFC on a display screen of said oscilloscope. - View Dependent Claims (22, 23, 24, 25)
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Specification