Spider DSA User’s Manual
69
the Spider-81 family have 2~16 analog input channels with isolated BNC
connector. And the input range is ±20 V with single-ended, differential, IEPE,
Charge Mode, and TEDS input type.
Figure 20:Spider-80X Input Channels
The block diagram for the inputs is shown above. The input chain has a number
of components that switch in or out of the signal path. There is a calibration
circuit used for internal calibration (see the separate Calibration Manual). There
is also a charge amplifier and an IEPE power supply.
The front-end amplifier operates in single-ended or differential mode. In single-
ended mode, the shield on the input jack is grounded, and the measured input
voltage is referenced to this ground. In differential mode, the shield is not
grounded and the measured input voltage is the potential difference between the
shield and center terminal. After this initial amplification stage, there is an
analogue high-pass filter for DC removal that is switched on only in AC input
modes. After that, there is the final analog amplification stage, the Analog to
Digital Converter, and the DSP processor.
The rest of the signal processing is done by the Digital Signal Processing (DSP)
microprocessor. This processor specializes in the floating-point arithmetic used to
process the input signal and generate an output.
The Spider-20 uses traditional multi-stage amplifiers in each input channel. It
does not have charge mode and TEDS detection. The Spider-80x and Spider-81
series have charge mode as well as TEDS detection. They also adopt the patented
dual A/D technology to achieve extremely high input dynamic range. A block
diagram of such front-end is shown below.
To Next Page
Loading...