NBFM Transmit

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Narrow Band FM Transmitter.

Takes a single float input stream of audio samples in the range [-1,+1] and produces a single FM modulated complex baseband output.

The only difference with WBFM Transmit is the size of the internal low pass filter for interpolation. Here it has a cutoff frequency of 4.5kHz with 2.5KHz of transition width.

Parameters[edit]

(R): Run-time adjustable

Audio rate
Sample rate of audio stream, >= 16k (integer)
Quadrature rate
Sample rate of output stream (integer). Must be an integer multiple of Audio rate.
Tau
Preemphasis time constant (float)
Max deviation (R)
Maximum deviation in Hz (float)
Preemphasis High Corner Freq
High frequency at which to flatten preemphasis; < 0 means default of 0.925*Quadrature rate/2.0 (float)

Example Flowgraph[edit]

This flowgraph shows a signal source feeding a Narrow Band FM modulator driving a PlutoSDR Sink block.

Pluto NFM xmt fg.png

Source Files[edit]

Python files
[1]
Block definition
[2]