How to generate a FM signal?

GNU Radio
1

Is anybody had a experiment about How to generate a FM signal?

or tell me how to use FM MOD or VCO module in GRC, what is the paramater
sensitive means?
Thanks

2

nansai hu wrote:

Is anybody had a experiment about How to generate a FM signal?

Use the wideband and/or narrowband fm blocks; just specify your data
rates.

http://gnuradio.org/cgit/gnuradio.git/tree/gnuradio-core/src/python/gnuradio/blks2impl

or tell me how to use FM MOD or VCO module in GRC, what is the paramater
sensitive means?

check the source :slight_smile:

-Josh

3

I tried to run your code wfm, but there is nothing happened in my
spectrum
analyzer.
I am just wondering that your code is in baseband or how to add a
carrier
freq by usrp source.

2009/10/24 Josh B. [email protected]

4

I appracite you could tell me what is the meaning of following
paramaters:
@param audio_rate: sample rate of audio stream, >= 16k
@type audio_rate: integer
@param quad_rate: sample rate of output stream
@type quad_rate: integer
@param tau: preemphasis time constant (default 75e-6)
@type tau: float
@param max_dev: maximum deviation in Hz (default 75e3)
@type max_dev: float

I try to change the max_dev from 10 to 1000,and give it to a usrp source
as
baseband signal,
but, the bandwith on spectrum analyize don not change.How to change
deviation of a fm signal?

2009/10/26 nansai hu [email protected]

5

nansai hu wrote:

I appracite you could tell me what is the meaning of following paramaters:
@param audio_rate: sample rate of audio stream, >= 16k
@type audio_rate: integer
@param quad_rate: sample rate of output stream
@type quad_rate: integer

This is the input and output rates of the block.

    @param tau: preemphasis time constant (default 75e-6)
    @type tau: float
    @param max_dev: maximum deviation in Hz (default 75e3)
    @type max_dev: float

No idea, check the source, but the default values are good to get a
working wbfm radio.

I try to change the max_dev from 10 to 1000,and give it to a usrp source as
baseband signal,

For transmit, the usrp expects numbers between +/- 2**15. Your transmit
amplitude should be on the order of 10k. What are you sending it?

-Josh

6

I just want to do a demo about two radios in one USRP by time divition,
both
are FM&FH, but with the intention to distingrish these radios,the FM
deviation and FH hop step should be different.Now I could control the
hop
step,but the FM deviation can’t be controled(FM deviation should be12.5K
and
25K,which input to max_dev in WBFM module)

2009/10/26 Josh B. [email protected]