[USRP-users] synchronizing multiple USRP N310

Jorge Chen superme991 at gmail.com
Fri Feb 22 08:15:19 EST 2019


Hi Marcus

Thanks for your reply.

Since I thought it works in the case using channel 0,4 with default subdev
spec setup(“A:0 A:1 B:0 B:1”), so I ignore setting the subdev spec.
However, I add the subdev spec setting and test again, but still failed to
transmit synchronized signal from 2 N310s.
Any other advices?


To take a note, Q3 yesterday,3. When does the N310 re-initialize the
daughter board?
-> I found that the time is after set_clock_source(ref) and
set_time_source(pps) commands.

All the best!
Jorge


Marcus D. Leech via USRP-users <usrp-users at lists.ettus.com>於 2019年2月22日
週五,上午3:27寫道:

> On 02/21/2019 10:18 AM, Jorge Chen via USRP-users wrote:
>
> Hi USRP Users
>
> I tried to synchronize 2 N310s throught the external PPS and reference
> clock, and tested by the application below.
> *tx_waveforms.exe  --args
> "addr0=192.168.30.3,addr1=192.168.40.3,clock_source=external,time_source=external,master_clock_rate=122.88e6"
> --rate 30.72e6 --freq 3.5e9 --wave-type SINE --wave-freq 10e6 --gain 20
> --channels "0,4"--ref "external" --pps "external"*
> The program runs without errors, but no signal outputs from the
> corresponding channels. ( No sine waveform on the scope, and the LED light
> are dark.)
>
> You have not included a subdev specification, so it's not going to be able
> to intuit what you mean.
>
>
> https://kb.ettus.com/N300/N310_Getting_Started_Guides#Subdevice_Specification_Mapping
>
>
>
>
> I've checked if the external PPS is available by the application
> "test_pps_input.exe".
> And if I only use 1 N310, it works normally.
> But failed in the 2 N310s synchronized case.
>
> The OS is Win10, and I use the UHD 3.13.1.
>
> My questions are:
> 1. Is the commands or the hardware/environment setting causing the failure
> on synchronizing the 2 N310s?
> 2. I found the eeprom_version and the rev information are different, does
> this difference affect?
> And two further questions:
> 3. When does the N310 re-initialize the daughter board? In the log (please
> see the attached file), it executes re-initializing routine 3 times.
> 4. What's the difference between specifying "clock_source=external,
> time_source=external" in the device argument and use the UHD API
> set_time_source("external"),and set_clock_source("external") if I'd like to
> synchronize multiple N310s.
> Are they both necessary?
>
>
> |    /
> |   |       Mboard: ni-n3xx-3151CB0
> |   |   eeprom_version: 1
> |   |   mpm_version: 3.13.1.0-gbbce3e45
> |   |   pid: 16962
> |   |   product: n310
> |   |   rev: 5
> |   |   rpc_connection: remote
> |   |   serial: 3151CB0
> |   |   type: n3xx
> |   |   MPM Version: 1.2
> |   |   FPGA Version: 5.2
> |   |   FPGA git hash: d0360f7.clean
> |   |   RFNoC capable: Yes
> |   |
> |   |   Time sources:  internal, external, gpsdo, sfp0
> |   |   Clock sources: external, internal, gpsdo
> |   |   Sensors: temp, gps_locked, gps_time, gps_sky, gps_tpv, ref_locked,
> fan
> |     _____________________________________________________
> |    /
> |   |       Mboard: ni-n3xx-3175D90
> |   |   eeprom_version: 2
> |   |   mpm_version: 3.13.1.0-gbbce3e45
> |   |   pid: 16962
> |   |   product: n310
> |   |   rev: 6
> |   |   rpc_connection: remote
> |   |   serial: 3175D90
> |   |   type: n3xx
> |   |   MPM Version: 1.2
> |   |   FPGA Version: 5.2
> |   |   FPGA git hash: d0360f7.clean
> |   |   RFNoC capable: Yes
> |   |
> |   |   Time sources:  internal, external, gpsdo, sfp0
> |   |   Clock sources: external, internal, gpsdo
> |   |   Sensors: gps_locked, fan, ref_locked, gps_tpv, gps_sky, gps_time,
> temp
>
>
>
> Any feedback or help are appreciated!
>
> All the best!
> Jorge
>
>
> Florian Kaltenberger via USRP-users <usrp-users at lists.ettus.com> 於
> 2018年12月20日 週四 下午4:48寫道:
>
>> Hi Michael,
>>
>> halleluja! that was it! Thanks for spotting this.
>>
>> Florian.
>> On 20/12/2018 02:34, Michael West wrote:
>>
>> Hi Florian,
>>
>> The device arguments are "clock_source" and "time_source".  I noticed in
>> your command you had them as "clock_src" and "time_src".  That may be the
>> source of the problem.
>>
>> Regards,
>> Michael
>>
>> On Mon, Dec 10, 2018 at 11:33 AM Florian Kaltenberger via USRP-users <
>> usrp-users at lists.ettus.com> wrote:
>>
>>> Dear Nate,
>>>
>>> no it says something like this is not supported with the N310 and I
>>> should pass it using the args options. Sorry, I don't have access to the
>>> N310 right now, so I can't give you the exact message, but I have tried
>>> that.
>>>
>>> Florian.
>>> On 10/12/2018 19:00, Nate Temple wrote:
>>>
>>> Hi Florian,
>>>
>>> If you pass the arg  "--ref external" to tx_waveforms, does it resolve
>>> this frequency offset?
>>>
>>>
>>> https://github.com/EttusResearch/uhd/blob/master/host/examples/tx_waveforms.cpp#L62
