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èíòåðôåéñà ïðîãðàììû, íàæìèòå
êíîïêó ñ ñèíèì êðóæêîì ðÿäîì ñ
ýìáëåìîé ÐÌ. çàòåì âûéäèòå èç ïðîãðàììû, è
âîéäèòå â íåå ñíîâà.
Oscilloscope. The general
information.
Switching of inputs.
The circuit of the
external device. Calibration.
The analysis of a
spectrum.
Two-coordinate mode
(dynamic characteriograph).
The generator.
Additional adjustment.
The Capacity - meter.
The Voltage -
Frequency Caracteriograph.
Switch off the speakers !
The built - in
virtual voltage - frequency characteriograph (VFC) allows
to observe the characteristics of various LF devices: filters,
amplifiers and so on. The characteriograph uses program resources
of sweep - generator and oscilloscope. To switch the VFC mode and
back press the screen button or the key F5.
The input of testing object should be connected to
the jack 3 of external device (see circuit),
and its output - to the jack 4, if there is no more than 1 V on
it (is tested the passive filter and so on), or to a jack 2, if
amplitude can be up to 25 V. The switch S1 of the device should
be established in the position of C / VFC. An action principle of
the characteriograph is illustrated by the circuit shown below.
There is the current value of frequency in
logarithmic scale on horizontal axis of VFC, and the
attitude of the voltages of an output and input in
decibels - on verical axis. Characteristic of a passive filter on 4 kHz is shown. |
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There are the current results in a numerical kind
at the top border of the screen :
- Number of a point (up to 256),
- Frequency,
- U1,
- U2,
- Attitude Y (see formula) in the given point,
- Derivative in the given point (steepness of the characteristic)
in decibels per octave.
The frequency range and deviation step are
established on the control panel of sweep - generator (on the
right in the bottom of the form). For their updating and also
changing of input sumpling frequency is necessary to leave from
the VFC mode.
Vertical scale of display can vary by the keys with
vertical arrows.
At the first activation of VFC the message
"Change the input " can appear. Do the following. In
the VFC mode press the Mixer button.
On its panel specify Linear input. It is necessary for making it
once, so that the program "has remembered" that input
as necessary to use in the VFC mode and specified it, if you
switched inputs.
The generator output voltage depends on the main
volume regulator position (on the Windows tasks panel). If the
volume is unsufficient for characteriograph function, the message
"Volume?" will appear,
then you should check up this regulator position, expose it to
the maximum. Also it is possible
to restore positions of all regulators pressing button Mixer, then Restore.
Remember: a capacity of your body influence result of
the measurement, therefore remove hands from the block after the
connection of the testing object.
The VFC adjustments panel is caused by the key F6. On the right of the panel there is a
switch of output jacks (4 or 2). At switching (without the
testing object changing) the measured attitude Y varies
approximately on 34 db, that corresponds to the divide
(R2'+R3')/R3' =50.
If you use the 2 jack, the program should take into
account a ratio of sensitivity of inputs, therefore it is
necessary (once - after manufacturing the external block) to make
calibration on the inputs of jacks 3 and 4. Connect the 3 and 4
jacks, connect to them any exemplary device (real oscilloscope)
for the measurement of the true peak value (100.. 800 mV). Then
in the oscilloscope mode activate the generator’s 1st channel
on a sine 1.. 2 kHz , establish a maximum level without
distortion of the form (flat tops). Measure amplitude of a signal
by the exemplary device (from peak up to peak). Activate the VFC
mode, cause the adjustments panel (F6),
type the real voltage in millivolts in the calibration window,
then press Enter.
The VF characteriograph has a software of noise
suppression. The noise looks as emissions in separate points of
the characteristic. This software allows after two passes of a
range to have a steady smooth VF curve. The software Antinoise is switched on and off by the
screen button on the adjustments panel, or by the key F7. When it is active, at the end of the
numerical line at the top of screen is present the established
criterial value of Antinoise operation in decibels per octave
(yellow colour). After the start of the VFC mode the first pass
of the range the program does without noise suppression, further
if the Antinoise is active, there is a following. After the start
of the VFC mode the first pass of the range the program does
without noise suppression, further if the Antinoise is active,
there is the following. Current derivative in a point (the
steepness of the characteristic) is compared with the criterial
value. If first is more, the result of the current measurement is
ignored, the diagram is painted in yellow colour. Therefore, if
the Antinoise is active, and you have changed the testing object,
the program continues to represent the same diagram, but in
yellow colour. If you use Antinoise,
temporarily deactivate it (F7) to change or recustomizing of the
testing object, or better restart sweeping (F4).
In the VFC mode the program automatically establishes
optimum display speed so that in all frequency range the
reception buffer contained some periods of the signal.
The VF characteriograph claims the high requirements
to Sound Card and its driver. The card should support the full
duplex stereo mode. It is preferable to work under Win XP, 2000,
NT. With Win 98 program is efficient, but requires more resources
of system.