Burst Measurements using
Manual Presetting
You can measure the frequency on Input A
and Input B to 300 MHz and on Input C with
limited specifications to the upper frequency
limit of the prescaler with the internally syn
-
chronized BURST function as follows:
–
Select Freq Burst under the Freq menu
–
Select A, B,orC as measurement input.
–
Press SETTINGS and Burst. Select a
Meas Time that is shorter than the burst
duration minus two CW cycles.
If you do not know the approximate burst pa
-
rameters of your signal, always start with a
short measurement time and increase it gradu
-
ally until the readout gets unstable.
–
Press Sync Delay and enter a value lon-
ger than the burst duration and shorter
than the inverse of the PRF. See Fig. 4-3.
–
Press Start Delay and enter a value lon
-
ger than the transient part of the burst
pulse.
–
Select Frequency Limit (160/300 MHz)
if Input A or Input B is to be used. Use
the low limit if possible to minimize the
number of cycles necessary to make a
measurement.
–
Press EXIT/OK to measure.
All relevant burst parameters can be read on
the display simultaneously.
n
Selecting Measurement Time
The measurement time must be shorter than
the duration of the burst. If the measurement
continues during part of the burst gap, no mat-
ter how small a period of time, then the mea-
surement is ruined. Choosing a measurement
time that is too short is better since it only re-
duces the resolution. Making burst frequency
measurements on short bursts means using
short measurement times, giving a poorer res-
olution than normally achieved with the coun-
ter.
n
How Does the Sync Delay
Work?
The sync delay works as an internal start arm
-
ing delay: it prevents the start of a new mea
-
surement until the set sync delay has expired.
See Fig. 4-5.
After the set measurement time has started,
the counter synchronizes the start of the mea
-
surement with the second trigger event in the
burst. This means that the measurement does
BURST A, B, C 4-5
Measuring Functions
B u r s t
S i g n a l
S y n c . d e l a
Fig. 4-3 Set the sync delay so that it ex
-
pires in the gap between the
bursts.
Fig. 4-4 Three time values must be set to
measure the correct part of a
burst
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