Configuring high and low cutoff filters
(remote operation only)
The Model 2016 includes low and high cutoff filters used to limit the range of frequencies
used in distortion measurements. The filters can be set in the range of 20Hz to 50kHz. Use the
low cutoff to limit noise frequencies below the fundamental for THD+noise and SINAD
measurements (the low filter does not have an effect in THD mode). When setting the low cutoff,
set the value lower than the fundamental signal frequency. Similarly, the high cutoff filter limits
noise frequencies above the specified frequency for THD+noise and SINAD measurements. In
THD mode, the limiting frequency is equal to the lower of the high cutoff filter or the harmonic
value.
:SENSe:DISTortion:LCO xxxx ;Sets the low cutoff frequency
:SENSe:DISTortion:LCO:STATe ON|OFF ;Turns the low cutoff on or off
:SENSe:DISTortion:HCO xxxx ;Sets the high cutoff frequency
:SENSe:DISTortion:HCO:STATe ON|OFF ;Turns the high cutoff on or off
The digital averaging filter (moving or repeat) can be used for THD. The RATE key sets the
gate time (FAST = 0.01s, MEDium = 0.1s, and SLOW = 1.0s).
Auto or Acquire frequency modes are recommended instead of Set mode, as the programmed
frequency of an external source may not be accurate.
Querying the RMS volts value in the distortion mode (:sens:dist:rms?) may yield a reading
slightly different from a reading in AC volts modes due to a difference in the way each mode
makes measurements.
The output impedance needs to be set prior to setting the amplitude of starting the sweep. The
impedance of the second output reflects the impedance of the main output.
:LCO <NRf> ;Sets the low cutoff frequency of the Bandpass filter.
:LCO? ;Querys the low cutoff frequency of the Bandpass filter.
:STATe <b> ;Sets LCO state on or off.
:STATe? ;Queries LCO state.
:HCO <NRf> ;Sets the high cutoff frequency of the Bandpass filter.
:HCO? ;Queries the high cutoff frequency of the Bandpass filter.
:STATe <b> ;Sets HCO state on or off.
:STATe? ;Queries HCO state.
Connections
Distortion connections
Assuming factory default conditions, the basic procedure is as follows:
1. Connect test leads to the INPUT HI and LO terminals. Either the front or rear inputs can
be used; place the INPUTS button in the appropriate position.
NOTE If the internal source is connected directly to the inputs, be sure the outer conductor
is connected to INPUT LO.
2-40 Basic Measurements
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