# Phase unwrapping **URL:** \ **Category:** GNU Radio\ **Created:** [June 16, 2014, 2:42pm UTC](https://www.ruby-forum.com/t/phase-unwrapping/230400 "2014-06-16T14:42:11Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [June 16, 2014, 2:42pm UTC](https://www.ruby-forum.com/t/phase-unwrapping/230400/1 "2014-06-16T14:42:11Z")
Hello, I just started to work with GNU radio for my very basic needs, so please excuse my naive questions and probably my inappropriate use of the jargon. My first trivial application of GNU radio is to simply measure the phase of a phase modulated signal with an Ettus R. USRP N210 and a LFRX daughter-board. Everything works as expected, but I haven’t found a way to do phase unwrapping (removing the 2pi ambiguity in the phase obtained from the arctan function looking at discontinuities in the phase data). Is this functionality offered somewhere, and I missed it, or should I look into implementing it myself? Thanks. Cheers, Daniele ---
**Author:** ![Daniele\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/74df32/32.png) [@Daniele\_N](https://www.ruby-forum.com/u/Daniele_N)\ **Post date:** [June 16, 2014, 3:46pm UTC](https://www.ruby-forum.com/t/phase-unwrapping/230400/2 "2014-06-16T15:46:21Z")
Daniele, The problem with phase unwrapping is that it is unbounded, and will tend to infinity. Once it gets very big, when you try to add a small number to a very big number, floating point loses precision. Eventually, adding small to extremely big returns the big number unchanged. This isn’t that useful. Matt On Mon, Jun 16, 2014 at 2:40 PM, Daniele N. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![Daniele\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/74df32/32.png) [@Daniele\_N](https://www.ruby-forum.com/u/Daniele_N)\ **Post date:** [June 16, 2014, 7:49pm UTC](https://www.ruby-forum.com/t/phase-unwrapping/230400/3 "2014-06-16T19:49:01Z")
Daniele, I have worked on this problem for a specific case as well. I have a document with source code and a short description of what’s happening that can be found here ( [Dropbox - Error - Simplify your life](https://www.dropbox.com/s/bcma7fqa7ip2own/unwrap_example.txt)). Michael On Mon, Jun 16, 2014 at 10:05 AM, Daniele N. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![Daniele\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/74df32/32.png) [@Daniele\_N](https://www.ruby-forum.com/u/Daniele_N)\ **Post date:** [June 16, 2014, 7:06pm UTC](https://www.ruby-forum.com/t/phase-unwrapping/230400/4 "2014-06-16T19:06:54Z")
Hello Matt, thank for your answer. I’m aware of the problem and in my application I can keep phase bounded, but not bounded to (-pi, +pi] therefore I need unwrapping to make sense of my modulation data. If such feature does not exist in GNU radio, I hope it is not too hard to code it myself. Thanks. Cheers, Daniele ---
**Author:** ![Daniele\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/74df32/32.png) [@Daniele\_N](https://www.ruby-forum.com/u/Daniele_N)\ **Post date:** [June 16, 2014, 7:54pm UTC](https://www.ruby-forum.com/t/phase-unwrapping/230400/5 "2014-06-16T19:54:21Z")
On 16/06/2014 19:47, Michael B. wrote: > I have worked on this problem for a specific case as well. I have a > document with source code and a short description of what’s happening > that can be found here Hello Michael, thank for your example code, but the algorithm is trivial, what I don’t yet know is how to implement it in such a way that it can be used within the gnuradio framework. I’m having a look at the documentation now. Cheers, Daniele ---
**Author:** ![Daniele\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/74df32/32.png) [@Daniele\_N](https://www.ruby-forum.com/u/Daniele_N)\ **Post date:** [June 16, 2014, 8:11pm UTC](https://www.ruby-forum.com/t/phase-unwrapping/230400/6 "2014-06-16T20:11:33Z")
If you take a look at the doc again, i updated it a little bit to show it working in an OOT work function. Michael On Mon, Jun 16, 2014 at 10:53 AM, Daniele N. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)