HP 70340A, User Manual

Page: 200 / 445

When the calibration p ortion of the program is run, y ou should disconnect a v erage p o w er
sensitive circuitry from the RF OUTPUT to a v oid damaging it. During the calibration, using
a substitute load with the exact c haracteristics as the circuit load will preserv e the sp ecied
CW-to-pulse lev el accuracy . The calibration should not b e p erformed un til the instrumen t
has had sucien t time to w arm up (usually 30 min utes). The calibration data remains v alid
as long as the ambien t temp erature remains stable. CW-to-pulse lev el accuracy degrades
nominally b y 0.07 dB/ C. F or b est accuracy , the calibration should b e rep eated whenev er the
ambien t temp erature c hanges.
The time the calibration routine takes to obtain the CW calibration v alues is equiv alen t to
the normal frequency and p o w er lev el switching times. In sp ecial pulse mo dulation mo de,
frequency and p o w er lev el c hanges (without an attenuator range c hange) o ccur faster than
during normal pulsed op eration.
When running the follo wing program, once the calibration is complete and sp e cial pulse
mo dulation mo de is enter e d , the following ev en ts will happ en during pulsed frequency
switching:
The frequency ( "FREQ ";Freqs(I);"MHZ" ) command is sen t: This causes the signal
generator to c hange frequency and the p o w er lev el will drop to the minimum v ernier lev el.
The output p o w er remains pulsed.
The p o w er lev el ( "POW ";Powers(I);"DBM" ) command is sen t: This causes the signal
generator to adjust only the attenuator range. The v ernier remains at its minimum lev el.
The ( "DIAG:IBUS 23,";Verniers(I) ) command is sen t: This adjusts the v ernier lev el to its
correct lev el. The signal generator is no w pulsing at the correct frequency and p o w er lev el.
Note
The preceding commands m ust alwa ys b e executed in the order presen ted for
prop er instrumen t op eration. Ho w ev er, there are t w o cases when use of the
frequency and/or p o w er lev el commands can b e minimized.
Case 1 - If the signal generator will only b e op erating at one frequency , the
frequency command only needs to b e sen t once.
Case 2 - If the signal generator will only b e op erating at one attenuator
range, the p o w er lev el command only needs to b e sen t once.
10 OPTION BASE 1
Sets the lowest element of al l arr ays to 1.
20 DIM Freqs(100),Powers(100),Verniers(100)
Dimensions arr ays.
30 Num_points=4
Sets variable \Num p oints" to 4 for this example. \Num p oints" must b e e qual to the numb er of fr e quency/p ower level
p airs in the D A T A statement.
40 DATA 1000,0,1330, 04,1750, 025,2000,12
The fr e quency/p ower level p airs to b e use d by this pr o gram. The rst numb er and every other numb er is a fr e quency;
the se c ond numb er and every other numb er is a c orr esp onding p ower level.
50 OUTPUT 719;"*RST"
Pr esets the signal gener ator.
60 OUTPUT 719;"PULM:SOUR EXT"
Sele cts external pulse mo de for this example. Mo dify this statement for your desir e d pulse mo de.
70 OUTPUT 719;"PULM:EXT:POL NORM"
Sele cts normal pulse p olarity for this example. Mo dify this statement for your desir e d pulse p olarity.
80 OUTPUT 719;"PULM:STAT ON"
T urns pulse mo dulation on.
90 INPUT "DISCONNECT AVERAGE POWER SENSITIVE DEVICES FROM THE RF OUTPUT,
THEN PRESS ENTER,"A.
5-90 Signal Generator Menus and Functions
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