Re: re-synchronize data transmission when parameter changes

[Marcus Müller]

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
>>
>