Logartihmic Amplifier in Simulink

Hello,

I need a block that function as a Logartihmic Amplifier for a sound level meter desing in simulink.

I tried ussing the Amplifier block, but i dont know how to adapt it to my needs.

Answer 1

[Daniel]

If you just want to implement this generically, it shouldn't be hard to build up from the mathematical definition.

1. Divide Vin by Vref with a Divide block or a Gain block. The block output is Vin/Vref.
2. Take the log of the output with a Log block. The block output is ln(Vin/Vref).
3. Multiply by K with a Gain block. The block output is K*ln(Vin/Vref).

If you want that to look pretty, you can package it in a subsystem, and perhaps create a mask to define K and Vref.

[Federico]

Thanks for your answer.

I attached the .slx code so you can see why the divide block wouldnt work for me, i dont have 2 impunt.

I look forward to your suggestions

[Daniel]

You can use a Gain block in that case, which has one input and one parameter.

You can also use Constant blocks to create non-varying signals.

[Federico]

Thanks ! Ill try that and will get back to you.