How to check if the signal level exceeds a threshold

Question

We like to define a threshold line using these remote commands

FSV: CALC:THR:STAT ON

FSV: CALC:THR -45DBM

and then want to check if the signal is above this threshold line.

How can we do this?

Answer

The threshold line defines the marker search limits. For example, the threshold line defines the minimum power for the marker peak search. It is not possible to use the threshold line to check whether a signal exceeds or stays below a defined level.

Checking whether a signal level is above or below a certain value can only be done with limit lines.

The script below shows the limit line setup. The blue lines define the limit line. The blue lines must be sent one time only . The red line returns the information good/fail. The black lines are for the instrument setup. Always check for errors using "SYSTEM:ERROR?".

FSV: *RST
FSV: *IDN?
FSV: SYSTEM:DISPLAY:UPDATE ON
FSV: FREQUENCY:START 800MHz
FSV: FREQUENCY:STOP 1.3GHZ

FSV: CALCULATE:LIMIT:NAME 'HUGO'
FSV: CALC:LIM1:COMM 'seine Linie'
FSV: CALCULATE:LIMIT:CONTROL:DOMAIN FREQUENCY
FSV: CALCULATE:LIMIT:UPPER:MODE ABSOLUTE
FSV: CALCULATE:LIMIT:UNIT DBM
FSV: CALCULATE:LIMIT:CONTROL:DATA 0MHz, 7GHz
FSV: CALCULATE:LIMIT:UPPER:DATA -40, -40
FSV: CALCULATE:LIMIT:UPPER:STATE ON
FSV: CALCULATE:LIMIT:STATE ON

FSV: CALCULATE:LIMIT:FAIL?

FSV: SYSTEM:ERROR?

Note: The above script was tested with the FSV. It should also work with other R&S spectrum analyzers.