Data digitization and display for an imaging system
First Claim
1. A method for processing data from an imaging system, comprising;
- sampling a signal from an optical detector with a first sample and hold, S/H, for a first sample time ts/h1 and with a second S/H for a second sample time ts/h2 where ts/h1>
ts/h2,producing a digital counter signal at a counter and a ramp signal at a ramp, wherein the counter and the ramp are timed such that the counter counts from 0 to a predetermined number of counts, Cmax−
x, wherein Cmax is a number of counts corresponding to the number of bits desired for an analog to digital conversion of the detector signal and x is an integer corresponding to a subset of the number of bits, in approximately the time taken for the ramp to ramp from 0 to a predetermined voltage, vs1,sending the first S/H output to a comparator and comparing it to the ramp signal,starting the counter and the ramp, after a time >
ts/h1,latching the count value if the ramp signal meets a threshold defined by the output of the first S/H before the counter counts to Cmax−
x, andif the latching does not happen before Cmax−
x is reached;
while the counter continues, sending the second S/H signal to the comparator,while the counter continues, resetting the ramp to zero and restarting the ramp at a slope sufficient to ramp from 0 to a predetermined voltage vs2 in the time required for x counts, andlatching the count value if the output of the ramp signal meets a threshold defined by the output of the second S/H, wherein the count latched is a digitization of the detector signal;
wherein a subset of count values greater than Cmax−
x comprise an excluded range of count values that do not correspond to possible values of the sampled signal, the excluded range corresponding to the time required for the restarted ramp to ramp from 0 to vs1.
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Accused Products
Abstract
A system and method for digitizing data from an imaging system includes sampling a signal from an optical detector with a first circuit having a first attenuation and with a second circuit having a second attenuation different than the first attenuation. The system and method further includes digitizing the sampled signal at a predetermined number of bits desired for an analog to digital conversion of the sampled signal by allocating a first portion of bits to digitizing a signal from the first circuit and allocating a second portion of bits to digitizing a signal from the second circuit. The system and method further includes encoding the first and second portion of bits into one monotonic digital word corresponding to a range of the sampled signal.
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Citations
22 Claims
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1. A method for processing data from an imaging system, comprising;
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sampling a signal from an optical detector with a first sample and hold, S/H, for a first sample time ts/h1 and with a second S/H for a second sample time ts/h2 where ts/h1>
ts/h2,producing a digital counter signal at a counter and a ramp signal at a ramp, wherein the counter and the ramp are timed such that the counter counts from 0 to a predetermined number of counts, Cmax−
x, wherein Cmax is a number of counts corresponding to the number of bits desired for an analog to digital conversion of the detector signal and x is an integer corresponding to a subset of the number of bits, in approximately the time taken for the ramp to ramp from 0 to a predetermined voltage, vs1,sending the first S/H output to a comparator and comparing it to the ramp signal, starting the counter and the ramp, after a time >
ts/h1,latching the count value if the ramp signal meets a threshold defined by the output of the first S/H before the counter counts to Cmax−
x, andif the latching does not happen before Cmax−
x is reached;while the counter continues, sending the second S/H signal to the comparator, while the counter continues, resetting the ramp to zero and restarting the ramp at a slope sufficient to ramp from 0 to a predetermined voltage vs2 in the time required for x counts, and latching the count value if the output of the ramp signal meets a threshold defined by the output of the second S/H, wherein the count latched is a digitization of the detector signal; wherein a subset of count values greater than Cmax−
x comprise an excluded range of count values that do not correspond to possible values of the sampled signal, the excluded range corresponding to the time required for the restarted ramp to ramp from 0 to vs1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A digitization system for digitizing data from an infrared imaging system, the system comprising:
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a sampling circuit configured to sample a signal from an infrared optical detector with a first sample time and a second sample time; and a processing circuit configured to digitize the sampled signal at a predetermined number of bits desired for an analog to digital conversion of the sampled signal with a first portion of bits allocated to digitizing the sampled signal having a first sample time and a second portion of bits allocated to digitizing the sampled signal having the second sample time, and to encode the first and second portion of bits into one digital word corresponding to a range of the sampled signal, wherein the encoding is a monotonic function having at least one discontinuity, the discontinuity comprising an excluded range of digital word values that do not correspond to possible values of the sampled signal. - View Dependent Claims (15, 16, 17)
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18. A method for digitizing data from an imaging system, comprising;
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sampling a signal from an optical detector with a first circuit having a first attenuation and with a second circuit having a second attenuation different than the first attenuation; digitizing the sampled signal at a predetermined number of bits desired for an analog to digital conversion of the sampled signal by allocating a first portion of bits to digitizing a signal from the first circuit and allocating a second portion of bits to digitizing a signal from the second circuit; and encoding the first and second portion of bits into one digital word corresponding to a range of the sampled signal, wherein the encoding is a monotonic function having at least one discontinuity, the discontinuity comprising an excluded range of digital word values that do not correspond to possible values of the sampled signal. - View Dependent Claims (19, 20, 21, 22)
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Specification