Re: [USRP-users] examples using N310 with ext LO

[Michael West via USRP-users]

Hi Rob,

Your procedure and commands look fine.  We are looking into the issue now
and will post an update as soon as possible.

Regards,
Michael

On Tue, Apr 10, 2018 at 6:27 PM, Rob Kossler via USRP-users <
usrp-users@lists.ettus.com> wrote:

> Still hoping to get example or instructions on how to operate & send
> tuning commands for the case of external LO with N310
>
>
> On Mon, Apr 9, 2018 at 12:35 PM, Rob Kossler  wrote:
>
>> Hi Robin,
>> I have duplicated the issue using the "rx_samples_to_file" stock example.
>> Attached you will find 2 screen shots as well as a console log containing
>> two executions of the rx_samples_to_file program.  In the first run, the
>> rx_lo_source is set to internal while in the second run, it is external.
>> Note that the two command lines are identical with the exception of the
>> rx_lo_source and the capture filename.
>>
>> In the first screenshot (ending in 33.png), you will see a spectral plot
>> of 100 equally spaced CW tones centered at 2444 MHz (slightly offset from
>> Rx center frequency of 2442 MHz). This plot shows the expected capture
>> spectrum.  In the second plot, you will see a distorted spectrum with
>> mirroring of tones across the Rx center frequency.
>>
>> It seems to me that the problem is either a bug or else improper usage of
>> the external LO option.  If the latter, perhaps you could comment on why
>> the rx_samples_to_file example program will not work correctly in an
>> external LO configuration.
>>
>> I am using an X310/UBX-160 to supply both the multitone signal (Tx 0) and
>> the LO reference (Tx 1).  The multitone signal is split 4 ways and applied
>> to the four Rx2 inputs on the N310 (with appropriate atten).  The LO CW
>> tone is split 2 ways and applied to the two rx_LO inputs on the N310 (4884
>> MHz, 3 dBm at each LO input).  Both of these signals were transmitting
>> constantly during both of the experiments.
>>
>> Note that although I applied the multitone signal to all four channels,
>> only the first channel (channel 0) is evaluated here because the
>> rx_samples_to_file program can not capture multiple channels.
>>
>> By the way, during the course of debugging this external LO issue, I came
>> across two unrelated UHD problems:
>> 1) rx_samples_to_file now includes a "channel" argument to specify which
>> channel you want.  However, it is not a useful feature because none of the
>> other channel setting options (such as setting gain, freq, etc) respect the
>> channel argument.  So, it really only works for channel 0 as it did all
>> along.
>> 2) kitchen_sink does not compile.  I tried to run this utility because of
>> problems / limitations with rx_samples_to_file.  However, it presently does
>> not compile because of recent UHD changes (messaging).
>>
>> Rob
>>
>> On Sat, Apr 7, 2018 at 10:31 PM, Robin Coxe  wrote:
>>
>>> Hi Rob.  You are specifying use of the RX external LO correctly via
>>> device arguments.   Each of the daughtercards on the N310 contains a single
>>> Analog Device AD9371 2 TX x 2 Rx RF integrated transceiver.   The two Tx
>>> channels share an LO and the 2 Rx channels share an LO.  Consequently, the
>>> TX or RX frequency of RF channel 0 and RF channel 1 are constrained by the
>>> RFIC to be the same and the TX or RF frequency of RF channel 2 and RF
>>> channel 3 must be the same.   The AD9371 is capable of FDD operation, so
>>> the TX frequency does not need to be equal to the RX frequency.
>>>
>>> The LO tuning code for the N310 daughterboard in UHD is (not obviously)
>>> located here and, as you correctly point out, is handled differently from
>>> previous USRPs:
>>> https://github.com/EttusResearch/uhd/tree/maint/host/lib/usr
>>> p/dboard/magnesium
>>>
>>> Magnesium is the internal code Ettus Research name for the N310
>>> daughterboard.We will make this obscure fact more obvious in the
>>> documentation.
>>>
>>> -Robin
>>>
>>>
>>> On Sun, Apr 8, 2018 at 2:31 AM, Marcus D. Leech via USRP-users <
>>> usrp-users@lists.ettus.com> wrote:
>>>
 On 04/07/2018 10:39 AM, Rob Kossler wrote:

 Hi Marcus,
 No, I haven't fooled with LO level adjustments.  I set the LO at about
 3 dBm and did not change it.  The LO freq is indeed 2x (LO at 4884MHz with
 center freq at 2442MHz).  I suspect that my custom software, which was
 developed for first B210 and then X310 with several daughterboard variants,
 may be sending tune commands in a way that is not ideal for an external LO
 configuration.  There was a similar issue when I first started using TwinRx
 with "companion" or "external" LO and UHD would issue warnings about tuning
 one channel first and then the other when both channels had to be at the
 same freq because they shared an LO.  So, my request for examples was to
 help me see if I am issuing the tuning requests correctly for this external
 LO config.

