Programming with GPIB Commands 2-18 Power-Offset-Table Commands
MG369xC GPIB PM PN: 10370-10374 Rev. F 2-47
2-18 Power-Offset-Table Commands
Table 2-19 lists the power-offset-table command mnemonic codes. These commands provide for maintaining a
consistent power level at a point within a test setup across the measurement frequencies. This “flattening” of
the test point power level is accomplished by summing a power offset word (from the power offset table) with
the signal generator’s normal power level DAC word at each frequency point.
The power-offset mode works in conjunction with the fast-frequency-switching mode (Section 2-17). The
frequency stack must be loaded before loading the power-offset table because the frequency loading sets the
upper limit for the number of entries in the power-offset table. The same pointer is used for both the frequency
stack and the power-offset table. Once the power-offset table is loaded, the PT1 command turns on the
power-offset mode; the PT0 command turns it off.
Loading the Power-Offset Table
To load the power-offset table, use the command, PTL clch dldh. . . , where “clch” is the number of
power-offset words and “dldh” is a power-offset word. Both “clch” and “dldh” are two-byte binary words sent
LOW byte first and HIGH byte second. The power-offset word is in hundredths of a dB. Negative power offsets
use 2’s complement representation.
To change a power-offset word in the table, use the PTC dldh command, where “dldh” is the new power-offset
word for the current power level setting.
Programming Note:
Care must be taken to send the exact number of power-offset words specified in the word count, “clch”. If too
few words are sent, the GPIB interface may not respond properly.
Figure 2-13 on page 2-48 shows an example of power-offset mode programming.
Table 2-19. Power-Offset-Table Commands
Mnemonic
Code Function
PT0 Disable the Power Offset Table.
PT1 Enable the Power Offset Table.
PTC Change a Power Offset Table entry (PTC dldh), where dldh is the new offset word for the current
table entry.
PTL Load a Power Offset Table (PTL clch dldh . . . ), where clch is the data word count and dldh is the
data word.
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