how to measure filoter roll-off rate ?

[fran1942]

Hello, I have taken the attached filter response graph of filter gain to frequency. My cutoff frequency is 1kHz.
How can I measure the roll off rate in db/Dec based on this graph ?
Any help would be appreciated.

 

[LvW]

Hello, I have taken the attached filter response graph of filter gain to frequency. My cutoff frequency is 1kHz.
How can I measure the roll off rate in db/Dec based on this graph ?
Any help would be appreciated.
View attachment 74997

There is nothing to "measure". Simply read the db difference within one decade. It is -40 dB/dec.
However, two comments:
1.) I doubt if the 3dB-cutoff is at 1 kHz
2.) Are you sure that the passband gain is correct (-60 dB)?