AnsweredAssumed Answered

distortion signal measurement problem

Question asked by wangyiliu99 on Jun 18, 2013
Latest reply on Jul 11, 2013 by tabbott

problem description

using PSA E4440A doing IP3 test.

when measuring the intermodulation signal, SA setting:
RBW: 10Hz, 
span: 0Hz,
Input attenuator: 20dB
Int Preamp: ON
using the following command to read the data.
init:cont off
read returned 1
freq:cent f1 mhz
read imdlvl out.

My problem is,
use the program, I could get IMD level of around -80dBm,
however, when the program finished running, I press "single",
I found the IMD level going from -80 to -120dBm. This is -120dBm
level is also confirmed by manual measurement.

I tried to solve the problem by setting the 
init:imm; *opc?
read returned 1
for twice, still problem exists.

Your help would be highly appreciated!