FSK using baseband modulation
显示 更早的评论
Hello,
I want to create a FSK modulator using the "*M-FSK Modulator Baseband*" block, the input is Bernoulli Binary Generator (0, 1) , but i cant get the good output ( 2 different frequencies ) on the scope in real time !!??
P.S : the output shown is bad because the frequency is the same whatever the input is 0 or 1. !!!
Thanks a lot,
Bye
2 个评论
Rick Rosson
2011-6-17
Can you please post a screen shot showing the mask parameters (dialog box settings) of the 2-FSK modulator block? Thanks!
al-comm
2011-6-19
采纳的回答
Rick Rosson
2011-6-20
1 个投票
The output of the Simulink model is correct. The reason that it is not the same as the "Good Output signal" is that the Simulink signal is the complex baseband equivalent of the desired FSK signal, whereas the "Good Output signal" is the real-valued passband signal. Although these two signals are not the same, they are related.
In fact, you can generate the real-valued passband signal in the Simulink model by adding a handful of blocks that represent the passband modulation. To do so, multiply the output of the baseband modulator by a complex exponential at the desired passband frequency, and then view the real- and imaginary- parts on the scope.
HTH.
3 个评论
al-comm
2011-6-20
Rick Rosson
2011-6-20
What are your specific questions?
Please let me know.
Thanks!
al-comm
2011-6-20
更多回答（2 个）
Rick Rosson
2011-6-21
You are getting closer to the right answer, but still not quite there yet. In your schematic, you are feeding the output of a real-valued sine wave to the input of the complex exponential function. So the output of the complex exponential block is:
exp(j*sin(2*pi*Fc*t))
where Fc represents the carrier frequency (in hertz). This modulation signal is not quite correct.
The correct output of the complex exponential should be:
exp(j*2*pi*Fc*t)
That means the input to the complex exponential function should be the simulation clock t feeding a gain block with a value of 2*pi*Fc.
Please give that a try.
Alternatively, I believe that you can generate a complex exponential output from the Sine Wave block. Please check the dialog box.
HTH.
Rick
Derek Eccles
2019-4-9
0 个投票
I am using a Math function block with the exp. function selected and the output data type as complex, to generate the carrier.
I then feed this to a complex to re-im block thinking this would get me the cosine and sine carriers which are required for 2_FSK.
The Im signal is a constant flat line, while the re signal is an exponential. Nothing like cosine or sine which I was hoping for ?
类别
在 帮助中心 和 File Exchange 中查找有关 FSK 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
