# Phase locked loop **URL:** \ **Category:** GNU Radio\ **Created:** [March 17, 2015, 2:31am UTC](https://www.ruby-forum.com/t/phase-locked-loop/234599 "2015-03-17T02:31:02Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [March 17, 2015, 2:31am UTC](https://www.ruby-forum.com/t/phase-locked-loop/234599/1 "2015-03-17T02:31:02Z")
Hi, Currently I am doing my Final Year Project to develop a phase measurement using Phase Locked Loop theory. I am using USRP N210 for the hardware and I have installed Gnuradio Companion in Ubuntu 12.04 LTS (running in VMplayer). I have studied online that I can’t use companion to add and drop the current available blocks to construct a phase locked loop. I managed to locate gr\_pll\_carriertracking\_cc.cc and gr\_pll\_carriertracking\_cc.h file from gnuradio source archive. I also know that I can use gr\_modtool to construct my own OOT module. But I am having some difficulties in using gr\_modtool. There are many functions is the gr\_pll\_carriertracking\_cc.cc. My question are (a) What should I include for the valid argument list during the gr\_modtool add process? reference link : [http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided\_Tutorial\_GNU\_Radio\_in\_C++#432-Specific-block-categories](http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_GNU_Radio_in_C++#432-Specific-block-categories) (4.2.3 Step 2) (b) Am I putting the whole code (gr\_pll\_carriertracking\_cc.cc) and generate it as ONE OOT module with few functions inside or should I separate the functions to become more OOT module and connect them using wire in companion? (c) How can I include all the header file into the make process? There are few header files being used in the code such as gr\_io\_signature.h , gr\_sincos.h…. I would really appreciate your help in guiding me. Thank you very much. Best regards, Wai Yee. ---
**Author:** ![yee\_yy1992](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/f04885/32.png) [@yee\_yy1992](https://www.ruby-forum.com/u/yee_yy1992)\ **Post date:** [March 17, 2015, 4:20am UTC](https://www.ruby-forum.com/t/phase-locked-loop/234599/2 "2015-03-17T04:20:09Z")
On 16.03.2015 18:05, yee\_yy1992 wrote: > My question are > > (a)What should I include for the valid argument list during the > gr\_modtool add process? > reference link : [http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided\_Tutorial\_GNU\_Radio\_in\_C++#432-Specific-block-categories](http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_GNU_Radio_in_C++#432-Specific-block-categories) (4.2.3 > Step 2) This depends what you want to achieve. Use gr\_modtool help add for more advice. > (b)Am I putting the whole code (gr\_pll\_carriertracking\_cc.cc > [http://cc.cc/](http://cc.cc/)) and generate it as _ONE_ OOT module with few functions > inside or should I separate the functions to become more OOT module and > connect them using wire in companion? More modular is usually better. > (c)How can I include all the header file into the make process? There > are few header files being used in the code such as gr\_io\_signature.h , > gr\_sincos.h. How good is your C++? Maybe it’s worth brushing up the basics first, or perhaps you might consider writing the block in Python. Also, I recommend looking at some of the blocks in GNU Radio as examples. I didn’t fully understand what your objective is, but there are PLL blocks which you can have a look at for input. Cheers, M ---
**Author:** ![yee\_yy1992](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/f04885/32.png) [@yee\_yy1992](https://www.ruby-forum.com/u/yee_yy1992)\ **Post date:** [March 17, 2015, 3:10pm UTC](https://www.ruby-forum.com/t/phase-locked-loop/234599/3 "2015-03-17T15:10:55Z")
Hi Daniele, > Also, I don’t see why you cannot combine other blocks to realize > your own PLL implementation. Where did you read that you “cant use > companion to add and drop the current available blocks to construct a > phase locked loop”? > Wai Yee has a point here – you can’t have a circle in your (sample > stream) flow graph – GNU Radio doesn’t allow that for reasons of > causality. You can have a “loose” loop with feedback done with message ports, but that’s not the same as a control loop (since there’s no defined delay between the sample for which a error was estimated and the sample where the error correction is applied when using the asynchronous messages). Thus, you can’t drag’n’drop together a “proper” control loop from discrete things like adders and integrators that you could design and analyze theoretically. In effect, GNU Radio’s control loops are monolithic blocks – that’s somewhat sad from a modularity perspective, but then again, there’s the control loop base class that allows you to implement arbitrary control loops rather easily, so Wai Yee, I recommend looking at the documentation [1], the referenced paper and the source code[2] of the existing costas loop. Best regards, Marcus M. PS: > I am using _USRP N210_ for the hardware and I have installed _Gnuradio > Companion_ in _Ubuntu 12.04 LTS_ (running in VMplayer). > as a side note, I don’t recommend running your digital signal processing > for a high-rate capable device inside a VM, unless you know what you’re > doing – the additional overhead in network packet handling might prove > to be a problem. At lower rates, it should work fine. > Also, why are you using a three years old Ubuntu? There’s a new LTS > release, almost a year old now, 14.04; I recommend using a modern > platform. [1] > **[GNU Radio Manual and C++ API Reference: gr::digital::costas\_loop\_cc Class...](https://www.gnuradio.org/doc/doxygen/classgr_1_1digital_1_1costas __loop__ cc.html)** [2] > ---
