3-4 Sweep Mode Operating Instructions
3.3.3 C-AVG
Definition
CISPR 16-1-1 defines the Average detector as designed to indicate the
weighted average value of the maximum value of the envelope of the signal
passed through the pre-detector stages:
up to 1000 MHz, is defined as the response of the measuring receiver to
pulses of repetition rate n Hz and impulse area of 1,4/n mVs emf at
50Ω source impedance that shall be equal to the response to an unmodulated
sine-wave signal at the tuned frequency having an emf with rms value of 66
dBµV.
The value of n shall be 500 for Band B, and 5000 for Bands C and D.
The average detector is useful to measure narrowband signals to overcome
problems associated with either modulation content or the presence of
broadband noise.
When the Average is measured according to CISPR 16-1-1, the maximum
value of the linear mean envelope during the measurement interval is
showwn.
The detector is used, for example, to measure pulsed sinusoidal signals with a
low pulse repetition rate. It is calibrated with the rms value of an unmodulated
sine wave signal. Averaging is carried out with lowpass filters of the 2nd order
(simulating a mechanical instrument).
3.3.4 Smart
Detector
The Smart Detector is an innovative special function implemented in the
PMM 7010 receiver with the purpose of reducing the test time and increasing
the productivity of the lab.
This function works only when at least one limit is loaded, therefore
remember to enable a limit to run the Smart detector function.
Selecting one out of the five Smart detectors the receiver will execute the
scan using at first the Peak detector and, if a peak value is found over the
selected limit minus a Margin set with the specific button, the reading is re-
measured and displayed with the chosen (C-Avg, AVG, C-Rms, RMS or
QPeak) detector.
Obviously this way of operation results in a much faster scan sweep and
moreover it immediately draws the attention of the test Engineer to the most
critical points. The limit associated to the Margin is displayed as a bold
colored line and is automatically selected by the receiver depending which
Smart detector is chosen; for example, if a Smart QP is selected, the
associated QP limit line will be displayed as a bold colored line.
It is immediately clear that this function is very useful to dramatically reduce
test time and increase the productivity of the test lab.
To deselect the Smart Detector function simply select a single detector.
The weighting time must be properly set in the Hold Time window to
allow the Smart detectors functions to operate as intended.
The Hold Time is the measurement time the receiver takes to value the input
signal and form result weighted by the selected detector.
When using the C-Avg (CISPR-Average) or the C-RMS (CISPR-RMS)
detector, since for definition they are characterized by a long time constant,
the minimum measurement time should be set long enough to allow a correct
measurement.
For this reason, when unknown signal are to be measured, the Hold Time
should be at least 1000ms to correctly weight signals pulsed at a rate of 5
Hz or faster.
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