[USRP-users] Sync problem in custom DUC

Jonathon Pendlum jonathon.pendlum at ettus.com
Mon Jul 13 16:01:06 EDT 2020


Hi Carlos,

Where are the sine waves coming from / how are they generated? What is
your entire flowgraph? What sampling rate are you running at?

Jonathon

On Fri, Jul 10, 2020 at 2:45 PM Carlos Alberto Ruiz Naranjo via USRP-users <
usrp-users at lists.ettus.com> wrote:

> This is the code for the adder (between dds_timed and axi_wrapper):
>
> assign s_axis_data_tvalid2[0] = s_axis_data_tvalid[1] &
> s_axis_data_tvalid[0];
> assign s_axis_data_tvalid2[1] = s_axis_data_tvalid[1] &
> s_axis_data_tvalid[0];
>
> assign s_axis_data_tuser2 = s_axis_data_tuser;
>
> assign s_axis_data_tlast2[0] = s_axis_data_tlast[0];
> assign s_axis_data_tlast2[1] = s_axis_data_tlast[1];
>
> assign s_axis_data_tdata2[15: 0] = s_axis_data_tdata[47:32] +
> s_axis_data_tdata[15: 0];
> assign s_axis_data_tdata2[31:16] = s_axis_data_tdata[63:48] +
> s_axis_data_tdata[31:16];
>
> assign s_axis_data_tready_aux = ~|(~{s_axis_data_tready_out[0
> ],s_axis_data_tready_out[1]} & 2'b11);
> assign s_axis_data_tready[0] = s_axis_data_tvalid[0] & s_axis_data_tvalid[
> 1] & s_axis_data_tready_aux;
> assign s_axis_data_tready[1] = s_axis_data_tvalid[0] & s_axis_data_tvalid[
> 1] & s_axis_data_tready_aux;
>
> El vie., 10 jul. 2020 a las 11:59, Carlos Alberto Ruiz Naranjo (<
> carlosruiznaranjo at gmail.com>) escribió:
>
>> Hi,
>>
>> I'm customizing the DUC block to do it 2input:1output
>>
>> input 0  ---> DUC --->
>>                                       add ---> output
>> input 1  ---> DUC --->
>>
>> I have added an addsub module between dds_timed and axi_wrapper.
>> Apparently it works fine. I can see two tones in the output if the inputs
>> are 2 tones.
>>
>> But I have a synchronization problem. If input_0 is a sine and input_1 is
>> a sine with pi phase the output should be 0. And the output is 0, but after
>> a while (3 minutes) no. I think that the channels are out of sync before
>> the adder.
>>
>> Any idea about what is happening?
>>
>> Thank you :)
>>
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