Hi all,
A little while back I submitted an issue
(http://gnuradio.org/redmine/issues/693) regarding the inability to
instantiate the delay block with a negative int (to consume samples)
despite the code comments and documentation.
Tom submitted a commit and clarified that you have to instantiate with a
int >=0, but that you can set a negative delay after the block is
instantiated via set_dly().
I am still unable to set a negative delay and I’m wondering if maybe I’m
misunderstanding something.
In a topblock, I do…
self.delay = blocks.delay(gr.sizeof_gr_complex, 0)
…and connect it to a USRP source.
Then in a main loop which I use to run the flowgraph, I do…
while True:
tb.delay.set_dly(-tb.fft_size)
tb.start()
tb.wait()
[…]
… I’d like to skip 1 fft_frame worth of samples for each run of the
flowgraph (after a frequency retune).
I get the following error, with both Ettus R.'s stable binary of
gnuradio/uhd and with pybombs gnuradio and uhd, built today:
terminate called after throwing an instance of ‘std::invalid_argument’
what(): buffer_add_reader: nzero_preload must be >= 0
Aborted (core dumped)
It seems that the delay block still can’t accept a negative delay (to
consume samples) even after instantiating at 0, or am I missing
something simple?
Thanks in advance!
-Doug
Douglas Anderson | Intern
DOC/NTIA/ITS-T | 325 Broadway St., Boulder, CO 80305 | P: 303 497 3582