# G U Radio Companion : Implementing DQPSK modultation **URL:** \ **Category:** GNU Radio\ **Created:** [February 6, 2011, 7:35pm UTC](https://www.ruby-forum.com/t/g-u-radio-companion-implementing-dqpsk-modultation/202810 "2011-02-06T19:35:10Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\ **Post date:** [February 6, 2011, 7:35pm UTC](https://www.ruby-forum.com/t/g-u-radio-companion-implementing-dqpsk-modultation/202810/1 "2011-02-06T19:35:10Z")
Hi , I am new to GNU Radio and am facing difficulties in implementing DQPSK modulation on Gnu Radio Companion. The system works fine , but for one small glitch. The DQPSK modulator/demodulator’s input and output are in Byte format, which makes it a little hard to comprehend the output. for eg : if the input is 00100001. The o/p of the demod is as follows : 00000000 00000000 11111111 00000000 00000000 00000000 00000000 11111111 (instead of 00100001). I would be really grateful if a way around this can be told. Kind Regards Varun Krishnamurthy MS ECE Georgia Tech. ---
**Author:** ![Varun\_Krishnamurthy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/898d66/32.png) [@Varun\_Krishnamurthy](https://www.ruby-forum.com/u/Varun_Krishnamurthy)\ **Post date:** [February 6, 2011, 7:59pm UTC](https://www.ruby-forum.com/t/g-u-radio-companion-implementing-dqpsk-modultation/202810/2 "2011-02-06T19:59:20Z")
On Sun, Feb 6, 2011 at 1:34 PM, Varun Krishnamurthy \< [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)\> wrote: > The o/p of the demod is as follows : 00000000 00000000 11111111 > 00000000 00000000 00000000 00000000 11111111 (instead of 00100001). > > I would be really grateful if a way around this can be told. > > Kind Regards > Varun Krishnamurthy > MS ECE > Georgia Tech. I believe this is what the block unpacked\_to\_packed is for. ---
**Author:** ![Varun\_Krishnamurthy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/898d66/32.png) [@Varun\_Krishnamurthy](https://www.ruby-forum.com/u/Varun_Krishnamurthy)\ **Post date:** [February 7, 2011, 9:32am UTC](https://www.ruby-forum.com/t/g-u-radio-companion-implementing-dqpsk-modultation/202810/3 "2011-02-07T09:32:23Z")
On Sun, Feb 06, 2011 at 01:58:17PM -0500, Steven C. wrote: > ``` > for eg : if the input is 00100001. > > The o/p of the demod is as follows : 00000000 00000000 11111111 > 00000000 00000000 00000000 00000000 11111111 (instead of 00100001). > > I would be really grateful if a way around this can be told. > > ``` > > I believe this is what the block unpacked\_to\_packed is for. Also, you should check why your demod outputs eight 1’s instead of one. And don’t forget to include a preamble or something like that in your transmission, otherwise you won’t be able to figure out which symbol maps to which bit, and the packed bit stream will actually be less informative than the unpacked one. MB – Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin B. Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT – University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association