Tektronix PSM3000 Series, User Manual

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Power Meter Application
Set Ref Set the reference value so that a subsequent power level can be measured relative
to the power measurement on the display. When Ref Offset is activated, the
REL
indicator will show in the digital readout display and the power units will change
to “dB relative”.
You can enable this setting from the Offsets & Response drop down menu item
called Relative Units On/Off.
Offset Set gain or loss offsets to be applied to all measurements. You can also fi nd this
item in the Offsets & Response drop down menu.
An OFS indicator will appear on the digital display when Offset is enabled.
Freq Resp Set frequency dependent gain or loss offsets to be applied to measurements. This
is a frequency sensitive offset, so as you change the measurement frequency the
response changes accordingly. Response amplitude is always expressed in dB
and the frequency is expressed in Hz. The interpolation is linear with respect to
frequency and dB. The frequency response feature must be enabled before it will
have an effect. A frequency response (RSP) indicator will appear on the digital
display readout when response correction is enabled.
The frequency response correction factors are speci fi ed as frequency and
amplitude pairs. To load the correction factors go to the Frequency Response
Offset window. Click Add after each frequency and offset entry to build the table.
Then select Show Graph to get a graphical presentation of the frequency offsets
that were entered in the table. The Response setup allows up to 201 points to be
entered.
You can also fi nd this item in the Offsets & Response drop down menu.
Anti-alias Control This function randomizes the sampling pattern to eliminate the effect of aliasing
due to undersampling. The real-time sample rate of the instrument is 500 kS/s.
As the baseband signals approach the Nyquist criteria (about 200 kHz in this
case) anti-aliasing can occur. If you are measuring signals that have baseband
content greater than about 200 kHz, enable anti-aliasing for the best measurement
accuracy. Anti-aliasing slows down measurements, so for faster reading rates on
signals with modulation bandwidth below 200 kHz, disable anti-aliasing.
This function is found in the Measurement drop down menu.
Measured Pulse Setup This value determines the portion of the pulse to be used to measure pulse power.
The default or automatic value is 3 dB below the measured peak value or the
50% down points.
This function is found in the Measurement drop down menu.
22 RF and Microwave Power Sensors/Meters