 Rob

 Understood.

 Hopefully, one 

Re: [USRP-users] examples using N310 with ext LO

[Robin Coxe via USRP-users]

Hi Rob.  You are specifying use of the RX external LO correctly via device
arguments.   Each of the daughtercards on the N310 contains a single Analog
Device AD9371 2 TX x 2 Rx RF integrated transceiver.   The two Tx channels
share an LO and the 2 Rx channels share an LO.  Consequently, the TX or RX
frequency of RF channel 0 and RF channel 1 are constrained by the RFIC to
be the same and the TX or RF frequency of RF channel 2 and RF channel 3
must be the same.   The AD9371 is capable of FDD operation, so the TX
frequency does not need to be equal to the RX frequency.

The LO tuning code for the N310 daughterboard in UHD is (not obviously)
located here and, as you correctly point out, is handled differently from
previous USRPs:
https://github.com/EttusResearch/uhd/tree/maint/host/lib/usrp/dboard/magnesium

Magnesium is the internal code Ettus Research name for the N310
daughterboard.We will make this obscure fact more obvious in the
documentation.

-Robin


On Sun, Apr 8, 2018 at 2:31 AM, Marcus D. Leech via USRP-users <
usrp-users@lists.ettus.com> wrote:

> On 04/07/2018 10:39 AM, Rob Kossler wrote:
>
> Hi Marcus,
> No, I haven't fooled with LO level adjustments.  I set the LO at about 3
> dBm and did not change it.  The LO freq is indeed 2x (LO at 4884MHz with
> center freq at 2442MHz).  I suspect that my custom software, which was
> developed for first B210 and then X310 with several daughterboard variants,
> may be sending tune commands in a way that is not ideal for an external LO
> configuration.  There was a similar issue when I first started using TwinRx
> with "companion" or "external" LO and UHD would issue warnings about tuning
> one channel first and then the other when both channels had to be at the
> same freq because they shared an LO.  So, my request for examples was to
> help me see if I am issuing the tuning requests correctly for this external
> LO config.
>
> Rob
>
> Understood.
>
> Hopefully, one of the R folks will chime in here.  I don't currently
> have one in my inventory, so running a bit blind.
>
>
>
> On Fri, Apr 6, 2018 at 7:32 PM, Marcus D. Leech via USRP-users <
> usrp-users@lists.ettus.com> wrote:
>
>> On 04/06/2018 05:14 PM, Rob Kossler via USRP-users wrote:
>>
>>> Hi,
>>> Are there any examples for using the N310 with external LO?  I have
>>> gotten some strange results (strange spectral mirror-ing) when using as
>>> just a 4 channel receiver.  I am using the "args" argument to set
>>> rx_lo_source, but my code is setting the individual channel frequencies as
>>> I do for other USRPs and I noticed various warnings in the terminal window
>>> for each channel that I tune.
>>>
>>> On a separate note, I get some strange results if I set the clock_source
>>> to external in the args (using with OctoClock). If I leave it internal, no
>>> problem. For now, I am leaving it internal until I can solve the problem
>>> above with LO source.
>>>
>>> Rob
>>>
>>>
>>> Rob, just shooting from the hip here, since I haven't "lived" with an
>> N310 yet...
>>
>> Have you tried adjusting the LO levels let's say 2dB in either direction
>> to see if that changes the imaging behavior?  Also, remember that the
>> external LO input
>>   on the N310 must be a 2XLO -- at twice the desired Fc, and only up to
>> 8GHz (giving a 4GHz antenna frequency).
>>
>>
>>
>>
>> ___
>> 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
>
>
___
USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

Re: [USRP-users] examples using N310 with ext LO

[Marcus D. Leech via USRP-users]

On 04/07/2018 10:39 AM, Rob Kossler wrote:

Hi Marcus,
No, I haven't fooled with LO level adjustments.  I set the LO at about 
3 dBm and did not change it.  The LO freq is indeed 2x (LO at 4884MHz 
with center freq at 2442MHz).  I suspect that my custom software, 
which was developed for first B210 and then X310 with several 
daughterboard variants, may be sending tune commands in a way that is 
not ideal for an external LO configuration.  There was a similar issue 
when I first started using TwinRx with "companion" or "external" LO 
and UHD would issue warnings about tuning one channel first and then 
the other when both channels had to be at the same freq because they 
shared an LO.  So, my request for examples was to help me see if I am 
issuing the tuning requests correctly for this external LO config.


Rob

Understood.

Hopefully, one of the R folks will chime in here.  I don't currently 
have one in my inventory, so running a bit blind.





