Signal detection and triggering using a difference bitmap
First Claim
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1. A test and measurement instrument comprising:
- an analog-to-digital converter for receiving an input radio frequency signal and producing a digital signal; and
a processor configured to;
process digital data from the digital signal by converting it into a series of temporal frequency spectra by frequency transform,accumulate the frequency spectra in a plurality of bitmaps by rasterizing each frequency spectrum, each rasterized frequency spectrum comprising an array of cells, and summing the values of each corresponding cell of each rasterized frequency spectrum in a particular frame to form one of the plurality of bitmaps, andsubtract one of the bitmaps referred to as a reference bitmap from another one of the bitmaps to produce a density difference bitmap.
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Abstract
A test and measurement instrument converts digital data that represents an input signal into a plurality of bitmaps, and then subtracts one of the bitmaps from another one of the bitmaps to produce a difference bitmap. The difference bitmap does not contain density values that are common to the two bitmaps, but instead only contains the density differences between the two, thereby revealing very small density variations in the presence of large density values. In some embodiments, the difference bitmap is displayed on a display device. In other embodiments, the difference bitmap is used to generate a trigger signal.
15 Citations
27 Claims
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1. A test and measurement instrument comprising:
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an analog-to-digital converter for receiving an input radio frequency signal and producing a digital signal; and a processor configured to; process digital data from the digital signal by converting it into a series of temporal frequency spectra by frequency transform, accumulate the frequency spectra in a plurality of bitmaps by rasterizing each frequency spectrum, each rasterized frequency spectrum comprising an array of cells, and summing the values of each corresponding cell of each rasterized frequency spectrum in a particular frame to form one of the plurality of bitmaps, and subtract one of the bitmaps referred to as a reference bitmap from another one of the bitmaps to produce a density difference bitmap. - View Dependent Claims (2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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4. A test and measurement instrument comprising:
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an analog-to-digital converter for receiving an input signal and producing a digital signal; a trigger detector for processing digital data from the digital signal by; converting it into a series of temporal frequency spectra by frequency transform, accumulating the frequency spectra in a plurality of bitmaps by rasterizing each frequency spectrum, each rasterized frequency spectrum comprising an array of cells, and summing the values of each corresponding cell of each rasterized frequency spectrum to form the plurality of bitmaps, and subtracting one of the bitmaps referred to as a reference bitmap from another one of the bitmaps to produce a density difference bitmap, and for generating a trigger signal when the density difference bitmap satisfies a user-specified trigger criterion; and a memory for storing digital data from the digital signal in response to the trigger signal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification