Stanford Research Systems DS345, Manual

Page: 56 / 139

Programming Commands
3-6
center freq + span/2. A negative span will generate a downward sweep, from
maximum to minimum frequency. The SPAN? query returns the current
sweep span.
SPCF (?) x
The SPCF command sets the sweep center frequency to x Hertz. An error
will be generated if the sweep frequency is less than or equal to zero or
greater than allowed by the current function. The SPCF? query returns the
current sweep center frequency.
SPFR (?) x
The SPFR command sets the sweep stop frequency to x Hertz. An error will
be generated if the sweep frequency is less than or equal to zero or greater
than allowed by the current function. The SPFR? query returns the current
sweep stop frequency. If the stop frequency is less than the start frequency
(the STFR command) a downward sweep from maximum to minimum fre-
quency will be generated.
SPMK
The SPMK command sets the sweep span to the sweep marker frequency.
That is, sets the start frequency to the start marker frequency, and the stop
frequency to the stop marker frequency.
STFR (?) x
The STFR command sets the sweep start frequency to x Hertz. An error will
be generated if the sweep frequency is less than or equal to zero or greater
than allowed by the current function. The STFR? query returns the current
sweep start frequency. If the start frequency is greater than the stop frequen-
cy (the SPFR command) a downward sweep from maximum to minimum fre-
quency will be generated.
TRAT (?) x
The TRAT command sets the trigger rate for internally triggered single
sweeps and bursts to x Hertz. x is rounded to two significant digits and may
range from 0.001 Hz to 10 kHz. The TRAT? query returns the current trigger
rate.
TSRC (?) i
The TSRC command sets the trigger source for bursts and sweeps to i. The
correspondence of i to source is shown in the table below. The TSRC?
query returns the current trigger source.
i Waveform
0 SINGLE
1 INTERNAL RATE
2 + SLOPE EXTERNAL
3 - SLOPE EXTERNAL
4 LINE
For single sweeps and bursts the *TRG command triggers the sweep.
Arbitrary Waveform and Modulation Commands
AMRT(?) i
The AMRT command sets the arbitrary modulation rate divider to i. i may
range from 1 to 2 23 -1. This controls the rate at which arbitrary modulations
are generated. Arbitrary AM takes 0.3
µ
s per point, arb FM takes 2
µ
s per
point, and arb PM takes 0.5
µ
s per point. The AMRT? query returns the cur-
rent divider.