Agilent Technologies 8360B, Руководство пользователя, Страница: 342 / 496

SCPI COMMAND SUMMARY
Frequency Subsystem
An y t w o frequency setting headers (ST AR t, STOP , CENT er, or
SP AN) may b e sen t in a single message and the resulting sw eep
is what w as requested. The order of the headers in the message
do es not make an y dierence in the nal result. When a message is
completed, coupling equations are used to x the unset parameters to
the correct v alues. These equations sp ecify that:
cen ter frequency = (start + stop) / 2
frequency span = (stop 0 start)
If more than t w o are sen t, then the last t w o in the message are used
to determine the sw eep and no errors are given.
If only one header is sen t in a message, then the assumed pairs are
cen ter/span and start/stop. In other w ords, if only cen ter is sen t,
then span is k ept constan t (if p ossible) while adjusting cen ter to the
requested v alue. The start/stop frequencies are up dated to reect the
c hanges based on the coupling equations.
The sw ept signal generator uses \bumping" to mov e unsp ecied
frequency parameters, but if the nal v alue of an y of the frequency
headers is the result of bumping, then an error is generated since
the user is not getting what w as sp ecied. This means, to guarantee
sequence indep endence requires sending the frequency pairs in a
single message.
Example 1: (presen t state start = 5 GHz, stop = 6 GHz)
FREQ:STARt 20 GHZ an err or r esults sinc e the
stop fr e quency is bump e d.
FREQ:STOP 22 GHZ the nal swe ep do es not
gener ate an err or
(20 to 22).
Example 2: (presen t state start = 5 GHz, stop = 6 GHz)
FREQ:STOP 22 GHZ no err or is gener ate d,
start fr e quency is unchange d.
FREQ:STARt 20 GHZ stil l no err or.
Example 3: (presen t state start = 5 GHz stop = 6 GHz)
FREQ:STARt 20 GHZ;STOP 22 GHZ b oth ar e ne,
FREQ:STOP 22 GHZ;STARt 20 GHZ no err ors.
FREQuency:CENTer <num>[freq
suffix]|MAXimum|MINimum|UP|DOWN
FREQuency:CENTer? [MAXimum|MINimum]
Sets and queries the cen ter frequency .
The *RST v alue is (MAX + MIN)/2.
FREQuency[:CW|:FIXed] <num>[freq
suffix]|MAXimum|MINimum|UP|DOWN
FREQuency[:CW]? [MAXimum|MINimum]
FREQuency[:FIXed]? [MAXimum|MINimum]
Operating and Programming Reference S-35