On 03/10/2018 09:26 PM, Sailor Jerry wrote:
Thanks a lot Marcus,
Let me restate my question in terms of the rx_samples_to_file.cpp
code. What line of code does turn the RX logic on?
I thought that once I'm passed check_locked_sensor() everything is
initialized. I guess the right answer is that the actual
initialization starts somewhere after rx_streamer::issue_stream_cmd()
is called, correct? Then I should discard few milliseconds worth of
data that came form rx_streamer::recv()
Yes, start-of-streaming generally does the last stage of turning the
receiver chain on. For example, it cannot really do DC-offset correct
on a data stream
that hasn't started yet....
On Sat, Mar 10, 2018 at 5:53 PM, Marcus D. Leech via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>> wrote:
On 03/10/2018 08:41 PM, Sailor Jerry via USRP-users wrote:
I'm using the rx_samples_to_file to capture the data.
I have pure noise connected to input. If I plot first few
milliseconds of IQ data I see some pull-in process.
Interestingly enough this pull-in time doesn't depend on
parameter "--setup".
Is it some fancy IQ calibration?
When does the samples capture start?
Should I ignore first samples?
Thanks a lot.
You're capturing an analog process, so there's no way to
definitively say sample <X> is your first valid sample.
It takes a few msec for the DC-offset and I/Q compensator on the
AD9361 to reach some kind of equillibrium when the RX logic is
turned on. It takes
a while for analog filters and other analog "bits and pieces" to
reach steady-state operations.
It takes a while for whatever DDC filters are in play to reach
steady-state operations. So, a few milliseconds on RX startup is
actually pretty good in
my book...
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