Keysight Technologies N5173B EXG - Page 239

Keysight CXG, EXG, and MXG X-Series Signal Generators Programming Guide 239
Creating and Downloading Waveform Files
Creating Waveform Data
21–29 the I and Q data), and interleave the I and Q data.
— shift the data pointer right 8 bits to the beginning of the high byte (ivalue >> 8)
— AND (boolean) the high I byte with 0xFF to make the high I byte the value to store
in the IQ array—(ivalue >> 8) & 0xFF
— AND (boolean) the low I byte with 0xFF (ivalue & 0xFF) to make the low I byte the
value to store in the I/Q array location just after the high byte [index * 4 + 1]
— Swap the Q byte order within the same loop. Notice that the I and Q data interleave
with each loop cycle. This is due to the I/Q array shifting by one location for each I
and Q operation [index * 4 + n].
Line Code Description—Interleaving and Byte Swapping for Little Endian Order
1 0 1 1 0 1 1 1
15 14 13 12 11 10 9 8
Data
Bit Position
Little Endian Order
1 1 1 0 1 0 0 1
7 6 5 4 3 2 1 0
Hex values = E9 B7
Data pointer
Data pointer shifted 8 bits
1 0 1 1 0 1 1 1
15 14 13 12 11 10 9 8
Hex value =B7
1 1 1 1 1 1 1 1
Hex value =FF
1 0 1 1 0 1 1 1
Hex value =B7
1 0 1 1 0 1 1 1
15 14 13 12 11 10 9 8
Data
Bit Position
I Data in I/Q Array after Byte Swap (Big Endian Order)
1 1 1 0 1 0 0 1
7 6 5 4 3 2 1 0
Hex value = B7 E9
10110111
15...................... 8
Data
Bit Position
Interleaved I/Q Array in Big Endian Order
11101001
7.................... 0
11100101
15...................... 8
01101011
7.................... 0
I Data
Q Data