On 03/12/2019 05:13 AM, Ivan Zahartchuk via USRP-users wrote:
Thanks for the information. But do not tell me why then in N 210 with
sbx there is no such problem? Just in the N 210 I am not satisfied
with the large central frequency. As I understand this is a surge in
direct current. But I can't get rid of him. And sometimes there are
problems with the mirror channel. If you have any advice on this, I
will be extremely grateful.
Because the SBX is a different piece of hardware, with different
architecture. It happens to tune a lot faster.
The DC offset can be dealt with using offset tuning:
https://files.ettus.com/manual/page_general.html
If you are seeing image frequencies, then use the
uhd_cal_rx_iq_balance
Utility on your N210 to caclulate and record calibration parameters that
will help to reduce I/Q imbalance. DC offset and I/Q imbalance are
inherent in a direct-conversion receiver design. These imbalances
need to be calibrated out. In the N210/SBX, host-side software does
"static' measurement of these (using the above mentioned tooling) and
records a calibrations file. Those calibrations are then applied
at run-time to compensate.
In the B210, the AD9361 chip does I/Q correction (and other corrections)
dynamically, which can cause it to be slower in tuning--because it
does the measurements whenever you re-tune.
See:
https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms1-ebz/iq_correction
For a discussion
пн, 11 мар. 2019 г. в 17:17, Ian Buckley <i...@ionconcepts.com
<mailto:i...@ionconcepts.com>>:
Ivan,
When the AD9361 is retuned, recalibration of various RF circuits
may (need to) reoccur. The device driver looks how far you have
retuned from a previous frequency, and if it exceeds a certain
distance rerun’s this calibration, which takes time.
Since Analog devices envisaged that this chip might need to be
used in applications where fast hopping is required, it does have
the ability to store multiple calibration settings locally in the
radio and switch between them quickly, but this is not
functionality that is used in basic operation under UHD. We may
well have put API hook’s in there so you can manually call this
functionality under UHD, but I can’t recall. Take a look at ADI’s
documentation for more info.
-Ian
> On Mar 11, 2019, at 7:49 AM, Ivan Zahartchuk via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>>
wrote:
>
> Hello. I have a problem with the usrp b200 board. I need a fast
frequency tuning for spectrum analysis. But when I increase the
band over 200 MHz, that is, more than 8 frequency adjustments, I
have problems with time. It increases dramatically.
> Here is the code section where I measure the execution time of
the frequency setting function:
> for i, freqq in enumerate (freq):
>
> recv_samps = 0
> self.usrp.set_rx_rate (bandwich [i])
> start = time.time ()
> self.usrp.set_rx_freq (lib.types.tune_request (freqq))
>
> print (time.time () - start)
> And I get the following results:
> 0.154153108597
> 0.00300002098083
> 0.0029628276825
> 0.00299215316772
> 0.00298380851746
> 0.153974056244
> 0.153841018677
> 0.00304222106934
> 0.00305104255676
> 0.0030951499939
> 0.0030038356781
> 0.153944015503
> 0.153861045837
> 0.00292587280273
> 0.00306510925293
> 0.00301003456116
> 0.0029399394989
> With USRP N 210 there is no such problem. Tell me why this
problem occurs and how can it be solved?
> Thanks in advance. Ivan
> _______________________________________________
> USRP-users mailing list
> USRP-users@lists.ettus.com <mailto:USRP-users@lists.ettus.com>
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
_______________________________________________
USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
_______________________________________________
USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