**Author:** ![yee\_yy1992](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/f04885/32.png) [@yee\_yy1992](https://www.ruby-forum.com/u/yee_yy1992)\ **Post date:** [March 17, 2015, 9:15am UTC](https://www.ruby-forum.com/t/phase-locked-loop/234599/4 "2015-03-17T09:15:03Z")
On 17/03/15 02:05, yee\_yy1992 wrote: > Hi, Currently I am doing my Final Year Project to develop a phase > measurement using Phase Locked Loop theory. I am using _USRP N210_ for > the hardware and I have installed _Gnuradio Companion_ in _Ubuntu 12.04 > LTS_ (running in VMplayer). I have studied online that I cant use > companion to add and drop the current available blocks to construct a > phase locked loop. Hello, what to you mean by that last sentence? GNURadio comes with PLL blocks in a few different fashions that can be used from the companion just fine. Also, I don’t see why you cannot combine other blocks to realize your own PLL implementation. Where did you read that you “cant use companion to add and drop the current available blocks to construct a phase locked loop”? Cheers, Daniele ---
**Author:** ![yee\_yy1992](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/f04885/32.png) [@yee\_yy1992](https://www.ruby-forum.com/u/yee_yy1992)\ **Post date:** [March 17, 2015, 4:30pm UTC](https://www.ruby-forum.com/t/phase-locked-loop/234599/5 "2015-03-17T16:30:03Z")
Hi Daniele, On 03/17/2015 03:38 PM, Daniele N. wrote: > I realized this while having my coffee this morning. I should avoid to > reply to emails before assuming the right amount of caffeine 🙂 > oh… I know that feeling! > > In effect, GNU Radio’s control loops are monolithic blocks – that’s > > somewhat sad from a modularity perspective, but then again, there’s the > > control loop base class that allows you to implement arbitrary control > > loops rather easily > > Last time I looked into it, this base class is not that generic: it can > > be easily used to implement phase-lock loops, but it did not seem > > designed to control other quantities, like amplitude for example. But I > > may have had a too quick loot at it. > > I’d have to admit, you’re right. I’m not quite sure, but I think Wai Yee > > really just wants a PLL – so that would be fine. Greetings, Marcus ---
**Author:** ![yee\_yy1992](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/f04885/32.png) [@yee\_yy1992](https://www.ruby-forum.com/u/yee_yy1992)\ **Post date:** [March 17, 2015, 3:39pm UTC](https://www.ruby-forum.com/t/phase-locked-loop/234599/6 "2015-03-17T15:39:52Z")
On 17/03/15 15:08, Marcus M. wrote: > You can have a “loose” loop with feedback done with message ports, but > that’s not the same as a control loop (since there’s no defined delay > between the sample for which a error was estimated and the sample where > the error correction is applied when using the asynchronous messages). > > Thus, you can’t drag’n’drop together a “proper” control loop from > discrete things like adders and integrators that you could design and > analyze theoretically. Hello Marcus, I realized this while having my coffee this morning. I should avoid to reply to emails before assuming the right amount of caffeine 🙂 > In effect, GNU Radio’s control loops are monolithic blocks – that’s > somewhat sad from a modularity perspective, but then again, there’s the > control loop base class that allows you to implement arbitrary control > loops rather easily Last time I looked into it, this base class is not that generic: it can be easily used to implement phase-lock loops, but it did not seem designed to control other quantities, like amplitude for example. But I may have had a too quick loot at it. Cheers, Daniele ---
**Author:** ![yee\_yy1992](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/f04885/32.png) [@yee\_yy1992](https://www.ruby-forum.com/u/yee_yy1992)\ **Post date:** [March 18, 2015, 10:43pm UTC](https://www.ruby-forum.com/t/phase-locked-loop/234599/7 "2015-03-18T22:43:29Z")
Hi Yee, Oh I did forget to put the link of the book, sorry!!! Here is the book: > **[Digital Communications: A Discrete-Time Approach: Rice, Michael: 9780130304971:...](https://www.amazon.com/Digital-Communications-Discrete-Time-Michael-Rice/dp/0130304972)** > > Digital Communications: A Discrete-Time Approach \[Rice, Michael\] on Amazon.com. \*FREE\* shipping on qualifying offers. Digital Communications: A Discrete-Time Approach If you want to implement a PLL by yourself, I prefer to see an example of QPSK Tx/Rx in Matlab: [http://www.mathworks.com/help/comm/examples/qpsk-transmitter-and-receiver.html](http://www.mathworks.com/help/comm/examples/qpsk-transmitter-and-receiver.html) However, it’s convenient to use available blocks in GNURadio. Best, Mostafa On Wed, Mar 18, 2015 at 4:11 AM, yee\_yy1992 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > If you want to have a loop within GNURadio, you must have a delay within > > > gr\_pll\_carriertracking\_cc.h file from gnuradio source archive. I also know > > Step 2) > > > > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > > Amirkabir University Of Technology > > Tehran > > IRAN > > Tel: +98 (919) 158-7730 > > LAB: [http://ele.aut.ac.ir/~mmwcl/?page\_id=411](http://ele.aut.ac.ir/~mmwcl/?page_id=411) > > Homepage: [http://ele.aut.ac.ir/~alizadeh/](http://ele.aut.ac.ir/~alizadeh/) > > * * * – * * * Department of Electrical Engineering Aboureyhan Building MMWCL LAB Amirkabir University Of Technology Tehran IRAN Tel: +98 (919) 158-7730 LAB: [http://ele.aut.ac.ir/~mmwcl/?page\_id=411](http://ele.aut.ac.ir/~mmwcl/?page_id=411) Homepage: [http://ele.aut.ac.ir/~alizadeh/](http://ele.aut.ac.ir/~alizadeh/) * * *