Elekta Neuromag NM21283A, Руководство пользователя

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7 Manual tuning
34 NM21283A-A
7.3 Measuring flux to current curves using Squiddler
The I- curves of a SQUID sensor can be measured using Squiddler and
acquisition program. For the meaning of I- curve, see “Operation of a
SQUID magnetometer” on page 27.
To measure I-Phi curves using Squiddler:
1. Start both acquisition program and the Squiddler program. See “Data
Acquisition User’s manual”.
2. Press the
x-y
button at the lower part of the raw data display to show
the x-y display.
3. Start acquisition. Default parameters are fine.
4. Set the measurement mode to tuning mode by selecting
Mode > Tune
from the Squiddler menu.
5. Select the channel to be viewed using Squiddler. You can either enter
the name of the channel into the text field Channel or use the slider by
the text field.
The I- curve should now be on the x-y display.
7.4 Measuring flux to current curves using Tuner
You can also use Tuner to measure the I- curves. To do this, you must
be using expert level 1. To change the expert level see “Setting the expert
level” on page 43.
To measure I-Phi curves using Tuner:
1. Select
Job > Manual tune
from the Tuner menu.
2. Press the “start button”.
3. You should now see a bar diagram showing the modulation depths of
all channels. Select one particular channel to see the I- curve.
4. To stop the measurements, press the “stop button”.
The various options available in Tuner are described in more detail in
Chapter 8. The information here should be enough to carry on the basic
manual tuning.
7.5 Measuring noise level
Manual tuning process also requires an ability to measure the noise level
of a sensor. Though the acquisition program does not provide this possi-
bility explicitly, the tuning of the noise level can be made by judging the
changes in noise level by eye, looking at the raw data display.
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