# Constellation Decoder problem in GRC **URL:** \ **Category:** GNU Radio\ **Created:** [March 30, 2014, 12:28pm UTC](https://www.ruby-forum.com/t/constellation-decoder-problem-in-grc/240142 "2014-03-30T12:28:15Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [March 30, 2014, 12:28pm UTC](https://www.ruby-forum.com/t/constellation-decoder-problem-in-grc/240142/1 "2014-03-30T12:28:15Z")
Hi, I am working in GRC and I am Designing My own 16 QAM Transceiver without using the QAM modulation and demodulation blocks of GRC. I have done modulation using the python function qam\_constellation from source code but now I have a problem how to demodulate the 16QAM without using the QAM demodulation block of grc while I am working in GRC window. My grc code is attached to this message below. ---
**Author:** ![Irfan\_U](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/57b2e6/32.png) [@Irfan\_U](https://www.ruby-forum.com/u/Irfan_U)\ **Post date:** [March 31, 2014, 4:01pm UTC](https://www.ruby-forum.com/t/constellation-decoder-problem-in-grc/240142/2 "2014-03-31T16:01:46Z")
On Sun, Mar 30, 2014 at 6:27 AM, Irfan U. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Hi, > I am working in GRC and I am Designing My own 16 QAM Transceiver without > using the QAM modulation and demodulation blocks of GRC. I have done > modulation using the python function qam\_constellation from source code but > now I have a problem how to demodulate the 16QAM without using the QAM > demodulation block of grc while I am working in GRC window. > My grc code is attached to this message below. Try using the Constellation Receiver instead of the Constellation Decoder. The Receiver implements phase and fine frequency tracking that you’ll need to recover the signal. The Decoder simply decodes the symbols to bits. Tom