Re: re-synchronize data transmission when parameter changes

Because hacktoberfest is upon us: Made this a formal feature request, with quite a lot of
instructions on how to implement it

https://github.com/gnuradio/gnuradio/issues/5113

On 29.09.21 19:11, Marcus Müller wrote:
> Hi Wei,
>
> it sounds to me like a bit of an "esoteric" use to adjust the number of repetitions at
> runtime for a transmission, but that should not stop you!
>
> Not all things can work, though:
>
>>  For example, by asking the two repeat blocks always
>> process the same amount of samples,
>
> No, that's not how GNU Radio works!
>
>> or each time I change the
>> parameters, the two file sources re-transmit the file from the beginning
>> simultaneously?
>
> That wouldn't solve the fact that the repetition factor of your two "Repeat" blocks aren't
> set synchronously.
>
> Instead:
> If you want, you can:
>
> Stream A -->|Streams to|               |Vector to|--->
> Stream B -->|  Vector  |--->|repeat|-->| Streams |--->
>
> By far the most elegant way would be if you wrote your own C++ repeat block that has an
> arbitrary number (instead of just 1) input (and the same number of outputs). Then, you
> could avoid the "Streams to vector" and "vector to streams" trickery.
>
> Best regards,
> Marcus
>
> On 29/09/2021 18.10, Huang Wei wrote:
>> Hello everyone,
>>
>> I am testing the transmission of the same signal in parallel through two repeat blocks
>> (see attached flowgraph). The repeat times of both repeat blocks are set by the same GUI
>> range from 2 to 10.
>> When I start running the flowgraph, the two output signals are exactly the same as
>> expected. But when I change the repeat times from the GUI range, the two signals are not
>> synchronized anymore (see attached signal plot).
>>
>> I am wondering, is there a way to keep the two signals always synchronized? For example,
>> by asking the two repeat blocks always process the same amount of samples, or each time
>> I change the parameters, the two file sources re-transmit the file from the beginning
>> simultaneously?
>>
>> I am doing this because I want to transmit the signals simultaneously through two
>> synchronized USRPs, and I don't want the mis-match of the signals due to changing the
>> parameter in the repeat blocks every time.
>>
>> Appreciate if someone could help me!
>>
>> Regards,
>> Wei
>>
>