about Local Oscillator block

Hi,

In the “Local Oscillator” block there are two parameters “Sample time” and “Frequency”. Must these two be related to Nyquist theory? That, 1/Sample time > 2 * Frequency.

Thanks Senmeis

[Sree Vamsi]

where can i find the local oscillator block ???

i need it for my receiver design.

Answer 1

[Azzi Abdelmalek]

• The frequency is the repetition of your signal
• The sample time is the interval of time between two values of your signal

both have nothing to do with Nyquist theorem. The sample time must be chosen respecting Shanon theorem

[Owen]

Shanon has three theorems. Which one did you mean?

Can you give me an example of the meaning of "Sample time" here?

Thanks Senmeis

[Azzi Abdelmalek]

That depends on what are you sampling, a signal or a system, And what are your objectives: control system, communication,...

If you want to make a discret control system, you must discretize your models with a sample time ts, that means all the signals must be sampled with ts.In this case ts choosen compared to the constant time of the output we want to control

Also if our signal is naturaly discret, Shanon theorem has nothing to do with it

[Owen]

It’s just an oscillator. The sample time shall only depend on its output frequency.

I have tried this block with different sample time and found out that the wished frequency can be obtained only if 1/Sample time > 2 * Frequency.

Is that not Nyquist theorem?

Senmeis