Tel: 886. 909 602 109 Email: [email protected]
www.salukitec.com
13
expansion factor. Thus, a signal which is only 10% of full scale can be expanded to provide 10 V rather than 1 V. The
general purpose for expansion is to increase the measurement resolution around some value which is not zero.
When the output does not exceed the full scale, the SE1022D can expand the output by multiplying with the expansion
factor from 1 to 256. The output with offset and expand is:
)
(
10
)
(
V
Expand
Offset
Sens
Signal
Output
Where <Offset> can be set up to
±
100% by the digital keyboard and the minimal step is 0.01%. <Expand> can be set
from +1 to +256 by the digital keyboard and the minimal step is 1. Related display interface is shown in Fig.7.
For example, there is:
)
(
6
)
(
10
2
)
2
.
0
1
1
.
0
(
V
V
mV
mV
Output
Fig.7 Output Offset and Expand
1.7 Dynamic Reserve
The definition of dynamic reserve is the ratio of the largest tolerable noise signal to the full scale signal, expressed in dB,
which is defined as:
Dynamic reserve = 20Lg(OVL/FS)(dB)
Here OVL is the total dynamic range of the input signal. FS is the dynamic range of the output signal. If the dynamic
reserve is 100 dB, the tolerable noise can be 10
5
times the input.
The ‘tolerable' means that the noise at the dynamic reserve limit should not cause an overload anywhere in the
instrument. Overload might appear at the input of the pre-amplifier and the output of DC amplifier. We can adjust the
distribution of the gain to achieve high dynamic reserve. This means that the input signal gain at the pre-amplifier should
be set very low so the noise is not likely to overload. Then the low pass filter removes the large noise component from
