Re: [Discuss-gnuradio] Simple digital data transmitter

[David Barton]

Thanks Eric.

 

So the packet encoder samples /symbol does not affect the bit rate but just needs to match the dpsk samples/ symbol rate?

 

Dave

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From: Eric Blossom <address@hidden>
To: David Barton <address@hidden>
Cc: address@hidden
Sent: Wed, May 12, 2010 2:02:42 PM
Subject: Re: [Discuss-gnuradio] Simple digital data transmitter

On Wed, May 12, 2010 at 09:06:13AM -0700, David Barton wrote:
> Hi,
>  
> I have set up the following simple digital data transmitter:
>  
>  
> File source -à   throttle    -à    packet encoder --- >  DBPSK modulator -à USRP2     
> File size             sample rate       samples/sym - 2        samples/sym – 2           Inter rate 32  
> -variable             3.125M             bits/sym - 1              excess BW – 0.35         Freq 400M
>                                                      access code – n/a      grey code - yes             Gain 0
>                                                      pad for USRP – yes
>                                                      payload len – 0
>  
>  
> What is the transmit (over the air) data rate of this line up ?
>  
> Please explain how the rate is derived.
>  
> Thanks,
> Dave

Remove the "throttle", it's not needed.

Your baseband sample rate is 100M/32 -> 3.125MS/s

You're using 2 samples/symbol, thus your symbol rate is
  3.125MS/s / 2 -> 1.5625Msymbols/s
And since you're using DBPSK, you're getting 1 bit/symbol, thus your
raw over-the-air bit rate is 1.5625Mbit/s

Eric