Filter - Agilent Technologies 3458A User Manual

10 OUTPUT 722;"PRESET NORM"
20 OUTPUT 722;"MEM FIFO"
30 OUTPUT 722;"SMATH MIN 9"
40 OUTPUT 722;"SMATH MAX 11"
50 OUTPUT 722;"CSB" "
60 OUTPUT 722;"RQS 2
70 OUTPUT 722;"NRDGS 20"
80 OUTPUT 722;"TRIG SGL"
90 OUTPUT 722;"MMATH PFAIL"
100 OUTPUT 722;"STB?";
110 ENTER 722; A
120 IF BINAND(A,2) THEN
130 PRINT "Hi/LOW LIMIT TEST FAILED"
140 OUTPUT 722;"RMATH PFAILNUM"
150 ENTER 722; B
160 PRINT "NUMBER OF READINGS THAT PASSED BEFORE FAILURE WERE";B
165
170 ELSE
180 PRINT "HI/LOW LIMIT TEST PASSED"
190 END IF
200 END

FILTER

124 Chapter 4 Making Measurements
!PRESET,NRDGS 1,AUTO, DCV 10, TRIG SYN
!ENABLE READING MEMORY, FIFO MODE
!LOWER LIMIT = 9(V)
!UPPER LIMIT = 11(V)
!CLEAR STATUS REGISTER
!ENABLE HI/LO STATUS REGISTER BIT
!20 READINGS/TRIGGER
!TRIGGER READINGS
!PERFORM POST-PROCESS PFAIL OPERATION
!QUERY SET BITS IN STATUS REGISTER
!ENTER QUERY RESPONSE
!IF BIT 2 IS SET:
!QUERY PFAILNUM REGISTER
!ENTER QUERY RESPONSE
!PRINT PFAILNUM RESPONSE
!IF BIT 2 WAS NOT SET:
The filter math operation simulates the output of a single pole, low pass, RC
filter. This allows you to reduce the effects of random noise while preserving
long term trends. The equation is:
Result = (Previous Result)×(DEGREE-1)/DEGREE + Reading/DEGREE
Where:
Previous Result is initially set to the value of the first reading and thereafter
is set to the result of this FILTER operation.
Reading is any reading.
DEGREE selects the step response of the filter.
The value of DEGREE corresponds to the step response of the low-pass filter.
That is, if 20 is the value of DEGREE, 20 readings are required for the step
response to achieve 63% of its final value. You can achieve slower response
or quieter readings by increasing the value of DEGREE. The actual time
constant (R×C) of the filter can be determined by:
1 1
t = -- - ------------------------------------ - 1 –
f DEGREE
s ln ------------------------------ -
DEGREE 1 –
Where:
t = the time constant (R×C)
f = the sampling rate which is: l/timer interval (when using the TIMER and
s
NRDGS commands) or l/effective interval {when using the SWEEP
command). If you are not using the TIMER or SWEEP command, refer to
"Determining the Reading Rate" earlier in this chapter.
If DEGREE is larger than 10, (R×C) can be approximated by:
»
t (l/f ) × DEGREE
s
!PRINT FAILURE MESSAGE
!PRINT TEST PASSED MESSAGE