1250 Frequency Response Analyzer The Sweep Facility
CHFR/1250/2 6-5
6.9.3 COMMANDS WHICH PRODUCE "SWEEP IDLE” OR "HOLD" STATUS
a. ANALYZER SINGLE. The Analyzers will complete the current measurement, display
a valid reading and stop. If SINGLE is pressed again, the Generator will step on to
the next frequency in the sweep, and a new measurement will be made. This
process may be continued until the sweep is complete.
Alternatively, if ANALYZER RECYCLE is pressed again, the sweep will continue
automatically. An application of this technique is given in Section 10.
b. SWEEP HOLD. The Analyzers will complete the current measurement, and display a
valid reading. Unlike method "a", however, the Analyzers will continue measuring
the signal, and the reading is continuously updated. This enables the user to make
fine adjustments to the Generator settings, whilst observing their effect on the
reading. See also Section 10 for other applications.
c. ANALYSER STOP. This command would not normally be used if all the sweep
readings are required. When given, the Analyzers complete the current cycle of
integration and display a reading, which may be accompanied by the message
ERROR 89. This implies that the reading is not valid.
The sweep can be restarted by pressing either ANALYZER RECYCLE or SINGLE.
d. GENERATOR STOP. This command will stop the sweep, but the current
measurement will not give a reading. To restart the sweep, press GENERATOR
START. The Analyzers will attempt to complete the measurement which was
interrupted by the STOP command, but the reading will be invalid. All further
measurements will be made correctly.
6.10 CHANGING PARAMETERS IN MID-SWEEP
When the sweep has been halted, preferably by either pressing SWEEP HOLD or
ANALYZER SINGLE, the user can change the settings and then continue. For example,
if the steps of the sweep are too coarse to permit detailed observation of a steep-sided
response curve, the sweep can be temporarily stopped somewhere near the area of
interest. The frequency increments can now be made smaller, logarithmic sweep
changed to linear, direction of sweep reversed etc., then the sweep continued.
If SWEEP HOLD is used, so that the Analyzers are continuously updating the displayed
reading, the VARIABLE key can be pressed, thus permitting extremely fine adjustments
to be made to the Generator settings, as described in Chapter 9.
6.11 HARMONIC SWEEP
6.11.1 INTRODUCTION
For this type of sweep, the Generator is left set to the required fundamental frequency.
The Analyzers then sweep through to measure the response at all the harmonics up to
the 16th (provided that this does not exceed the maximum frequency of the instrument).
The SWEEP MENU soft key settings are ignored in this mode.
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