>>>
>>> Regards,
>>> Nate Temple
>>>
>>> On Thu, Dec 6, 2018 at 12:22 AM Florian Kaltenberger via USRP-users <
>>> usrp-users at lists.ettus.com> wrote:
>>>
>>>> Hi Marcus,
>>>>
>>>> I have measured this with a spectrum analyzer simply by setting markers
>>>> to the peak of the sinusoid (one marker per measured USRP) and then taking
>>>> the delta.
>>>>
>>>> Could it be that the USRP is ignoring the external reference when used
>>>> alone? Remember, I am doing the test with one USRP at a time, as the test
>>>> using multiple USRP simultaneously does not work.
>>>>
>>>> Florian.
>>>> On 06/12/2018 00:29, Marcus Müller wrote:
>>>>
>>>> oh! That means 341 ppb frequency error, which *really* shouldn't be
>>>> happening.
>>>>
>>>> I'd like to get some statistics of that error, how are you measuring
>>>> it?
>>>>
>>>> Best regards,
>>>> Marcus
>>>>
>>>> On Wed, 2018-12-05 at 12:55 +0100, Florian Kaltenberger wrote:
>>>>
>>>> Sorry typo. I did use a frequency of 3.51GHz.
>>>>
>>>>
>>>> On 5 Dec 2018, at 12:54, Marcus Müller <marcus.mueller at ettus.com> <marcus.mueller at ettus.com>
>>>> wrote:
>>>>
>>>> Hi Florian,
>>>>
>>>> trying to get my head to understand the order of problems here:
>>>> Could you try to use a higher frequency (say, --freq 2e9 instead of
>>>> 3.5e6)?
>>>> I'd thing 3.51 MHz is out of range for the N310, anyway?
>>>>
>>>> Best regards,
>>>> Marcus
>>>>
>>>> On Wed, 2018-12-05 at 11:49 +0100, Florian Kaltenberger via USRP-
>>>> users
>>>> wrote:
>>>>
>>>> So I can confirm that there is a frequency offset between the two
>>>> USRP N310s when using only an octoclock (10MHz + PPS) to
>>>> synchronize.
>>>> I have measured with the tx_waveforms program
>>>> ./tx_waveforms --args
>>>> "addr=192.168.x.2,time_src=external,clock_src=external,master_clo
>>>> ck_r
>>>> ate=122.88e6" --rate 122.88e6 --freq 3.51e6 --wave-type SINE --
>>>> wave-
>>>> freq 10e6 --gain 100
>>>> on the first USRP N310 (x=10) and then on the other (x=20). There
>>>> is
>>>> an offset of 1200Hz between the peaks of the sinusoids between
>>>> the
>>>> two measurements.
>>>> Using an external LO didn't change anything either. Unless I need
>>>> to
>>>> provide any other arguments in that case?
>>>> I also tried to do a test where I use both USRPs simultaneously
>>>> ./tx_waveforms --args
>>>> "addr0=192.168.10.2,addr1=192.168.20.2,time_src=external,clock_sr
>>>> c=ex
>>>> ternal,master_clock_rate=122.88e6" --rate 122.88e6 --freq 3.51e6
>>>> --
>>>> wave-type SINE --wave-freq 10e6 --gain 100--channels "0,4"
>>>> but unfortunately that does not work at all at my testbench
>>>> (program
>>>> hangs and no signal transmitted).
>>>> My UHD version is 3.13.0.2 (UHD_3.13.0.HEAD-0-g0ddc19e5)
>>>> Any help appreciated.
>>>> Thanks!
>>>> Florian.
>>>>
>>>>
>>>> On 04/12/2018 21:29, Florian Kaltenberger via USRP-users wrote:
>>>> Hi Marcus and Robin,
>>>> thanks for your answers, this is helpful information. I should
>>>> add,
>>>> that I actually tried the synchronization with an octoclock
>>>> (10MHz
>>>> + PPS), but it did not give me the expected results, i.e., I
>>>> saw
>>>> some residual frequency offsets. But maybe I screwed up at some
>>>> point. Let me do some more measurements and get back to you on
>>>> this.
>>>> Florian.
>>>>
>>>>
>>>> On 04/12/2018 18:57, Marcus D. Leech via USRP-users wrote:
>>>> On 12/04/2018 10:14 AM, Florian Kaltenberger via USRP-users
>>>> wrote:
>>>>
>>>> Hi there,
>>>> I just discovered that in addition to the external 10MHz
>>>> reference in, the USRP N310 also has external local
>>>> oscilator
>>>> inputs, one for each daughterboard and each TX/RX. So does
>>>> that
>>>> mean that in order to synchronize multiple N310 in
>>>> frequency,
>>>> phase, and time, it is no longer sufficient to use an
>>>> octoclock
>>>> to provide a 10MHz reference and PPS? If so, at what
>>>> frequency
>>>> do you have to drive the external LOs and at what power?
>>>> Florian.
>>>>
>>>>
>>>> In addition to what Robin posted, I'll observe that the
>>>> external
>>>> LO port is an *additional feature* of this device.
>>>>
>>>> You should still be able to use the external 10MHz and 1PPS
>>>> ports
>>>> the same way you would with a B210 or E310, since the AD9371
>>>>  front-end chip is similar to the AD9361 chip used in the
>>>> B210
>>>> and E310.
>>>>
>>>> The thing about synchronizing multiple independent PLL
>>>> synthesizers, though, compared to a strictly-shared-LO, is
>>>> that
>>>> the former will
>>>>  experience both phase ambiguities, and have a higher mutual
>>>> phase-noise than the latter, which is why you might decide to
>>>> choose
>>>>  the latter.
>>>>
>>>>
>>>>
>>>>
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|    陳建旻                    (^_^)     |
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