×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

#### Jobs

(OP)
The attached simulink file is a very simple model of a signal source with a scope and spectrum analyser attached.

The signal source produces a constant value of 1 over the entire simulation time. The spectrum analyser has been setup with a HANN window.

From the spectrum analyser you can see the value at zero hertz is 30 dBm. With Hann windowing I was expecting the value to be about 6 dBM less than this ?

For simple signal analysis such as this I find simulink incredible difficult. Any suggestions for easier to use signal processing software would be more than welcome.

Regards, derick007

You definitely have something odd. 1 what? 1 Vrms? 1 Vrms^2/50 = 20 mW -> 13 dBm, not 30 dBm. I expect 17 dB less with a rectangular window.

Why don't you try putting a few frequency sources in your window? That way you can see if your window shape is behaving as you expect.

Z

Check the area of the Hann window. A DC output signal will be scaled by the area of the window divided by the number of samples.

The value for 0Hz is 30dBm = 0dBW = 1W for a Hann (and for most other) window, because you are inputting a constant 1 signal.

If you want to input a pulse, you should adjust the parameters Pulse Generator>Pulse Width and Pulse Generator>Phase properly.

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!