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SIRIUS

® 

TECHNICAL REFERENCE MANUAL 



6.1.4. Filter design 

Since ideal ﬁltering is not possible, we need to carefully design our ﬁlters to achieve the desired results. 

One important goal is that we want to have a very sharp damping, so we need a high order ﬁlter, which                     

in turn means, that we will use a digital ﬁlter. Moreover we want to have a linear phase, so we choose a                      

FIR ﬁlter (the performance of the DSP in SIRIUS® is powerful enough to handle this demanding                

computation). 

Another important goal is to minimise errors introduced by aliasing. So the FIR ﬁlter alone will not be                  

sufﬁcient (since digital ﬁlters are subject to aliasing). 

In the following examples, we assume that we want to measure a signal between 0 and 800 Hz and we                    

will consider how higher frequency components in the input signal affect the measurement result. 

6.1.4.1. Sampling and digital ﬁlter 

Our ﬁrst try is quite naïve: we sample the signal at 2 kHz (over twice the frequency that we are                    

interested in) and then apply a digital ﬁlter. Illustration below “Sampling and Digital Filter” includes 3                

diagrams (from top to bottom): 

● Input Signal: e.g. the analog signal that we input to the AD converter 

● Sampled Signal: the output of the AD converter 

● Filtered Signal: the output of the digital ﬁlter (the ﬁlter input is the Sampled Signal) 

SIRIUS

V20-1 273 / 336  

Category	Data Loggers
Manufacturer	DEWESOFT
Series	SIRIUS
Resolution	24-bit
Interface	USB, EtherCAT
Software	DEWESoft X
Channels	Expandable
Sampling Rate	Up to 200 kS/s per channel
Input Types	Voltage, Current, IEPE, Strain, Thermocouple, RTD, Resistance, Digital, Counter
Input Voltage Range	±10 V, ±200 V
Isolation	Channel-to-channel and channel-to-ground
Connectivity	Ethernet, USB
Operating Temperature	-10 °C to +50 °C
Storage Temperature	-20 °C to +70 °C
Power Supply	10 to 30 V DC
Dimensions	Varies depending on module configuration
Weight	Varies depending on module configuration
Analog Inputs	Yes, depending on module configuration

DEWESOFT SIRIUS Series User Manual

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