Keysight Technologies 3458A Guide D'utilisation page 182

4 Making Measurements
The following program uses the real-time DB operation to determine an
amplifier's voltage gain. Line 40 stores the amplifier's input voltage (0.1 V) in the
REF register. The amplifier's output voltage is measured and the gain of the
amplifier is computed.
10 OUTPUT 722;"PRESET NORM"!PRESET,NRDGS 1,AUTO, DCV 10, TRIG SYN
20 OUTPUT 722;"ACV"!AC VOLTAGE MEASUREMENTS, AUTORANGE
30 OUTPUT 722;"SETACV ANA"!ANALOG ACV METHOD
40 OUTPUT 722;"SMATH REF 0.1"!WRITE 0.1 TO REF REGISTER
50 OUTPUT 722;"MATH DB"!ENABLE REAL-TIME DB OPERATION
60 ENTER 722;A!SYN EVENT, ENTER DB
70 PRINT A!PRINT DB
80 END
For example, if the input voltage is 0.1 V and the output voltage is 10 V, the gain
is:
The following program is similar to the preceding program except that it uses the
post-process DB operation.
10
20
30
40
50
60
70
80
85!PERFORM DB OPERATION
90
100 END
DBM
The DBM math operation calculates the power delivered to a resistance
referenced to 1 mW. The equation is:
182
20@log (10/0.1) = 20@log
10
OUTPUT 722;"PRESET NORM"!PRESET,NRDGS 1,AUTO, DCV 10, TRIG SYN
OUTPUT 722;"ACV"!AC VOLTAGE MEASUREMENTS, AUTORANGE
OUTPUT 722;"SETACV ANA"!ANALOG ACV METHOD
OUTPUT 722;"MEM FIFO"!ENABLE READING MEMORY, FIFO MODE
OUTPUT 722;"SMATH REF 0.1"!WRITE 0.1 TO REF REGISTER
OUTPUT 722;"MMATH DB"!ENABLE POST-PROCESS DB OPERATION
OUTPUT 722;"TRIG SGL"!TRIGGER READING
ENTER 722;A!RECALL READING USING IMPLIED READ,
PRINT A!PRINT DB RESULT
Result = 10@log (Reading
10
Where:
Reading is any voltage reading.
RES is the resistance value in the RES register (default = 50)
100 = 40 dB
10
2
/RES/1 mW)
Keysight 3458A User's Guide