[USRP-users] Transmitting with the N210

Dave NotTelling dmp250net at gmail.com
Sun Mar 13 16:21:36 EDT 2016


Nate,

     The board does power up without the UBX installed.  The power supply
did squeal even without the daughterboard.  I did find that the power
supply had to warm up before it started squealing.  For the first 30
minutes of testing things it didn't make a sound.  Once it had warmed up it
always made noise.  The pitch of the squeal would directly correlate to
changes to the RX and TX parameters.  For instance, increasing the RX
bandwidth from 5 MHz to 25 MHz would cause a noticeable change in the pitch
of the squeal.  Modifying the TX amplitude / gain would also case changes
in pitch.

     While testing the voltage on J102, I could see that the voltage would
dip as low as 5.65 volts while transmitting at full power.  5.88-5.98 Volts
was about the norm when idle just after startup.


     LEDs:
          RXing: C D E F
          TXing: A D E F
          Idle: D E F

     J105: 2.42 - 2.52 Volts
     J104: 3.32 - 3.36 Volts
     J103: 1.16 - 1.24 Volts

     D203 comes on when I plug the board in.  It goes off about two seconds
later, then comes on after another 1-2 seconds, and finally goes off about
3 seconds after that.  It does not appear to come back on at any point
including RX/TXing.



Thank you!

-David

On Sat, Mar 12, 2016 at 8:49 PM, Dave NotTelling <dmp250net at gmail.com>
wrote:

> Nate,
>
>      I'll make sure to try the N210 without the UBX.
>
>      This is the UBX-40 and it is only a week or two old at this point.
>
> Thank you!
>
> -David
>
> On Sat, Mar 12, 2016 at 8:47 PM, Nate Temple <nate.temple at ettus.com>
> wrote:
>
>> Hi David,
>>
>> Ideally, yes you should test the power supply when it is running.
>>
>> Before you test the power supply with an oscilloscope, can you try
>> running the N210 without the UBX in it? When running the N210 by itself,
>> does the power supply continue to squeal? Does the N210 by itself respond
>> normally with uhd_usrp_probe ?
>>
>> Is this a UBX-40? and how old is it?
>>
>> - Nate
>>
>>
>>
>> > On Mar 12, 2016, at 4:39 PM, Dave NotTelling <dmp250net at gmail.com>
>> wrote:
>> >
>> > Nate,
>> >
>> >      Thank you for the speedy reply!!
>> >
>> >      Unfortunately I do not have eyes on the device right now.  Here is
>> what I can answer in the short term:
>> >
>> >       • I have not tested the power supply yet.  I thought about
>> hooking it up to an oscilloscope to see if it was noisy or under/over
>> voltage.  My concern was that I would not be able to get an accurate
>> measurement unless the power supply were loaded down.  That would mean
>> hooking my scope up to a running board.  Under normal circumstances that
>> would be no problem.  Unfortunately I didn't have the probes on hand a the
>> time and thought it wise not to poke random alligator clips into the
>> running device.  Does the measurement need to happen with the N210 running
>> (actively RX/TXing)?
>> >       • I did re-seat the UBX
>> >       • They are nice and tight.  Double checked.
>> >       • RX does appear to be working fine.  The only think I noticed
>> was that if I went from something high like 5 GHz and then tuned to
>> something lower than 500 MHz, then I would see a small signal (~500 KHz
>> across) slowly sweep across the spectrum (~ 25 MSPS).  I could not recreate
>> it after power cycling the N210.
>> >      I have tried this on the maint branch of UHD as well as the master
>> branch.  I think the versions were 3.10 and 3.9.2 respectively.  I cloned
>> fresh copies of the UHD repo for both on Friday.
>> >
>> >      As for your second set of ideas:
>> >
>> >       • The fan definitely does spin
>> >       • I'll have to check the LEDs when I have eyes on it next
>> >       • The Ethernet lights to flash and I am hooked directly into the
>> 1 Gbps LAN connection on my motherboard.  I can verify with bwm-ng that I
>> am getting samples at just under 1 Gbps when RXing 25 MSPS.
>> >       • I'll check those voltages when I have eyes on it next
>> >       • No idea about the D203 light.  I'll have to look
>> >
>> >      I can also say that the RX and TX lights on the UBX do come on
>> when they are supposed to.
>> >
>> >      I am not using the GPSDO.  The power supply I have is what came
>> with the N210.  6 Volts at 3 Amps.
>> >
>> >      Thank you very much for the assistance!!
>> >
>> > -David
>> >
>> > On Sat, Mar 12, 2016 at 7:05 PM, Nate Temple <nate.temple at ettus.com>
>> wrote:
>> > Hi David,
>> >
>> > Just a quick follow up question. Are you using a GPSDO along with the
>> UBX on the N210? If so, it is required to use a 6V/4A power supply.
>> >
>> > - Nate
>> >
>> >
>> > > On Mar 12, 2016, at 6:58 AM, Dave NotTelling via USRP-users <
>> usrp-users at lists.ettus.com> wrote:
>> > >
>> > > I am having issues transmitting with my N210 using the UBX
>> daughterboard.  The signal is so weak that I have to put another radio
>> directly next to it to even see the transmitted signal at all.  The
>> transmit test was done using osmocom_siggen and uhd_siggen_gui.  I tried
>> cranking the gain and amplitude up all the way in both interfaces and it's
>> barely 1-2 dB above the noise floor.  Additionally, the heatsink gets too
>> hot to touch and the power supply emits a high pitch squalling noise when
>> the radio is actually being used.  The power supply itself gets pretty warm
>> too.  Is there something that I am not doing right that could be causing
>> this?  Maybe some argument that I'm not passing in that I should be?
>> > >
>> > > Thank you!
>> > >
>> > > -David
>> > > _______________________________________________
>> > > USRP-users mailing list
>> > > USRP-users at lists.ettus.com
>> > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>> >
>> >
>>
>>
>
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