Large dynamic range digitizing apparatus and method
AssigneeThe United States of America as represented by the Secretary of the Army
InventorC. Lee Francis
Life of this patent
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Abstract
An apparatus and method for digitizing an analog signal and optimizing the dynamic range of the digitized signal. Dual analog-to-digital converters are preceded by respective amplifiers with different gains for receiving an analog input signal. The digital output signal from the analog-to digital converter preceded by the amplifier of higher gain is selected and stored when it is not clipped. Otherwise, the analog-to-digital converter preceded by the amplifier of lower gain is selected and its digital output signal is stored. Once digital memory is filled, an adaptive formatting program selects the most appropriate parts of the memory words to achieve maximum resolution and dynamic range in an output word size.
Claims14
An apparatus for digitizing an analog signal and optimizing the dynamic range of the digitized signal comprising:
- (I) a low gain amplifier for receiving and amplifying the analog signal;
- (II) a high gain amplifier for receiving and amplifying the analog signal;
- (III) a first analog-to-digital converter connected to the output of the low gain amplifier for converting the low gain amplified analog signal to low gain digital data;
- (IV) a second analog-to-digital converter connected to the output of the high gain amplifier for converting the high gain amplified analog signal to high gain digital data;
- and
- (V) means for
- (A) detecting whether or not the high gain digital data is clipped;
- (B) selecting and storing in a memory the high gain digital data when the high gain digital signal is not clipped;
- (C) detecting whether or not the low gain digital data is greater than or equal to positive half scale dr less than or equal to negative half scale when the high gain digital data is clipped;
- (D) selecting and storing in the memory the low gain digital data when the high gain digital data is clipped;
- (E) depending on the result of the detecting steps, adaptively, reformatting the stored data when the memory is full to produce an output word with maximum dynamic range.
An apparatus for digitizing an analog signal and optimizing the dynamic range of the digitized signal comprising:
- a low gain amplifier for receiving and amplifying the analog signal;
- a high gain amplifier for receiving and amplifying the analog signal;
- an analog-to-digital converter connected to the output of the low gain amplifier for converting the low gain amplified analog signal to low gain digital data;
- an analog-to-digital converter connected to the output of the high gain amplifier for converting the high gain amplified analog signal to high gain digital data;
- means for detecting whether or not the high gain digital data is clipped;
- means for selecting and storing in a memory the high gain digital data when the high gain digital data is not clipped;
- means for detecting whether or not the low gain digital data is greater than or equal to positive half scale or less than or equal to negative half scale when the high gain digital data is clipped;
- means for selecting and storing in the memory the low gain digital data when the high gain digital data is clipped;
- and
- means, depending on the result of the detecting steps, for adaptively reformatting the stored data when the memory is full to produce an output word with maximum dynamic range.
A method of digitizing an analog signal and optimizing the dynamic range of the digitized signal comprising the steps of:
- (a) receiving and low-gain amplifying the analog signal;
- (b) receiving and high-gain-amplifying the analog signal;
- (c) converting the low-gain-amplified analog signal to low gain 14-bit digital data;
- (d) converting the high-gain-amplified analog signal to high gain 14-bit digital data;
- (e) performing a first test to determine whether the high gain digital data is clipped;
- (f) if the first test is negative, writing the value of the high gain digital data in a memory and incrementing the memory address;
- (g) if the first test is positive, setting a clip flag and performing a second test to determine if the low gain digital data value is greater than or equal to ½full scale or less than or equal to −½full scale;
- (h) if the second test is negative, setting a tag bit and writing the value of the low gain digital data in the memory and incrementing the memory address;
- (i) if the second test is positive, setting a half scale flag and the tag bit and writing the value of the low gain digital data in the memory and incrementing the memory address;
- (j) performing a third test to determine whether the memory is full;
- (k) if the third test is negative, repeating steps (e)-(j);
- and
- (l) if the third test is positive, adaptively reformatting the data stored in the memory to produce an output word with maximum dynamic range.
Dependencies are inferred from the claim text.