Agilent Technologies Infiniium 90000 Series Programmer's Manual page 959

Channel In
Aux Out
Figure 10 Data Flow in Infiniium
This process continues until all 256 digital codes are calibrated. The
calibration process removes most of the non- linearity error of the ADC
which yields more accurate vertical voltage values.
During normal operation of the oscilloscope, the output of the ADC is
used as an address to the Calibration Look- up Table which produces
16- bit data for the oscilloscope to process and display. The output of the
ADC is a signed 8- bit integer and the output of the Calibration Look- up
Table is a signed 16- bit integer. If the amplitude of the input waveform is
larger than the maximum dc reference level of the ADC, the ADC will
output the maximum 8- bit value that it can (255). This condition is called
ADC clipping. When the 255 digital code is applied to the Calibration
Look- up Table, a 16- bit value, such as 26,188 could be produced which
represents an ADC clipped value. This number will vary from one
oscilloscope to the next.
WORD and BYTE
When downloading the waveform data in WORD format, the 16- bit signed
Data Formats integer value for each data point is sent in two consecutive 8- bit bytes
over the remote interface. Whether the least significant byte (LSB) or the
most significant byte (MSB) is sent first depends on the byte order
determined by the BYTeorder command.
Before downloading the waveform data in BYTE format, each 16- bit signed
integer is converted into an 8- bit signed integer. Because there are more
possible 16- bit integers than there are 8- bit integers, a range of 16- bit
integers is converted into single 8- bit numbers. For example, the following
16- bit numbers are all converted into one 8- bit number.
Agilent Infiniium 90000 Series Oscilloscopes Programmer's Reference
D
7
D
6
D
Analog
5
Calibration
D
to 4
D Look-up
3
Digital
D
Table
2
Converter
D
1
D
0
Calibration
Digital
to
CPU
16 bits
Analog
Converter
ASCII
Format
WORD
Format
16 bits
BYTE
Format
34
Waveform Commands
Stream of
8 bit
Characters
16 bits
8 bits
959