Hi there,
I work at a company that develope tuner modules.I am a student and want to simulate mulitpath fading for fm broadcast signals. That is my thesis.
The model/scenario should work like this:
Imagine that the transmitter is locatetd and 0 kilometer. The car (or receiver) is driving infront the transmitter in a distance X a continuous circle
At this point there would be a LOS so only the doppler effect would affect the received signal.
Additionaly I want to define a point where the signal will be reflected. So LOS-Path + NLOS-Path.
My Signal source have to be a 1kHz Tone, FM modulated and with a deviation of 22.5kHz.
As far as I can see, GnuRadio has two fading models. "Fading Model" and the "Frequency Selective Fading Model".
What does these models actually contain? I think that the meaning of this model is not clear enough for me.
Fading effect occure because of multipath signal propagation. So I would assume to have a parameter where I can tell the block how much paths I want and how long is the time delay betweet the several paths.
Talking about the doppler effect there are two different equations: One for the case that the receiver is moving away from the transmitter and one for the case when it is moving towards the transmitter.
The normalized max. Doppler is a static function, so how does itdistinguish between the directions of movement? How does it affect the signal?
When I select the NLOS Model: How many paths do the model actually simulate? Just one and I have to use n blocks for n paths ?
Can't I simulate a simple fading by adding a source and the same source but delayed together ??
Mayby someone can help me with this issue?
Or is my approach completely wrong ?
Attached you find my flowgraph.
Thank you very much!
wav+sine_wbfm_200khz_modulator+channelmodel.grc