Keysight Technologies X-Series, Programming Manual

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206 Keysight CXG, EXG, and MXG X-Series Signal Generators Programming Guide
Creating and Downloading Waveform Files
Understanding Waveform Data
Understanding Waveform Data
The signal generator accepts binary data formatted into a binary I/Q file. This
section explains the necessary components of the binary data, which uses ones
and zeros to represent a value.
Bits and Bytes
Binary data uses the base–two number system. The location of each bit within
the data represents a value that uses base two raised to a power (2
n–1
). The
exponent is n – 1 because the first position is zero. The first bit position, zero, is
located at the far right. To find the decimal value of the binary data, sum the
value of each location:
1101 = (1 x 2
3
) + (1 x 2
2
) + (0 x 2
1
) + (1 x 2
0
)
= (1 x 8) + (1 x 4) + (0 x 2) + (1 x 1)
= 13 (decimal value)
Notice that the exponent identifies the bit position within the data, and we read
the data from right to left.
The signal generator accepts data in the form of bytes. Bytes are groups of
eight bits:
01101110 = (0 x 2
7
) + (1 x 2
6
) + (1 x 2
5
) + (0 x 2
4
) +(1 x 2
3
) + (1 x 2
2
) + (1 x 2
1
)
+ (0 x 2
0
)
= 110 (decimal value)
The maximum value for a single unsigned byte is 255 (11111111 or 2
8
–1), but
you can use multiple bytes to represent larger values. The following shows two
bytes and the resulting integer value:
01101110 10110011= 28339 (decimal value)
The maximum value for two unsigned bytes is 65535. Since binary strings
lengthen as the value increases, it is common to show binary values using
hexadecimal (hex) values (base 16), which are shorter. The value 65535 in hex
is FFFF. Hexadecimal consists of the values 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D,
E, and F. In decimal, hex values range from 0 to 15 (F). It takes 4 bits to
represent a single hex value.
For I and Q data, the signal generator uses two bytes to represent an integer
value.
1 = 0001 2 = 0010 3 = 0011 4 = 0100 5 = 0101
6 = 0110 7 = 0111 8 = 1000 9 = 1001 A = 1010
B = 1011 C = 1100 D = 1101 E = 1110 F = 1111