Created on 2008-07-11 13:11:00
The ADSR measurement looks at the four segments of an envelope expressed as amplitude vs. time;
- Attack — time for a signal to reach full amplitude.
- Decay — time for the signal to drop from the initial attack level to the sustain level.
- Sustain — time the signal remains at the constant amplitude.
- Release — time for the signal to return to an off or zero amplitude condition.
ADSR measurements are typically used in characterizing dynamic altering devices such as compressors and/or limiters. For example, determining the accuracy or sensitivity of the compression ratio parameter.
In this example we'll be using the Burst option in the 2722 analog generator. Our DUT (Device Under Test) is a compressor. The DUT output(s) feed the analog analyzer which feeds the FFT spectrum analyzer.
|Starting with the Analog Generator, select the normal burst waveform at 1 kHz. Set the burst on to 800 msec and the interval to 1 sec. I set the low level to -80 dB. Select the output configuration for your DUT.
|In the Analog Analyzer panel I selected the unbalanced input and turned off auto ranging. I set the input range to 5 V, allowing plenty of headroom and signal level from my DUT. I left the bandwidth wide open (<10 Hz. to >500 kHz.)
|On the Digital Analyzer panel select FFT spectrum analyzer, set the acquire to 72k and the display to Absolute Values. The triggering should be setup for at least 10 msec of pre trigger, so set the Delay to -10 msec and the source to Analog Gen.
|On the Sweep panel select fft amplitude (Fft. Ch. 1 Ampl) for data 1 and enable Autoscale. Select fft time (Fft. FFT Time) for source 1. Set the start time to -50 msec. and the stop time to 1 sec.
Here is the ADSR envelope of my compressor (DUT.)
This measurement looks at the four segments of an envelope expressed as amplitude vs. time; Attack, time for a signal to reach full amplitude, Decay, time for the signal to drop from the initial attack level to the sustain level, Sustain, time the signal remains at the constant amplitude, and Release, time for the signal to return to an off or zero amplitude condition.