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Program Comments
Reference
Oscillator Sources
AFG Frequency
Modes
Frequency Points
Specifying a
Sweep Time
Chapter 4
The following information is associated with sweeping and frequency-shift
keying. Included are details on the operation of these functions, and on the
various modes, ranges, etc., used in the programs in this chapter.
There are two reference oscillator sources for the AFG which are selected
by the
[SOURce:]ROSCillator:SOURce
: The AFG's front panel "Aux In" BNC .
EXTernal
: The internal 42.94967296 MHz oscillator.
INTernal
The
reference oscillator gives a frequency resolution of .01 Hz.
INTernal
is the default reference oscillator source. Thus, in many programs,
INTernal
the source is not specified.
There are three frequency " modes" available in the AFG. The modes
selected by the
[SOURce:]FREQuency:MODE
CW|FIXed
: Single frequency mode.
: Frequency shift keying mode.
FSKey
: Frequency sweep mode.
SWEep
The number of frequencies generated (points) in a frequency sweep can be
from 2 to 1,073,741,824. The default number is 1001. The number of points
is set with the
SOURce:SWEep:POINts
only.
The sweep time (set by
SOURce:SWEep:TIME
generation of the first frequency in the sweep or list to the generation of
the last frequency (see below).
The duration (t) of each frequency is:
specified sweep time/(frequency points - 1)
For multiple sweeps or repetitions through the list, the duration of the last
frequency (f
) is also t. To maintain a constant rate between sweeps or
n
repetitions, the duration of f
Sweep time
= Sweep repetition time
specified
HP E1340A Sweeping and Frequency-Shift Keying
command:
command are:
command and applies to sweeps
) is the period from the
must be accounted for as follows:
n
* ((points - 1)/points)
desired
94
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