# Packet loss and BER OFDM/DQPSK

**URL:** <https://www.ruby-forum.com/t/packet-loss-and-ber-ofdm-dqpsk/232062>\
**Category:** GNU Radio\
**Created:** [September 16, 2014, 1:58pm UTC](https://www.ruby-forum.com/t/packet-loss-and-ber-ofdm-dqpsk/232062 "2014-09-16T13:58:08Z")\
**Posts on this page:** 1\
**Page:** 1

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**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:** [September 16, 2014, 1:58pm UTC](https://www.ruby-forum.com/t/packet-loss-and-ber-ofdm-dqpsk/232062/1 "2014-09-16T13:58:08Z")

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Good morning,  
I’m evaluating the difference between a single carrier modulation and a  
multi carrier modulation, so I decided to implement a TX-RX system in  
GNURadio companion working with USRP N210.

I’d like to plot a graph of the packet loss in these two modulation,  
placing the antennas at different distances, but I’m not able to know  
the transmitted packets and the received ones, can you help me?

My parameters are:

DQPSK Transmitter:  
Audio Source → Packet encoder → DPSK MOD-\> UHD:USRP SINK

OFDM Transmitter  
Audio Source -\>Packet encoder -\>OFDM MOD-\> UHD:USRP SINK

Using a OFDM simulation, I tried to find the TX and RX packets as the  
way of the attached file.

Moreover, placing the same blocks at this link  
[http://gnuradio.org/redmine/attachments/download/399/screenshot-grc-bersimu.png](http://gnuradio.org/redmine/attachments/download/399/screenshot-grc-bersimu.png)  
in order to evaluating the BER in a TRANSCEIVER SIMULATION with a vocal  
source, it doesn’t works.  
How can I find the BER in a simulation using DQPSK and in another one  
using OFDM?

Thank you very much!!

Mattia