Hello,
I think that the declare_sample_delay (and/or the way it is used) is
implemented incorrectly for interpolator blocks. Using GR 3.7.6.
The delay should be added **after** scaling the offset by the interpolation
ratio, not before. For example, using the
filter.interp_fir_filter(4,[1,2,3,4]):
If a tag is on sample2, and the sample_delay is declared as one, the output tag
should be on sample 2*4+1=9. However, it falls on sample 12 = (2+1)*4.
Here's an example to demonstrate the error:
from gnuradio import gr, blocks, filter
import pmt
top = gr.top_block()
tag = gr.tag_utils.python_to_tag((2,
pmt.to_pmt('A'),
pmt.PMT_NIL,
pmt.PMT_NIL))
src = blocks.vector_source_f(range(0, 50, 10), tags=[tag])
dut = filter.interp_fir_filter_fff(4, [1, 2, 3, 4])
dut.declare_sample_delay(1)
snk = blocks.vector_sink_f()
top.connect(src, dut, snk)
top.run()
result = snk.data()
tags = snk.tags()
print tags[0].offset
Regards.
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