User Manual

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7.2.4 Repetitive Operations
A common requirement for a spectrum analyzer user is to change repetitively between two or
more frequency ranges. The PSAxx02 provides several methods for doing this.
1. When setting the centre frequency using the keyboard, the Previous key can be used to
toggle between two centre frequencies - see section 7.2.1. The same facility is provided for Set
Span, Set Start and Set Stop.
2. Frequency Presets, selected via the Frequency/Span menu group, enable up to six
frequency spans to be stored and rapidly recalled - see section 4.1.5. Only Centre/Span or the
equivalent Start/Stop frequencies are stored. Other parameters such as RBW are not affected
(unless set to Auto).
3. Trace States are files which contain not only the frequency span, but the RBW, the Level
setting and the graticule scale and units. Up to 999 trace files can be stored and are recalled
from the Traces/Stores control screen - see section 4.6.1.
4. The hard key marked PRESET brings up a menu of set-up states - see section 4.11. Note,
however, that these change many parameters of the instrument simultaneously.
7.3 Measuring Relative Amplitude
When both measurement markers are turned on, a readout is provided of the difference
between them in terms of both frequency and level.
A common requirement is to measure the signal amplitude at a specific frequency under
different conditions. The PSAxx02 provides a convenient method of doing this.
Having measured the amplitude in the initial condition using marker M1, the value can be fixed
from the Marker Setup sub-group menu (Traces/Markers > Marker Setup > ). The
M1 readout shows at the left hand side. With the new condition applied, the measurement
can be made again by moving M2 to the same frequency using the key . The
difference in amplitude level can then be read directly.
To return M1 to normal operation, press again. See section 4.7.1.
7.4 Triggered Operation
Triggered operation is only available when the upgrade option U01 is fitted (see section 6).
Triggering is used either to start or stop the sweep, or to initiate logging of sweeps or screen
images. The trigger can be generated manually (by a key press), externally (from the trigger
input) or internally from the sweep in combination with a limit line or limit pattern.
For a description of Triggered Sweep see section 4.4.3.3. For a description of Triggered
Logging see section 7.7.
7.4.1 External Trigger Input
The external trigger input is provided via the 3.5mm jack socket at the top of the instrument.
This can be converted to a standard BNC socket using the adaptor provided. The selection
between positive or negative transition triggering is made from the Sweep Trigger or Logging
Trigger functions. It has a TTL threshold and a high input impedance. Maximum input
voltage is limited to +/-20V. Voltages above this level could damage the instrument.
7.4.2 Trigger Output
A trigger output pulse can be generated using the same socket as trigger input (see above).
The signal is generated by the Limits comparator function (see section 7.6.3) and is a positive
going TTL level pulse of approximately 10ms duration from a 1k source impedance.
The trigger output is not available if either sweep trigger or log trigger is set to external
triggering.