PMX40 RF Power Meter – INSTRUCTION MANUAL
4-7
Filter Time:
Available in Continuous mode only. Sets the length of the integration filter. The filter is
a “sliding window” which averages samples taken within a time window whose duration is set by this
field. All samples within the time window are equally weighted.
Duty Cycle:
Available in Continuous mode only. Sets the duty cycle in percent for calculated CW
pulse power measurements. Setting the duty cycle to 100% is equivalent to a CW measurement.
Video BW:
Sets the sensor video bandwidth for the channel. HIGH is
appropriate for most measurements, and the actual bandwidth depends
upon the sensor model. LOW bandwidth offers additional noise reduction for
CW or signals with very low modulation bandwidth. If LOW bandwidth is
used on signals with fast modulation, measurement errors may result if the
sensor cannot track the fast-changing envelope of the signal.
Peak Hold:
Set the operating mode of the selected channel’s peak hold function. When set to OFF,
peak values are not held. When set to instantaneous (INST) instantaneous peak readings are held until
reset by a new acquisition or cleared manually. This setting is used when it is desirable to hold the
highest peak over a long measurement interval without any decay. When set to average (AVG) peak
readings are held for a short time, and then decayed towards the average power at a rate proportional
to the Averaging setting. This is the best setting for most signals, because the peak will always represent
the peak power of the current signal, and the resulting peak-to-average ratio will be correct shortly
after any signal level changes.
dB Offset:
Sets a measurement offset in dB for the selected channel.
This is used to compensate for external couplers, attenuators, or amplifiers
in the RF signal path ahead of the power sensor.
Zero:
Performs a zero offset null adjustment. The sensor does
not need to be connected to any calibrator for zeroing. This action removes
the effect of small, residual power offsets, and should be performed prior
to low-level measurements. The procedure is often performed in-system.
There should be no RF signal applied to the sensor input prior to zeroing.
Fixed Cal:
Performs a single point sensor gain calibration of the
selected channel at 0 dBm and the current frequency setting. This requires a calibrated 0 dBm (1.00
mW) signal source at the current measurement frequency. This procedure calibrates the sensor’s gain
at a single point. At other levels, that gain setting is combined with stored linearity factors to compute
the actual power.
Caution
The built-in test source of the PMX40 is not a sufficiently calibrated source for
performing a fixed calibration. An
external
calibration source is required. Note that
fixed calibration is NOT REQUIRED for USB power sensors.
