---
name: "gr_plot_fft"
section: "1"
platform: "linux"
package: "gnuradio"
version: "3.10.12.0-18"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/gr_plot_fft"
---

# gr\_plot\_fft(1)

Frequency domain GNU Radio plotting

## NAME

gr\_plot\_fft - Frequency domain GNU Radio plotting

## SYNOPSIS

**gr\_plot\_fft:** \[*options*\] *input\_filename*

## DESCRIPTION

Takes a GNU Radio complex binary file and displays the I&Q data versus time as well as the frequency domain (FFT) plot. The y-axis values are plotted assuming volts as the amplitude of the I&Q streams and converted into dBm in the frequency domain (the 1/N power adjustment out of the FFT is performed internally). The script plots a certain block of data at a time, specified on the command line as **-B** or **--block**. This value defaults to 1000. The start position in the file can be set by specifying **-s** or **--start** and defaults to 0 (the start of the file). By default, the system assumes a sample rate of 1, so in time, each sample is plotted versus the sample number. To set a true time and frequency axis, set the sample rate (**-R** or **--sample-rate**) to the sample rate used when capturing the samples.

## OPTIONS

- **-h**, **--help**

  show this help message and exit

- **-d** DATA\_TYPE, **--data-type**=*DATA\_TYPE*

  Specify the data type (complex64, float32, (u)int32, (u)int16, (u)int8) \[default=complex64\]

- **-B** BLOCK, **--block**=*BLOCK*

  Specify the block size \[default=1000\]

- **-s** START, **--start**=*START*

  Specify where to start in the file \[default=0\]

- **-R** SAMPLE\_RATE, **--sample-rate**=*SAMPLE\_RATE*

  Set the sampler rate of the data \[default=1.0\]

## SEE ALSO

[gr\_plot\_fft\_c(1)](/gr_plot_fft_c/1.md) [gr\_plot\_fft\_f(1)](/gr_plot_fft_f/1.md)