First, download the LspCAD demo:http://www.ijdata.com/LspCAD_demo.html
Unzip and startup either Pro or Standard (I've never used standard but it should work).
You have to follow a few common LspCAD steps to start your project:
- Start a new project
- Insert a "generator"
- Attach a "Analog/Digital Transfer Function" to the generator
- Attach a "Gain (output buffer)" to the A/D Transfer Function
- Attach a "Driver unit (measured data)" to the Gain
- Attach a ground to the driver
- Click on the "Simulate" tab towards the top
(the first picture shows the result of steps 1-7)
This creates the minimum structure needed to simulate a Biquad.
To implement the Biquad follow these steps:
- Double-click on TF1 (the A/D transfer function you created)
- In the dialog that appears, select "Digital Bi-quad" from the dropdown on the right
- Below that you will need to set the "fs"...it is the sampling rate of your DSP. THe minidsp uses 48khz.
- There is a drop-down on the left where you can select the type of Bi-quad such as LP, HP, shelv, etc.
(the second picture shows the Transfer Function dialog box)
Depending on the type of filter you are designing, a different set of parameters will appear in the upper lefthand corner.
When you alter these parameters a new set of biquad variables will be shown in the lower left hand corner.
I left out the more general LspCAD steps. There are tutorials to explain that. The demo also includes some example projects.