Hi:
Thanks Marcus and Martin.So kindly of you.Thanks.
Now I understand the command get_tags_in_range.Thank you.
But
>> void ofdm_chanest_vcvc_impl::forecast (int noutput_items,
>> gr_vector_int &ninput_items_required)
>> {
>> ninput_items_required[0] = (noutput_items/d_n_data_syms) *
>> (d_n_data_syms + d_n_sync_syms);
>> }
>> And I think ninput_items_required[0] = (1/1) * (1 + 2)=3.
>If you say so?! I don't know the value of any of these variables at the
>time GNU Radio calls this. Usually, the scheduler doesn't ask for a
>single output item, but for more, so noutput_items >> 1.
For the block:OFDM Channel Estimation,can I say noutput_items=1?Because I know
every time,the block output just one vector(item).Can you explain it to
me?Thank you so much.
Best regards,
xd
At 2014-08-07 03:47:53, "Marcus Müller" <[email protected]> wrote:
>Hi Xianda,
>
>On 07.08.2014 08:10, xianda wrote:
>> Hi all:
>> I'm reading the source code ofdm_chanest_vcvc_impl.cc.And I don't
>> know this command:
>> // Propagate tags
>> std::vector<gr::tag_t> tags;
>> get_tags_in_range(tags, 0,nitems_read(0), nitems_read(0)+framesize);
>>
>> I will try my best to explain my question more clearly.
>> 1. I read:
>> void ofdm_chanest_vcvc_impl::forecast (int noutput_items,
>> gr_vector_int &ninput_items_required)
>> {
>> ninput_items_required[0] = (noutput_items/d_n_data_syms) *
>> (d_n_data_syms + d_n_sync_syms);
>> }
>> And I think ninput_items_required[0] = (1/1) * (1 + 2)=3.
>If you say so?! I don't know the value of any of these variables at the
>time GNU Radio calls this. Usually, the scheduler doesn't ask for a
>single output item, but for more, so noutput_items >> 1.
>> Then nitems_read(0)=3.Is it right?(nitems_read:Return the number of
>> items read on input stream which_input. )
>Wrong, nitems_read(0) is the number of items that have been consumed by
>a block up to now. "read" is past tense, here.
>> 2. const int framesize = d_n_sync_syms + d_n_data_syms;
>> Then framesize=2+1=3.
>this obviously depends on what your instance uses as number of sync
>symbols and data symbols.
>> 3.Then get_tags_in_range(tags, 0,nitems_read(0),
>> nitems_read(0)+framesize);---->>>get_tags_in_range(tags, 0,3, 6);
>> But:
>> {0 1 2}--->>>blk--->>>{0}
>> It don't have 3 4 5 item.Can someone explain it to me?Thank you.
>> Best regards,
>> xd
>get_tags_in_range stores the tags in the tag vector you supply as first
>argument:
>
>get_tags_in_range(tags, 0,nitems_read(0), nitems_read(0)+framesize);
>
>
>The second argument is the input stream number (0), the third is the
>start of the range, in this case the number of items that have already
>been consumed in previous calls to work, which is the number of the
>first item in the current call to work. The third argument is the end of
>the range.
>
>Hope that cleared things up a little!
>
>Greetings,
>Marcus
>
>
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