HP 3562A Operating Manual page 308

N U M BER POLES-used to specify the number of poles for a curve fit operation. Con­
jugate pairs are considered two poles. If USER ORDER (in the FIT FCTN
menu) is active, the curve fitter finds the specified number of poles. If AUTO
ORDER is active, the curve fitter finds the optimum number of poles, with­
out exceeding the specified number. Any number of poles from 0 to 40 can
be selected.
If the system order is unknown, it is best to specify a large number of poles,
then use the auto order feature (see FIT FCTN) to determine the actual
order. Otherwise, a general rule is to use two poles for each peak in the
curve, plus one pole at the origin, plus several extra to allow for any hidden
poles.
N U M BER ZEROS-used to specify the num ber of zeros for a curve fit operation. Con­
jugate pairs are considered two zeros. If USER ORDER (in the FIT FCTN
menu) is active, the curve fitter finds the specified number of zeros. If AUTO
ORDER is active, the curve fitter finds the optimum number of zeros, with­
out exceeding the specified number. Any number of zeros from 0 to 40 can
be selected.
If the system order is unknown, it is best to specify a large number of zeros,
then use the auto order feature (see FIT FCTN) to determine the actual
order. Otherwise, a genera l rule is to use two zeros for each negative peak
in the curve, plus one zero at the origin, plus several extra to allow for any
hidden zeros.
RETURN-redisplays the previous menu.
SCALE FREQ-use to enter the scaling frecuency, which is multiplied by the pole and
zero values to shift the curve up or down in frequency without actually
changing any values. Enter the frequency, from 1 �Hz to 1 MHz, using the
Entry group. The default is 1 Hz.
STOP FIT -stops the curve fit process. The message "Stopped" is displayed as soon
as the curve fitter stops to remind you that the fit was not completed.
STORE WEIGHT-stores the user-defined weighting function. The function is stored
in nonvolatile memory and is not erased when power is removed, but it is
removed if a new measurement is run. If any changes are made to the
weighting function, it must be stored for the changes to be implemented.
SYNTH � FIT-transfers the contents of the pole/zero synthesis table to the curve fit
table. To transfer a pole/residue or polynomial table to the curve fitter, first
convert it to a pole/zero table using the CONVRT TABLE menu (under
SYNTH), then transfer it using SYNTH � FIT.
CURVE FIT (cont)
Chapter 12-0peratinq Reference
12-19