[USRP-users] USRP Tx interpolation factor

Mike McLernon Mike.McLernon at mathworks.com
Thu Feb 14 16:43:05 EST 2013


Hi Ciao,

 

Several points:

1.       The Simulink sample time has no relationship to wall clock time.  It is a simulation artifact.

2.       Having said that, it aids sanity to set the Simulink sample time to be consistent with the USRP D/A or A/D.  Those data converters run at 100 MHz.

3.       If you have a sample time of 1e-6, it corresponds to a sample rate of 1e6.  You would use an interpolation factor of 100 to achieve that consistency between Simulink and the USRP D/A.

4.       The insertion of a Buffer block between your data source and the SDRu Transmitter block will change the Simulink frame time.  This frame time is  (sample time * frame length).  The underlying Simulink sample time is unchanged, but if you turn on sample time colors for the model, it will show the frame time, not the sample time.

 

Hth,

Mike

 

 

From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of Invizible Box
Sent: Thursday, February 14, 2013 11:52 AM
To: usrp-users at lists.ettus.com
Subject: [USRP-users] USRP Tx interpolation factor

 

Hello everyone,

I am new to the USRP world. I am working on USRP n210.

I want to implement a transmitter using simulink-matlab. I have I/Q data saved in a file which I read into simulink and I have a sample time of 1e-6 at the ''From Workspace'' block. 

I want to know how we select the interpolation factor in the sdru Tx block and how it effects the input sample time. How will it change if i put a buffer between the sdru tx and my source data.

 

Thanking in advance,

Ciao

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