On 12/11/2022 06:58, Ze Zhang wrote:
Hello Kyeong Su Shin
Thanks very much for your kindly reply.
First, the information about the software radio structure contains
three kinds, which are Low-pass sampling architecture, RF direct
band-pass sampling architecture, and IF band-pass sampling
architecture. Among them, according to the second generation USRP
structure, only the IF band-pass structure is designed for analog
down-conversion.
The N210's structure(reference attachment) contains the DDC notation.
And DDC contains the digital down conversion. As you
mentioned thelow-frequency IF stage is optional. Does this mean that
the digital shifting in the IF is to adjust for the bias caused by the
previous down-conversion? Or this step can be controlled by command.
It is frequently the case that the frequency "step size" of a
synthesized down/up-converter is finite and somewhat large.
So, among other things, the DDCs are there to make sure that the I/Q
signal delivered to the host computer is at exactly
0Hz.
This process is normally completely automatic, but fine control over it
is documented here:
https://files.ettus.com/manual/page_general.html#general_tuning
You haven't shared which daughtercard you're using with yoru N210--the
details will change depending on which daughtercard.
Kyeong Su Shin 于2022年11月11日周五 16:52写道：
Hello Ze Zhang:
First, there is a dedeicated mailing list for USRP-specific
questions: USRP-users. https://kb.ettus.com/Mailing_Lists
"the information mentioned that the common structure for all USRPs
is the IF bandpass sampling structure," -> where did you find this
information? This is, in general, not true. USRP N200/N210s,
especially, usually default to zero-IF (direct conversion) mode
(not always, though).
In case of the USRP N200s/N210s, daughterboards implement the
RF/IF (if exists) stages of the transceivers and the motherboards
implement the baseband and the digital stages of the transceivers.
The daughterboards often do not have any IF stages, and directly
convert the signal to the baseband. The motherboards CAN implement
a low-frequency IF stage by digitally shifting the baseband
signals before the decimation stage. This is optional, and not
used by default.
Regards,
Kyeong Su Shin
*보낸 사람:* Ze Zhang 대신
discuss-gnuradio-bounces+ksshin=postech.ac...@gnu.org
*보낸 날짜:* 2022년 11월 11일 금요일 오후 3:56
*받는 사람:* discuss-gnuradio@gnu.org
*제목:* Questions about the IF signal processing structure of USRP
N210
Hi,
I am using the URSP N210, and have some questions regarding the
internal IF (intermediate frequency) signal processing structure
of USRP N210.
In the websites, the information mentioned that the common
structure for all USRPs is the IF bandpass sampling structure, and
in the previous
question(https://lists.gnu.org/archive/html/discuss-gnuradio/2013-09/msg7.html)
it was mentioned that USRP N210 is the common second generation
USRP structure.
So is there any difference between the second-generation USRP
structure and the digital IF transceiver structure? Also, what is
the IF frequency range of the RF signal received by the N210 after
analog down-conversion?
Is it possible to get the value of the local oscillator frequency
or the value of IF frequency by the setting carrier frequency?
