Filter
Top Products
1-7
Introduction
Multiple Databases
CHANnel2:DISPlay ON,APPend
For a example of using multiple databases, refer to “multidatabase.c Sample Program” on
page 2-35.
Downloading a
Database
The general process for downloading a color grade/gray scale database is as follows:
1 Send the command :WAVEFORM:SOURCE CGRADE
This will select the color grade/gray scale database as the waveform source.
2 Issue :WAVeform:FORMat WORD.
Database downloads only support word formatted data (16-bit integers).
3 Send the query :WAVeform:DATA?
The data will be sent by means of a block data transfer as a two-dimensional array, 451 words
wide by 321 words high (refer to “Definite-Length Block Response Data” on page 1-26). The
data is transferred starting with the upper left pixel of the display graticule, column by column,
until the lower right pixel is transferred.
4 Send the command :WAVeform:XORigin to obtain the time of the left column.
5 Send the command :WAVeform:XINC to obtain the time increment of each column.
6 Send the command :WAVeform:YORigin to obtain the voltage or power of the vertical center
of the database.
7 Send the command :WAVeform:YORigin to obtain the voltage or power of the incremental row.
The information from steps 4 through 7 can also be obtained with the command :WAVe-
form:PREamble.
Auto Skew Another multiple database feature is the auto skew. You can use the auto skew feature to set
the horizontal skew of multiple, active channels with the same bit rate, so that the waveform
crossings align with each other. This can be very convient when viewing multiple eye dia-
grams simultaneously. Slight differences between channels and test devices may cause a
phase difference between channels. Auto skew ensures that each eye is properly aligned, so
that measurements and mask tests can be properly executed.
In addition, auto skew optimizes the instrument trigger level. Prior to auto skew, at least one
channel must display a complete eye diagram in order to make the initial bit rate measure-
ment. Auto skew requires more data to be sampled; therefore, acquisition time during auto
skew is slightly longer than acquisition time during measurements.