# Changeset 9617

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10/05/09 13:49:45 (4 years ago)
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• ## ossiedev/branches/hvolos/docs/OSSIETalkWithUSRP/OSSIETalkWithUSRP.tex

r9604 r9617
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56 \title{OSSIE Lab \#:The OSSIETalk Waveform}
56\title{OSSIE Lab: The OSSIETalk Waveform}
5757\author{Haris I. Volos and Carl B. Dietrich\\
5858Virginia Tech, Blacksburg, VA\\

7171
7272\section{Objective}
73 The objective of this lab is to familiarize the user with the OSSIETalkUSRP waveform.
73The objective of this lab is to familiarize the user with digital voice waveforms.
7474
7575\section{Version}

117117\item File $\rightarrow$ New $\rightarrow$ OSSIE Waveform
118118\item Project name: OSSIETalkStep1''
119 \item Add the following components in the waveform panel:OSSIETalk, PacketResizer, Conv\_Enc, DigitalModulator, FrameAssembler, amplifier,Channel, DigitalDemodulator, and Conv\_Dec
120 \item Add the default\_GPP\_USRP\_node to the platform panel
121 \item Expand the the node, and add all the components, one by one, the the GPP device.
119\item Add the following components to the waveform panel:OSSIETalk, PacketResizer, Conv\_Enc, DigitalModulator, FrameAssembler, amplifier,Channel, DigitalDemodulator, and Conv\_Dec
120\item Add the default\_GPP\_node to the platform panel
121\item Expand the the node, and add all the components, one by one, to the GPP device.
122122\item Set the OSSIETalk component as the assembly controler
123123\item Make the following connections:

147147\end{verbatim}
148148
149 \subsubsection{DigitalModulato1}
149\subsubsection{DigitalModulator1}
150150\begin{verbatim}
151151ModScheme=QPSK

172172\subsection{Waveform Testing}
173173\begin{enumerate}
174  \item Run the waveform and press the Push to Talk'' button while talking at the microphone. You should hear your voice from the speakers. Note that the CVSD encoding used has an inherent distortion. At 400000 noise power (20dB SNR) the any channel distortion should be negligible.
174 \item Built and run the waveform using the default\_GPP\_node and press the Push to Talk'' button while talking at the microphone. You should hear your voice from the speakers. Note that the CVSD encoding used has an inherent distortion. At 400000 noise power (20dB SNR) the any channel distortion should be negligible.
175175\item Change the noise power to 1265000 (approx. 15dB SNR), the voice should be still comprehensible.
176176\item Change the noise power to 400000 (approx. 10dB SNR), the voice may not come through.

190190
191191\subsubsection{FrameSynchronizer1}
192 Performs carrier recovery, symbol sychnronization and extracts the frame information added by the FrameAssembler component.
192Performs carrier recovery, symbol sychnronization and extracts the frame information added by the FrameAssembler. The component is using a polyphase synchronizer that requires two samples per symbol.
193193
194194\subsubsection{Interpolator1}

205205\item File $\rightarrow$ New $\rightarrow$ OSSIE Waveform
206206\item Project name: OSSIETalkStep2''
207 \item Add the following components in the waveform panel:OSSIETalk, PacketResizer, Conv\_Enc, DigitalModulator, FrameAssembler, amplifier, Interpolator, Channel, Decimator, AutomaticGainControl, FrameSynchronizer, DigitalDemodulator, and Conv\_Dec
208 \item Add the default\_GPP\_USRP\_node to the platform panel
209 \item Expand the the node, and add all the components, one by one, the the GPP device.
210 \item Set the USRPTalk as the assembly controler
207\item Add the following components to the waveform panel:OSSIETalk, PacketResizer, Conv\_Enc, DigitalModulator, FrameAssembler, amplifier, Interpolator, Channel, Decimator, AutomaticGainControl, FrameSynchronizer, DigitalDemodulator, and Conv\_Dec
208\item Add the default\_GPP\_node to the platform panel
209\item Expand the the node, and add all the components, one by one, to the GPP device.
210\item Set the OSSIETalk as the assembly controler
211211\item Make the following connections:
212212\begin{enumerate}

278278\subsection{Waveform Testing}
279279\begin{enumerate}
280  \item Run the waveform and press the Push to Talk'' button while talking at the microphone. You should hear your voice from the speakers. The SNR should be about 20dB. An increased delay between talking and hearing back your voice is normal and it is due to the long component chain and computer processing limitations.
280 \item Run the waveform with the default\_GPP\_node and press the Push to Talk'' button while talking into the microphone. You should hear your voice from the speakers. The SNR should be about 20dB. An increased delay between talking and hearing back your voice is normal and it is due to the long component chain and computer processing limitations.
281281\item Change the noise power to 2846250 (approx. 15dB SNR), the voice should be still comprehensible.
282282\item Change the noise power to 9000000 (approx. 10dB SNR), the voice should still come through, the matched filtering improves the SNR.

284284
285285\section{Step 3}
286 In this step describes how to build the complete waveform that uses the USRP and the FLEX400 board.
286This step describes how to build the complete waveform that uses the USRP and the FLEX400 board.
287287\osfigvs{blockdiagram3}{Block Diagram}{0.6}
288288

369369rx_decim=256
370370tx_interp=512
371 tx_freq=462.5625e6
372 rx_freq=462.5625e6
371tx_freq=462.5625e6 (3e6 if using BasicTx/Rx)
372rx_freq=462.5625e6 (3e6 if using BasicTx/Rx)
373373\end{verbatim}
374374

376376\begin{verbatim}
377377I_gain=1
378 Q_gain=-1
378Q_gain=-1 (Only for FLEX400, 1 otherwise)
379379\end{verbatim}
380380

417417\subsection{Waveform Testing}
418418
419 Run the waveform in two separate PCs and press the Push to Talk'' button while talking at the microphone. You should hear your voice from the other computer. The voice delay should be significantly reduced compared to the last steps.
419Run the waveform in two separate PCs and press the Push to Talk'' button while talking at the microphone. You should hear your voice from the other computer. The voice delay should be significantly reduced compared to the previous steps.
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