Peak; Alarm Function V/M; Sound Demodulation Function; Analogue Output - Chauvin Arnoux C.A 41 Mode D'emploi

Note : When the RECORD and SMOOTH symbols are displayed, the smoothed values
(MIN, MAX and AVG) are recorded with a measurement constant of 4 seconds.
PEAK MEASUREMENT
The PEAK function allows the user to take measurements with an aquisition speed of 1 ms
for peak measurements.
The 50 Hz filter for the rejection of low frequency fields is switched OFF. The C.A 41 becomes
sensitive to the power supplies of electrical equipment, to mains cable runs,...
A first press on the button switches ON the function and the PEAK symbol

PEAK

appears on the display.
- The bargraph indicates the average value of the highest peak values measured during 100 ms.
- The digital display indicates the average value of four measurements of the bargraph. This
corresponds to the average of the 16 peak values measured during 400 ms. A second press
on switches OFF rapid aquisition and the PEAK symbol goes out.
PEAK
Note : When the RECORD and PEAK symbols are displayed, the peak values are recorded
(MIN, MAX and AVG) with a measurement constant of 1 ms.
ALARM FUNCTION
When the rotary switch is positioned on the V/m (AL) symbol, the alarm function is ON and the
HI AL symbol appears on the display.
All the measurements are compared to the threshold value preset by the user (see below).
If the value measured is greater than or equal to this threshold value displayed in inverse video
on the bargraph, then the buzzer is permanently ON (at F = 4 kHz) and a triangle appears on
the display, on the right of the HI AL symbol.
Adjusting the alarm threshold
The alarm threshold is preset at the factory : 3 V/m.
To modify the alarm threshold :
- with the instrument switched OFF, open the battery compartment on the back of the
instrument with a coin (tool release screw).
- the adjustment potentiometer is accessible via a hole located in the upper left corner of the
battery compartment.
- check that the battery is still correctly attached to the instrument.
- turn the rotary switch to the V/m or V/m (AL) position whilst pressing the
button (the present threshold value is displayed).
- keep the button pressed and vary the value of the alarm threshold by
PEAK
turning the potentiometer.
- once the value is displayed, leave the potentiometer in position and release the
button.
PEAK
- close the cover.
PEAK
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SOUND DEMODULATION FUNCTION

The demodulation function allows the amplitude modulation which may be present on the HF
signal to be heard on an internal loud speaker. This detection of modulation is limited to the
audible frequencies between 500 Hz and 5 kHz inclusive.
The best result is obtained for fields measured between 5 V/m and 30 V/m inclusive with a
modulation depth of 50% minimum. As a result of the filtering constants of the instrument, this
function is only available on PEAK mode.
This function is controlled by a switch coupled to a single turn potentiometer (4) of the
instrument. The potentiometer allows adjustment of the sound volume as a function of the field
and the depth of modulation.
Note : The power consumed by the internal speaker greatly reduces the service life of the
battery. Please only use this function for real applications. We recommend switching
OFF the demodulation function with switch (4) as soon as it is no longer used.

ANALOGUE OUTPUT

The analogue output makes it possible to record data on a plotter, graphic recorder... with a
minimum impedance of 100 kΩ.
An analogue amplifier adapts the voltage output from the sensor to obtain a proportional DC
signal in accordance with a pseudo-quadratic law.
The output connector allows connection to screened cable in order to maximize the elimi-
nation of interference effects on the measurement field.
The output is specified up to 1.5V; the graph below defines the transfer function of this output
up to 3V.
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