Re: [Discuss-gnuradio] DQPSK Modulation/Demodulation issue

[Harald Welte]

Hi Marcin,

some answers - unfortunately only to those of your questions that I
feel confident to answer.

On Thu, Apr 29, 2010 at 06:45:23AM -0700, marcin_w wrote:

> Getting back to the USRP model, i can't seen to work out whether my
> bitrates/sample rates are correct. 
> For instance, the interpolation of my USRP sink is set to 500, meaning it
> should be accepting samples at a rate of of 256ks/s.

This is correct.

> 2) Do i need to use the throttle block in my graph to control the bit rates?
> , or does simply setting the interpolation on the usrp automatically control
> this?

You only need a throttle block in case you _dont_ have a real hardware source
or sink.  Once you use the USRP sink, it will "pull" the respective number
of samples into the sink, which is what drives all the preceding blocks to
generate some output.

> 3) Would setting the interpolation of the usrp to 500, automatically set the
> bit rate to 128kb/s if my graph looks like this:
> 
> Vector Source [180] > Packed To Unpacked > Mapper [Binary 2 Gray] >
> Differential Encoder >
> Chunks to Symbols > Interpolating FIR Filter (RRC) [samples/symbol = 2 ,
> interpolation = 2 ] > USRP sink [ interp: 500]

At least as far as I understand: yes.

Regards,
        Harald
-- 
- Harald Welte <address@hidden>           http://laforge.gnumonks.org/
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