VTI Instruments EX1401, Руководство пользователя

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VTI Instruments Corp.
38 EX1401 Basic Operation
V
OLTAGE
M
EASUREMENT
R
ANGES
The EX1401 provides ±0.01 V, ±0.10 V, ±1.0 V, and ±10.0 V voltage measurement ranges on all
input channels. Channels which are configured for thermocouple inputs will use ±0.10 V range.
Voltage measurement range is programmable on a per-channel basis.
The default selection for voltage channels is the ±10 V range.
H
ARDWARE
/A
NALOG
A
NTI
-A
LIAS
F
ILTER
Each EX1401 input channel has a fixed, 2-pole, 30kHz RC low pass filter for anti-alias filtering.
The analog signals after the anti-alias filter are over sampled at 320kHz to 640kHz by the ADCs.
This combination of anti-alias filter with ADC oversampling provides 60dB of rejection at the
aliasing band.
D
IGITAL
F
ILTER
The EX1401 allows the user to configure different types of digital filters per channel. These digital
filters are implemented inside the FPGA of the device, such that they perform consistently and
without loading the host computer resources. Users can optimize the filter settings for aggressive
filter performance or lower data latency time. In addition, users can customize the FIR filter
performance by editing the coefficients of the filter. This provides ultimate flexibility in designing
a filter to suit the application needs. The digital filter parameters for each channel can be defined
independently. Final data throughput is a complex parameter and depends on the basic sampling
rate and digital filter selection. Choosing the correct sampling rate and digital filter parameters is
critical for achieving optimum performance levels of common model signal rejection, roll-off rate,
and data latency. Please refer to Sampling Rate/Filters/Noise Floor for more details.
M
EASUREMENT
R
ANGE
/I
NPUT
P
ROTECTION
The specified input voltage range of the EX1401 thermocouple channels is up to ±10V for voltage
measurements. This level refers to the maximum differential voltage, or voltage that is applied
between the (+) and (–) input terminals, that can be measured without distortion, and range where
the specifications are guaranteed. The native input range of amplifier is 14.4V, but the outer 4.4V
is left out since the performance in this region will not be linear.
The measurement range of the EX1401 in terms of temperature is a function of its input voltage
range and the capabilities of the thermocouple sensors themselves. Specifically, the measurement
range of the EX1401 for the standard thermocouple types is the following:
Type Min (°C) Max (°C) Min (°F) Max (°F)
J -210 1200 46 2192
K -200 1372 -328 2502
T -200 400 -328 752
E -200 1000 -328 1832
S -50 1768 -58 3214
R -50 1768 -58 3214
B 250 1820 482 3308
N -200 1300 -328 2372
T
ABLE
3-1: EX1401 M
EASUREMENT
R
ANGE
The maximum common mode voltage (the voltage level, that is applied to the + and – inputs
together, with reference to chassis ground), that can be applied without causing out-of-specification
distortion of the differential measurement is ±500 V
PEAK
. Application of differential voltages