Indeed, there seems to be a problem here; sadly, I'll really need some
sleep tonight ;)

To answer your question, yes, Packet Encoder is really old and IMHO
should be deprecated in favor of the architecture you'd find in the
ofdm_tx.grc example (should be installed somewhere like
/usr/(local/)share/gnuradio/examples/gnuradio/digital/ofdm )

However, if you just need a preamble:
use a second vector source for the preamble (or something else), and use
the "patterned interleaver", e.g. with something like pattern =
[1]*header_len + [0]*payload_len

Best regards,
Marcus

On 22.03.2016 23:17, Miguel Santos wrote:
> As an attachment I send the .grc on which I'm doing tests.
> So:
>      - with head and/or throttle between source and packet encoder -> fine
>      - bypassing Head and Throttle -> huge file
>      - bypassing Head, Throttle and Encoder -> fine
> I answered your questions below.
>
> Another question: I'm using Packet Encoder only to add a preamble to 
> perform frame sync. Is it the only way?
>
> On 22-03-2016 21:42, Marcus Müller wrote:
>> Hi Miguel,
>>
>> On 22.03.2016 21:54, Miguel Santos wrote:
>>> On 22-03-2016 20:32, Marcus Müller wrote:
>>>> Hi Miguel,
>>>>
>>>> On 22.03.2016 17:14, Miguel Santos wrote:
>>>>> Yes, it's set to repeat.
>>>> oh!
>>>>> My real flow graph ends with a file sink, but
>>>>> here, as an example to test which block was the problem, I used a number
>>>>> sink just to be able to run it and test it.
>>>> But then, how does your flow graph decide it's done?
>>> It doesn't. For now, I'm dealing with transmitting and receiving
>>> problems, so I don't really care about the message. For testing purposes
>>> I'm transmitting an infinite amount of 0s and 1s (the same repeated
>>> sequence defined in Vector Source block) and I manually stop the flow
>>> graph after a certain amount of time.
>> Ah, so there's no "right" amount of samples. It all depends on when you
>> decide to manually stop, and on the speed at which samples are processed.
>> I'd recommend adding a "head" block somewhere. That will signal "hey,
>> we're done" as soon as the specified amount of samples have passed.
> Exactly! I tested with the Head block and it behaves as it should. I 
> think the problem occurs only when vector source is connected directly 
> to packet encoder.
> By the way, why does the file becomes empty if "Num items"<4096? I'm new 
> to this world and there's a LOT of things I don't understand.
>
>>>   The differences between the two
>>> cases I presented were noted running the flow graph for, for instance, 5
>>> seconds (counted by me). It's not very accurate, I know, but we're
>>> talking of a big difference (like a few KB or MB to hundreds of MB or
>>> even a few GB), so it's not important.
>> So, sorry for asking again, but I really want to be sure: *with* the
>> packet_encoder, the file is much much larger than without, right?
>>
>> Best regards,
>> Marcus
> Yeah, that's it: WITH
>
>>> Thanks for your time and sorry for not being explicit enough.
>> Don't worry! If this is a bug, it's really worth figuring out.
>> Also, we're a helpful bunch of people.
>>
>> Best regards,
>> Marcus
>>>> Best regards,
>>>> Marcus
>>>>> I've made more tests and if I switch Throttle with Packet Encoder, it's
>>>>> all good. The same happens if I connect File Sink to Throttle (when they
>>>>> are switched).
>>>>> So maybe the problem is with the position of throttle? After watching
>>>>> the tutorials I thought that its position was irrelevant...
>>>>>
>>>>> On 22-03-2016 08:02, Marcus Müller wrote:
>>>>>> Hi Miguel,
>>>>>>
>>>>>> I assume your Vector Source is not set to "Repeat"? Or how does your
>>>>>> Flow graph Terminate?
>>>>>> Generally, no block can modify its input buffer; hence, what File Sink
>>>>>> "sees" as an input number sequence must be identical (unless we really
>>>>>> have a bad memory access bug at hand, which I don't think).
>>>>>>
>>>>>> Bet regards,
>>>>>> Marcus
>>>>>>
>>>>>> On 22.03.2016 00:39, Miguel Santos wrote:
>>>>>>> Hi all!
>>>>>>> While I was using the block Packet Encoder I realized that my input file
>>>>>>> (saved before that block) becomes a lot bigger.
>>>>>>> So I made a simple example to show that problem.
>>>>>>>
>>>>>>> Vector Source ---> Packet Encoder ---> Throttle ---> Number Sink
>>>>>>>                   ---> File Sink
>>>>>>>
>>>>>>> Just to make it clear, File Sink is connected to Vector Source, BEFORE
>>>>>>> Packet Encoder.
>>>>>>> Running the flow graph the same amount of time, I get an input file of
>>>>>>> 700~800 MB for this flow graph and ~3MB for the same flow graph with
>>>>>>> Packet Encoder bypassed.
>>>>>>> Is this a bug? Could it be a larger processing time of that block that's
>>>>>>> delaying the data flow? Am I missing something? How can I solve that?
>>>>>>> Any help would be nice.
>>>>>>>
>>>>>>> Thanks for your time,
>>>>>>> Miguel
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
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