# Obtain Envelope

**URL:** https://discourse.julialang.org/t/obtain-envelope/46643
**Category:** Signal and Image Processing
**Tags:** dsp
**Created:** [September 15, 2020, 3:04pm UTC](https://discourse.julialang.org/t/obtain-envelope/46643 "2020-09-15T15:04:40Z")
**Posts on this page:** 1
**Showing post:** 2

<div class="post-metadata">

### Author: ![ElOceanografo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/eloceanografo/32/624_2.png) [@ElOceanografo](https://discourse.julialang.org/u/ElOceanografo)
#### Post date: [September 15, 2020, 4:12pm UTC](https://discourse.julialang.org/t/obtain-envelope/46643/2 "2020-09-15T16:12:30Z")

</div>

You can do it using a Hilbert transform, like so:

```julia
using DSP, Plots
x = 0:0.1:200
y = sin.(x) .+ sin.(1.2x)
env = abs.(hilbert(y))
plot(x, y)
plot!(x, env)
plot!(x, -env)

```

![image](https://global.discourse-cdn.com/julialang/original/3X/5/e/5e7fbb6228b6b9acc114577526df314386d6a509.png)

---

_[View the full topic](https://discourse.julialang.org/t/obtain-envelope/46643)._