Re: [Discuss-gnuradio] trouble with gr_multiply_const_ff

On Sat, Nov 30, 2013 at 5:00 AM, atools_cook <liwenpuxjtu@gmail.com> wrote:
> Hi Marcus,
>
> Thanks for your attention.
> I have upload a bigger size image below. the x axis is sampling point which
> reflects time and the y axis is margin which reflects the power.
> I plot the image from the rx block of the gen2_reader project. The signal is
> transmitted by the tx block of gen2_reader.
> The to_complex block is use to trasfer the float data to complex data for
> transmitting by tx block.
>
> The input data of gr_multiply_const_ff block are the same, they come from
> the reader block.
> It's weird that the output data of gr_multiply_const_ff are the same in
> matlab image with different amplitude(bigger than 40 or not) but the signal
> tx block transmiting are not.
>
> I can't figure out how the amplitude in gr_multiply_const_ff block influence
> the signal in tx block without change the output data.
> By the way, we use a gen2_monitor with another usrp to get signal
> transmitted from the gen2_reader tx blcok, it has the same signal image to
> the rx block of gen2_reader. So, we can assume that there is no problem with
> our equipments
>
> Lee

Lee,

You know that the UHD transmitter takes signal samples from 0 to 1? So
after the multiply_const block, what's the value of the signal? If
it's > 1, you're not going to get any change in the transmit power.

Tom

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