In the GRC Frequency mod block the doc says

analog_frequency_modulator_fc make(float sensitivity) -> frequency_modulator_fc_sptr Frequency modulator block. float input; complex baseband output

`Takes a real, baseband signal (x_m[n]) and output a frequency`

`modulated signal (y[n]) according to:`

`Where x[n] is the input sample at time n and is the frequency`

`deviation. Common values for are 5 kHz for narrowband FM channels such`

`as for voice systems and 75 KHz for wideband FM, like audio broadcast FM`

`stations.`

`In this block, the input argument is , not the frequency`

`deviation. The sensitivity specifies how much the phase changes based on`

`the new input sample. Given a maximum deviation, , and sample rate , the`

`sensitivity is defined as:`

Constructor Specific Documentation: Build a frequency modulator block. Args: sensitivity : radians/sample = amplitude * sensitivity

`There is somejhing missing at: " Where x[n] is the input sample at`

`time n and ____________ is the frequency deviation"`

`Here https://wiki.gnuradio.org/index.php/Frequency_Mod the same is`

`missing too.`

`I guess it refers to sensitivity = K =`

`(2*pi*freq_deviation)/samp_rate correct?`

Second question related to this one.

`If I the use Quadrature_demod for demodulation of the signal, the gain`

`parameter will be the inverso of this one isnt it?`

`gain=samp_rate/((2*pi*freq_deviation) but when I insert the quadrature`

`demod block it is autofilled with`

samp_rate/(2*math.pi*fsk_deviation_hz/8.0) where does the 8.0 come from? best regards