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
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 (
). 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.
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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