On 2021-09-08 7:28 p.m., Ernest Fardin wrote:
Thanks Marcus,
A couple more questions on this:
[1] Would it be possible for us to buy a USRP X310 (which supports the
reference power API), run uhd_power_cal and then transfer the UBX DB
to the N210 and expect calibrated power measurements? Or does the
reference power API need to be working on the N210 in order to apply
the calibration data?
I believe that the caibration is for the ENTIRE CHAIN (which makes
sense), so simply moving it to an N210 would not be meaningful.
[2] In order to get the reference power API to work on the N210, would
that require changes to the N210 firmware, or just UHD?
Probably just UHD -- taking a VERY cursory look at the CAL code, it
looks like it can store CAL data in a host-based file database, so even if
the hardware doesn't have enough EEPROM or FLASH storage for the
tables, it can be stored in a file on the host. It looks like there
would need to be work
in usrp_calibrator.py to define a N200Calibrator class and override
the relevant things from the base class. But I'm not the person who
developed this,
so I'm speaking entirely from a cursory inspection of the code.
What is it you ACTUALLY want to achieve? Turn your USRP into a
laboratory instrument? Have some vague notion of how much power you're
receiving at the
antenna input? Because for a limited parameter space, it's fairly
easy to do that yourself. The Cal/Reference API was only VERY recently
added and people
have been doing without it with USRP products since 2004 or so. It's
a VERY young API, and provides only very limited device coverage--for
example, I can't
really determine if it understands the concept of pluggable
daughtercards, so that the total index is composed of both the
motherboard AND daughtercard
serial numbers. Because, without that, any calibration data are
suspect, etc.
Regards,
Ernest
On Thu, Sep 9, 2021 at 7:34 AM Marcus D. Leech
<[email protected] <mailto:[email protected]>> wrote:
On 2021-09-08 5:27 p.m., Ernest Fardin via USRP-users wrote:
Hi,
Following up on this, the question I'm trying to answer is: "Can
I calibrate the rx power on an N210 + UBX platform?"
With the N210, has_rx_power_reference()
<https://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__usrp.html#af0307aa83d1454e92a7ec91fb4100b98>
returns False. Can I conclude from this that an rx power
calibration is not possible on this device?
It means that there is no reference calibration API available for
this device.
The calibration reference API is fairly new, so it will only be
available (at least initially) on newer devices. The N2xx series
is about 10 years old
at this point.
On Tue, Sep 7, 2021 at 9:00 PM Ernest Fardin <[email protected]
<mailto:[email protected]>> wrote:
Hi,
I'm trying to calibrate the receive power on a USRP N210 with
a UBX daughterboard. Using UHD 4.0, I can get
uhd_power_cal.py to run by adding an N210Calibrator class to
usrp_calibrator.py. N210Calibrator overloads the
USRPCalibratorBase class.
class N210Calibrator(USRPCalibratorBase):
"""
N210/UBX Calibration
"""
mboard_ids = ('N210r4',)
default_rate = 2.5e6
min_freq = 50e6
max_freq = 50e6
tune_settling_time = .5
When the calibration completes, the store() method in
usrp_calibrator attempts to write the calibration table to
the UBX with
database.write_cal_data(
cal_key,
cal_serial,
cal_data.serialize())
The chan_info string returned by the N210 is:
{'mboard_id': 'N210r4', 'mboard_name': '', 'mboard_serial':
'318EFF3', 'rx_antenna': 'TX/RX', 'rx_id': 'UBX-40 v2
(0x007c)', 'rx_serial': '318D55F', 'rx_subdev_name': 'UBX
RX', 'rx_subdev_spec': 'A:0'}
What values to use for cal_key and cal_serial?
Thanks in advance!
Ernest
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