EM 1110-2-2907
1 October 2003
255
204
192
150
138
121
118
112
103
99
95
92
68
54
0
Time
Dashed lines denote the sampling interval.
DN value is given above the sampled point.
Figure 2-26. Diagram illustrates the digital sampling of continuous analog voltage data. The
DN values above the curve represent the digital output values for that line segment.
Table 2-5
Digital number value ranges for various bit data
Number of bits
Exponent of 2
Digital Number (DN)
Value Range
26
6
64
063
28
8
256
0255
210
10
1024
01023
216
16
65536
065535
b. Diversion on Data Type. Digital number values for raw remote sensing data are
usually integers. Occasionally, data can be expressed as a decimal. The most popular
code for representing real numbers (a number that contains a fraction, i.e., 0.5, which is
one-half) is called the IEEE (Institute of Electrical and Electronics Engineers, pro-
nounced I-triple-E) Floating-Point Standard. ASCII text (American Standard Code for
Information Interchange; pronounced ask-ee) is another alternative computing value sys-
2-30
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