On Fri, Apr 6, 2018 at 7:32 PM, Marcus D. Leech via USRP-users 
> wrote:


On 04/06/2018 05:14 PM, Rob Kossler via USRP-users wrote:

Hi,
Are there any examples for using the N310 with external LO?  I
have gotten some strange results (strange spectral mirror-ing)
when using as just a 4 channel receiver.  I am using the
"args" argument to set rx_lo_source, but my code is setting
the individual channel frequencies as I do for other USRPs and
I noticed various warnings in the terminal window for each
channel that I tune.

On a separate note, I get some strange results if I set the
clock_source to external in the args (using with OctoClock).
If I leave it internal, no problem. For now, I am leaving it
internal until I can solve the problem above with LO source.

Rob


Rob, just shooting from the hip here, since I haven't "lived" with
an N310 yet...

Have you tried adjusting the LO levels let's say 2dB in either
direction to see if that changes the imaging behavior?  Also,
remember that the external LO input
  on the N310 must be a 2XLO -- at twice the desired Fc, and only
up to 8GHz (giving a 4GHz antenna frequency).




___
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

Re: [USRP-users] examples using N310 with ext LO

[Rob Kossler via USRP-users]

Hi Marcus,
No, I haven't fooled with LO level adjustments.  I set the LO at about 3
dBm and did not change it.  The LO freq is indeed 2x (LO at 4884MHz with
center freq at 2442MHz).  I suspect that my custom software, which was
developed for first B210 and then X310 with several daughterboard variants,
may be sending tune commands in a way that is not ideal for an external LO
configuration.  There was a similar issue when I first started using TwinRx
with "companion" or "external" LO and UHD would issue warnings about tuning
one channel first and then the other when both channels had to be at the
same freq because they shared an LO.  So, my request for examples was to
help me see if I am issuing the tuning requests correctly for this external
LO config.

Rob

On Fri, Apr 6, 2018 at 7:32 PM, Marcus D. Leech via USRP-users <
usrp-users@lists.ettus.com> wrote:

> On 04/06/2018 05:14 PM, Rob Kossler via USRP-users wrote:
>
>> Hi,
>> Are there any examples for using the N310 with external LO?  I have
>> gotten some strange results (strange spectral mirror-ing) when using as
>> just a 4 channel receiver.  I am using the "args" argument to set
>> rx_lo_source, but my code is setting the individual channel frequencies as
>> I do for other USRPs and I noticed various warnings in the terminal window
>> for each channel that I tune.
>>
>> On a separate note, I get some strange results if I set the clock_source
>> to external in the args (using with OctoClock). If I leave it internal, no
>> problem. For now, I am leaving it internal until I can solve the problem
>> above with LO source.
>>
>> Rob
>>
>>
>> Rob, just shooting from the hip here, since I haven't "lived" with an
> N310 yet...
>
> Have you tried adjusting the LO levels let's say 2dB in either direction
> to see if that changes the imaging behavior?  Also, remember that the
> external LO input
>   on the N310 must be a 2XLO -- at twice the desired Fc, and only up to
> 8GHz (giving a 4GHz antenna frequency).
>
>
>
>
> ___
> 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

Re: [USRP-users] examples using N310 with ext LO

[Marcus D. Leech via USRP-users]

On 04/06/2018 05:14 PM, Rob Kossler via USRP-users wrote:

Hi,
Are there any examples for using the N310 with external LO?  I have 
gotten some strange results (strange spectral mirror-ing) when using 
as just a 4 channel receiver.  I am using the "args" argument to set 
rx_lo_source, but my code is setting the individual channel 
frequencies as I do for other USRPs and I noticed various warnings in 
the terminal window for each channel that I tune.


On a separate note, I get some strange results if I set the 
clock_source to external in the args (using with OctoClock). If I 
leave it internal, no problem. For now, I am leaving it internal until 
I can solve the problem above with LO source.


Rob


Rob, just shooting from the hip here, since I haven't "lived" with an 
N310 yet...


Have you tried adjusting the LO levels let's say 2dB in either direction 
to see if that changes the imaging behavior?  Also, remember that the 
external LO input
  on the N310 must be a 2XLO -- at twice the desired Fc, and only up to 
8GHz (giving a 4GHz antenna frequency).





___
USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

[USRP-users] examples using N310 with ext LO

[Rob Kossler via USRP-users]

Hi,
Are there any examples for using the N310 with external LO?  I have gotten
some strange results (strange spectral mirror-ing) when using as just a 4
channel receiver.  I am using the "args" argument to set rx_lo_source, but
my code is setting the individual channel frequencies as I do for other
USRPs and I noticed various warnings in the terminal window for each
channel that I tune.

On a separate note, I get some strange results if I set the clock_source to
external in the args (using with OctoClock).  If I leave it internal, no
problem. For now, I am leaving it internal until I can solve the problem
above with LO source.

Rob
___
USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com